Rice Husk Activated Carbon Research Articles

Turning waste into wonder: Arsenic removal using rice husk based activated carbon

In this study, rice husk activated carbon (RHAC) was synthesized by physicochemical activation, which consists of heat treatment with CO2 gasification and KOH chemical treatment to eliminate arsenic (As) from the polluted water. Initial arsenic concentrations, solution pH, solution temperature and contact time are the parameters that have been tested in this study. The characterization study showed that RHAC has a high BET surface area (815.52 m2/g) and its pore structure was found to be mesoporous with an average pore diameter of 2.96 nm. Characterization studies, including X-ray diffraction analysis (XRD), Raman spectroscopy and scanning electron microscopy (SEM) were employed to determine the RHAC’s performance. The adsorption of As towards RHAC followed the Freundlich isotherm model and pseudo-first order with adsorption process was favorable at higher arsenic concentrations. The mechanism study also signified that the adsorption of As-RHAC was limited by film-diffusion. Thermodynamic studies indicated that the As-RHAC adsorption system was endothermic, random, spontaneous, feasible in nature and governed by the chemisorption process. Desorption and regeneration studies of RHAC showed that it can be utilized up to 5 cycles and is stable for the water treatment facilities.

Adsorptive removal of a nitrate ion from the aqueous solution of sodium nitrate by application of double fixed-bed column

This study focuses on the removal of nitrate ions from aqueous solutions using rice husk activated carbon (RHAC). The RHAC was subjected to characterization via Fourier transform infrared (FTIR), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), and X-ray florescence (XRF) to ascertain its functional groups, surface morphology, and oxide/elemental composition, respectively. Batch experiments were conducted to assess the impact of nitrate concentration, bed height, and number of packing layers on removal efficiency. FTIR spectra revealed favorable sorption-related functional groups within RHAC, while SEM analysis indicated the presence of effective sorption sites on its surface. EDS analysis of the rice husk adsorbent before adsorption (RHBS) demonstrated a significant composition of Si (42.20%), O (35.30%), and Ca (12.33%). The batch study unveiled a concentration-dependent decrease in nitrate removal efficiency, alongside the enhanced performance with increased bed height and number of packing layers. Kinetic data fitting favored the Yoon–Nelson and Adams–Bohart models. Overall, RHAC exhibited efficient nitrate ion removal, with column performance notably improved by utilizing multiple packing layers. These results will enhance our understanding of the mechanisms involved in removing nitrate ions and highlight the potential effectiveness of RHAC, especially when utilized with multiple packing arrangements in column setups.

Comparison of surface adsorption efficacies of eco-sustainable agro/animal biomass-derived activated carbon for the removal of rhodamine B and hexavalent chromium.

Effective management and remediation strategies are crucial to minimize the impacts of both organic and inorganic contaminants on environmental quality and human health. This study investigates a novel approach utilizing cotton shell activated carbon (CSAC), rice husk activated carbon (RHAC), and wasp hive activated carbon (WHAC), produced through alkali treatment and carbonization under N2 atmosphere at 600°C. The adsorption capacities of biomass-derived mesoporous activated carbons (CSAC, RHAC, WHAC) alongside macroporous commercial activated carbons (CAC) were evaluated for removing rhodamine B (Rh B) and hexavalent chromium (Cr6+). The CSAC exhibits remarkable adsorption efficiency (255.4mg.g-1) for Cr(VI) removal, while RHAC demonstrates superior efficacy (174.2mg.g-1) for Rh B adsorption. Investigating various optimal parameters including initial pH (pH 3 for Cr and pH7 for Rh B), catalyst dosage (200mg.L-1), and initial concentration (20mg.L-1), the Redlich-Peterson isotherm model is applied to reveal a hybrid adsorption mechanism encompassing monolayer (chemisorption) and multilayer (van der Waals adsorption) processes. Kinetic analysis highlights the pseudo-second-order and Elovich models as the most suitable, suggesting physiochemisorption mechanisms. Thermodynamic analysis indicates the endothermic nature of the adsorption process, with increased randomness at the solid-solution interface. Isosteric heat investigations using Clausius-Clapeyron, Arrhenius, and Eyring equations reveal a heterogeneous surface nature across all activated carbons. Further confirmation of Rh B and Cr(VI) adsorption onto activated carbons is provided through FTIR, FESEM, and EDAX analysis. This study highlights the innovation and promise of utilizing biomass-derived activated carbons for effective pollutant removal.

