Adsorption of Methylene Blue by Soybean Stover and Rice Hull Derived Biochars Compared to that by Activated Carbon

This study investigated the potential use of soybean stover (SS) (0.1-0.5 g/100 mL)and rice hull (RH) (1.5-3.5 g/100 mL) derived biochars for removing methylene blue (100 mg/L) from wastewater compared to activated carbon (AC) (0.1-0.5 g/100 mL). The adsorption equilibrium data were best represented by Langmuir adsorption isotherm. The calculated maximum adsorption capacity was 71.42 mg/g for AC, 30.30 mg/g for SS, and 4.76 mg/g for RH. The adsorption kinetics was found to follow the pseudo-second order kinetics model. The rate constant was 0.0020-0.0065 g/mg.min for AC, 0.0069-0.5787 g/mg.min for SS, and 0.1370-0.3060 for RH. AC and SS biochars showed considerable potential for adsorption.