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Adsorption of Rhodamine 6G from aqueous solutions on activated carbon
Abstract
The effects of particle size (0.5-1.0 mm), temperature (30-60 degrees C), and solution pH (7-9) on the adsorption equilibrium of dye Rhodamine 6G by activated carbon were studied in batch modes. The isotherm data could be well described by the Langmuir equation. Under the ranges tested, a maximum adsorption capacity of 44.7 mg/g was obtained. Batch kinetic parameters such as the Lagergren's rate constant and intraparticle diffusion coefficient of adsorption were determined. It has been shown that the intraparticle diffusion of dye molecules within the adsorbents was identified as the rate-limiting step in the present adsorption process.
... The effect of concentration on the % U of rhodamine 6G and acid orange 10 dyes (A) in addition to the removal capacity of the EK600 and EK800 adsorbents (B). Additionally, the removal capacity of the EK600 and EK800 synthesized nanocomposites towards rhodamine 5G and acid orange 10 dyes was superior to that of many other adsorbents, as shown in Table 6 [49][50][51][52][53][54][55][56]. ...
It is essential to remove rhodamine 6G and acid orange 10 dyes from contaminated water because they can induce cancer and irritate the lungs, skin, mucous, membranes, and eyes. Hence, in the current work, the Pechini sol–gel method was used for the facile synthesis of ZrO2/CdMn2O4/CdO as novel nanocomposites at 600 and 800 °C. The synthesized nanocomposites were used as novel adsorbents for the efficient removal of rhodamine 6G and acid orange 10 dyes from aqueous media. The nanocomposites, which were synthesized at 600 and 800 °C, were abbreviated as EK600 and EK800, respectively. The synthesized nanocomposites were characterized by EDS, XRD, N2 adsorption/desorption analyzer, and FE-SEM. The patterns of XRD showed that the average crystal size of the EK600 and EK800 nanocomposites is 68.25 and 85.32 nm, respectively. Additionally, the images of FE-SEM showed that the surface of the EK600 nanocomposite consists of spherical, polyhedral, and rod shapes with an average grain size of 99.36 nm. Additionally, the surface of the EK800 nanocomposite consists of polyhedral and spherical shapes with an average grain size of 143.23 nm. In addition, the BET surface area of the EK600 and EK800 nanocomposites is 46.33 and 38.49 m2/g, respectively. The optimal conditions to achieve the highest removal of rhodamine 6G and acid orange 10 dyes are pH = 8, contact time = 24 min, and temperature = 298 kelvin. The greatest removal capacity of the EK600 and EK800 adsorbents towards rhodamine 6G dye is 311.53 and 250.63 mg/g, respectively. Additionally, the greatest removal capacity of the EK600 and EK800 adsorbents towards acid orange 10 dye is 335.57 and 270.27 mg/g, respectively. The removal of rhodamine 6G and acid orange 10 dyes using the EK600 and EK800 adsorbents is spontaneous, exothermic, follows the Langmuir adsorption isotherm, and fits well with the pseudo-first-order kinetic model.
... There are several adsorbent materials such as activated carbon, polymers, zeolites, etc., which have been widely studied [27,28]. Some of the adsorbents used to remove R6G from aqueous solution include coffee ground powder [2], sodium alginate-bentonite [29], clay mineral [30], zeolite ZSM-22 [31], activated carbon [32], among others. In this regard, recent studies have reported that adsorbents materials from mineral origin such as clays and natural zeolites are very advantageous because of their excellent adsorption properties in addition to their worldwide abundancy and consequently low cost [33]. ...
In this work, we studied the adsorption of Rhodamine 6G (R6G) using a simple removal system consisting of raw natural zeolite, clinoptilolite (CLI) packed within a cellulose membrane. The structural properties of CLI were characterized by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX) and revealed that the natural zeolite consisted of a crystalline phase of calcium clinoptilolite (CLI) from the monoclinic system with Si/Al ratio of ~4.33. Besides, textural characterization obtained with Brunauer–Emmett–Teller (BET) showed a relatively large specific surface area of 17.4 m2/g and the Barrett–Joyner–Halenda (BJH) described the pore size distribution of CLI. The adsorption studies were carried out by immersing the CLI-membrane system into R6G solutions with various concentrations (C0 = 32, 47, 94, 168 mg/L), at 25 °C. The cellulose membrane facilitated the mobility of R6G molecules by enhancing their removal from the solution and allowed the easy recovery of the contaminated zeolite after the experiment. The adsorption equilibrium was suitably represented by nonlinear Liu model with an adsorption capacity of 8.7 mg R6G/g CLI. The nonlinear kinetics were described by Mixed-order and Elovich at low and high R6G concentrations, respectively. In addition, diffusional nonlinear models confirm the participation of various diffusional mechanisms during the adsorption of R6G. Our approach showed its potential for the adsorption of R6G and can be further applied in the treatment of wastewater contaminated with dyes, pesticides, ions, and dangerous molecules generated either by the industry or at the laboratory level.
... The same tendency has been obtained in some previous studies. [56][57][58][59][60][61][62] To better understand the effect of contact time onto the Pb(II) adsorption process, the rst-order second Pseudo (eqn (3)) and second-order Pseudo models (eqn (4)) were used to t data: ...
We herein present a simple, fast, efficient and environmentally friendly technique to prepare graphene oxide (GO) from graphite rods of recycled batteries by using solution plasma exfoliated techniques at atmospheric pressure. The prepared GO with an average 3 nm-thickness and 1.5 μm-length, having large surface area and high porosity, has been used to remove Pb(II) ions from the water. The obtained results indicated that the adsorption of Pb(II) onto GO depends on pH, contact time, temperature and initial concentration of Pb(II). The maximum adsorption capacity of Pb(II) onto GO determined from the Langmuir model (with a high R² value of 0.9913) was 180.1 mg g⁻¹ at room temperature. A removal efficiency of ∼96.6% was obtained after 40 min. Calculations of thermodynamic parameters (ΔG°, ΔH° và ΔS°) show the adsorption of Pb(II) ions on the GO surface is spontaneous and intrinsically heat-absorbing. The potential mechanism can be suggested here to be the interaction of the π–π* bonding electrons and Pb(II) as well as the electrostatic attraction between Pb(II) and the oxygen-containing functional groups on GO.
... Among the different strategies such as electrochemical separation, adsorption, coagulation, and membrane filtration, adsorption has been attractive and favorable due to the cost-effective mechanism. Several adsorbents used to remove R 6G from aqueous solution include activated carbon [6], shells of palm [7], and almond [8], graphene derived materials [9], metaleorganic frameworks [10], clay minerals [11], magnetic silica nanoparticles [12], but no signs of mesoporous materials/zeolites derived from the CFA. ...
Zeolite Rhodamine 6G ZSM-22 Adsorption a b s t r a c t The present study reveals the potential of coal fly ash (CFA) as the environmental pollutant adsorbent. The conventional approach of alkali fusion followed by hydrothermal treatment of Taiwan based coal fly ash resulted in new and novel zeolite material ZSM-22. The composition, morphology, chemical structure, and the surface properties of as-prepared zeolite were investigated using BET, SEM, FT-IR, XRD, and XRF. The specific surface area (S SA) of the zeolite is enhanced from 1.28 m 2 /g to 30.21 m 2 /g with a drop in Si/Al ratio of 3.1 to 2.4 suggesting the improvement of crystallinity. Further, the application of zeolite on the adsorption of the cationic dye Rhodamine 6G (R 6G) from aqueous solution in a batch process was investigated. Besides, the effect of parameters such as the effect of time, temperature, pH, dosage, agitation speed, kinetics, and isotherms on the removal of dyes was studied. The results indicate that adsorption of dye is more significant at pH ¼ 6 indicating the zeolite surface is positively charged. The proficient sorption efficacy of R 6G onto ZSM-22 followed pseudo-second-order kinetic model and fits well with the Langmuir adsorption isotherm with maximum specific removal of 195.3 mg/g. Moreover, the possible adsorption mechanism for the selective separation of dye using CFA is mainly due to the electrostatic interactions and the hydrogen bonding. Finally, the key takeaways of the present research are that zeolite ZSM-22 is a prospective candidate as an adsorbent for the separation of dye molecules. j o u r n a l o f m a t e r i a l s r e s e a r c h a n d t e c h n o l o g y 2 0 2 0 ; 9 (6) : 1 5 3 8 1 e1 5 3 9 3
... In general, reactive dyes are most problematic among the other dyes [5] . Dyes are used in various industries such as textile, leather, paint, paper, food and cosmetics etc [6] . At present, more than 10,000 dyes with an estimated annual production of 7×10 5 metric tons are commercially available worldwide [7] . ...
... In general, reactive dyes are most problematic among the other dyes [5] . Dyes are used in various industries such as textile, leather, paint, paper, food and cosmetics etc [6] . At present, more than 10,000 dyes with an estimated annual production of 7×10 5 metric tons are commercially available worldwide [7] . ...
