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Heterogeneous photocatalysis is an advanced oxidation process (AOP). This technique is used to degrade a wide range of pollutants in water. In this study, photocatalytic oxidation and mineralization of malachite green in an aqueous suspension containing nickel-based catalysts and copper supported on TiO 2 prepared by wet diffusional impregnation wa...
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... Upon plotting the change of concentration of MB against time, it can be seen that the degradation plot (Fig. 5) follows pseudo first order kinetics. As has been stated by Djebbari et al. [14], plots having correlation coefficient more or equivalent to 0.9 can be considered to be abiding first order kinetics. The equation followed for first order kinetics is lnC 0 /C t where C 0 is the initial concentration while C t is the final Content courtesy of Springer Nature, terms of use apply. ...
... concentration at time t [14]. Content courtesy of Springer Nature, terms of use apply. ...
The paper intended to focus on the extent of degradation of Methylene blue and study the impact of Tween 80 on the rate and mechanism of degradation process. In this study, microbes were isolated from industrial wastewater, and based on primary screening on mineral salt media, two strains were chosen. The strains were identified as Bacillus cereus strain EBCH14 and Bacillus cereus strain SG4 via 16srrRNA. Upon optimising parameters like pH, temperature, initial dosage of Methylene blue, and surfactant, final degradation kinetics were carried out with five set of samples. The samples consisted of four flasks with individual strains with or without the presence of surfactants and the fifth flask consisted of both the strains in the presence of surfactant. The extracted values from the kinetic study could deduce that high level of degradation could be achieved within 7 days. But in presence of surfactants, the degradation took place within 72 h while the ones without surfactants, it took more than 144 h. Upon analysing the samples via GCMS, majority of the metabolites were alkanes, acid esters, glycerols, and alcohols. The plotted metabolic pathway proved that the degradation mechanisms are similar in all the samples, and the final products are simple compounds with negligible toxicity. As surfactants are organic compounds, the initial chemical oxygen demand values were high in samples with surfactants. The ones without surfactants could achieve higher rate of reduction as their initial starting values were considerably lower than their counterparts. It can be summed up that the strains of Bacillus cereus are individually capable enough to completely mineralise Methylene blue dye, but in presence of surfactant, the reaction time is quite less. In future, research must focus on how to remove the surfactants remaining in the degraded products.
... Based on these observations, the best pH value for achieving the maximum percentage of photocatalytic activity of the EA600 and EA800 samples towards malachite green dye is determined to be 9. The percentages of photocatalytic activity of the EA600 and EA800 samples towards malachite green dye were compared with those of other photocatalysts such as CuO/TiO 2 , NiO/TiO 2 , CuCo 2 O 4 , chitosan/Ce/ZnO, EDTA/ZnO, Fe(III)cross-linked alginate-carboxymethyl cellulose, cobalt oxide/citric acid, Dy 2 O 3 /SiO 2 , and lanthanide cerate, as given in Table 1 [64][65][66][67][68][69][70][71]. Consequently, we can assume that the EA600 and EA800 photocatalysts were highly efficient for the decomposition of the malachite green dye. ...
The release of malachite green dye into water sources has detrimental effects on the liver, kidneys, and respiratory system. Additionally, this dye can impede photosynthesis and disrupt the growth and development of plants. As a result, in this study, barium titanate nanoparticles (BaTiO 3 ) were facilely synthesized using the Pechini sol–gel method at 600 °C (abbreviated as EA600) and 800 °C (abbreviated as EA800) for the efficient removal of malachite green dye from aqueous media. The Pechini sol–gel method plays a crucial role in the production of barium titanate nanoparticles due to its simplicity and ability to precisely control the crystallite size. The synthesized barium titanate nanoparticles were characterized by several instruments, such as X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy, and a diffuse reflectance spectrophotometer. The XRD analysis confirmed that the mean crystallite size of the EA600 and EA800 samples is 14.83 and 22.27 nm, respectively. Furthermore, the HR-TEM images confirmed that the EA600 and EA800 samples exhibit irregular and polyhedral structures, with mean diameters of 45.19 and 72.83 nm, respectively. Additionally, the synthesized barium titanate nanoparticles were utilized as catalysts for the effective photocatalytic decomposition of malachite green dye in aqueous media. About 99.27 and 93.94% of 100 mL of 25 mg/L malachite green dye solution were decomposed using 0.05 g of the EA600 and EA800 nanoparticles within 80 min, respectively. The effectiveness of synthesized BaTiO 3 nanoparticles as catalysts stems from their unique characteristics, including small crystallite sizes, a low rate of hole/electron recombination owing to ferroelectric properties, high chemical stability, and the ability to be regenerated and reused multiple times without any loss in efficiency.
