Rice Husk Based Activated Carbon Research Articles

Rice husk-based activated carbon/carbon nanotubes composites for synergistically enhancing the performance of lead-carbon batteries

Lead-carbon batteries (LCBs), an advanced form of lead-acid battery (LAB) technology, incorporate super-capacitive carbon materials into the negative electrode. Rice husk-based activated carbon (RHAC) is a promising additive for LCBs due to its favorable properties. However, RHAC's amorphous structure impedes electronic conduction, and its zigzag microporous channels hinder ion transport, leading to degraded high-rate performance. This study addresses these issues by growing carbon nanotubes (CNTs) in situ on RHAC through a one-step heat treatment, resulting in carbon nanotubes-loaded RHAC (CNTs/RHAC), and the electronic conductivity and ionic conductivity are simultaneously enhanced. When CNTs constitute 30 wt.% of CNTs/RHAC, the negative electrode achieves a cycle life of 4721 cycles at a 2C rate under 50% state of charge, which is 10.04 times that of the blank anode. The enhanced performance is attributed to the synergistic effects of CNTs and RHAC, where CNTs form long-range conductive networks among the negative electrode active material (NAM) and facilitate the diffusion and electro-deposition of Pb2+, while the high specific surface area (SSA) and hierarchical porous structure of RHAC enhance its capacitive function, leading to a stable lead-carbon composite structure.

PEDOT-coated rice husk-based activated carbon: Boosting lead-acid battery performance

Despite the surge in novel energy storage systems, lead-acid batteries remain entrenched in the market, chiefly attributed to their well-established technology, affordability, and dependable safety profile. Yet, they are not without shortcomings, notably their limited energy density and abbreviated cycle life. The profound impact of positive electrode materials on lead-acid batteries is undeniable, as these materials directly dictate the batteries' charging and discharging efficiency, energy density, cycle longevity, and overall stability. Here we report on an innovative positive active material additive, wherein the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is coated onto rice husk-based activated carbon (RHAC) surfaces via in-situ polymerization in solution to form a composite material (PEDOT@RHAC). Astonishingly, lead-acid batteries fortified with PEDOT@RHAC within their positive plates showcased remarkable electrochemical prowess. Incorporating PEDOT@RHAC into the positive plates of lead-acid batteries has demonstrated exceptional electrochemical performance. The enhanced deep cycling capability of these batteries is evident, with a substantial increase in cycle life by 2.08 times and an augmentation in discharge capacity by 1.3 times compared to the control batteries. This positive electrode additive plays a pivotal role in augmenting the overall performance and extending the lifespan of lead-acid batteries, potentially paving the way for their broader commercial application.

Removal of Cr(VI) from aqueous solution by Rice-husk-based activated carbon prepared by Dual-mode heating method

Rice husk-based activated carbon was prepared with the help of zinc chloride using microwave and electrical dual-mode heating. The pore characteristics and chemical properties of rice husk-based activated carbon (RH-AC) were characterized by BET, XRD, Raman spectra, FTIR and pHIEP (pH of isoelectric point). The specific surface area of RH-AC is 1719.32 m2/g with a total pore volume of 1.05 cm3/g. The performance of RH-AC for removing Cr(VI) from aqueous solution was examined considering the variation of the contact time (0–120 min), pH value (2.0–9.0), adsorbent dose (0.5–3.0 g/L), initial concentration (28–145 mg/L) and solvent temperature (15–45 °C). The ideal pH for Cr(VI) removal is between 2.0 and 3.0 with the equilibrium time of 90 min, achieving the maximum adsorption capacity of 56.82 mg/g with the pH of 3.0. Comparable study on the established kinetic models and isotherms to simulate the removal of Cr(VI) by RH-AC was carried out to sort out the inherent mechanism of the absorption. Reasonable agreements could be obtained by the pseudo-second-order kinetic model and Langmuir, Freundlich and Tempkin isothermal models. Results from Body model simulation suggest that external mass transfer was the essential cause for rate-controlling in the adsorption process of Cr(VI).