The mesoporous materials have variety of applications in several field particularly it has a main role in Catalysis, Petrochemical industries and Adsorption. Normally the porous material has well ordered 3Dimensional structure, huge surface area, high thermal stability and active acid sites. The properties of these materials can be varied because it is mostly depends on its template, synthesis method and isomorphous substitution of metal ions. There are two major mesoporous materials which are aluminosilicate and aluminophosphate. In this present investigation AlCl 3 and FeCl 3 are used in equal amount for the synthesis of mesoporous material. The synthesized material is characterized by FT-IR, XRD, TGA, BET, EDAX and TPD. Morphological images were studied by SEM. These characterization techniques confirm the formation of mesoporous molecular sieves.
... The rhodamine 6G (Fig. S1b) was purchased from Sigma-Aldrich Corp., USA. The removal of rhodamine 6G from water was carried out in accordance with the procedure from the literature [30,31]. ...
Self-activation was employed for the manufacturing of activated carbon (AC) using kenaf core fibers, which is more environmentally friendly and cost-effective than the conventional physical/chemical activations. It makes the use of the gases emitted from the thermal treatment to activate the converted carbon itself. The mechanism was illustrated by the Fourier transform infrared spectroscopy and mass spectrometry analysis of the emitted gases, showing that CO2 served as an activating agent. The AC from self-activation presented high performance, for instance, the Brunauer-Emmett-Teller surface area was up to 2296 m2 g-1, Using the Density Functional Theory (DFT), the pore volume (PV) was determined to be 1.876 cm3 g-1. Linear relations of PVDFT-micropore/iodine number, and PVDFT-mesopore/tannin value were established, indicating a strong relationship between the pore structure of AC and its adsorbing preference. Adsorption results for copper (II) and rhodamine 6G also indicated that the pore size of AC should be designed based on the molecular size of the contaminants.
... A comparison of the maximum monolayer adsorption capacity (q max ) of rhodamine 6G with various adsorbents reported in literature is shown in Table 3 (Annadurai, Juang, and Lee 2001;Annadurai et al. 2003;Maheria and Chudasam 2007;Sadhasivam, Savitha, and Swaminathan 2007;Sreelatha and Padmaja 2008;Senturk, Ozdes, and Duran 2010;Chang et al. 2011;Shen and Gondal 2013;Ren et al. 2014;Vanamudan, Bandwala, and Pamidimukkala 2014;Vanamudan and Pamidimukkala 2015). Although the polybutadiene rubber-bentonite hybrid composite's adsorption capacity for rhodamine 6G is low compared to some adsorbents shown in Table 3, it is much higher than that of other adsorbents in the same table, such as trichoderma harzianum mycelial waste, biological sludge, exhausted coffee ground, palm shell powder, and graphene oxide. ...
Here is reported the adsorption of rhodamine 6G from aqueous solution using a phosphorus-containing polybutadiene rubber-bentonite hybrid composite. The polybutadiene rubber-bentonite hybrid composite was synthesized via oxidative chlorophosphorylation of polybutadiene rubber and bentonite with subsequent hydrolysis. The static exchange capacity of the polybutadiene rubber-bentonite hybrid composite and the concentration of phosphorus were evaluated. The functional groups present in the polybutadiene rubber-bentonite hybrid composite were characterized by infrared spectroscopy. The adsorption of rhodamine 6G on the polybutadiene rubber-bentonite hybrid composite was investigated on the bases of the initial rhodamine 6G concentration, contact time, and temperature. The equilibrium isotherm was analyzed using Langmuir, Freundlich and Dubinin-Radushkevich models. The adsorption equilibrium measurements of rhodamine 6G in solution correlated well with the Langmuir isotherm equation. This model revealed that the maximum monolayer adsorption capacity of polybutadiene rubber-bentonite hybrid composite was 32.2 mg g−1. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were employed to characterize the adsorption kinetics of rhodamine 6G. The dynamic data fitted well with the pseudo-second-order kinetic model. The Gibbs free energy, enthalpy, and entropy changes indicated that the rhodamine 6G adsorption on polybutadiene rubber-bentonite hybrid composite was spontaneous and endothermic. The results were compared with corresponding data in the literature. This study demonstrates that the polybutadiene rubber-bentonite hybrid composite is an effective adsorbent for rhodamine 6G.
... Methyl orange (MO) is one of the most frequently used acidic and anionic dyes in the textile, printing, paper, and food industries and in many research laboratories. The removal of dyes from water is difficult because most are stable to light and oxidation [3]. Methods such as ion exchange, precipitation, ultrafiltration, reverse osmosis, and electrodialysis are typically used [4]. ...
In this study, a 23 full factorial design, rather than a conventional method, was used for determining the optimum working parameters and choosing the best adsorbent for removal of methyl orange (MO) from aqueous solution. Regenerated multiwall carbon nanotubes (reg-MWCNT), which had been used in previous studies, and granular-activated carbon (GAC) were selected as adsorbents for this application. The experimental design determined the effect of three factors (temperature, pH, and initial dye concentration) and the interactions between them. The extent of removal of MO by reg-MWCNT was higher than by GAC. All experimental factors were examined and their interactions were found to be significant for percentage removal of MO, with pH being the most significant. Using only eight experiments, the highest percentages of MO removal on reg-MWCNT and GAC were 98.51 and 84.66%, respectively, achieved when the pH of the dye solution was 2 at 25°C and with 20 mg/L initial dye concentration.
... Scardina and Edwards (2001) Methylene Blue, showed a higher adsorption tendency towards activated carbon over anionic dyes represented by an ate-type reactive compound. Activated carbon was also used by Annadurai and Juang (2001) to remove dyes such as Rhodamine 6G from aqueous solutions. Under the ranges tested, a maximum adsorption capacity of 44.7 mg/g was obtained. ...
In this chapter, the physicochemical processes used in the treatment of aqueous streams such as domestic and industrial wastewaters, drinking water, contaminated groundwater, and aqueous residuals from soil treatment are reviewed. Processes that have their own chapter in the WEF review are not included in this chapter.
... The apparent free energy, E, values (14.74-20.41 kJ/mol) were comparable to that of chemisorption that amounted to 40 kJ/mol [26]. The three-parameter isotherm model, Langmuir-Freundlich, was applied to represent dye adsorption data under surface heterogeneity conditions that revealed from both the Freundlich and D-R isotherm models. ...
A simple and effective technique for reduction of graphene oxide at low temperature (70 °C) using acetone was reported for the first time. Magnetically recoverable acetone reduced graphene oxide (ARGO)/Fe3O4 composite was synthesized by uniformly decorating Fe3O4 on ARGO. The synthesized ARGO/Fe3O4 composite was characterized by the powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform-infrared spectroscopy and thermogravimetric analysis. An organic dye rhodamine 6G was used as an adsorbate for investigating the adsorption characteristics of the composite. The adsorption kinetic data were best described by the pseudo-second-order model, and equilibrium was achieved within 2 h. Dye adsorption was favored in basic conditions (pH 9–11) and governed by intraparticle diffusion process. The maximum dye adsorption on the composite was 93.37 mg/g at 293 K, and it followed the Langmuir–Freundlich model. The calculated thermodynamic parameters (ΔG°, ΔH° and ΔS°) showed that the dye adsorption onto composite was feasible, spontaneous and exothermic. The ARGO/Fe3O4 composite was easily controlled in magnetic field for desired separation, leading to an easy removal of the dye from wastewater, which holds great potential for dye decontamination.
... Adsorption is one of the most promising physical means for industrial remediation applications, in particular for water purification . Extensive literature has been reported regarding dye removal from aqueous solutions by using a myriad of adsorbents derived from clay minerals (Khan et al., 2004), activated carbon (Annadurai et al., 2001; Pelekani and Snoeyink, 2000; Ramuthai et al., 2009), coal (Mohan et al., 2002b), wood (Garg et al., 2003), carbon xerogels (Figueiredo et al., 2011), fly ash (Lin et al., 2008; Mohan et al., 2002a; Shaobin et al., 2005), and bio-materials (Debrassi and Rodrigues, 2011; Hii et al., 2009). However, owing to the lack of effective adsorbateeadsorbent interactions, which can be ascribed either to the relatively limited surface area or clogged " dead volume " in the pores of adsorbents, a number of the above mentioned materials are found to be sluggish for the adsorption of dyes. ...
... In the relationship between the residual concentration of acid orange 7 and the square root of elapsed time, a good linearity was recognized. Annadurai et al. 16) reported that the relationship between the amount of Rhodamine 6G adsorbed onto activated carbon and the square root of elapsed time demonstrated a linear characteristic, therefore, the adsorption process is controlled by the intraparticle diffusion. The adsorption rate of acid orange 7 onto charcoal from coffee grounds could be controlled by intraparticle diffusion. ...
