Document Type : Research Article
Department of Environmental Engineering, College of the Environment and Natural Resources, Can Tho University, Can Tho 900000, VIETNAM
College of the Environment and Natural Resources, Can Tho University, Can Tho 900000, VIETNAM
Department of Environmental Sciences, College of the Environment and Natural Resources, Can Tho University, Can Tho 900000, VIETNAM
A novel magnetic biochar (Fe3O4-biochar) using rice straw as the raw material and magnetite (Fe3O4 nanoparticles) as the objective magnetic medium was successfully synthesized under high-temperature and oxygen-free conditions. Several techniques and methodologies (SEM/EDX, FT-IR, N2 adsorption-desorption isotherms, and pHpzc measurements) were used to determine the surface functional groups and physicochemical properties of Fe3O4-biochar, which showed that the Fe3O4-biochar was successfully synthesized and deposited on the surface of the pristine biochar. The surface area of the Fe3O4-biochar was measured as 337.77 m2/g and 0.227 cm3/g pore volume. Then the adsorption behavior of phosphate (PO43-) and methyl orange (MO) from the aqueous solution onto the Fe3O4-biochar was investigated. The influence of variables including pH, initial concentration of PO43-/MO, adsorbent dosage, and contact time was studied in detail. The optimal adsorption amount of PO43- (189.2 mg/g) was obtained with 0.1 Fe3O4-biochar g/L, at pH of 2 for 240 min; whereas the optimal adsorption amount of MO (37.31 mg/g) was obtained with 0.03 Fe3O4-biochar g/L, at pH of 2 for 240 min. The equilibrium data were fitted to both Langmuir and Freundlich isotherms (R2>0.92 for PO43-, R2 >0.96 for MO). Besides, the pseudo-second-order exhibited a better fit for the kinetic studies (R2>0.79 for PO43-, R2>0.88 for MO). This study showed that Fe3O4-biochar could be utilized as an efficient, magnetically separable adsorbent for the removal of anions PO43 and MO from the aqueous mediums.