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The XRD patterns of the final products synthesized using the Na2O/SiO2 ratio equal (a) 0.9, (b) 6, and (c) 9.
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Nanozeolite NaA was synthesized by the hydrothermal method with silica extracted from rice husk as silica source. Amorphous silica with 87.988 wt% SiO 2 was extracted from rice husk ash by a suitable alkali solution. The effect of the crystallization time and the ratio of Na 2 O / SiO 2 on the properties of the final product was investigated. The...
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... Fig. 2a displays the PXRD results that were obtained for pristine adsorbent (NT-RH), and adsorbate (Cd-metal) loaded adsorbent (Cd@NT-RH) in a 2θ = 10-70range. An obvious, intense, and broader spike above 20 in the NT-RH diffraction pattern indicates that silica is the only crystalline phase in the sample; the characteristic diffraction peaks for other metallic constituents (oxides of aluminum, iron, calcium, magnesium, sodium, and potassium) were not observed, likely because of the very low percentage contents or the amorphous phase of these elements [18,19]. Along with the silica spike, the diffraction profile of Cd@NT-RH material has three other sharp spikes at 33.7 (1 1 1), 38.2 (2 0 0), and 55.4 (2 2 0). ...
This study describes a novel semi-synthetic sorbent for the sorption of cadmium nanoparticles (Cd-NPs) made from rice husks functionalized with nitric acid (NT-RH). Powder X-ray diffraction (PXRD) analysis verified the NT-RH synthesis and Cd sorption at the NT-RH (Cd@NT-RH). The surface functionalities of NT-RH that contributed most to the sorption of Cd-NPs were discovered using FTIR analysis. Scanning electron microscopic (SEM) examination shows that the acid-functionalized rice husk-based sorbent has a porous structure resembling a network with macro-sized voids. These voids practically vanish in the Cd@NT-RH, indicating their effective contribution to the sorbent's overall sorption activity. The elemental analysis further supports the PXRD and FTIR results and confirms the formation of NT-RH and Cd@NT-RH. Furthermore, the effect of varied working temperatures, sorbent dosages, sorbent-sorbate …
... Bamboo leaves are one of the main ingredients in making bamboo charcoal and are also commonly used to wrap food in the Asian region. Since bamboo leaves are typically discarded after being used for building materials or pulp manufacture, they are a good source of biodegradable material waste [26][27]. Research on bamboo leaves first centered on their potential as a pozzolanic material in cement manufacturing. ...
... The bamboo leaves will be cleaned with tap water to remove any impurities or any soil that stuck around the bamboo leaves. After that, the bamboo leaves will be cut into smaller pieces so that it will make easier to dry [24][25][26][27] Then, the bamboo leaves will be put into aluminium foil and then dry in oven for 90℃ for duration 24 hours [30]. Next, the bamboo leaves were calcined in manual furnace that have in the wood workshop in UMK in 300℃ for 30 minutes to produce coal. ...
Bamboo leaves, a readily available agricultural waste globally, serve as a valuable source of organic silica, often referred to as biosilica. Despite containing a substantial silicon dioxide (SiO2) content, bamboo leaves are frequently discarded by communities. Remarkably, the silica content in bamboo leaves exceeds 70%. Acid leaching is employed to extract the silica, with various factors and types of acids being compared in the process. The resulting silica is highly porous and firmly bonded. The extracted silica's purity, amorphous nature, and the presence of functional groups have been verified through XRD and FTIR studies. Additionally, TGA is utilized to monitor the material's weight changes with increasing temperature.
... This behavior is similar to the XRD patterns of RHA obtained in this work and by other authors at different temperatures. For instance, Muramatsu et al. 26 have reported two diffraction peaks at 23° and 43° on RHA obtained at 430 °C/2 h; Ghasemi et al. 27 have shown a main diffraction peak at 21.9° on RHA obtained at 700 °C for 6 h, showing the crystalline phase in the form of cristobalite, tridymite, and quartz. On the other hand, by increasing the temperature and time, the formation of crystalline phases is observed on AGA8005h sample through the appearance of several peaks, some of them shown at 21.9°, 23.5°, 25.8°, 27.7°, 29.7°, 30.8°. ...