From the viewpoints of decreasing environmental burdens and recycling of materials, the adsorption ability of charcoal from coffee grounds for acidic dye (acid orange 7) removal was investigated by the batch method. Differences in the removal ratio and removal rate of acid orange 7 could be explained by differences in the properties of charcoal such as specific surface area and pore volume. In the relationship between the amount of acid orange 7 adsorbed at each elapsed time and the square root of elapsed time, a good linearity was recognized. Since the good linearity between the acid orange 7 adsorption and the square root of elapsed time was recognized, the intraparticle diffusion of acid orange 7 onto pores of adsorbents was identified as the rate-limiting step in the adsorption process.
... The q of our material (GSC) is 75.4 mg/g in terms of carbon content. The q of AC for R6G reported in batch experiments is 44.7 mg/g [35] which is much lower than that observed for GSC. For CP, GSC exhibited a q of 52.6 mg/g of carbon under identical conditions (supplementary data Fig. ...
An in situ strategy for the preparation of graphene immobilized on sand using asphalt, a cheap carbon precursor is presented. The as-synthesized material was characterized in detail using various spectroscopic and microscopic techniques. The presence of G and D bands at 1578cm(-1) and 1345cm(-1) in Raman spectroscopy and the 2D sheet-like structure with wrinkles in transmission electron microscopy confirmed the formation of graphenic materials. In view of the potential applicability of supported graphenic materials in environmental application, the as-synthesized material was tested for purifying water. Removal of a dye (rhodamine-6G) and a pesticide (chlorpyrifos), two of the important types of pollutants of concern in water, were investigated in this study. Adsorption studies were conducted in batch mode as a function of time, particle size, and adsorbent dose. The continuous mode experiments were conducted in multiple cycles and they confirmed that the material can be used for water purification applications. The adsorption efficacy of the present adsorbent system was compared to other reported similar adsorbent systems and the results illustrated that the present materials are superior. The adsorbents were analyzed for post treatment and their reusability was evaluated.
... The removal of Rhodamine 6G, a common organic dye, from water was performed using a procedure adopted from the literature (Annadurai et al. 2001). In brief, 10 mg of the individual solid adsorbents (Norit CA1, C-800, and FeNP@C-800) were added into three vials each containing 10 mL 400 lM Rhodamine 6G aqueous solution. ...
Iron-based nanoparticles supported on carbon (FeNPs@C) have enormous potential for environmental applications. Reported is a biomass-based method for FeNP@C synthesis that involves pyrolysis of bleached wood fiber pre-mixed with Fe3O4 nanoparticles. This method allows synthesis of iron-based nanoparticles with tunable chemical reactivity by changing the pyrolysis temperature. The FeNP@C synthesized at a pyrolysis temperature of 500 degrees C (FeNP@C-500) reacts violently (pyrophoric) when exposed to air, while FeNP@C prepared at 800 degrees C (FeNP@C-800) remains stable in ambient condition for at least 3 months. The FeNPs in FeNP@C-800 are mostly below 50 nm in diameter and are surrounded by carbon. The immediate carbon layer (within 5-15 nm radius) on the FeNPs is graphitized. Proof-of-concept environmental applications of FeNPs@C-800 were demonstrated by Rhodamine 6G and arsenate (V) removal from water. This biomass-based method provides an effective way for iron-based nanoparticle fabrication and biomass utilization.
... The maximum adsorption of Rhodamine 6G on microwave treated sludge adsorbent is an order below that for commercial activated carbon (Annadurai et al., 2001). However, the reuse of waste activated sludge is appealing in terms of resource utilization. ...
The capacity of adsorbent recycled from microwave thermal treatment to remove a synthetic dye, Rhodamine 6G, from a water bath, was examined. The acidified, dewatered sludge was microwave heated for 1–4 min. Batch adsorption tests were conducted on this sludge at various pH values and solution temperatures. Equilibrium of dye adsorption was obtained in 30 h. Three kinetic models—pseudo first-order, pseudo second-order and intra-particle diffusion—were applied to elucidate the adsorption kinetic data. Experimental results indicate that higher adsorption efficiency could be derived at higher pHytemperature levels. Moreover, the sample treated for 1 min by microwaves adsorbed more dye than did the sample so treated for 4 min. Sludge samples were also characterized to interpret the experimental findings. Energy cost analysis demonstrated the feasibility of the present microwave process.
In this work, we investigated the potential of pristine biochar (obtained from poultry manure by pyrolysis at 725°C in a laboratory pyrolysis reactor under N 2 environment) as an efficient adsorbent for removing tetracycline (TC) and rhodamine 6G (R6G) from aqueous solutions. Microscopic and spectroscopic analyses demonstrated a developed surface of the investigated biochar free from toxic organic compounds that could form within the annealing. The removal of TC and R6G was analyzed with UV-vis spectrometry in the function of the pH, ionic strength, and adsorbent dosage. The maximal adsorption capacity for TC and R6G is 65 and 63 mg g-1 , respectively, indicating that pristine biochar from poultry manure has an excellent adsorption ability for both compounds demonstrating its high potential for removing various compounds of this type from water media. The enhanced adsorption on the investigated biochar is mainly controlled by the strong π-π and n-π interactions between the surface of the biochar and the two contaminants. The investigated poultry manure derived biochar can be a promising "green", sustainable and carbon-rich material for low-cost and facile environmental applications, including the removal of contaminants from municipal wastewater.
With the growing concern about water quality requirements and the looming energy crisis, researchers all over the world have committed to the development of novel single low-cost porous materials for a variety of applications (ex: environmental and energy applications). Treatment of dye contaminants before they are released into the environment is considered as a significant challenge in the field of water treatment. Treatment of such dye contaminants remains as challenging task and evolved as the most persistent issues in the environmental remediation field. To address all these specific limitations present investigation involves the conversion of inexpensive Cilantro plants (C. sativum) into Activated Carbon (AC) which can be utilized as a fascinating alternative potential low-cost AC material for the treatment of toxic dye contaminants (environmental) and supercapacitor (energy) applications with improved performances. The fundamental physical–chemical properties of AC were confirmed by using various analytical and spectroscopic techniques. It is substantial to mention, obtained AC possesses a microporous structure and a large specific surface area of 2200 m²g⁻¹. Further, AC was employed for the adsorption of methyl orange (MO) and rhodamine-6G (Rh-6G) dyes from aqueous solutions. The rapid adsorption process occurred within the contact time of 14 and 20 min for MO and Rh-6G. In addition, demonstrated with > 99 % removal efficiencies and an outstanding maximum adsorption capacity of 467.29 mg/g for MO and 143.47 mg/g for Rh-6G was witnessed surpassing the commercially available activated carbon material (CAC). To prove the efficacy of AC, the real-time application was evaluated by taking an industrial wastewater sample which showed 99.45 % of removal efficiency. Furthermore, a cartridge was developed and utilized for the treatment of dye solution for an on-field demonstration to assess potable water. Moreover, the synthesised AC witnessed a removal efficiency of > 80 % even up to the 4th cycle. Most importantly, to mark the waste management process the regenerated AC adsorbent and desorbed pollutants are treated effectively and can be utilized for further applications. Interestingly, the AC material obtained at 700 °C displayed optimum specific surface area (SSA), surface functionalities which help electrode wetting, surface redox reaction and pseudo-capacitance from ion diffusion and showed specific capacitance of 162.4F/g at 1 A/g (three electrode system). Notably, the AC symmetric supercapacitor provides a high-power density of 243.94 W/kg and could be reversibly cycled with very minimal capacitance loss over 5000 cycles at 10 A/g.
The present study aimed to evaluate the potential of mesoporous silica MCM-41 and Al-MCM-41 (molar ratio Si/Al = 20) for the removal of Rhodamine 6G (Rh6G) from aqueous solution. The adsorbents were characterised by XRD, FTIR, SEM-EDX, BET, and UV-Raman. Obtained results related to XRD analysis indicated that the MCM-41 structure remained intact after the incorporation of Al species. Kinetic adsorption study showed that the higher removal (88.75 %, 26.62 mg g−1) of Rh6G dye was achieved by Al-MCM-41 at 60 min. FTIR analysis showed that hydrogen bonding played the dominant role in the Rh6G removal mechanism, while the pH results showed that electrostatic interaction was also a key factor. This study shows that the prepared mesoporous materials are inexpensive and efficient adsorbents for the removal of cationic dyes
The Rhodamine 6G (Rh6G), a cationic dye is actively being used as a potentially tracing dye in the field of biotechnology for immunological studies. The peel powder of Litchi Chinensis was employed in native condition to explore the sorption properties at different experimental conditions like initial dye concentration, contact time, dosage of biosorbent, temperature and pH. The detailed characteristics of Litchi chinensis peel before and after adsorption were performed by using sophisticated instruments like SEM-EDX, FTIR, BET and XRD. From the adsorption studies it was observed that the equilibrium data followed Pseudo-second order rate kinetics and Freundlich isotherm. The Langmuir adsorption capacity (Qo) was found to be 6.66 mg/g, and the adsorption process was spontaneous and exothermic in nature (based on ΔG, ΔH and ΔS values). All the laboratory experiments proven to be an evident for the Litchi chinensis peel as an efficient biosorbent for the removal of Rhodamine 6G in the liquid/solid phase system.
