Removal of Mn(II) ion from aqueous solution onto cassava stem-derived activated carbon: Process optimization for improved adsorption capacity

The high cost of commercial activated carbon due to high production expenses, has driven increasing demand in lignocellulosic biomass-derived activated carbons as low-cost adsorbents for adsorbing emerging contaminants from drinking and wastewater due to their high surface area and high adsorption capacity. In this study, cassava stem-derived activated carbon was used to remove Mn(II) from aqueous solution. Response Surface Methodology (RSM) with Box- Behnken design (BBD) was applied to optimize adsorption parameters which include initial Mn(II) ion concentration, pH, adsorbent dosage, and temperature, for adsorption capacity (response). Analysis of Variance (ANOVA) was used to evaluate the significance of these parameters. The optimum conditions were identified as initial Mn(II) ion concentration of 3999.70 mg/L, pH of 9.00, adsorbent dosage of 0.47 g/L and temperature of 45 ⁰ C, with desirability of 0.702 resulting in adsorption capacity of the activated carbon for Mn(II) ion of 584.846 mg/g. The Langmuir monolayer adsorption capacity (555.56 mg/g) obtained in this study is a very high value highlighting the potential of cassava stem-crude potash derived activated carbon as an effective adsorbent for environmental applications to remove contaminants [Mn(II) ion].