SYNTHESIS AND CHARACTERIZATION OF ACTIVATED CARBON PREPARED FROM RICE HUSK BY PHYSICS-CHEMICAL ACTIVATION

Activated carbon is an amorphous carbon material predominantly composed of free carbon atoms with high adsorption capacity. The amorphous structure in activated carbon affects its adsorption capacity; the higher the percentage of amorphous carbon, the greater the adsorption capacity of the activated carbon. Activated carbon can be obtained from rice husk waste containing 30-40% C in cellulose, hemicellulose, and lignin. Therefore, this study was conducted to observe activated carbon's phases, morphology, elemental composition, and particle size. Activated carbon was synthesized using a physics-chemical activation method, which began with washing the rice husk samples, followed by air drying, carbonizing into charcoal, and grinding it finely. The rice husk charcoal powder was then physically activated at a temperature of 500℃. The physically activated product was then chemically activated using 6M HCl with a charcoal-to-activator ratio of 1:10 (m/V), stirred at 250 rpm for 1 hour, and then allowed to settle for 24 hours. It was then washed and dried to produce activated carbon powder. XRD test results showed diffraction peaks at 2θ = 22.23° without sharp or pointed peaks, indicating that the activated carbon has an amorphous structure. SEM test results showed the morphology of rice husk-activated carbon with spherical particle shapes and a particle size distribution of 20-70 nm. EDX test results showed that the rice husk activated carbon is predominantly composed of C, O, and Si with respective percentages of 54.31%, 40.04%, and 2.49%.

BIO-ADSORPTION OF HEAVY METAL ION FROM WATER USING ACTIVATED CARBON

The discharge of effluent polluted with heavy metals have become a growing concern for researchers around the world. This study evaluated the removal efficiency of commercial activated carbon and rice husk activated carbon as adsorbents for the removal of copper ion in water. A nominal size of 1 mm was obtained after sieving the Rice Husk, washed with distilled water, dried in an oven t at 80 ℃ for 12 hours, and pyrolyzed in a furnace at 550 ℃ for 30 minutes. The chars produced were later air-dried and then activated with lemon juice. The Rice Husk Activated Carbon (RHAC) and Commercial Activated Carbon (CAC) purchased from the market were both subjected to the following analyses: bulk density, X-ray Fluorescence (XRF), Brunauer–Emmett–Teller (BET), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) in order to characterise the adsorbents and to understand their suitability for the removal of copper ion in water. One of the properties of an adsorbent is large pores which is exhibited by the activated carbons as revealed by the SEM analysis. Likewise, the XRF and EDX analyses confirmed that the adsorbents had larger proportion of Silica (50.1 – 50.25%), Carbon (60.06 – 84.87 wt .%) and Oxygen (15.13 – 21.60 wt. %) which is a property of a good adsorbent. BET analysis showed that the surface areas of the rice husk activated carbon and the commercial activated carbon were 998.35 and 1208.25 m2/g, respectively. The bulk densities of the rice husk activated carbon and the commercial activated carbon were 0.3325 and 0.2812 g/cm3, respectively. The maximum removal efficiency using RHAC was observed at 60 ℃ and 120 minutes at 83.96 and 89.21 %, respectively while for CAC the maximum removal efficiency was observed at 60 ℃ at 84.61 % and 30 minutes at 83.3 %. Initial concentration of 20 mg/l was observed to have the highest removal efficiency for the two activated carbon specimens. The modelled effect of initial concentration, temperature and contact time on removal efficiency yielded R2 values of 1, 0.918; 1,1 and 1,1 respectively for the CAC and RHAC.

Rice husk-activated carbon (RHAC) composited with V2O5 for lithium-ion batteries

Rice husk-activated carbon (RHAC) composited with V2O5 for lithium-ion batteries

Assessment of Rice Husk-Based Activated Carbon as Adsorbent in Domestic Wastewater Treatment

