A novel chitosan modified magnesium impregnated corn straw biochar for ammonium and phosphate removal from simulated livestock wastewater

Livestock wastewater is an important source of agricultural non-point pollution, causes serious pollution to water bodies. At the same time, corn straw is also an important agricultural waste , and its resource utilization has been the focus of global attention. The novel biochar material made from corn stalk can be used to treat livestock wastewater, which is helpful to control agricultural non-point source pollution and improve the efficiency of agricultural waste resource utilization. A novel chitosan modified magnesium impregnated corn straw biochar (CS-MgCBC) was synthetic for the removal of NH 4 + ${}_4^{+}$ -N and PO 4 3 − ${}_4^{3-}$ -P from livestock wastewater. The experiments results show that the adsorption of NH 4 + ${}_4^{+}$ -N and PO 4 3 − ${}_4^{3-}$ -P by CS-MgCBC is more consistent with the second-order kinetic model and Langmuir model, and the maximum Langmuir adsorption capacity for NH 4 + ${}_4^{+}$ -N (35.59 mg/g) and PO 4 3 − ${}_4^{3-}$ -P (221.89 mg/g), compared with other studies on NH 4 + ${}_4^{+}$ -N and PO 4 3 − ${}_4^{3-}$ -P adsorption, the average maximum adsorption capacity of CS-MgCBC has been improved 48.3% and 68.9%. When pH = 6 and pH = 9, the adsorption effect of PO 4 3 − ${}_4^{3-}$ -P and NH 4 + ${}_4^{+}$ -N can be reached 99.6% and 48.4%, respectively. The chitosan modification increased the surface area, and abundance of functional groups (-OH, -CH 3 , -NH 2 , etc.) on the surface of biochar, thus improving the adsorption capacity of CS-MgCBC. The electrostatic adsorption, precipitation, and ligands exchange were the main mechanisms in the sorption of NH 4 + ${}_4^{+}$ -N and PO 4 3 − ${}_4^{3-}$ -P on CS-MgCBC. Excellent adsorption capacity and environmental-friendliness made CS-MgCBC an efficient adsorbent for the removal of NH 4 + ${}_4^{+}$ -N and PO 4 3 − ${}_4^{3-}$ -P in livestock wastewater.