In this work, mesoporous silica nanoparticles (MSN) hybridized with an organosilane are grafted with hyper-crosslinked poly(vinylbenzyl chloride) (PVBC), which is anchored into the mesopores and onto the external surface of MSN. The obtained nanoparticles are characterized by a MSN-templated hierarchical porosity composed of micropores, mesopores and macropores originated from the hyper-crosslinking of the PVBC phase, with a microporous fraction reaching up to 28% of the total pore volume. Tested for the adsorption of a model dye (Rhodamine 6G, Rh6G), these nanoparticles result much more efficient in Rh6G adsorption with respect to plain MSN, showing a Rh6G uptake of about 125 mg/g in highly concentrated solutions (1000 mg/L) and quite complete removal (about 98%) of the dye in more diluted conditions (30 mg/L) with comparable efficiency in repeated adsorption cycles. Overall results demonstrate the key role of the hierarchical porosity of the hyper-crosslinked PVBC-grafted MSN to tailor their adsorption properties.
Recently, organic dyes are highly found in wastewater because of the plastic, painting, cosmetics, paper, leather, and food industries. They are dangerous and can affect the environment in addition to the human beings. Many methods were studied in order to get rid of them. Among all the techniques, adsorption was determined to be a successful, economic, ecofriendly, and efficient one. Zinc oxide nanoparticles were complexed with curcumin in order to generate zinc curcumin oxide nanoparticles that will be used as adsorbent. The efficiency of zinc curcumin oxide nanoparticles as adsorbent was investigated for different organic dyes such as congo red (CR), methyl orange (MO), methylene blue (MB), rhodamine 6G (Rh6G), and rhodamine B (RhB). The effect of pH was investigated in this study for the diverse anionic and cationic dyes. The highest adsorption capacities qe of the dyes were determined for CR, MO, MB, Rh6G, and RhB to be 94.54, 44.38, 34.71, 38.184, and 28.34 mg/g respectively. Only congo red had the highest adsorption capacity at an acidic pH while the other dyes had the highest adsorption capacity at a basic pH. In addition, all the adsorption processes that were studied followed a pseudo-second order kinetic model.
The hydroxyapatite (HAp) was conjugated on carboxylated graphene nanoplatelets (Gra-C to GHAp) or multi-wall carbon nanotubes (CNT-C to CHAp) by its in-situ synthesis using the wet-chemical precipitation method, to increase their surface areas and, thus, negatively-charged active sites for adsorption of cationic pollutants as dyes from a water solution. Various characterization techniques have been utilised for the analysis of crystallinity, bulk and surface chemistry, as well as the morphological structure of synthesized nanocomposites, while Rhodamine 6G was used in adsorption experiments as target pollutant to study. The results show much higher adsorp-tion capacity (90 mg g-1) for GHAp, compared to CHAp (59 mg g-1) or their original counterparts (6.5 mg g-1 for HAp, 25 mg g-1 for Gra-C, 20 mg g-1 CNT-C), be related to quantitatively higher electrostatic attraction of dye molecules with the surface located carboxylic and phosphorus groups from Gra-C and equally distributed HAp particles, respectively, resulting to a monolayer adsorption capacity and heterogeneous sorption. Pseudo-second-order kinetic and Freundlich isotherm model are revealed to be the best described their adsorption behavior. The reusability of nanocomposites was also confirmed by up to 77% of adsorption efficiency after three repeated desorption and regen-eration cycles, indicating them as a promising adsorbent for dyes removal from wastewater.
The organization of organic species on the ordered structures of clays and clay minerals is one way to produce inorganic-organic hybrids with controlled microstructures and properties. The reactions of the adsorbed species and their arrangement on the clay surfaces can be guided by the choice of clay and of adsorbed species. The purpose of the present study was to intercalate alkylammonium ions into a Thai bentonite and to study the effect on dye-adsorption efficiency. A series of alkylammonium ions, CnH2n+1NH3+ (n = 8, 10, 12, or 18), was incorporated into the interlayer spaces of a natural bentonite by mixing an aqueous dispersion of bentonite with an aqueous solution of protonated alkylamines at room temperature. The basal spacings of the intercalation compounds varied depending on the alkyl chain lengths and the amount of alkylammonium ions. The alkylammonium ions adsorbed formed lateral monolayer, bilayer, pseudo-trimolecular layer, paraffin-type monolayer, and/or paraffin-type bilayer structures. The adsorption efficiency of alkylammonium-bentonites was determined using batch adsorption experiments of rhodamine 6G from a water-ethanol solution; the greatest efficiency was 87% while that of the bare bentonite was 47%. The loading amount and the arrangement of the intercalated alkylammonium ions in the interlayer spaces, as well as the specific surface area and pore volume, played important roles in the adsorption efficiency of alkylammonium-bentonite. The adsorption equilibrium data for rhodamine 6G on the best adsorbent were interpreted using the Langmuir isotherm model and a pseudo-second order kinetics model. The adsorption efficiency of the adsorbent decreased by only 17% after five runs.
Hydrolysis lignin is a major product of the enzymatic fractionation of lignocellulosic biomass and its functionalization plays a crucial role in valorizing this material. In this work, functional hydrolysis lignin-derived polymer (hydrolysis lignin-acrylic acid polymer, AA-HL) was generated to act as an adsorbent and coagulant for eliminating ethyl violet (EV) dye from solutions. AA-HL was partially soluble in water. The soluble fraction of the lignin polymer in the coagulation studies led to the complete dye removal from the solutions at a 6 mg/g dosage following the charge neutralization mechanism. The performance of insoluble AA-HL as an adsorbent was also investigated using a Quartz crystal microbalance with dissipation (QCM-D), and the results indicated the great adsorption of the dye to the insoluble AA-HL. The high stability of AA-HL adsorbent was also confirmed in the dye adsorption process at 40 ᵒC. Furthermore, the dye adsorption on AA-HL was promoted by increasing the ionic strength of the solution to 500 mM NaCl, suggesting the existence of the strong hydrophobic interaction between the dye moiety and AA-HL. The results suggested that soluble and insoluble super functional lignin derivatives can be produced from hydrolysis lignin with a strong affinity toward dyes.
Artificial micro-/nano-motors are tiny machines as newly emerging tools capable of achieving numerous tasks. In principle, the self-phoretic motions require asymmetric structures in geometry and chemistry. However, conventional production techniques suffered from complex and time consuming multi-step process in low uniformity, and difficult to endow multi-functions into motors. This work disclosed a continuous-flow synthesis of triple-responsive (thermophoretic, chemical and magnetic movement) nano-motors (m-SiO2/Fe3O4-Pdop/Pt) via microfluidic Pickering emulsification in a process of integrated and scalable manner. The droplet microfluidic process allows efficient self-assembly of the silica nanoparticles surrounding the spherical interface of resin droplet, rendering excellent Pickering efficiency and reproducibility, and followed by anisotropic decoration of polydopamine (Pdop) and Pt catalyst in a serial flow process. The obtained Janus nanoparticles reveal double- or triple-responsive self-propulsions with synergic mobility by combining thermophoresis powered by light, catalytic driven motion in H2O2 or magnetic movement by magnet. Further, a non-metallic polydopamine based thermophoretic motion as well as an automated nano-cleaner for rapid water purification by dye removal are convincingly functioned. Finally, this novel integrated flow strategy proves a scalable manufacturing production (> 0.7 g hr⁻¹) of the nano-motors using inexpensive single microreactor, fulfilling quantitative and qualitative needs for versatile applications.
In this study, Fe3O4 nanoparticle-loaded biochar derived from the pomelo peel (FO-PPB) was synthesized and applied as an affordable material for the adsorption of Reactive Red 21 (RR21) in an aqueous solution. The characteristics of FO-PPB were evaluated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), Raman spectra, Fourier transform infrared spectra (FTIR), and Brunauer–Emmett–Teller (BET) surface area. The adsorption process of FO-PPB with RR21 was evaluated through batch experiments to examine various parameters including solution pH, contact time, adsorbent dose, initial RR21 concentration, and solution temperature. Results show that FO-PPB produced by the impregnation ratio between iron (Fe) and pomelo peel biochar (PPB) of 5 : 1 (w/w) had the best adsorption performance. The adsorption capacities of PPB and FO-PPB at optimum experimental conditions (solution pH 3, contact time of 60 min, solution temperature of 40°C, initial RR21 concentration of 300 mg/L, and adsorbent dose of 2 g/L) were 18.59 and 26.25 mg/g, respectively. The adsorption isotherms of RR21 on PPB and FO5-PPB were described well by Langmuir and Sips models with high R2 values of 0.9826 and 0.9854 for FO5-PPB and 0.9701 and 0.9903 for PPB, respectively. The obtained data also well matched the pseudo-first-order and pseudo-second-order models with R2 values ≥ 0.96. Chemisorption through sharing or electronic exchange was determined as the main adsorption mechanism.