Abstract This paper presents a study about the characterization of dielectric properties (dielectric constant $${\varepsilon }_{r}$$ ε r and dielectric-loss constant $$\mathrm{tan}\delta$$ tan δ ) of samples derived from two different biomass types: rice husk ash (RHA) and annoni grass ash (AGA).The procedure is carried out using the resonant cavity method along with a vector network analyzer. For this purpose, four different ashes were produced, by burning rice husk and annoni grass at two different temperatures and burning times: 400 °C/30 min (RHA40030 and AGA40030) and 800 °C/5 h (RHA8005h and AGA8005h). These ashes were combined with Bakelite to produce cylindrical samples with diameter of 30 mm and thickness of 4.5 mm, which were characterized considering the frequency in the test band for 5G technologies ( $${f}_{o}=3.5$$ f o = 3.5 GHz). Experimental results showed that the samples burnt at high temperature showed very high $$\mathrm{tan \delta }$$ tan δ when compared to the samples burnt at low temperature, mainly for AGA8005h. These values are $$\mathrm{tan \delta }=$$ tan δ = 0.1690 and 1.4900 for RHA8005h and AGA8005h, respectively. The resulting dielectric constants are $${\varepsilon }_{r}$$ ε r = 3.87 for RHA8005h and $${\varepsilon }_{r}$$ ε r = 15.14 for AGA8005h). These very high dielectric loss tangent, indicate that these materials exhibit formidable properties for electromagnetic energy absorption, hence allowing the application as radiation-absorbent material (RAM).
... 39-1425. Similar findings have been reported in previous studies (Ghasemi and Younesi 2011;Costa and Paranhos 2018;Almeida et al. 2019;Bakdash et al. 2020). Upon coating, a slight change in the peak is observed. ...
This work presents the synthesis of SiO2/Nb2O5 and SiO2/ZnS heterostructures using the microwave-assisted hydrothermal (MAH) method, which is fast and has low temperature. The silica used in the synthesis was obtained by burning the rice husk without any pre- or post-treatments. The obtained samples were characterized using various techniques such as X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and UV-visible. The obtained silica was found to be amorphous, and the materials used for modification showed characteristic of the type of synthesis used. SEM images showed that Nb2O5 and ZnS interacted with the SiO2 surface, filling the voids. In the photocatalytic process, the heterostructures showed enhanced decolorization efficiency for dyes such as rhodamine B (RhB) and methylene blue (MB) compared to SiO2. For RhB, the silica decolorized approximately 24%, and for MB, it discolored approximately 27%; SiO2/Nb2O5 showed 91.24% decolorization efficiency for RhB and 72.77% MB, while SiO2/ZnS showed approximately 96% for RhB and 100% for MB. All samples were tested under the same conditions. This demonstrates that the use of rice husk residue not only improves the photocatalytic activity of heterostructures but also promotes the utilization of improperly discarded residues.
... Thus, the crystalline or amorphous phase of the RHA samples can be directly linked to the combustion processes and to the temperatures adopted, as confirmed by the XRD analysis. 23 Regarding the zeolite synthesis, amorphous silica is advantageous since it is more reactive 24,25 and easily dissolving in NaOH solution. 26,27 Figure 3 shows SEM images of the ashes RHA01, RHA02 and RHA03. ...
... The crystallization time, the final average crystal size, and the degree to which the product is contaminated with other zeolite phases are all dependent on the properties of the silica source. 25,36,37 Conclusion Rice husk ash was successfully used as a raw material to synthesize LTA zeolite. The high silica content of this material opens a possibility for its use as a zeolite precursor. ...
... The performance of the hydrothermal method is affected by several parameters including pressure, temperature, batch composition, Si/Al ratio, reactant materials, overall alkalinity, aging time, template condition and seeding [80,81]. Several attempts on zeolites synthesis via hydrothermal methods have been reported [82][83][84][85][86]. The hydrothermal method is traditionally adopted due to several advantages, which include low energy consumption, ease of maintenance, low air pollution. ...