Indiscriminate discharge of wastewater into the environment is of utmost concern, especially in developing countries. This study evaluated the efficiency of rice husk based activated carbon in wastewater samples harvested from a students’ hostel and a restaurant within the Federal University of Technology, Akure. The adsorbent used was produced from rice husk using hydrogen tetraoxosulphate (VI) acid (H2SO4) as the activating agent. The aim of this study was to assess rice husk-activated carbon for the reduction of physicochemical parameters such as hardness, pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), total dissolved solid (TDS), total suspended solid (TSS), and heavy metals which include chromium (Cr), lead (Pb), manganese (Mn), and iron (Fe). The wastewater samples were treated using activated rice hush ash of particle size (180 µm) at four different doses (30, 35, 40, 45 grams/400 ml). The results showed that the different doses of activated carbon had different removal efficiency. It was observed that the optimum dosage was 40g for DO, COD, BOD, and TDS while 30g was optimum for Hardness. It was also observed that an increase in the concentration of rice husk adsorbent led to an increase in the removal efficiency for the heavy metals (Cr, Mn, Pb, and Fe). The maximum percentage removal of DO, COD, BOD, TDS, and TSS, with rice husk was 21%, 58%, 72%, 21%, and 57% respectively. After the treatment of the domestic wastewater and comparing with the WHO standard, the treated wastewater quality was found to be safe for direct discharge into surface water bodies and irrigation purposes.

Fabrication of High-Performance Asymmetric Supercapacitors Using Rice Husk-Activated Carbon and MnFe2O4 Nanostructures

To meet the growing demand for efficient and sustainable power sources, it is crucial to develop high-performance energy storage systems. Additionally, they should be cost-effective and able to operate without any detrimental environmental side effects. In this study, rice husk-activated carbon (RHAC), which is known for its abundance, low cost, and excellent electrochemical performance, was combined with MnFe2O4 nanostructures to improve the overall capacitance of asymmetric supercapacitors (ASCs) and their energy density. A series of activation and carbonization steps are involved in the fabrication process for RHAC from rice husk. Furthermore, the BET surface area for RHAC was determined to be 980 m2 g−1 and superior porosities (average pore diameter of 7.2 nm) provide abundant active sites for charge storage. Additionally, MnFe2O4 nanostructures were effective pseudocapacitive electrode materials due to their combined Faradic and non-Faradic capacitances. In order to assess the electrochemical performance of ASCs extensively, several characterization techniques were employed, including galvanostatic charge –discharge, cyclic voltammetry, and electrochemical impedance spectroscopy. Comparatively, the ASC demonstrated a maximum specific capacitance of ~420 F/g at a current density of 0.5 A/g. The as-fabricated ASC possesses remarkable electrochemical characteristics, including high specific capacitance, superior rate capability, and long-term cycle stability. The developed asymmetric configuration retained 98% of its capacitance even after 12,000 cycles performed at a current density of 6A/g, demonstrating its stability and reliability for supercapacitors. The present study demonstrates the potential of synergistic combinations of RHAC and MnFe2O4 nanostructures in improving supercapacitor performance, as well as providing a sustainable method of using agricultural waste for energy storage.

Pengaruh Variasi Konsentrasi H3PO4 Sebagai Zat Aktivator Terhadap Karakteristik Karbon Aktif dari Sekam Padi

Rice husk is an organic material that has a high lignocellulosic content so it has the potential to be turned into activated carbon. One method of making activated carbon is activation with a phosphoric acid activator (H3PO4). The purpose of this research was to study the effect of varying concentrations of H3PO4 as an activator on the characteristics of rice husk-activated carbon. The characterization refers to SNI 06-3730-1995 regarding the technical quality requirements of activated charcoal. Activation of rice husk carbon was carried out by contacting the carbon with H3PO4 for 24 hours and shaking it. The H3PO4 consisted of 3 concentration variations, namely 4M, 6M, and 8M. From the research results, the water content was 3.936%; 4.037%; 4.070%, the absorption of iodine has met the character of activated charcoal according to SNI, namely 1217.204 mg/g; 1204.255 mg/g; 1184.832 mg/g while the ash content value does not meet the SNI standard, which is still above 10%. The highest adsorption capacity and adsorption efficiency could be activated with 8M H3PO4, namely 22.42 mg/g and 89.68%. IR spectra on activated carbon with three variations of H3PO4 concentration showed the presence of aromatic C-H, C=C, and C-O anhydride functional groups.