Many organic dye pollutants have been identified in rivers and lakes around the world, and concern is growing with them as they cause serious changes in the ecological balance of aquatic environments. One of these dyes is rhodamine R6G, which is very water-soluble and has a high corrosive power. Therefore, Clitoria fairchildiana (CF) pods were used as a biosorbent to remove R6G from synthetic dye effluents. CF was characterized by infrared spectroscopy, thermogravimetric analysis, x-ray diffraction, elemental analysis, Boehm titration, and zero charge point measurements. The influence of various factors, such as solution pH, contact time, adsorbent mass, and concentration of R6G, was studied using batch equilibrium experiments. The optimum contact time to reach equilibrium was found to be 15 min, while the optimum adsorbent dose was 8 g L −1. The maximum adsorption capacity of CF (73.84 mg g −1) was observed at pH 6.4 and 298.15 K. Adsorption kinetics followed a pseudo-second-order law, and the isotherm could be best fitted with a Liu model. The obtained thermodynamic parameters indicate that the adsorption of R6G is spontaneous and enthalpy-driven. We thus conclude that CF is an efficient, green, and readily available biosorbent for dye removal from wastewater.
Magnetic Graphene Oxide nanocomposite prepared by the co-precipitation method based on concept of nanoarchitectonics. In co-precipitation method, Graphene oxide converts into Magnetic graphene oxide nanocomposite with uniform deposition of Fe₃O₄ nano particles on the surface of Graphene oxide. Field Emission Scanning Electron Microscopy spectroscopy technique reveals the size (~2.5 nm) and uniformity of Fe₃O₄ nano particles on Graphene oxide surface. The other properties characterized by Scanning electron microscopy, Raman spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and vibrating-sample magnetometer. For Adsorption process, time, temperature, dose of adsorbent, initial concentration of dye solution and pH factors are optimize for Rhodamine 6G dye. Kinetic data expressed by Pseudo first order model and Pseudo second order model. Langmuir, Freundlich and Temkin isotherms used to evaluate the adsorption isotherm of Rhodamine 6G onto the surface of Magnetic graphene oxide nanocomposite and thermodynamic parameters tell us about the nature of reaction.
Carboxymethyl starch-g-polyvinylpyrolidones (CMS-g-PVPs) were prepared by grafting of carboxymethyl starch (CMS) with N-vinylpyrolidone (NVP) using different initiators. The grafting percentage of all the modified starches was determined and the modified starch (CMS-g-PVP-5) with maximum grafting percentage was characterized by elemental analysis, ¹H NMR and FT-IR spectroscopy. Crystallinity and thermal properties of CMS-g-PVP-5 were analysed by XRD and TGA, respectively. CMS-g-PVP-5 was then utilized for the adsorption of Rhodamine 6G (dye) from water under different pH, temperature, adsorbate doze and adsorbent concentration. This modified starch showed good adsorption ability towards Rhodamine 6G. CMS-g-PVP-5 was also applied for the adsorption of ammonia gas and proved an exciting adsorbent for ammonia.
Usually production of activated carbon (AC) requires activation at high temperature. AC was produced from a new source of residual fuel oil at low temperature (170 °C) by chemical treatment with a mixture of sulfuric (65 vol.%), phosphoric (20 vol.%) and nitric (15 vol.%) acids. BET analysis illustrated surface area, pore volume and average pore width of 50.7 m²/g, 0.092 cm³/g and 17.18 nm, respectively. FTIR analysis showed that the surface of the AC had carbonyl (CO) and carboxyl (C-O) groups. DSC-TGA illustrated a weight loss of 11% in the range of 25 °C to 210 °C. Adsorption of aqueous MB and R6G on the AC in single system provided monolayer adsorption capacity of 85.6 mg/g for MB and 64.3 mg/g for R6G. The isotherm data were fitted by Freundlich and Langmuir isotherm models and found that Freundlich model best fitted the date based on MPSD error function. Multicomponent isotherms for both dyes showed antagonism effect where MB and R6G competed on similar sites on the surface of the AC. Thermodynamic parameters, including ΔG°, ΔH°, ΔS° indicated the adsorption of MB and R6G were endothermic and exothermic, respectively, and spontaneous in the temperature range of 25–45 °C. Binary isotherm models of Non-modified, modified and extended Langmuir and extended Freundlich models were applied to fit the binary isotherm data and found that extended Freundlich isotherm model best fitted the experimental binary data adequately. This activated carbon can be used as low cost material for removal of dyes from downstream.
This work reports a one-pot solvothermal synthesis approach of magnetic γ-Fe2O3/N-rGO composite and its multifunctional application for detection, adsorption removal and degradation of organic pollutants. The uniform dispersed γ-Fe2O3 nanoparticles (NPs) are in situ grown on the surface of nitrogen doped reduced graphene oxide (N-rGO) sheets, thus forming a three-dimensional (3D) γ-Fe2O3/N-rGO composite with high specific surface area (146.2 m²·g⁻¹). The morphology and textural properties of the samples were characterized by scanning and transmission electron microscopies, X-ray diffraction, Raman and X-ray photoelectron spectroscopies. The γ-Fe2O3/N-rGO composite with 3D interconnected porous structure possesses multifunctional performance for dye removal with convenient magnetic separation operation. It exhibits good removal ability for Rhodamine 6G (R6G) with an adsorption capacity of 44.0 mg·g⁻¹. Meanwhile, the γ-Fe2O3/N-rGO composite shows a high sensitive surface-enhanced Raman spectroscopy (SERS) response toward R6G molecules where the detection limit is as low as to 5×10⁻⁷ mol·L⁻¹. Besides, it also serves as a photocatalyst to degrade the adsorbed R6G molecules under in situ SERS monitoring. Thus, the multifunctional γ-Fe2O3/N-rGO composite can present a promising potential for organic dye wastewater treatment and other applications.
This research paper reports the synthesis and usage of the polyacrylamide (PAAm) grafted gum karaya (Gk) and nickel sulphide nanoparticle based hydrogel to effectively remove rhodamine 6G dye (R6G) from aqueous solution. Initially, the hydrogel polymer of the Gk with the PAAm was synthesized using the graft co-polymerization technique. In the second step, the nickel sulphide nanoparticles were incorporated in situ within the hydrogel polymer matrix. The synthesized hydrogel nanocomposite was characterized using different characterization techniques such as XRD, FTIR, SEM, and TEM. The changes in the surface area, pore volume and pore diameter after the incorporation of nanoparticles were studied using the BET technique. The adsorption of R6G onto the hydrogel nanocomposite followed the Langmuir adsorption isotherm with a maximum adsorption capacity of 1244.71 mg g À1. The adsorption kinetics followed the pseudo-second order rate model. Furthermore, various thermodynamic parameters such as DS , DH and DG were calculated to check the spontaneity and nature of the process of adsorption. The hydrogel nanocomposite was used for five successive cycles of adsorption–desorption. Therefore, the nanocomposite hydrogels have proved their potential for the removal of cationic dyes from aqueous solutions.
The distribution coefficients, Kd, for navy brown 3REL, direct red, procion red H8B, methylene blue, metamega chrome yellow and lanasyn green 5 GL, solar violet and procion blue H5G from their aqueous solutions, at pH 3.2 and 7.5 on saw-dust phosphate (SDP) have been reported. Effect of pH and added surfactant concentration on the percent removal of lanasyn green 5 GL has been studied. Percent dye removal increases with the decrease in pH. The applicability of the Freundlich and Langmuir equation has been tested for equilibrium data of which Langmuir isotherm model is found to be most appropriate. The values of Langmuir and Freundlich constants as well as the distribution constants show that SDP is a good adsorbent for all dyes, being better for basic dyes. The kinetics of adsorption of lanasyn green 5 GL on SDP was investigated at pH 3.2 and temperatures 25, 30, 35 and 40°C. It is first order with respect to the dye and less than unity with respect to SDP. The values of Kad, Kp and kf at 30° was found to be 2.18 × 10-4 s-1, 15.33 × 10-5 s-1 and 20.72 × 10-4 s-1 respectively.
Application of activated carbon (CSAC) and polypyrrole composite (PPC) developed from the precursor, fruit of the gardening plant material Cordia sebestena has been investigated for the removal of Direct Green 6 (DG6) from aqueous solution. Batch adsorption experiments were carried out using CSAC and PPC and a comparative study was also made. Effect of parameters, namely initial dye concentration, contact time, pH and temperature was studied. The kinetic studies were analysed with pseudo-first-order and pseudo-second-order models. Experimental isotherm data were also analysed with Langmuir and Freundlich adsorption isotherm models. Thermodynamic parameters were also measured. Experimental results showed that percentage removal of DG6 was higher with PPC than the percentage removal obtained by CSAC. Hence, it is proposed that PPC is superior and efficient adsorbent for the removal of DG6 from aqueous solutions.
