Optimization of Production Conditions for Activated Carbons from Rice Husk by Potassium Carbonate Using Response Surface Methodology

Abstract

A three-factor-three-level experiment was developed by the central composite design (CCD) and Response surface methodology to discuss the effects of concentration of K2CO3, activation temperature and time on the adsorption capacity of the activated carbon (AC) derived from the rice husk and to identify the key preparation parameters. The performance of the AC was characterized by nitrogen adsorption isotherm as Brunauer–Emmett–Teller (BET) and scanning electron microscope (SEM), respectively. The optimal parameters were obtained: Rice husk was soaked in K2CO3 solution (2.32 mol/L) with an impregnation ratio (rice husk: K2CO3=1:3) (wt. %), activated at 1239 K for 0.48 h. The results showed that iodine adsorption capacity of the AC was 1268.52 mg/g, the error between the models predicted (1356.98 mg/g) was only 6.2%. The AC has a large apparent surface area (SBET = 1312 m2/g), total pore volume (0.78 cm3/g) and average pore diameter (11.92 Å).