جستجوی مقالات مرتبط با کلیدواژه « rice-husk » در نشریات گروه « شیمی »

SiO2 is considered a promising candidate for future high-power energy Li-ion batteries thanks to its affordability and accessibility, low discharge potential (0.7 V vs. Li+/Li), and high specific capacity of 1965 mAh g-1. Rice husk naturally contains SiO2 in the form of nanoparticles, making it a reasonably priced anode material with a high silica content. In this study, amorphous and porous SiO2/C anode materials are successfully synthesized by calcinating rice husk with NaOH, an activating agent. The prepared anode materials exhibited a surface area of 210 m2 g-1 with pore sizes ranging from 50 to 100 nm. In addition, SiO2 particles were coated by a 3-5 nm carbon layer to depress volume expansion and thus enhance cycling performance. The SiO2/C anode provided a capacity of 1625.3 mAh g-1 in the 1st cycle and maintained around 645 mAh g-1 in the following 50 cycles. The optimal negative/positive capacity ratios were determined in coin cells and the high-capacity pouch cells (4x6 cm2, 40 mAh) were further assembled to demonstrate a potential application of SiO2/C in high-power Li-ion batteries.

Nitrate contamination of surface water through different human activities is an alarming issue for Human sound health survivorship. So, we have attempted to estimate and remove nitrate contamination levels in water samples, collected from the Rushikulya River in Odisha, India. A detailed study is done on the impact of nitrate contamination in various aspects and their removal is absorbed through an experimental composite adsorbent that is prepared taking rice husk dust and Bagasse waste from corn (Argo-based waste product) with different proportions of each. The nitrate absorbance was analyzed with the spectrophotometric method. The efficiency of adsorbents is identified through SEM and found that with an increase in the alkaline state of water sample up to 13 and composite proportion ratio with 20% rice husk and 80% bagasse waste from corn, removes nitrate up to 95% from contaminated water sample. A maximum of 98.0% of nitrate was removed from the water at a pH of 11. Also, maintaining the COD range of 250 mgL-1, the nitrate could be removed up to 94%.  The composite of CM-9 has the highest density of 279.88 kg m-3. These matrices are applied for the treatment of contaminated river water samples to remove nitrate.

The concern for the removal of pesticides in water resources is grown in recent years, which justifies the search for alternative technologies to those applied in conventional water treatment processes. The use of agricultural wastes directly for the preparation of the adsorbents, is a viable method, combining removal efficiency, low cost, and biodegradability of the material applied. The present work was carried out to evaluate the employability of Rice Husk (RH), a waste from rice agriculture, in Methyl parathion (MP) removal from aqueous solutions. To find the optimum removal yield of (MP) onto (RH), the effects of various experimental factors: adsorbent dosage, pH, and the effect of contact time were studied by using the batch experiments mode. The adsorption kinetic data were analyzed using the Pseudo First Order (PFO), Pseudo Second Order (PSO), and Elovich models. For the kinetic study, the adsorption process fitted the PSO model. Three adsorption isotherms namely the Langmuir, Freundlich, and Sips isotherms were applied to the adsorption equilibrium data. The results indicated that the parameters isotherm models are found to be suitable for fitting the present adsorption isotherms data in the following subsequent order: Sips > Langmuir> Freundlich.  The Sips isotherm exponent n is near the unity indicating that the adsorption data were more of Langmuir form suggesting that the surface of RH is homogeneous for MP adsorption. The monolayer adsorption capacity, qm, was found to be 4.38 mg/g. The present study showed that RH is a promising adsorbent for the removal of MP from an aqueous solution.

A series of bismuth-silicate photocatalysts were synthesized via the sol-gel method for photodegradation of methylene blue (MB) under sunlight irradiation, utilizing rice husk ash as a silica precursor. The scanning electron microscopy/energy dispersive X-ray (SEM/EDX) analysis detected Bi content in 3-10 wt% range. Furthermore, it can be seen that the porosity decreased as the Bi concentration increased. The N2 adsorption-desorption analysis indicates the presence of mesopores with an average diameter of 297-554 Å with Brunauer–Emmett–Teller (BET) surface area of 5.6-30.5 m2/g. The photocatalyst with a Bi concentration of 4 wt% (RHSBi-A2) was the most active in the photodegradation of MB; the removal reached 90% within 4 h. The photodegradation is proposed to be driven by superoxide ( ), hydroxyl (•OH) radicals, and hole (h+) based on the valence band (VB) and conduction band (CB) potentials. The porous silica framework is proposed to act as an electron reservoir, allowing better MB adsorption and enhancing light absorption.