An activated carbon-based multicarboxyl adsorbent has been synthesized for selective removal of cationic dyes from aqueous solutions. The adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), N2 adsorption measurement and zeta potential. The adsorption behavior of cationic rhodamine 6G on the activated carbon-based multicarboxyl adsorbent from an aqueous medium was studied by varying the parameters such as pH, contact time and initial dye concentration. Dye adsorption was dramatically dependent on solution pH and the optimum pH is 4.45. After being modified by multicarboxyls, the adsorption capacity of rhodamine 6G on the activated carbon dramatically increased from 33.18 mg L-1 to 122.55 mg L-1 at pH 4.45. The multicarboxyl adsorbent has obvious selectivity to cationic dyes. Adsorption isotherms could be well described by the Langmuir model, adsorption kinetics fitted well with a pseudo-second-order kinetic equation and exhibited a 3-stage intraparticle diffusion mode. The electrostatic interaction was the main mechanism for the cationic dye adsorption.
This review surveyed recent publications on the adsorption uptakes of heavy metals and dyes from water and wastewater streams using low-cost adsorbents derived from agricultural waste, industrial wastes, inorganic particulates, or some natural products. Most adsorption works adopted either the Langmuir or Freundlich isotherms (or both) for adsorption data correlation. Despite a few exceptions, the waste-derived adsorbents have lower adsorption uptakes than the activated carbon. However, the cheapness of the former represents the major advantage for possible applications. Effects of process parameters, such as temperature and pH, on and the possible mechanisms to metals or dyes adsorption were addressed in some detail. We also highlighted the compensation effects during thermodynamic parameter evaluation, which were possibly overlooked in current literature.
A series of core-shell SiO2@MgxSiyOz(SM) composites were synthesized with high efficiency for the adsorption of Rhodamine B (RhB). The composites were characterized by powder X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), nitrogen adsorption-desorption. The influences of different magnesium oxide addition, adsorbent dosage, temperature, contact time and initial RhB concentration on RhB adsorption were investigated, and the optimized adsorption parameters were also obtained. The adsorption data was evaluated using Langmuir and Freundlich models, but high correlation coefficients (R2) confirmed the validity of Langmuir isotherm, with maximum adsorption capacity of 52.71mg/g at 313K. The kinetic data fitted pseudo-second order model well and thermodynamic studies showed that the adsorption process was spontaneous and endothermic. Even after successive five cycles for the adsorption–desorption of RhB, the regenerated powders remained excellent adsorption capacity with more than 99% dye removal which could be utilized as an efficient and low-cost adsorbent for adsorption of RhB dye in wastewater.
A series of Chitosan-g (N-Vinyl Pyrrolidone)/Montmorillonite hydrogel composites were synthesized by insitu intercalative polymerization. The properties of the composites were investigated by FTIR, XRD, scanning electron microscopy and differential scanning calorimetry. The morphologies of the hydrogel composites were sponge like with a homogeneous structure. The effects of clay on the swelling, morphology, glass transition (Tg), and water structure were studied. The swelling of the hydrogel composites formed was found to be affected by the pH of the medium and the electrolyte. Maximum swelling was observed in the hydrogel containing low percentage of clay (H-0.2) and was used to investigate the adsorption of a water soluble cationic dye Rhodamine 6G (Rh6G). The results show that the adsorption capacity for the dye increased with increase in dose, contact time but there was no change observed with respect to increase in temperature. The adsorption kinetics of Rh6G followed Pseudo second order model and the equilibrium data was found to fit Freundlich model.
The direct release of untreated wastewaters from various industries and households results in the release of toxic pollutants to the aquatic environment. Advanced oxidation processes (AOP) have gained wide attention owing to the prospect of complete mineralization of nonbiodegradable organic substances to environmentally innocuous products by chemical oxidation. In particular, heterogeneous photocatalysis has been demonstrated to have tremendous promise in water purification and treatment of several pollutant materials that include naturally occurring toxins, pesticides, and other deleterious contaminants. In this work, we have reviewed the different removal techniques that have been employed for water purification. In particular, the application of TiO 2-SiO 2 binary mixed oxide materials for wastewater treatment is explained herein, and it is evident from the literature survey that these mixed oxide materials have enhanced abilities to remove a wide variety of pollutants.
The direct release of untreated wastewaters from various industries and households results in the release of toxic pollutants to the aquatic environment. Advanced oxidation processes (AOP) have gained wide attention owing to the prospect of complete mineralization of nonbiodegradable organic substances to environmentally innocuous products by chemical oxidation. In particular, heterogeneous photocatalysis has been demonstrated to have tremendous promise in water purification and treatment of several pollutant materials that include naturally occurring toxins, pesticides, and other deleterious contaminants. In this work, we have reviewed the different removal techniques that have been employed for water purification. In particular, the application of TiO2-SiO2 binary mixed oxide materials for wastewater treatment is explained herein, and it is evident from the literature survey that these mixed oxide materials have enhanced abilities to remove a wide variety of pollutants.
The removal of three dyes, methylene blue, malachite green, and rhodamine B from aqueous solutions at different concentrations, pH and temperatures by Akash Kinari coal has been studied. It has been found that per cent adsorptions of methylene blue, malachite green, and rhodamine B onto the adsorbate decrease from 97.18 to 83.90, 89.16 to 79.77, and 78.40 to 67.35, respectively, when their concentrations in solutions are increased from 5 to 20 mg/L at 30±1 °C and at pH 6.8, 7.2 and 5.8, respectively. The rate constants of adsorption (Kad) for methylene blue, malachite green, and rhodamine B are found to vary between 4.27-3.95 × 10-2, 4.53-4.61 × 10-2 and 4.39-4.20 × 10-2 /min at 20, 30, and 40 °C, respectively. The calculated values of the Langmuir constant for adsorption capacity of the dyes (Q0) on the adsorbent at different temperatures vary from 2.12 to 1.59, 2.68 to 1.15 and 1.23 to 0.78 mg/g. There is an increase in the adsorption of methylene blue, malachite green, and rhodamine B from 74.39 to 92.80 per cent, 62.16 to 83.42 per cent, and 51.57 to 71.78 per cent, respectively (at 30±1 °C and 10 mg/L concentration) with increase in pH from 3.8 to 7.2. The adsorption of dyes, however, decreases beyond pH 7.2. Various thermodynamic parameters (ΔG °, ΔH ° and ΔS °) have also been calculated. The results show that Akash Kinari coal is a good adsorbent for removal of colour from textile wastewater.
Batch adsorption studies were conducted to investigate the potential of pine bark subjected to three different pretreatments (washing with hot water, Soxhlet extraction and formaldehyde treatment) to remove the cationic dye methylene blue from water. Experimental adsorption isotherms showed that all three pretreated bark adsorbents demonstrated considerable capacities for methylene blue. The simple Langmuir isotherm model was found to exhibit good fit to the isotherm data. The best uptake was observed using the bark adsorbent pretreated with Soxhlet extraction. The maximum dye uptake obtained was 115 mg/g. Adsorption of methylene blue was a slow process and reached apparent equilibrium after a contact time of 6 h. The kinetic data could be adequately described by a mathematical model predicated on the kinetic form of the Langmuir isotherm model.
Sodium boroaluminosilicate glasses, (Na2O)0.22(K2O)0.029(B2O3)0.05(SiO2)0.69(Al2O3)0.011 and (Na2O)0.05(K2O)0.029(B2O3)0.22(SiO2)0.69(Al2O3)0.011 having different B2O3 to Na2O mole ratio of 0.23 and 4.4 respectively were investigated for their uptake characteristics of cationic dyes, namely Rhodamine 6G and methylene blue, from aqueous solutions. Both the glasses have been found to adsorb these dyes. However, the glass with B2O3 to Na2O ratio of 0.23 is found to have more uptake capacity with 2.5 and 1.8mmol of Rhodamine 6G and methylene blue respectively per gram of the glass sample. For Rhodamine 6G dye, the amount of uptake by glass is found to be significantly higher than that of conventionally used activated charcoal (0.1mmol/g). Based on 29Si and 11B magic angle spinning nuclear magnetic resonance technique, it is confirmed that the increased concentration of Si–O− Na+ and BO4− Na+ linkages present in the glass with B2O3 to Na2O mole ratio of 0.23 is responsible for the increase in its uptake of the dye compared to the glass sample with B2O3 to Na2O mole ratio of 4.4. From fluorescence studies, incorporation of the dye molecules in the glass matrix is confirmed. The present study is quite relevant for the removal of dye molecules present in untreated aqueous solutions generated from the textile industry.
On the utilization of agricultural by-product, charcoal from rice bran was produced. The adsorption characteristics of indigo carmine onto charcoals from rice bran were investigated by the batch method. The yield and surface area of charcoal were decreased and increased with increase of carbonization temperature, respectively. The removal ratio of indigo carmine was high with the charcoal carbonized at higher temperature. In the relationship between the amount of indigo carmine adsorbed and the square root of elapsed time, a good linearity was recognized. The kinetic constant of adsorption removal for indigo carmine was rapid in the charcoal carbonized at higher temperature. The adsorption characteristics for indigo carmine removal by charcoal from rice bran were dominated by the value of their surface area.