Preparation and characterization of rice husk activated carbon-supported zinc oxide nanocomposite (RHAC-ZnO-NC)

Indiscriminate waste discharge into water bodies has increased the level of water pollution via anthropogenic activities. Hence the need for the development of sustainable and environmentally benign nanomaterials has the potential for wastewater treatment. Rice husk activated carbon (RHAC) prepared by orthophosphoric acid activation was successfully loaded with freshly prepared ZnO nanoparticles by a bottom-up approach via precipitation method resulting in the RHAC-ZnO-NC. RHAC-ZnO-NC's mineralogy with 72% zincite was determined by XRD, morphology by SEM, and the functional group by FTIR. The physicochemical parameters showed surface area 615.2 m2 g-1, pH (pzc) (6.62), pH (6.53), bulk density (0.88 g/cm3), ash content (18.45%), and volatile matter (58.08%). The porosity was determined by iodine number. Boehm titration was carried out for oxygen-bearing functional group determination. The study substantiated RHAC-ZnO-NC as a promising material for adsorption and photocatalytic degradation.

Fixed-Bed Adsorption of Phenol onto Microporous Activated Carbon Set from Rice Husk Using Chemical Activation

In the course of this research, the potential of activated carbon from rice husk was examined as being a phenol removal medium from an aqueous solution in a fixed-bed adsorption column. The activated carbon was characterized through FESEM (Field-Emission Scanning Electron Microscopy) and BET (Brunauer–Emmett–Teller) surface area. According to the FESEM micrograph and BET surface area, RHAC (rice husk activated carbon) had a porous structure with a large surface area of 587 m2·g−1 and mean diameter of pores of 2.06 nm. The concentration effects on the influent phenol (100–2000 mg·L−1), rate of flow (5–10 mL·min−1), and bed depth (8.5–15.3 cm) were examined. It was found that the capacity of bed adsorption increased according to the increase in the influent concentration and bed depth. However, the capacity of bed adsorption decreased according to the increase in the feed flow rate. The regeneration of activated carbon column using 0.1 M sodium hydroxide was found to be effective with a 75% regeneration efficiency after three regeneration cycles. Data on adsorption were observed to be in line with many well-established models (i.e., Yoon–Nelson and Adams–Bohart, as well as bed depth service time models).

Performance Studies of Biomass Derived RHAC and MgO Nanocomposite Electrode Materials for Supercapacitor Applications

The electrode materials for supercapacitors based on biomass-produced Rice Husk Activated Carbon (RHAC) and RHAC+50% MgO nanocomposite are compared in this article. The crystallinity, structural morphology, and crystalline size of the particles were determined using microstructural and electrochemical characterization. Scanning Electron Microscope and X-Ray Diffraction techniques were used to determine the surface morphology and crystallinity of the materials. The XRD results reveal that RHAC which has broad peaks indicates amorphous nature whereas RHAC+50% MgO nanocomposite which has sharp peaks exhibits crystalline nature. The RHAC+50% MgO nanocomposite electrode exhibits a specific capacitance of 220.52 F/g however RHAC electrode exhibited only 162.91 F/g at a scan rate of 2mV/s by Cyclic Voltammetry in 1 M KOH electrolyte. After 2500 cycles of Galvanic charge-discharge, it was discovered that RHAC+50% MgO nanocomposite has capacitance retention of 76.71% and RHAC has capacitance retention of 80.49%.

Linear and nonlinear kinetics analysis and adsorption characteristics of packed bed column for phenol removal using rice husk-activated carbon

The linear and nonlinear kinetics analysis and adsorption characteristics of phenol adsorption onto activated carbon synthesized from rice husk biomass were investigated in a packed bed column. Several analyses such as physical properties, BET surface area, pore size distribution, FTIR, and SEM were used to investigate the adsorption properties of the rice husk-activated carbon (RHAC). The column adsorption studies indicated that the adsorption of phenol onto RHAC is favored by an increase in bed height and a decrease in solution flow rate, influent phenol concentration, and particle size. Various dynamic adsorption parameters depicting the adsorption characteristics of phenol onto RHAC were estimated from the breakthrough analysis of the experimental data. The fitting of the experimental data to the Thomas, Adams–Bohart, Yoon–Nelson, and Wolborska models using linear and nonlinear regression techniques showed that the four models gave good fits to the experimental data. The R2 values for the regressed lines ranged from 0.6827 to 0.9918, and 0.9958 to 1.0000 for the linear and nonlinear regression techniques, respectively. Experimentally, a maximum adsorption capacity value of 14.57 mg/g was obtained; at the same experimental conditions, 14.88 mg/g was predicted by the nonlinear regression, while 9.78 mg/g was predicted by the linear regression of the Thomas model. The results affirmed the potency of RHAC for the treatment of phenol-contaminated wastewater. It provided comprehensive data needed for the design of phenol adsorption columns using RHAC. It equally revealed that a better model analysis would be achieved with the application of nonlinear regression.

