Synthesis of biochar from tamarind seed: experimental optimization using response surface methodology design

Abstract The present study aimed to optimize the synthesis of biochar using hydrothermal carbonization. Response surface methodology based on Box–Behnken design was utilized to optimize three experimental parameters, namely, the hydrothermal carbonization temperature, the reaction time, and the concentration of the chemical activator (H 3 PO 4 ). To evaluate prepared biochars (as adsorbents), the removal of 2,4-Dichlorophenol (2,4-DCP) from wastewater was selected as a response. The results showed that, the removal of 2,4-DCP from wastewater was most significantly influenced by the hydrothermal carbonization temperature and H 3 PO 4 concentration, whereas the reaction time effect had a lower statistical significance. The optimum synthesis conditions for the highest removal of 2,4-DCP were predicted to be H 3 PO 4 concentration of 1.19 mol/L, a reaction time of 8 h, and a hydrothermal temperature of 187 °C. Under these optimum conditions, the model predicted removal of 2,4-DCP by model was 47.31%, while the experimental removal was 45.84%. Characterizations of the biochar synthesized at the optimum conditions showed clear improvement in terms of adsorption capacity as compared to the raw material without treatment by hydrothermal process. Graphical abstract