This paper describes a green method for the synthesis of graphenic material from cane sugar, a common disaccharide. A suitable methodology was introduced to immobilize this material on sand without the need of any binder, resulting in a composite, referred to as graphene sand composite (GSC). Raman spectroscopy confirmed that the material is indeed graphenic in nature, having G and D bands at 1597 and 1338 cm-1, respectively. It effectively removes contaminants from water. Here, we use rhodamine 6G (R6G) as a model dye and chloropyrifos (CP) as a model pesticide to demonstrate this application. The spectroscopic and microscopic analyses coupled with adsorption experiments revealed that physical adsorption plays a dominant role in the adsorption process. Isotherm data in batch experiments show an adsorption capacity of 55 mg/g for R6G and 48 mg/g for CP, which are superior to that of activated carbon. The adsorbent can be easily regenerated using a suitable eluent. This quick and cost-effective technique for the preparation of graphenic material and its application for water purification could be developed into a commercial water filter with appropriate engineering.
The object of this work was to investigate sev-eral adsorbents to determine their effective removal of benzene from wastewater. Tea and coffee lees were found to effectively adsorb benzene. Equilibrium adsorption isotherms conformed to the Freundlich isotherm (log-log linear). Adsorption of benzene by tea or coffee lees was observed in the pH range of 1 to 11. At equilibrium, the adsorption efficiency of tea or coffee lees for benzene was lower than that of activated carbon. The removal of benzene by tea or coffee lees was attributed to the uptake by intracellu-lar particles called spherosomes. Ninety minutes after application of lees to wastewater (pH 10) containing 0.1 g/l of benzene, 75 to 82% of the benzene had been removed.
The water consumption in textile industry, especially in dyeing and washing processes is too high. Therefore, large amount of wastewater is produced and discharged to the receiving environment during textile production process. Discharge of colored effluents without decoloration originated from textile industries may cause serious problems in the receiving environments. Besides water resources are limited. The textile industry should look for recycling and reusing this water. The objective of this chapter is to explain the use of various natural materials like basaltic tephra and clinoptilolite to remove basic, acidic and reactive types of dyes from textile wastewater. The determination of dye removing capacities and adsorption isotherms of these adsorbents are among the objectives of this study.
The second objective is to modify the surface properties of these adsorbents by using a surfactant chemical and then determine their equilibrium sorbent capacities again with basic, acidic and reactive dyes. The results showed that removal efficiencies for cationic basic dyes are higher than those for anionic acidic and reactive dyes with the natural materials. Therefore, modification of surface properties of natural materials with a cationic surfactant was considered to increase the removal efficiencies of those for anionic dyes. After modification of the surface properties, adsorption capacities of adsorbents for anionic dyes were higher than those of natural materials. The results showed that the adsorption of dyes on adsorbents used in this study fitted nicely to the Langmuir Isotherm Equations.
This paper evaluates three inorganic adsorbents (activated bauxite, fullers earth and a synthetic clay), relative to activated carbon, for the removal of several representative contaminants of major concern and frequent occurrence in UK textile industry effluents; reactive dyes, pentachlorophenol and Propetamphos. The results indicate that, for the removal of reactive dyes, the synthetic clay was the most effective adsorbent over the pH range from pH 5.5 to pH 8.5 and temperature range from 20 to 40°C, although comparable dye removals were exhibited by activated carbon under neutral and alkaline conditions. Under acidic conditions activated bauxite was as effective as activated carbon. Fullers Earth was largely ineffective. With regard to the removal of pesticides activated carbon was highly effective, whereas the three inorganic adsorbents showed negligible removals.
This paper evaluates three inorganic adsorbents (activated bauxite, fullers earth and a synthetic clay), Relative to activated carbon, for the removal of several representative contaminants of major concern and frequent occurrence in UK textile industry effluents; reactive dyes, pentachlorophenol and Propetamphos. The results indicate that, for the removal of reactive dyes, the synthetic clay was the most effective adsorbent over the pH range from pH 5.5 to pH 8.5 and temperature range from 20 to 40°C, although comparable dye removals were exhibited by activated carbon under neutral and alkaline conditions. Under acidic conditions activated bauxite was as effective as activated carbon. Fullers Earth was largely ineffective. With regard to the removal of pesticides activated carbon was highly effective, whereas the three inorganic adsorbents showed negligible removals.
Laboratory investigations show that rates of adsorption of persistent organic compounds on granular carbon are quite low. Intraparticle diffusion of solute appears to control the rate of uptake, thus the rate is partially a function of the pore size distribution of the adsorbent, of the molecular size and configuration of the solute, and of the relative electrokinetic properties of adsorbate and adsorbent. Systemic factors such as temperature and pH will influence the rates of adsorption; rates increase with increasing temperature and decrease with increasing pH. The effect of initial concentration of solute is of considerable significance, the rate of uptake being a linear function of the square-root of concentration within the range of experimentation. Relative reaction rates also vary reciprocally with the square of the diameter of individual carbon particle for a given weight of carbon. Based on the findings of the research, fluidized-bed operation is suggested as an efficient means of using adsorption for treatment of waters and waste waters.
The effects of alkaline magnesium carbonate-hydrated basic as a coagulant, have been investigated in colour reduction experiments using Jar Test apparatus. The raw wastewater was synthetic containing 300 mg/dm3 reactive red dye 519. It has been found that no single flocculant (Mg(OH)2, Ca(OH)2 or CaCO3) can satisfactorily effect colour removal. The effective colour reduction achieved using alkaline magnesium carbonate-hydrated basic has been attributed to the synergistic sorbing capacity of the flocculants Mg(OH)2 and CaCO3.
The adsorption characteristics of Astrazone Blue on wood particles have been investigated. The effects of contact time and initial dye concentration have been studied in an attempt to explain the adsorption process. Adsorption isotherms have been obtained and applied to the conventional equations and the results listed. A series of fixed bed experiments have been undertaken using Astrazone Blue to study the influence of the dye solution velocity on the breakthrough curves, and, in addition, the influence of varying the bed height on the service time of the bed has been assessed.
The use of fly ash for the removal of victoria blue (C126,44045) from aqueous solution at different concentrations and pH has been investigated. The process follows first order adsorption rate expression and the rate constant was found to be 1. 70 multiplied by 10** minus **2 min** minus **1 at a victoria blue concentration of 1. 0 multiplied by 10** minus **4 M and 25 degree C. The uptake of victoria blue by fly ash is diffusion controlled and the value of mass transfer coefficient is 1. 25 multiplied by 10** minus **5 cm sec** minus **1. The equilibrium data fit well in the Langmuir model of adsorption. Maximum removal was noted at pH 8. 0. Low desorption of dye from adsorbent surface indicates that the process may not be essentially a reversible one.
A rational framework for selecting the least-cost treatment technology for aqueous organic wastes was developed by using performance and cost models. The following three treatment options were evaluated for 15 different chemicals in this research: packed tower air
stripping, packed tower air stripping followed by gas-phase adsorption (granular activated carbon) of off-gases, and liquid-phase adsorption (granular activated carbon). The least-cost air stripping tower design was found to change when off-gas treatment was added. Air stripping without off-gas
treatment was determined to be less expensive than liquid-phase adsorption in nearly every case. A methodology was created for comparing the relative costs of liquid-phase adsorption and air stripping with gas-phase adsorption. The comparison methodology is based upon physical parameters of
the target chemical: Henry's constant and the solute distribution parameter. The result is a diagram for rapid identification of cases for which one treatment option is significantly less expensive than the other.
The adsorption of phenol and the substituted phenols, 4-nitrophenol, 2,4-dinitrophenol, 4-chlorophenol, and 2,4-dichlorophenol in aqueous solution, has been determined at 298 K on a series of activated carbons, prepared from olive stones, having a wide range of burn-off (8–52%) and micropore size distributions. The adsorption process is controlled predominantly by the porosity of carbon when the microporosity is narrow in range. If the ragne of microporosity is wide then the adsorption process is affected by the chemical nature of the carbon and by the nature of the substituent group in the phenol. The adsorption isotherm of 2,4-dinitrophenol is a step function, which is interpreted as being due to the coexistence of neutral and anionic adsorbate species, and not due to a change in the orientation of the neutral adsorbate species.
The potential of chrome sludge, a waste product from the electroplating industries, to remove colour from aqueous solutions was investigated. Results indicated that the sludge had better affinity for acid than basic dyes. Equilibrium data can be fitted into the Langmuir isotherm with maximum sorption of 30 – 60 mg g−1 for the range of acid dyes studied. The process followed a first order rate kinetics and the rate of dye removal was influenced by concentration and agitation speed.
The efficiency of Giridih coal and crushed coconut shell in removing cadmium from solution was investigated in batch experiments after eliminating other sorbents in the initial screening tests. Both sorbents were found to adsorb cadmium from solution. The batch sorption kinetics and equilibria may be described by a first order reversible reaction and Freundlich isotherm respectively. The first order rate constant for forward and reverse reactions have been calculated for both sorbents. In order to establish the rate limiting step the pore and film diffusion coefficients were evaluated from the half time equations. Film diffusion appears to be rate limiting. The cadmium adsorption for both the sorbents was found to be a function of pH of the reaction mixture, which increased with pH increase up to pH 10. A decreasing trend in sorption was observed beyond pH 10. The mechanism of sorption in terms of electrostatic forces and chemical interactions has been indicated with the aid of zero point of charge (pHzpc).