Adsorption-based post-combustion carbon capture is a promising emerging technology for capturing CO2 emissions from fossil-fueled power plants due to the ease of adsorbent regeneration in comparison with solvent-based technologies. To increase its competitiveness, research efforts have focused on the development of new adsorbent materials and processes. This paper presents a state-of-the-art review of such efforts, focusing on lab synthesis and characterization of adsorbent materials, (carbon capture) experimental studies, molecular simulation, process modelling\simulation and techno-economic analysis. Most experimental studies on adsorption-based post-combustion capture are at bench scale. Just a few experimental studies are at pilot scale. There are currently no commercial deployment of adsorption-based post-combustion capture technology. This review paper points out challenges encountered in these experimental investigations utilizing different adsorbent materials, limiting its commercial deployment. These gaps in experimental investigations need further research especially in the chemical modification of the adsorbent materials to increase the adsorption capacity. Molecular simulation of adsorbents and process modelling\simulation of carbon capture processes are cost-effective and time efficient approaches for the assessment of adsorbents’ CO2 capture performance. The review also highlighted the need for more research in the model development of adsorbent materials at molecular scale and the model development of adsorption-based post-combustion process adopting new reactor configurations to further reduce the cost of CO2 capture.
... X-ray diffraction analysis was carried out to understand the crystalline structure of nickel loaded SiO 2 -RH catalysts and the patterns are reported in Fig. 1. All the XRD patterns showed a broad peak at 2θ = 22 ∘ , which is a reflection of amorphous silica, [41] (Fig. 1A) [42]. The sharp peaks indicated that the crystallite size of NiO has increased with an increase in NiO loading. ...
SiO2 derived from rice husk (SiO2-RH) has been used as a support for NiO catalyst for azide-alkyne cycloaddition in aqueous media at 60 °C. The 10wt%NiO/SiO2-RH catalyst was found to be an efficient and reusable catalyst for the regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles with broad substrate scope that included carbohydrate triazoles and one-pot synthesis of triazoles. The reaction mechanism followed through a nickel π-complex on the surface of the NiO/SiO2-RH catalyst. The catalyst was recycled up to four times that showed consistent activity and selectivity. The structure-activity correlation and mechanistic studies were established by BET-SA, H2-TPR, NH3-TPD, SEM-EDX, XPS, XRD, ²⁹Si SS MAS NMR and H2-pulse chemisorption studies and a plausible reaction mechanism has been proposed.
... The XRD patterns of the nano-zeolite prepared (illustrated in Figure 5) showed that the disorderly peaks of 2θ between 6.33-23.778 and 40-50 indicate to amorphous zeolite [37][38][39]. For 1% Ag2O3/nano-zeolite, the clear peaks (shown in this Figure 5) at 2θ of 23.5, 31.5, Figure 5. ...
Oxidative desulfurization process (ODS), enhanced with a novel metal oxide (Ag ions) as an active component over nano-zeolite that has not been reported in the literature, is used here to improve the fuel quality by removing mercaptan (as a model sulfur compound in the light naphtha). Nano-crystalline (nano-support (Nano-zeolite)) composite is prepared by Incipient Wetness Impregnation method loaded with a metal salt to obtain 0.5, 1 and 1.5% of Ag2O3 over Nano-zeolite. The new homemade nano-catalysts (Ag2O3/Nano-zeolite) prepared are characterized by Brunauer–Emmett–Teller (BET) (surface area, pore volume and pore size), X-ray Diffraction (XRD), Fourier Transform Infra Red (FTIR), and Scanning Electron Microscopy (SEM) analysis. The ODS process is then used to evaluate the performance of the catalysts for the removal of sulfur at different reaction temperatures (80–140 °C) and reaction times (30–50 min) in a batch reactor using the air as oxidant. 87.4% of sulfur removal has been achieved using 1% silver oxide loaded on Nano zeolite (1% of Ag2O3/Nano-zeolite) giving a clear indication that our newly designed catalyst is highly efficient catalyst in the removal of sulfur compound (mercaptan) from naphtha. A new mechanism of chemical reaction for sulfur removal by oxygen using the new homemade catalyst (Ag2O3/Nano-zeolite) prepared has been suggested in this study. The best kinetic model parameters of the relevant reactions are also estimated in this study using pseudo first order technique based on the experimental results. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
... The success of biosorption technique has been influenced by the proper selection and operation of an effective biosorbent. Several dried biomasses such as Dunaliella, Nostoc, Anabaena, and Spirulina (Arthrospira) have been investigated by many researchers and concluded as effective removal agent for heavy metal ion elimination from effluent (Harikumar et al. 2012;Ghasemi and Younesi 2011). The removal of Cr(VI) was performed using the autotrophic Chlorella vulgaris under different reduction conditions (H.-W. ...
