Preparation of Lanthanum /Pumice Composite Phosphorus Removal Material and Its Phosphorus Removal Performance in the River Sewage

Phosphorus is a limiting factor for the outbreak of harmful algal blooms. At present, lanthanum-based phosphorus locking agents are commonly used for phosphorus removal, but there are some drawbacks, such as high dosage, excessive sludge, and settled phosphorus will be dissolved waiting for an opportunity, which cannot achieve satisfactory phosphorus removal results. In this paper, a kind of lanthanum/pumice composite dephosphorization material (LPC) was prepared by using light floating mineral pumice as carrier and lanthanum chloride (LaCl₃ ·6H₂O) as modifier. The effects of preparation pH, LaCl₃ ·6H₂O concentration, LPC dosage, water sample pH, reaction temperature and coexisting ions on phosphate (？？) removal efficiency were discussed. Pumice and LPC were characterized by SEM and XRF, and their adsorption mechanisms were explored through adsorption kinetics and adsorption isotherm equation. The results showed that the optimum preparation conditions of LPC were pH of 11, LaCl₃·6H₂O concentration of 15 g/L, optimal adsorption capacity of 0.18 mg/g, and the phosphate removal efficiency achieves 89.79%. The optimal water treatment conditions for LPC are water temperature of 20 ℃, pH of 7, and adding 6 g of LPC to 200 mL of river sewage, resulting in a removal rate of 87.38%. The presence of coexisting ions ？？ and Cl^- has almost no effect on the phosphorus removal efficiency of LPC, while the existence of ？？ will hinder the adsorption process of LPC. When the concentration of HCO^3- increases to 4 mmol/L, the phosphate removal rate decreases from 87.84% to 77.13%; The quasi second order kinetic model and Langmuir model can better describe the adsorption process of phosphate by LPC. The adsorption of phosphorus in river sewage by LPC is mainly chemical adsorption, supplemented by physical adsorption, which belongs to endothermic reaction.