Liquid-phase adsorption of two dyes on activated carbon was measured in the 283–323 K temperature range. Higher capacity and faster kinetics of adsorption were obtained for a basic dye than for an acidic dye under comparable conditions, probably due to the different ionic natures of the dyes. The equilibrium data for acidic dye could be well described by the Freundlich equation, but the best-fit model for basic dye changed from the Langmuir to the Freundlich equations when the temperature was raised. In addition, the thermodynamic functions were determined. A plot of the fraction of adsorption against (time) was adopted to describe the adsorption process. It was shown that for an acidic dye the amount of adsorbent used played an important role in the adsorption mechanism.
Microbial cultures immobilised on various matrices are used to protect the microbes from confronting shock loads of concentrated organic pollutants during wastewater treatment. Activated carbon is generally used as carrier material in comparison to other matrices. In this study a mutant strain of Pseudomonas pictorum (MU 174) was immobilised on rice bran based activated carbon. The effect of contact time, pH, mass of activated carbon, temperature and ionic strenth on adsorption of MU 174 on to activated carbon has been investigated. The optimum temperature and pH for adsorption of MU 174 on to activated carbon were 31 °C and 7, respectively. The adsorption kinetic parameters Kp, Kad and ΔH have been determined. The rate constant values and the intraparticle diffusion of MU 174 on to activated carbon obtained were 5 × 10−3–17.5 × 10−3min−1 and 0.75–2.9 min0.5, respectively, and the enthalpy of adsorption was observed to be −47.9 kJ/Avogadro number of cells.
Activated carbon fiber was used as a new adsorbent for direct removal of iodine and iodide compounds from acetic acid solutions under static and dynamic conditions. In aqueous solution as well as in acetic acid, methanol, or ethanol, activated carbon fiber showed excellent iodine removal efficiency, superior to that of activated carbon, silica gel, alumina, NaY zeolite, Ag ion-exchanged NaY, and Ag ion-exchanged Amberlyst XN 1010. Water was a promoter for the removal of iodine on activated carbon fiber. The amount of iodine removed followed the reverse order of solubility of iodine in the solution. Activated carbon fiber could be used as an iodine removal adsorbent without significant change in the removal efficiency over a wide range of iodine concentration and contact time. The activated carbon fiber used was completely regenerated by He flushing above 200-degrees-C. In addition to the excellent iodine removal characteristics, activated carbon fiber showed a good performance in the removal of iodide compounds such as hydrogen iodide.
In the favorable-equilibrium adsorption region, the constant-pattern form of the isothermal breakthrough curves is known only approximately for the solid-diffusion (or pore-surface-diffusion) mechanism, and is not soluble analytically for the pore-diffusion mechanism. Numerical solutions for both these cases, in a widely applicable dimensionless form, have been obtained for a range of Langmuir isotherms by stepwise computation on a digital computer. These numerical results merge smoothly into the respective analytic solutions for completely irreversible equilibrium; for this case, combinations of pore diffusion and external mass transfer are also analyzed.
Equilibrium isotherms have been studied for the adsorption of four dyestuffs, namely, Acid Blue 25, Acid Blue 158, Mordant Yellow 5, and Direct Red 84, onto chitin. Langmuir and Freundlich constants have been determined and the effects of chitin particle size and solution temperature have been investigated. Theoretical isotherms have been compared with experimental data and good agreement was obtained using a composite isotherm of the general form: Ye = iCe/(1 + jCem), where i,j, and m are constants.
The adsorption of two basic dyes in aqueous solutions onto lignite is reported. The adsorption equilibrium isotherms are recorded for the dyes in single component solution. The isotherms are plotted to obtain the Freundlich constants, the Langmuir constants, and the Redlich-Peterson constants.
The factors affecting the rate processes involved in the removal of phenolic compounds, e.g. initial phenol concentration, particle size, impregnation of fly ash (IFA), pH and temperature have been studied. The removal rate of phenols varied in the order p-nitrophenol m-nitrophenol > o-nitrophenol > p-cresol > phenol > m-cresol > o-cresol. The process followed first order rate kinetics. The sorption data generally fit the Lagergren equation and the intraparticle diffusion rate equation from which adsorption rate constants, diffusion rate constants and diffusion coefficients were determined. Intraparticle diffusion was found to be the rate-limiting step. These kinetic parameters were compared for various phenols under different conditions using fly ash (FA) and impregnated fly ash (IFA).
The use of fly ash for the removal of victoria blue (C126, 44045) from aqueous solution at different concentrations and pH has been investigated. The process follows first order adsorption rate expression and the rate constant was found to be 1.70 × 10−2 min−1 at a victoria blue concentration of 1.0 × 10−4 M and 25°C. The uptake of victoria blue by fly ash is diffusion controlled and the value of mass transfer coefficient is 1.25 × 10−5 cm sec−1. The equilibrium data fit well in the Langmuir model of adsorption. Maximum removal was noted at pH 8.0. Low desorption of dye from adsorbent surface indicates that the process may not be essentially a reversible one.
The ability of Fuller's earth to adsorb a basic dye (Astrazone Blue — Basic Blue 69) and an acidic dye (Telon Blue - Acid Blue 25) has been studied. The equilibrium saturation adsorption capacities were 1200 mg dye g–1 Fuller's earth and 220 mg dye g–1 Fuller's earth for Astrazone Blue and Telon Blue, respectively.The kinetics of the adsorption processes were studied in an agitated batch adsorber. The time to reach 90% equilibrium value was achieved in less than 1 h. The variables investigated were agitation, adsorbent mass, initial dye concentration and temperature.A limited number of studies were undertaken using a fired clay but significantly lower saturation capacities were obtained, namely, 7 mg dye g–1 fired clay and 40 mg dye g–1 fired clay for Telon Blue and Astrazone Blue, respectively.
Box-Behnken design with three variables like temperature, pH and particle size at three different levels was studied to identify a significant correlation between the effect of these variables to the amount of dye adsorbed. The methodology identifies the principal experimental variables, which have the greatest effect on the adsorption process. The experimental values are in good agreement with predicted values, the correlation coefficient was found to 0.9250.
The adsorption of reactive dye on chitin has been investigated with a view to obtain the design data for batch processing of effluents for dye adsorption. The effect of several factors governing the dye adsorption such as the adsorbent concentration, adsorbent size, temperature and pH have been elicited. Desorption of the dye at different temperatures and pH have also been investigated.
A comparative study of the sorption of phenol and p-chlorophenol from water has been performed using novel samples prepared by carbonisation and subsequent activation of straw and used rubber typres as well as conventional activated carbons based on coal, coconut shell and wood. Pseudo-equilibrium sorption of phenol and p-chlorophenol obeys a Freundlich type adsorption isotherm of the form; q = kcn in the adsorbate concentration range 0–6 mmol 1−1. Measured values of k and n indicate that the sorption of phenol and p-chlorophenol onto active carbons derived from straw and used rubber tyres is almost identical to that for conventional activated carbons. The rate of adsorbate uptake has been measured and the sorption half-times lie in the range 1.4–15 min for phenol. The sorption kinetics of the straw and rubber tyre based carbons are likewise identical to conventional carbons based on coal and wood but appreciably faster than the coconut shell sample selected for comparison.
Effect of initial metal ion concentration, agitation time, temperature and pH on Cd(II) adsorption by “waste” hydroxide was investigated in batch mode studies. The equilibrium data could be described well by the Langmuir and Freundlich isotherm equations. The Lagergren rate constants of adsorption are reported. The intraparticle diffusion of Cd(II) through pores in the adsorbent was shown to be the main rate limiting step. Desorption of Cd(II) was 70% at pH 3.80. The studies showed that the “waste” hydroxide can be used as an efficient adsorbent material for Cd(II) removal from wastewater.
The adsorption capacity of agricultural by-products, namely peat and rice hulls, for acidic and basic dyes has been investigated and compared with that of activated carbon. The effect of contact time, pH and adsorbent particle size were studied. Fixed-bed flow experiments were performed to simulate industrial conditions on a small scale. Economic evaluation indicates that peat and rice hulls have high adsorptive capacities, as well as being very cheap.
- G Mckay
- H S Blair
- J R Gardner
McKay, G.; Blair, H.S.; Gardner, J.R. Adsorption of Dyestuffs on Chitin. I.
Equilibrium Studies. J. Appl. Polym. Sci. 1982, 27, 3043-3057.
Mechanism of Dye Waste Water Color Removal by Magnesium Carbonate-Hydrated Basic
- J Panswed
- S Wongchaisuwan
Panswed, J.; Wongchaisuwan, S. Mechanism of Dye Waste Water Color
Removal by Magnesium Carbonate-Hydrated Basic. Water Sci. Technol.
1986, 18, 139-144.