Fractal-like kinetics for adsorption of Pb (II) on graphene oxide/hydrous zirconium oxide/crosslinked starch bio-composite: Application of Taguchi approach for optimization

This study deals with the decontamination of Pb (II) from aqueous environment using graphene oxide/ hydrous zirconium oxide/crosslinked starch bio-composite (GZS-BC). Various instrumental techniques were used to characterize the GZS-BC. The main factors of Pb (II) sorption were optimized by Taguchi method. Under optimum conditions, (adsorbent dose: 40 mg, contact time: 180 min and initial Pb (II) concentration: 50 mg/L) maximum removal efficiency (98.50%) was achieved at pH 6. Various isotherm models were tested to fit the adsorption data and Freundlich isotherm model was the best fit model with high R2 values (0.9977-0.9983) and low values of v2 (0.01-0.02) and APE (0.90-1.14). The kinetic data were investigated using classical and fractal-like kinetic equations. The fractal-like mixed 1,2-order kinetic model was the best fit model which pointed towards heterogeneous surface of GZS-BC with more than one type of sorption sites. Thermodynamic study shows that Pb (II) sorption onto GZS-BC was spon-taneous and endothermic in nature. The values of DG & DEG; indicated that physisorption together with chemisorption was responsible for uptake of Pb (II).& COPY; 2023 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study investigates the decontamination of Pb (II) from aqueous environment using a graphene oxide/ hydrous zirconium oxide/crosslinked starch bio-composite (GZS-BC). The optimization of Pb (II) sorption was conducted using the Taguchi method, and the best conditions resulted in a maximum removal efficiency of 98.50% at pH 6. The Freundlich isotherm model was found to be the best fit with high R2 values and low v2 and APE values. The kinetic data suggested a heterogeneous surface of GZS-BC with multiple sorption sites, and the thermodynamic study indicated that both physisorption and chemisorption played a role in the uptake of Pb (II).