The exaggerated release of industrial wastes especially those containing phenol into the environment led to the contamination of both surface and groundwater supplies. In the present work a synergistic and combined system technique between three operations, adsorption of phenol via (rice husk or granular activated carbon GAC as adsorbents) together with stripping by airflow and advance oxidation via hydrogen peroxide as the oxidation agent, to evaluate the possibility of using a proposed new design for internal airlift loop reactor for removing the phenol from wastewater. The experiments were set up in a cylindrical Perspex column consisting of a transparent outer column having a 15 cm inside diameter and 150 cm height that included an internal draught tube of 7.5 cm and extending vertically to 120 cm top contains a bed having a dimension (7.5 x 30 cm) filled with adsorbent materials (rice husk, granular activated carbon GAC) and a volume capacity 25 liters. The experiments were conducted under the influence of both of the following variables air flow rate (2-20) (L/min), treatment time (5-60 min), the molar ratio of hydrogen peroxide to phenol,(1:10, 1:15, and 1:20)). The results showed the success of the proposed design with obtaining a removal efficiency (83%),( 81%)when using GAC and the rice husk as adsorbent materials respectively, with a minimum remediation time 60 minutes, airflow rate of 18 L/min, and molar ratio(20) hydrogen peroxide to phenol. This study demonstrated that the proposed synergistic system could be utilized for the remediation of contaminated aqueous systems.

e husk is counted as an agricultural waste that results in environmental problems during its handling. In this work, rice husk was used as raw material for producing liquid biofuel (pyrolysis oil) via pyrolysis. The pyrolysis reaction was carried out at temperatures of 450, 500, and 550°C for 1 hour. The pyrolysis oil was collected and weighted for every 10 minutes. The results showed that the increase in pyrolysis temperature caused the yield of pyrolysis oil to increase. The properties in the term of heating value also increased while viscosity and density of pyrolysis oil decreased.  These properties were almost similar to diesel oil with a slightly lower heating value. The proposed model using the single reaction model and two stages model were fit to represent the mechanism of rice husk pyrolysis reaction in this study. However, the results of two stages model gave a lower error than those of the single reaction model. Furthermore, the rate of pyrolysis reaction at various temperatures could be determined using the kinetic data obtained from the developed model. This information would be useful for designing the pyrolysis reactor especially for producing biofuel (pyrolysis oil) from the rice husk.

In this work, mesoporous MCM-41 nanoparticles (MCM-41NPs) were synthesized using the rice husk ash (RHA), as the silica source at room temperature. Ag2O quantum dots were prepared using a chemical method in matrix nanoparticles, and used as an antibacterial material. Bactericidal activity of the nanomaterials was investigated against E. coli and S. aureus bacteria. The synthesized materials were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscope (TEM). The minimum concentrations of nanocomposite to inhibit the growth of E. coli and S. aureus strains were 12.5 µg/mL. The Ag2O quantum dots indicated acceptable antimicrobial properties, with an average diameter of 16 mm.

This study evaluates the adsorption of bisphenol-A (BPA) from aqueous solutions using nanosilica obtained from rice husk. Nanosilica (79 nm) was extracted from acid and thermal treated rice husk waste. The rice husk nanosilica (RHS) was fully characterized through X-Ray Diffraction Spectroscopy (XRD), Scanning Electron Microscopy (SEM), X-Ray Fluorescence Spectroscopy (XRF) and Fourier Transmittance Infrared Spectroscopy (FTIR). The spectroscopic analyses results revealed that the rice husk ash contains large fraction of amorphous silica. Batch adsorption experiments were carried out on BPA as a function of initial concentration, contact time, pH, adsorbent dosage and temperature. The maximum amount of BPA adsorbed was 4.267 mg/g with an optimum contact time of 45 min for 50 mg/L BPA solution at pH 8. The adsorption data were analyzed with adsorption isotherms and fitted best into the Langmuir model with R2 value of 0.994. The adsorption process followed the pseudo second order kinetics and was exothermic while the negative value of Gibbs free energy obtained revealed that the process is feasible at lower temperature.