... The first order kinetic model was used to determine the rate constant of the photocatalyst (Figure 7c). The first order kinetic model is given by Equations (8) and (9) [69], where r is the photocatalytic reaction rate (mg/(L min)), C is concentration in (mg/L), K app is the apparent rate constant (min −1 ), and t is the irradiation time (min). ...
Numerous treatment methods such as biological digestion, chemical oxidation, and coagulation have been used to treat organic micropollutants. However, such wastewater treatment methods can be either inefficient, expensive, or environmentally unsound. Here, we embedded TiO2 nanoparticles in laser-induced graphene (LIG) and obtained a highly efficient photocatalyst composite with pollutant adsorption properties. TiO2 was added to LIG and lased to form a mixture of rutile and anatase TiO2 with a decreased band gap (2.90 ± 0.06 eV). The LIG/TiO2 composite adsorption and photodegradation properties were tested in solutions of a model pollutant, methyl orange (MO), and compared to the individual and mixed components. The adsorption capacity of the LIG/TiO2 composite was 92 mg/g using 80 mg/L MO, and together the adsorption and photocatalytic degradation resulted in 92.8% MO removal in 10 min. Adsorption enhanced photodegradation, and a synergy factor of 2.57 was seen. Understanding how LIG can modify metal oxide catalysts and how adsorption can enhance photocatalysis might lead to more effective pollutant removal and offer alternative treatment methods for polluted water.
... As compared to lower BO-ZnO NPs concentrations, 0.080 g of the catalyst concentration attained rapid degradation in a short time. The decrease in degradation time is directly proportional to the increase in catalyst concentration, due to the enormous production of radicals (Khairnar and Shrivastava, 2019;Djebbari et al., 2021;Kumar et al., 2021;Yulizar et al., 2020;Dhir, 2020;Kim et al., 2020). The increased degradation percentage of MB dye is maybe due to the presence of more active sites and higher surface area in the catalyst. ...
Green synthesis of nanomaterials has emerged as an ecofriendly sustainable technology for the removal of dyes in the last few decades. Especially, plant leaf extracts have been considered as inexpensive and effective materials for the synthesis of nanoparticles. In this study, zinc oxide nanoparticles (ZnO NPs) were prepared using leaves extract of Brassica oleracea var. botrytis (BO) by co-precipitation and applied for photocatalytic/antibacterial activity. The synthesized BO - ZnO NPs was characterized by different instrumental techniques. The UV-Vis Spectrum of the synthesized material showed maximum absorbance at a wavelength of 311 nm, which confirmed the formation of BO-ZnO NPs. The XRD pattern of BO-ZnO NPs represents a hexagonal wurtzite structure and the average size of particles was about 52 nm. FT-IR spectrum analysis confirms the presence of hydroxyl, carbonyl, carboxylic, and phenol groups. SEM images exhibited a flower like morphology and EDX spectrum confirming the presence of the elements Zn and O. Photo-catalytic activity of BO-ZnO NPs was tested against thiazine dye (methylene blue-MB) degradation under direct sunlight irradiation. Around 80% of the MB dye got degraded at pH 8 under 75 min of sunlight irradiation. Further, we examined the antimicrobial and larvicidal activity of BO-ZnO NPs obtained through green synthesis. The antimicrobial study results showed that BO-ZnO NPs formed zones against human bacterial pathogens. The results showed the formation of an inhibition zone against B. subtills (16 mm), S.aureus (13 mm), K. pneumonia (13 mm), and E. coli (9 mm) respectively at a concentration of 100 μg/ml of BO-ZnO NPs. The larvicidal activity of the BO-ZnO NPs was tested against the fourth instar of Culex quinquefasciatus mosquito larvae The LC50 and LC90 values estimated through the larvicidal activity of BO-ZnO NPs were 76.03, 190.03 ppm respectively. Hence the above findings propose the synthesized BO-ZnO NPs by the ecofriendly method can be used for various environmental and antipathogenic applications.
