Potassium Hydroxide Activation as an Adsorbent for Kinetic Models of Hexavalent Chromium Adsorptions onto <i>Garcinia mangosteen</i> Shell

Abstract

The utilized adsorption kinetic models, i.e., pseudo-zero order, pseudo-first-order, pseudo-second order, intraparticle diffusion, Bangham’s pore diffusion, liquid film diffusion, modified Freundlich and Elovich models have been cultivated the hexavalent chromium adsorption process. A high correlation coefficient (R2) and a small residual root mean square error (RMSE) and Chi-square (χ2) can be depicted in the pseudo-first order for the kinetic adsorption process of hexavalent chromium adsorption on the activated mangosteen shell with potassium hydroxide and carbonized at 400 °C for 2 h as a biochar adsorbent which has a specific surface area of 164 m2/g.