The methodology involves preparing polyvinyl sulfuric acid as a solid acid by simple mixing ofpolyvinyl alcohol with chlorosulfonic acid in CH2Cl2 at room temperature. The catalytic ability ofthe solid acid was investigated for the facile conversion of benzylic alcohols to the unsymmetricalethers with aliphatic alcohols in the presence of the solid acid. Results show that the solid acid isan appropriate catalytic agent for these condensation reactions. The silica was also extracted fromlow-cost rice husk and the amorphous silica gel nanoparticles were prepared with sol- gel method.The polyvinyl sulfuric acid was supported on nano rice husk silica. Then the catalytic effect of thissystem was investigated for synthesis of unsymmetrical ethers which consisted of a combination ofhigh acidic power for this solid acid and high- surface area of nanoparticles. Results show that totallycatalytic effect of polyvinyl sulfuric acid supported on nano silica is more suitable than polyvinylsulfuric acid. The reason for this is in its ability to produce the end products in shorter reaction timeswhile having high isolated yields.

An agricultural waste and eco-friendly biosorbent i.e. rice husk has been used as a cheap adsorbent for the removal of methylene blue dye from aqueous solutions. The physical properties of the developed adsorbent were characterized using FTIR. The study was realized using batch experiments. The effects of contact time, pH, initial dye concentration, biosorbent dose and temperature were investigated. The adsorption data were evaluated by Freundlich and Langmuir isotherm models. The adsorption isotherm is best fitted by the Freundlich model, while the adsorption kinetics is well described by the pseudo-secondorder model. Different thermodynamic parameters i.e., changes in standard free energy, enthalpy and entropy have also been evaluated and it has been found that the dye adsorption onto rice was a spontaneous, endothermic and physical reaction.

In this study the effect of nano sized silica particles (nano-SiO2) on the physical and mechanical properties of rice husk and Old Corrugated Container (OCC)-cement boards was investigated. Modulus Of Rupture (MOR), Modulus Of Elasticity (MOE), Internal Bonding Strength (IB), density, water absorption and thickness swelling after 24 hours immersion in water and hardness were measured. Results showed that rice husk-cement boards with 2% nano SiO2 demonstrated the best physical and mechanical properties. It is related to better distribution and compaction of particles during compression without particles agglomerating. A higher property of 2%-nano-SiO2 content rice-husk-cement boards was confirmed by their higher hydration temperature. Addition of 3% nano-SiO2 to the mixture reduced the density because of both the substitution of denser cement particles by lighter nano-SiO2 particles and air entrapment in the boards. Furthermore, Scanning Electron Microscopy (SEM) analyses showed that the optimum amount of nano-SiO2 (2%) can fill micro pores and make a uniform structure with a rough surface which improves properties of composite boards.

An agricultural waste i.e. rice husk has been used as a cheap adsorbent for the removal ofleadas a harmful heavy metal from contaminated water via adsorption. The adsorption capacity of rice husk was calculated by equilibrium models. The results showed that the adsorption process has the best accordance with Langmuir model. The kinetics of the adsorption was also investigated and obtained that the experimental data has the best fit with pseudo-second kinetic model. In this study, the effect of the adsorbent amount as well aspH value on the results was also investigated.

An agricultural waste and eco-friendly biosorbent i.e. rice husk has been used as a cheap adsorbent for the removal of methylene blue dye from aqueous solutions. The physical properties of the developed adsorbent were characterized using FTIR. The study was realized using batch experiments. The effects of contact time, pH, initial dye concentration, biosorbent dose and temperature were investigated. The adsorption data were evaluated by Freundlich and Langmuir isotherm models. The adsorption isotherm is best fitted by the Freundlich model, while the adsorption kinetics is well described by the pseudo-secondorder model. Different thermodynamic parameters i.e., changes in standard free energy, enthalpy and entropy have also been evaluated and it has been found that the dye adsorption onto rice was a spontaneous, endothermic and physical reaction.

An agricultural waste i.e. rice husk has been used as a cheap adsorbent for the removal ofleadas a harmful heavy metal from contaminated water via adsorption. The adsorption capacity of rice husk was calculated by equilibrium models. The results showed that the adsorption process has the best accordance with Langmuir model. The kinetics of the adsorption was also investigated and obtained that the experimental data has the best fit with pseudo-second kinetic model. In this study, the effect of the adsorbent amount as well aspH value on the results was also investigated.