The current investigation focuses on a systematic study of application of two dried algal biomass (i.e., Nostoc sp. and Turbinaria vulgaris) in removal of Cr(VI) from synthetic solution as well as tannery industrial wastewater. The optimized conditions for Cr(VI) removal are nearly same for the both the biosorbents (i.e., pH 2.8, initial Cr(VI) concentration 100 mg L⁻¹, biomass dosage of 1.2g L⁻¹, contact time 120 and 110 min). Nostoc sp. (qmax=23.94mg g⁻¹) was observed to possess a superior removal capability when compared to Turbinaria vulgaris (qmax=21.8mg g⁻¹). Desorption studies were performed with four different desorbing agents. Application study was conducted using tannery wastewater with Nostoc sp. and 94.20% removal of Cr(VI) was obtained. Hence, this study revealed that Nostoc sp. and T. vulgaris both have great potential to be an environment friendly and economic biosorbent for removal of Cr(VI) containing industrial effluent.
Graphical abstract
... The XRD of RHA (Fig. 4a) shows a distinct peak at 21.9º is a shred of strong evidence that advocates the crystalline nature of silica in rice husk ash. The uncontrolled burning conditions of rice husk at 700 °C for 7 h have been accounted for the crystallization of silica in rice husk ash in other similar studies [42]. The XRD of SiNP (Fig. 4b) shows a strong peak centered at a 2θ angle of 22° which confirms the presence of pure, amorphous state nanosilica and also the absence of other impurities [43]. ...
Nanocomposites have been acknowledged to revolutionize various fields including food science due to their nature-friendly approach, and has gained high-priority in food preservation and safety. In this study, silver nanoparticles (AgNPs) were synthesized using Hydrilla verticillata leaf extract as the reducing agent and nanosilica was prepared from rice husk ash by a simple non-conventional method. The obtained nanosilica was found to be spherical, homogenous, and monodispersed with a diameter range of 11–13.6 nm. The synthesized nanosilica was mixed with reduced silver nanoparticle solution to form silver-silica (Ag–SiO2) nanocomposite. Scanning electron microscopy obervations showed that the nanocomposite was spherical shape with diameter ranges between 20.1–42.6 nm, and the micrograph also revealed that the AgNPs appear as bright spots over the surface of nanosilica. Fourier Transform Infrared Spectroscopy results illustrated the formation of Ag–SiO2 nanocomposite by the changes in intensity and appearance of newer absorption prominent bands compared to nanosilica alone. The X-Ray Diffraction of nanocomposite showed three distinct diffraction peaks recorded at 2θ values 27.84º, 32.28º and 46.25° corresponds and confirms the presence of AgNP in Ag–SiO2. The nanocomposite was then formulated with sodium alginate to form a sodium alginate-based nanocomposite edible coating solution. The effect of the application of the nanocomposite formulation on the quality of fresh apple and pear cut-fruits was evaluated for degree of browning, weight loss, total soluble protein, total phenol content, and microbial growth. The results indicated that the formulation is effective and promising for the preservation of fresh-cut fruits.
