Insights into the Adsorption of Cr(VI) on Activated Carbon Prepared from Walnut Shells: Combining Response Surface Methodology with Computational Calculation

• Published in: Clean technologies Vol. 6; no. 1; pp. 199 - 220
• Main Authors: Yazid, Hicham, Bouzid, Taoufiq, El mouchtari, El mountassir, Bahsis, Lahoucine, El Himri, Mamoune, Rafqah, Salah, El haddad, Mohammadine
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.03.2024
• Subjects: Activated carbon; Adsorbents; Adsorption; Analysis; Carbon, Activated; Chromium; Chromium (VI); Energy consumption; Environmental aspects; Environmental restoration; experimental design; Experiments; Heavy metals; Hydrochloric acid; Independent variables; Methods; Optimization techniques; Pollutants; Potassium; Response surface methodology; Shells; Surface chemistry; Toxicity; Walnut; walnut shell; Walnuts; Morocco; United States > US
• ISSN: 2571-8797; 2571-8797
• DOI: 10.3390/cleantechnol6010012

Walnut shells were used to produce highly microporous activated carbon. The prepared activated walnut shells were found to be an efficient adsorbent for removing Cr(VI). The study used the response surface methodology to investigate four independent variables effect: Cr(VI) concentration, pH, AC-Ws dose, and temperature on the Cr(VI) removal efficiency, which was studied in the concentration range of 0.1 to 0.3 g/L, 4 to 10, 15 to 35 °C and 1 to 5 mg/L, respectively. Through experiments designed, the optimum conditions were determined to be 4, 0.23 g/L, 298 k, and 2 g/L, respectively. At these conditions, the efficiency of removal was found to be 93%. The thermodynamic study of the adsorption process showed a spontaneous and exothermic nature. The kinetic model that explains the experimental data is the pseudo-second-order model. Furthermore, the Langmuir isotherm model was estimated to be an excellent representation of the equilibrium data. Quantum calculations and NCI analyses were also performed to get more light on the adsorption mechanism of the Cr(VI) atom and its complex form on the prepared AC-Ws surface.