Synthesis and Characterization of Activated Carbon from Agrowastes for the Removal of Acetic Acid from an Aqueous Solution

In this study, activated carbons prepared from agrowastes by chemical activation were used to remove acetic acid from an aqueous solution through a batch process. The prepared adsorbents were characterized by SEM, XRD, FT-IR, and point of zero charge (pHpzc). The effects of adsorbent dosage, initial concentration, and contact time were considered. Equilibrium data was tested using Langmuir, Freundlich, Temkin, and Frenkel–Halsey–Hill models. The degree of adsorption of acetic acid increased for both adsorbents as contact time, and adsorbent dosage and initial concentration were increased. The adsorption data were described well by the (Freundlich=Frenkel–Halsey–Hill) models with the highest regression coefficient of [Formula: see text] and [Formula: see text] for Rice Husk Activated Carbon (RH-AC) and Potato Peels Activated Carbon (PP-AC), respectively. This suggests a multilayer through the existence of a heterogeneous pore distribution in the adsorbent surface. Kinetic data agreed well with pseudosecond-order ([Formula: see text] and [Formula: see text]) RH-AC and PP-AC, correspondingly. This indicates that the adsorption process was chemisorption in nature. The regeneration studies showed that the adsorbents prepared could be renewed and reused before losing their adsorbing affinity for acetic acid.

Removal of Fe (II) ions from Aqueous solution using Rice-husk Adsorbents in fixed-bed column

Rice husk has been converted into activated carbon for the adsorbent to remove the heavy metal from the aqueous solution. This study aimed to convert rice husk to activated carbon (AC) for use in the adsorption of Fe ions in a fixed-bed column. Rice husk was first pyrolyzed in an atmosphere of nitrogen gas at 400 oC, then a chemical activation method using sodium hydroxide. The rice husk activated carbon (RH-AC) was characterized using Fourier transform infrared (FTIR) and Scanning electron microscope (SEM) to identify the functional group and microstructure of carbon. The performance of the carbon was tested on the Fe removal from an aqueous solution in a continuous column. The adsorption process was carried out using Fe solution with an initial concentration of 3 mg/L as an artificial sample. The amount of carbon is 25, and 50 g were filled in an adsorber column with a diameter of 5.4 cm and height of 40 cm. SEM images revealed that the activated carbons shown with well-developed pore sizes and pore structure were produced after the chemical activation. The FTIR absorption bands observed in the RH-AC sample confirmed the presence of hydroxyl (-OH), carbonyl, and carboxylic (-COOH) groups of RH-AC adsorbent. The highest Fe removal efficiencies were 91.9% on chemically activated carbon and column mass 50 g at 400 minutes. The overall study revealed the potential value of chemically activated RH-AC as a possible commercial adsorbent in a continuous column wastewater treatment strategy.

Ultrafast capacitive deionization using rice husk activated carbon electrodes

Capacitive deionization (CDI) has attracted much attention as a promising desalination technology, since inexpensive carbon electrodes can be employed at a large scale. In this work, rice husk activated carbon (RHAC) was utilized to obtain electrodes for desalination. The RHAC materials were synthesized using different carbonization temperatures. After their physicochemical and electrochemical characterization, it was observed that the electrodes produced with the RHAC obtained at lower carbonization temperatures (450 or 650 °C) provided better desalination performance with a salt removal capacity of 15.5 mg g−1 (1.2 V and C0 = 600 mg L-1). However, the most remarkable feature of the RHAC electrodes was their ultrafast kinetics. To the best of our knowledge, here we report the fastest electrosorption rates observed for carbon electrodes applied for CDI (10.52 mg g−1 min−1). From a simultaneous analysis considering the electrosorption/desorption kinetics and the electrosorption capacity, the RHAC carbonized at 600 °C displayed an outstanding value of 5.2 g of salt removed per gram of electrode per day. Importantly, the electrodes remained stable even up to 80 electrosorption/desorption cycles, with both the kinetics and the electrosorption capacities remaining close to the initial values.

