Removal of malachite green (MG) from aqueous solution by adsorption on eggshell biochar using response surface methodology (RSM)

This study focus on the adsorption of malachite green (MG) dye using eggshell biochar as adsorbent. Agricultural waste of eggshell turned into low cost and eco- friendly biochar adsorbent was studied. Batch adsorption studies were carried out to investigate the effect of various adsorption parameters which are initial concentration, adsorbent dosage and contact time while the response in this study is malachite green (MG) removal (%). Optimisation studies were performed using response surface methodology (RSM). Quadratic model or second-order polynomial model containing linear and two factors terms was studied using central composite design
(CCD). The correlation coefficient, R² for the quadratic model was found to be 0.9563. The interactions of the variables were studied using the three dimensional surface graph and contour plot. The physical characterization of adsorbent was studied using FTIR to analyse the functional group of adsorbent. The optimum condition predicted by RSM were found to be at initial concentration of 70 mg/L, adsorbent dosage of 1.99 g, contact time of 16.25 minutes; the removal of MG up to 92.39% at desirability of 0.998.