... The COO-group of the carboxylic acid salt could be accountable for the peak at 1385 cm −1 [36]. As can be seen in the graph below, escin produced distinct peaks caused by its C-H group: asymmetrical peaks at 2924 cm −1 and symmetrical peaks at 2854 cm −1 , respectively; a stretching peak at 1113 cm −1 ; and an out-of-plane bending peak at 955 cm −1 [37,38]. The stretching vibration of the Cu-O and Ti-O bonds also appeared at nearly 710, 594, and 532 cm −1 [39]. ...
Nanocomposites comprised of CuO-TiO2-chitosan-escin, which has adjustable physicochemical properties, provide a solution for therapeutic selectivity in cancer treatment. By controlling the intrinsic signaling primarily through the mitochondrial signaling pathway, we desired nanocomposites with enhanced anticancer activity by containing CuO-TiO2-chitosan-escin. The metal oxides CuO and TiO2, the natural polymer chitosan, and a phytochemical compound escin were combined to form CuO-TiO2-chitosan-escin nanocomposites. The synthesized nanocomposites were confirmed and characterized using FTIR spectroscopy, TEM, and UV-Vis absorption spectroscopy. A human leukemia cell line (MOLT-4) was used to assess the efficacy and selectivity of nanocomposites. Based on a cytotoxicity study, CuO-TiO2-chitosan-escin nanocomposites had inhibition concentrations (IC50) of 13.68, 8.9, and 7.14 µg/mL against human T lymphoblast cells after 24, 48, and 72 h of incubation, respectively. Compared with untreated MOLT-4 cells, CuO-TiO2-chitosan-escin nanocomposite-treated cells significantly increased (p < 0.05) caspase-3, -8, and -9 and decreased the levels of antioxidant enzymes GR, SOD, and GSH. Furthermore, MDA for lipid peroxidase and ROS levels significantly increased (p < 0.05) in the treated cells than in the untreated cells. Remarkably, CuO-TiO2-chitosan-escin nanocomposite-mediated control of cell cycles were mainly achieved through the activation of caspase-3, -8, and -9.
... Despite the slight decreased photodegradation efficiency, both concentrations (40 and 60 ppm) reveal better results in terms of reaction kinetics compared to 20 ppm, especially for the first two hours. Moreover, these slight differences in photodegradation efficiency could be due to the saturation of photocatalytic active sites by the adsorbed dye [53]. In addition, the saturation of these active sites decreases the adsorption of O2 and OH˙ radicals which affects the generation of photons that are vital to the photocatalytic degradation. ...
Advanced Oxidation Processes (AOPs) have been developed in the field of environmental technologies. The aim of this study was to verify the efficiency of heterogeneous photocatalysis in the AOPs for the degradation of organic pollutants. The photocatalytic degradation processes were carried out under sunlight and microwave irradiation in remediation of malachite green (MG) dye taken as model organic pollutant. The copper oxide and copper-cobalt bimetallic oxide (Cu-500 and CuCo-500) were prepared by a simple coprecipitation method and calcined at 500°C. The synthesized photocatalysts were characterized by X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDX), and Diffuse Reflectance Spectroscopy (DRS) analysis for optical properties (band gap of 1.49 and 1.44 eV for Cu-500 and CuCo-500, respectively). Thereafter, the catalytic activities of the prepared photocatalysts for MG photodegradation were investigated. The influence of different parameters on the photocatalytic reactions, such as photocatalyst mass, initial dye concentration, and irradiation source, was studied. The results reveal the efficiency of the synthesized photocatalysts in the photodegradation of MG with higher rate and good reusability. Hence, the monometallic Cu-500 photocatalyst exhibited better catalytic performance compared to bimetallic CuCo-500.
... Decrease in the wavelength with irradiation time of malachite green and rhodamine B dyes with CoS·2HDA nanoparticles are shown in Figs. 12 and 13, respectively. Effect of acidic and alkaline pH was also tested while studying dye degradation behaviour and best degradation was obtained at pH 7. The present study finds importance from the point of view that amount of the CoS·2HDA nanoparticles required for degradation as well as the total degradation time of malachite green and rhodamine B were comparable to that reported in literature [51][52][53][54][55][56]. ...
