Application of Response Surface Methodology (RSM) for Cr(VI) removal through hemp and hemp-derived biochar; nonlinear adsorption isotherm, kinetics, and Artificial Neural network /

Abstract

Hexavalent Chromium (Cr (VI)) are highly hazardous metal ion present in industrial wastewater. The effective removal of (Cr (VI)) from the aqueous solution is of utmost importance. The study aims to use a cost-effective, environmentally friendly, and potential adsorbent as a hemp and hemp-derived biochar synthesized using a pyrolysis process and characterize using SEM, EDX, FTIR, and XRD analysis before and after adsorption. The influence of the starting concentration, adsorbent dose, and adsorption time was determined, and the best parameters were evaluated using RSM. Different amounts of time (5-240 min) and (Cr (VI)) concentrations (1-20 mg/l) were used in the batch experiment. Non-linear adsorption isotherm and kinetics were used to determine the mechanism, and ANN was used to confirm the efficacy of hemp and hemp-derived biochar in removing the contaminants. The result depicts that the highest (Cr(VI)) for hemp (97.898%) and hemp-derived biochar (99.168%) was obtained with the optimized parameters of 1 mg/L of (Cr(VI)) concentration, 0.1 g of adsorbent dose, and 240 min of adsorption time. Freundlich isotherm and Pseudo-1st order best fit well described the adsorption behavior. The maximum adsorption capacity of hemp value of 9.768 mg/g and hemp-derived biochar of 11.2850 mg/g to uptake Cr (VI). A multilayer perceptron (MLP-2-3-1, MLP-2-8-1) artificial neural network structure best fits the response for hemp and hemp-derived biochar. These findings provide valuable insight for future research by using both hemp as well as hemp-derived biochar as an effective adsorbent for Cr (VI) removal from industrial wastewater to attain SDG.