The influence of the characteristics of rice husk-based activated carbon on the performance of lead-carbon batteries and its potential mechanisms

We explore the effects of rice husk-based activated carbon (RHAC) with different pore structure and functional groups on the performance of lead-carbon batteries (LCB) in high-rate partial state of charge (HRPSoC) and its potential mechanisms. The results show that the performance of negative electrode is mainly affected by the rate and efficiency of RHAC on electrocatalytic of lead deposition. Notably, the reaction of phosphoric acid with silica in rice husk can significantly increase the content of phosphorus functional groups, which can enhance the electrocatalytic rate by complexing lead ions and inhibit hydrogen evolution reaction (HER). Micropore is more prone to hydrogen evolution in the medium-to-high polarization region (-1.25V∼-1.5 V vs Hg/Hg2SO4) and hinder lead ion mass transfer, which leads to the general cycle performance of LCB containing high microporosity RHAC. In addition, RHAC only has a certain electric double layer capacitance (EDLC) contribution at the end of cycle, which is still on the premise that RHAC has high specific surface area (SSA) and mesoporosity.

Performance investigation of the hybrid methods of adsorption or catalytic wet air oxidation subsequent to electrocoagulation in treatment of real textile wastewater and kinetic modelling

The performances of two hybrid wastewater treatment methods were compared to determine which method is more effective for improving the reusability of textile industry wastewater as irrigation water. In the hybrid treatment processes, either adsorption or catalytic wet air oxidation (CWAO) was performed subsequent to the electrocoagulation. The performances of the adsorption and catalytic wet air oxidation methods were evaluated according to the irrigation water criteria. Rice husk based activated carbon (RHAC) was used as adsorbent and catalyst support material in the adsorption and CWAO, respectively. BiNiO3-RHAC catalyst was prepared and used in CWAO process. The irrigation water criteria for total organic carbon (TOC), turbidity, and color were met and 91 % TOC reduction was achieved after the sequential application of electrocoagulation and adsorption. Freundlich isotherm and second order adsorption kinetics were regarded as the most suitable models to fit the adsorption data. The application of electrocoagulation and catalytic wet air oxidation yielded 62 % TOC removal whereas the oxidation reaction followed a two-step second order reaction kinetics.

Single and Binary Dye Adsorption of Methylene Blue and Methyl Orange in Alcohol Aqueous Solution via Rice Husk Based Activated Carbon: Kinetics and Equilibrium Studies

The present work was mainly focused on the single and binary adsorption of methylene blue(MB) and methyl orange(MO) from alcohol aqueous solution over rice husk based activated carbon(RHAC). The study of single dye adsorption equilibrium experiments found that the Langmuir adsorption model was consistent with the adsorption behavior of RHAC on MB and MO, indicating that it was a single layer adsorption. The adsorption behavior conformed to the pseudo-second-order kinetic model. The binary dye adsorption experiments showed that the Langmuir-Freundlich model could be applied to describe the adsorption behavior of RHAC on MB and MO. Comparation with the single dye system, the adsorption capacity on the binary dye system was larger, and there was “competitive adsorption” and “synergistic adsorption” effects existed. Meanwhile, the pseudo-second-order kinetic model also fit for the binary dye adsorption behavior.

Long‐Life Lead‐Acid Battery for High‐Rate Partial‐State‐of‐Charge Operation Enabled by a Rice‐Husk‐Based Activated Carbon Negative Electrode Additive

AbstractLead sulfation severely shortens the cycling life of lead‐acid battery under high‐rate partial‐state‐of‐charge (HRPSoC) operation. Adding carbon materials into negative active mass has been demonstrated as an effective strategy to suppress the sulfation. In this paper, rice‐husk‐based activated carbon (RHAC) with high specific surface area and high pore volume exhibits excellent performances on enhancing the discharge capacity, the dynamic charge acceptance and especially the cycling life of negative electrode of lead acid battery. Results show that the HRPSoC cycling life of negative electrode with RHAC exceeds 5000 cycles which is 4.65 and 1.42 times that of blank negative electrode and negative electrode with commercial activated carbon, respectively. These outstanding performances are ascribed to the unique architectural properties of RHAC comparing with commercial activated carbon, such as three‐dimensional porous structure for acid storage, high mesopore volume for efficient ions transport and large external specific surface area for energetic Pb deposition.

