Removal of Anions PO۴۳- and Methyl Orange Using Fe-Modified Biochar Derived from Rice Straw

A novel magnetic biochar (Fe۳O۴-biochar) using rice straw as the raw material and magnetite (Fe۳O۴ nanoparticles) as the objective magnetic medium was successfully synthesized under high-temperature and oxygen-free conditions. Several techniques and methodologies (SEM/EDX, FT-IR, N۲ adsorption-desorption isotherms, and pHpzc measurements) were used to determine the surface functional groups and physicochemical properties of Fe۳O۴-biochar, which showed that the Fe۳O۴-biochar was successfully synthesized and deposited on the surface of the pristine biochar. The surface area of the Fe۳O۴-biochar was measured as ۳۳۷.۷۷ m۲/g and ۰.۲۲۷ cm۳/g pore volume. Then the adsorption behavior of phosphate (PO۴۳-) and methyl orange (MO) from the aqueous solution onto the Fe۳O۴-biochar was investigated. The influence of variables including pH, initial concentration of PO۴۳-/MO, adsorbent dosage, and contact time was studied in detail. The optimal adsorption amount of PO۴۳- (۱۸۹.۲ mg/g) was obtained with ۰.۱ Fe۳O۴-biochar g/L, at pH of ۲ for ۲۴۰ min; whereas the optimal adsorption amount of MO (۳۷.۳۱ mg/g) was obtained with ۰.۰۳ Fe۳O۴-biochar g/L, at pH of ۲ for ۲۴۰ min. The equilibrium data were fitted to both Langmuir and Freundlich isotherms (R۲>۰.۹۲ for PO۴۳-, R۲ >۰.۹۶ for MO). Besides, the pseudo-second-order exhibited a better fit for the kinetic studies (R۲>۰.۷۹ for PO۴۳-, R۲>۰.۸۸ for MO). This study showed that Fe۳O۴-biochar could be utilized as an efficient, magnetically separable adsorbent for the removal of anions PO۴۳ and MO from the aqueous mediums.

کلیدواژه ها:

Adsorption ، Fe۳O۴-biochar ، Methyl orange ، Phosphate ، rice straw