Present study reports the simple and cost effective thermolytic method for the synthesis of cobalt sulphide nanoparticles (CoS NPs). The PXRD spectrum of cobalt sulphide (CdS) nanoparticles exhibited four peaks indexed to (100), (101), (102) and (110) crystal planes. The average particle size observed from DLS and PXRD was in the range 4.81-12.20 nm. A blue shift in band gap was observed from UV-visible spectra. The FESEM and TEM studies revealed that cobalt sulfide nanoparticles are of cubic and rectangle shapes. FTIR spectra of hexadecylamine (HDA) capped CoS NPs exhibited ν(N-H) absorption around 3350-3240 cm–1. The stretching frequency due to ν(Co-S) appeared in the region 334-332 cm–1. Proton NMR (1H) spectra of CoS NPs showed signals at nearly same positions as in case of capping agent, suggesting its capping nature. ESI-MS analyses of cobalt sulphide nanoparticles displayed peak at m/z = 124.93 corresponding to the [CoS2]+ ion. Thermogravimetric curves showed single step decomposition corresponding to 84.28% weight loss and 15.72% as final residue due to cobalt oxide. The degradation rate of rhodamine B and malachite green dyes after irradiating with sunlight showed 92-94% degradation while irradiated with UV-light of 4.8 eV show much slower degradation rate.
... The disappearance of the organic groups in FTIR demonstrates that complete degradation was occurring (see Figs. S4 and S5). Microwave degradation efficiencies for MG using 2D AFO are significantly higher than those reported in the literature for other types of material, as illustrated in Fig. S6 (Djebbari et al., 2021;Riaz & Ashraf, 2015;Zhang et al., 2016;Mao et al., 2018). ...
Prompt degradation of organic pollutants renders microwave (MW) catalysis technology extremely lucrative; ideal microwave catalysts are therefore being hunted with an unprecedented urgency. Ideal functional microwave catalyst should be highly crystalline, room temperature ferromagnetic (for magnetic retrieval), highly dielectric (for sufficient microwave absorption) apart from being structurally stable at high temperature. The potential of silver ferrite 2D sheets (2D AFO) synthesized using a novel microwave technique as a microwave catalyst for the degradation of a variety of organic dyes and antibiotics was investigated in this article. While organic dyes like malachite green (MG), brilliant green (BG) and nile blue A (NB) achieved 99.2%, 98.8% and 95.2%, respectively; antibiotic tetracycline hydrochloride (TCH) molecule resulted in 75.8% degradation efficiency. Total organic carbon (TOC) measurements yielded 76%, 59.1%, 49.1% and 47.6% of carbon content for MG, BG, NB and TCH, respectively. The reaction pathway via intermediates and subsequent degradation to CO2 and H2O is revealed by liquid chromatography-mass spectrometry (LCMS). Both superoxide and hydroxyl radicals are participating in the process, according to scavenger tests. The evolution of silver ferrite as a new 2D material and its demonstration as an ideal microwave catalyst will lead to a new beginning in catalysis science and technology.
We have successfully synthesized green carbon nanodots (CDs) on a large scale through catalytic hydrothermal carbonization, using apple and grape pomace as the primary carbon sources and KOH as a catalyst. The resulting nanodots are named ACD and GCD, respectively. We then created a nanocomposite by combining CDs and commercially available rutile TiO2 to enhance its photocatalytic and optical characteristics. Several analytical techniques were applied in the characterization of CDs and/or TiO2/CDs nanocomposites such as XRD, FTIR, IR, TEM, HRTEM, thermal analysis, spectrophotometric absorbance, and photoluminescence (PL). CDs exhibited a graphite structure with conjugated sp² domains and surface functional groups of carboxylate and hydroxyl, showing an average particle size of approximately 4 nm. When CDs were incorporated into TiO2, they acted as a peptizing agent and led to a reduction in size, decreasing aggregations, and increasing stability. This resulted in a synergistic effect that enhanced the material’s electronic and photophysical properties. TEM images and XRD analysis indicate that the TiO2/CDs nanocomposites exhibit considerably reduced particle dimensions in the nanoscale, in contrast to the original micrometer-sized TiO2. To investigate the TiO2/CDs nanocomposites’ photocatalytic efficiency, we used malachite green (MG) as a pollutant model. The photocatalytic performance of rutile TiO2 increased by about 21% after synergistic action with CDs for MG photodegradation during 45 min of reaction under UV illumination. This enhancement of photocatalytic oxidation increased in a basic medium. The addition of CDs to TiO2 increased its absorption in the UV-visible light region. Superoxide radicals (O2•−) and positive holes (h⁺) were identified as the primary active species accountable for the effective photocatalytic degradation of MG by the TiO2/CDs nanocomposites.
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