Removal of Pb(II) from water by the activated carbon modified by nitric acid under microwave heating

The rice husk based activated carbon (RH-AC) was treated by nitric acid under microwave heating, in order to improve its capability for the removal of heavy metal ions from water. The optimal conditions for the modification of RH-AC (M-RH-AC) were determined by means of orthogonal array experimental design, giving those as the concentration of nitric acid of 8mol/L, modification time of 15min, modification temperature of 130°C and microwave power of 800W. The characteristics of the M-RH-AC and RH-AC were examined by BET, XRD, Raman spectrum, pH titration, zeta potential, Boehm titration and FTIR analysis. The M-RH-AC has lower pore surface area, smaller crystallite, lower pHIEP and more oxygen-containing functional groups than the RH-AC. Removal capacity of Pb(II) ions by the M-RH-AC and RH-AC from water solution was estimated concerning the influence of contact time, pH value, and initial concentration. The equilibrium time of Pb(II) removal was found to be around 90min after modification process. Two kinetic models are adopted to describe the possible Pb(II) adsorption mechanism, finding that the adsorption rate of Pb(II) ions by the M-RH-AC is larger than that of RH-AC.

High surface area rice husk‐based activated carbon prepared by chemical activation with ZnCl2‐CuCl2 composite activator

In this study, rice husks (RHs), an agriculture by‐product, were used as precursor for the production of activated carbon by chemical activation with ZnCl2‐CuCl2 composite activator. The effect of process variables, such as ZnCl2 concentration, CuCl2 concentration, activation temperature, and activation time, were investigated. The optimal process condition was obtained through orthogonal test. Then the morphology, pore structure, and surface chemistry of rice husk‐based activated carbon (RAC) were analyzed. When using 5 mol/L ZnCl2 and 0.4 mol/L CuCl2 at the carbonization temperature of 500°C for 1.5 h, the BET surface area of the produced activated carbon was as high as 1924 m2/g and the total pole volume reached 1.493 cm3/g. The surface area was strongly affected by ZnCl2 concentration and the subsequent activation temperature. RAC prepared under the optimum conditions had remarkable adsorptive properties and notable treatment effect for fuchsine. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 133–140, 2016

A green technology for the preparation of high capacitance rice husk-based activated carbon

Rice husk (RH) is a kind of biomass with huge amount in the world. Comprehensive utilization of RH is of great significance for a sustainable society. In this paper, a green technology to produce high capacitance rice husk-based activated carbon (RHC) was developed. High capacitance RHC was prepared by KOH activation of RH. The waste liquid produced in the washing procedure of RHC was transformed into nano-SiO2 by acidification with HCl. The KCl saline solution produced from the preparation of nano-SiO2 was used to obtain water via evaporation and prepare KOH via electrolysis. Importantly, the collected water and KOH was reused in this technology. The obtained RHC possessed a specific surface area as high as 3263 m2 g−1, and exhibited a high specific capacitance of 330 F g−1 in 6 mol L−1 KOH aqueous solution. The nano-SiO2 was amorphous with average diameter of ∼30–40 nm. In addition, the economic analysis demonstrated a significant gross profit margin of 70.72% for the products. The technology is simple, feasible, low-cost and environmentally friendly for large-scale production.

Adsorptive Removal of Ni<sup>2+</sup> from Aqueous Solution Using Rice Husk-Based Activated Carbon

An attempt was made to study the potential of rice husk as an alternative cheap precursor for activated carbon to remove Ni2+ from aqueous solution. Rice husk was treated chemically (with NaOH) and physically (carbonization) to prepare rice husk based activated carbon (RHAC). The textural properties of RHAC, i.e. surface area (255 m2/g) and pore volume (0.17 cm2/g), were determined by N2 adsorption using Brunauer-Emmett-Teller (BET) surface analyzer. RHAC was also characterized for its morphology and its elemental compositions. The adsorption studies for the removal of Ni2+ from aqueous solution were carried out using different dosage of RHAC as adsorbent as a function of varied contact time. The concentration of Ni2+ was determined by atomic absorption spectrometer (AAS). The results obtained from adsorption studies indicate good potential of rice husk as a cheap precursor to produce activated carbon for the removal of Ni2+ from aqueous solution. The equilibrium data from adsorption studies fitted well the of Langmuir and Freundlich isotherm models.

