Process Optimization and Modeling of Low-cost Activated Carbon Preparation and Its Application in Chromium (VI) Removal

In this study, Salacca zalacca seed (SS) agricultural waste was employed as a material for the preparation of activated carbon. Salacca zalacca seed activated carbon (SSAC) was chemically activated using H3PO4 and used as an adsorbent for chromium (VI) adsorption. The effect of various experimental parameters such as activation temperature, impregnation ratio, and H3PO4 concentration (%) on adsorption capacity was determined using response surface methodology (RSM). The optimum condition prediction of these values from RSM alines well with experimental data; activation temperature (800 °C), impregnation ratio (3.50) and H3PO4 concentration (75 %). SSAC activated at the optimum condition were intensively characterized to understand the morphology, surface charge density, chemical composition and textural property by using SEM, pHpzc, FTIR, CHON analysis, and N2 adsorption- desorption. Maximum chromium (VI) adsorption was 7.94 mg/g. Langmuir adsorption model was effectively fi tted to the equilibrium adsorption information. Furthermore, the pseudo-second-order kinetic model also explains the experimental data well. Overall, the results suggested that RSM could optimize the preparation conditions of Salacca zalacca seed biochar, leading to enhancing the adsorption capacity of chromium (VI) using Salacca zalacca seed-activated carbon. Moreover, SSAC provides a excellent reusability for up to 6 cycles. This result ensures that SSAC has great potential as a low-cost, high-value agricultural waste adsorbent for chromium (VI) removal.