Adsorption of COD in wastewater by Activated Carbon from Rice Husk

Organic pollution occurs due to the presence of organic compound that will causing oxygen depletion and gives potential adverse impacts on human health and the environment. Wastewater from the fish cracker industry typically has high chemical oxygen demand (COD) and it is needed to be treated before release to water bodies in order to reduce the organic pollution. The treatment of COD was done using rice husk activated carbon (RHAC) that produced from agricultural wastes that contributed to waste minimization and reduce the environmental pollution. Therefore, this study emphasized on the feasibility of rice husk activated carbon for removing the COD from fish cracker wastewater. It was also to identify the optimization factors (pH, flow rate and initial concentration of COD) that affecting adsorption by rice husk activated carbon. RHAC was produced by chemical activation using phosphoric acid, H3PO4 and a real wastewater from fish cracker industry was collected, characterized, and treated by using continuous fixed bed column adsorption method. The result shows that the adsorption of COD by RHAC was optimum at pH 2, flow rate 5 ml/min and 5 % v/v initial COD concentration with the COD removal at 31.8% (150 mg/L) which comply with Standard B. Thus, RHAC could be used to develop an alternative method and suitable carbonaceous substances that was used to treat water and wastewater.

Adsorption of Hg(II) in an Aqueous Solution by Activated Carbon Prepared from Rice Husk Using KOH Activation.

With the development of industry, the discharge of wastewater containing mercury ions posed a serious threat to human health. Using biomass waste as an adsorbent to treat wastewater containing mercury ions was a better way due to its positive impacts on the environment and resource saving. In this research, activated carbon (AC) was prepared from rice husk (RH) by the KOH chemical activation method. The characterization results of scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), Fourier transform infrared (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) showed that rice husk-activated carbon (RHAC) had good pore structure and oxygen-containing functional groups. The influences of contact time, initial concentration of Hg(II), adsorbent dosage, pH, and ionic strength on mercury ion removal were investigated. The Langmuir model was most suitable for the adsorption isotherm of RHAC, and its maximum adsorption capacity for Hg(II) was 55.87 mg/g. RHAC still had a high removal capacity for Hg(II) after five regeneration cycles. RHAC had excellent removal efficiency for mercury ion wastewater. At the same time, RH could be used as a nonpolluting and outstanding characteristic adsorbent material.

Extraction of SiO2 from gasified rice husk carbon simultaneously rice husk activated carbon production: Restudy on product properties, activation mechanism, and evolution law of pore structure

The goal of this work was to provide a theoretical basis for efficient and harmless utilization of gasified rice husk carbon (RHC), and further understand its activation mechanism and evolution law of pore structure. K2CO3 was used to extract SiO2 from RHC, and then the rice husk activated carbon (RAC) was prepared by activating the separated rice husk activated carbon precursor (ACP). Results showed that the specific surface area of the RAC prepared via the ACP was 1006.208 m2/g upon the yield of SiO2 was 20.64%. Compared with the particle size of RHC, the K2CO3 mass fraction have a significant effect on the yield of SiO2 and the K2CO3 content of ACP surface The activation process of ACP mainly depended on the content of K2CO3 adsorbed on its inner surface and internal structure. With an increase in K2CO3mass fraction, the pore structure of RAC roughly went through two primary stages (full development period to transitional development period). Besides, SiO2 has a great amount of ∼5 nm of mesopores and tended to crystallize upon sintered at 950°C for 4 h

Adsorption of Cr(VI) ions from aqueous solution using rice husk–based activated carbon: Optimization, kinetic, and thermodynamic studies

AbstractThe effectiveness of rice husk–activated carbon (RHAC) in the adsorption of Cr(VI) from an aqueous solution was investigated. The adsorbent was prepared, characterized, and subjected to optimization, kinetics, and thermodynamics studies. Optimization was done using response surface methodology (RSM) based on the Box–Behnken design. Accordingly, optimum adsorption factors obtained were shaking speed of 176.90 rpm, adsorbent dosage of 1.96 g, and initial concentration of 50.12 mg/L for 93.49% removal of Cr(VI) at a desirability of 1.00. The maximum adsorption capacity obtained was 98.14 mg/g. An equilibrium adsorption isotherm model and a kinetic model of Cr(VI) on RHAC were fitted to experimental data. The data were well represented by the Freundlich adsorption isotherm model, with R2 of 0.9956, which presumes an energetically heterogeneous surface. Furthermore, the adsorption kinetic data were well described by the pseudo‐second order model with R2 range of 0.9969–0.9997, indicating a high agreement between experimental and calculated values. Finally, thermodynamic parameters such as mean Gibbs free energy (∆G) showed that adsorption of Cr(VI) ions onto RHAC was spontaneous and endothermic under examined conditions. In this view, RHAC is a viable adsorbent for the optimum removal of Cr(VI) ions from wastewater.