Hybrid supercapacitors integrated rice husk based activated carbon with LiMn2O4

The technology development of supercapacitor is in the progress to meet the strong demands for increasing specific energy and reducing cost. We present a hybrid supercapacitor that integrated rice husk based activated carbon (RHC) with LiMn2O4. The electrochemical investigations revealed that the specific energy of the hybrid supercapacitor (LiMn2O4/RHC) has reached up to 29.5 W h kg−1, and the energy retention is 81.2% over 10 000 cycles at 0.3 A·g−1 charge/discharge current. The excellent double layer electrical storage of the RHC is mainly attributed to its high specific surface area of 2516 m2 g−1 and the average pore diameter of 3.02 nm.

Rice Husk and Sugarcane Baggase Based Activated Carbon for Iron and Manganese Removal

Iron and manganese are commonly present in groundwater supplies used by many water systems. The presence of iron and manganese in the drinking water is not harmful to human bodies. However, higher concentration causes discoloration, staining, turbidity and bad taste problems. It also form iron oxide or manganese dioxide accumulations in pipes.In the present work, low cost methods have been evolved for the removal of iron and manganese from ground water using Rice Husk based Activated Carbon (RHAC) and Sugarcane Baggase based Activated Carbon (SBAC). Exhaustive experiments have been conducted in the Laboratory on sediment columns with variable depths of 10, 20, 30, 40, and 50cm. Four graded types of sediment collected from the banks of Rivers Brahmani, Koel, Sankha and Budhabalanga were studied for proper removal of suspended solids by maintaining sufficient infiltration rates. It has been observed that the infiltration rate is maintained for the soil column of 50cm without having any impact of the suspended solids. The Iron and manganese concentrations are found to be removed 100% after passing through the filter material in both the cases.

Adsorptive Removal of Ni<sup>2+</sup> from Aqueous Solution onto Rice Husk-Based Activated Carbon

The potential of rice husk-based activated carbon (RHAC) as an alternative low-cost adsorbent for the removal of Ni2+ from aqueous solution was studied. RHAC was prepared via chemical treatment using NaOH followed by the carbonization process. The textural properties of rice husk-based activated carbon, i.e. surface area (253 m2/g) and pore volume (0.17 cm2/g), were determined by N2 adsorption. The adsorption studies to remove Ni2+ from aqueous solution using RHAC were carried out at a fixed initial concentration of Ni2+ (150 ppm) with varying RHAC as a function of contact time at room temperature. The concentration of Ni2+ was determined by atomic absorption spectrophotometer (AAS). The maximum removal of Ni2+ was increased from 40% to 89% when the amount of RHAC was increased from 0.1 g to 0.5 g. The isotherm and kinetic analyses showed that equilibrium data of adsorption studies fitted well Langmuir, Freundlich and second order kinetic models.

Integrated Bacillus sp. immobilized cell reactor and Synechocystis sp. algal reactor for the treatment of tannery wastewater

The wastewater discharged from leather industries lack biodegradability due to the presence of xenobiotic compounds. The primary clarification and aerobic treatment in Bacillus sp. immobilized Chemo Autotrophic Activated Carbon Oxidation (CAACO) reactor removed considerable amount of pollution parameters. The residual untreated organics in the wastewater was further treated in algal batch reactor inoculated with Synechocystis sp. Sodium nitrate, K(2)HPO(4), MgSO(4).7H(2)O, NH(4)Cl, CaCl(2)·2H(2)O, FeCl(3) (anhydrous), and thiamine hydrochloride, rice husk based activated carbon (RHAC), immobilization of Bacillus sp. in mesoporous activated carbon, sand filter of dimensions diameter, 6 cm and height, 30 cm; and the CAACO reactor of dimensions diameter, 5.5 cm and height, 30 cm with total volume 720 ml, and working volume of 356 ml. In the present investigation, the CAACO treated tannery wastewater was applied to Synechocystis sp. inoculated algal batch reactor of hydraulic residence time 24 h. The BOD(5), COD, and TOC of treated wastewater from algal batch reactor were 20 ± 7, 167 ± 29, and 78 ± 16 mg/l respectively. The integrated CAACO system and Algal batch reactor was operated for 30 days and they accomplished a cumulative removal of BOD(5),COD, TOC, VFA and sulphide as 98 %, 95 %, 93 %, 86 %, and 100 %, respectively. The biokinetic constants for the growth of algae in the batch reactor were specific growth rate, 0.095(day(-1)) and yield coefficient, 3.15 mg of algal biomass/mg of COD destructed. The degradation of xenobiotic compounds in the algal batch reactor was confirmed through HPLC and FT-IR techniques. The integrated CAACO-Algal reactor system established a credible reduction in pollution parameters in the tannery wastewater. The removal mechanism is mainly due to co-metabolism between algae and bacterial species and the organics were completely metabolized rather than by adsorption.

Integrated biological and catalytic oxidation of organics/inorganics in tannery wastewater by rice husk based mesoporous activated carbon–– Bacillus sp.

The rice husk based activated carbon (RHAC), used in this study was precarbonized and activated using phosphoric acid. The activated carbon was characterized with the help of N 2-adsorption/desorption, FT-IR and scanning electron microscope to determine surface area, functional groups and surface morphology respectively. Bacillus sp. isolated from tannery wastewater was immobilized in this rice husk based activated carbon and packed in a reactor (named CAACO reactor). The wastewater having the following characteristics––chemical oxygen demand (COD): 1716 ± 392 mg/l; biological oxygen demand (BOD): 393 ± 114 mg/l, sulphate: 940 ± 217 mg/l and sulphide: 193 ± 56 mg/l––was applied at a hydraulic loading rate of 0.7376 m 3/m 3/day and surface loading rate of 0.2438 m 3/m 2/day to the CAACO reactor. The temperature was maintained at 30 °C and the pressure at one atmosphere. It was found that the reduction in COD, BOD, sulphide and sulphate were respectively 87%, 96%, 100% and 40% under an air oxidation of 2 h.

Adsorption of Cr(VI) on micro- and mesoporous rice husk-based active carbon

The adsorption of hexavalent chromium from aqueous medium by rice husk-based activated carbon (RHC) was studied. The extent of adsorption was studied as a function of pH, contact time, contact temperature, adsorbate concentration and adsorbent with different pore structure. The removal of Cr(VI) by RHC was first introduced. The adsorption of two carbons activated by KOH-activation and NaOH-activation was discussed. The difference was studied through pore size distribution, pore volume and the adsorption capacity.

Alcohol from sulphite cellulose waste lyes: C. G. Schwalbe.( Zeit. Angew.. Chent., xxiii, 1537.)

The rice husk based activated carbon (RH-AC) was treated by nitric acid under microwave heating, in order to improve its capability for the removal of heavy metal ions from water. The optimal conditions for the modification of RH-AC (M-RH-AC) were determined by means of orthogonal array experimental design, giving those as the concentration of nitric acid of 8 mol/L, modification time of 15 min, modification temperature of 130 °C and microwave power of 800 W. The characteristics of the M-RH-AC and RH-AC were examined by BET, XRD, Raman spectrum, pH titration, zeta potential, Boehm titration and FTIR analysis. The M-RH-AC has lower pore surface area, smaller crystallite, lower pHIEP and more oxygen-containing functional groups than the RH-AC. Removal capacity of Pb(II) ions by the M-RH-AC and RH-AC from water solution was estimated concerning the influence of contact time, pH value, and initial concentration. The equilibrium time of Pb(II) removal was found to be around 90 min after modification process. Two kinetic models are adopted to describe the possible Pb(II) adsorption mechanism, finding that the adsorption rate of Pb(II) ions by the M-RH-AC is larger than that of RH-AC.