Preparation And Performance Study Of Magnetic Composite P-removal Agent

Phosphorus?P?is the main nutrient element in natural water.Excess P is generally considered to be an important factor for eutrophication.It is an urgent problem to remove the phosphorus from natural water.Up to now,the eutrophication of natural water caused by point and non-point contaminant sources has attracted attention,and a series of progress has also been made in pollution control.However,the eutrophication of natural water has not improved significantly.This is mainly due to the traditional phosphate removal technology only reduces the concentration of phosphate in natural water,and the phosphate cannot be separated and recycled effectively.The sink of internal P becomes the internal source of eutrophication in natural water.However,the source-to-sink conversion of P has not been changed,and P still exists in natural water.Therefore,it is necessary to carry out research on the methods,control conditions and mechanism of separation and recovery of phosphate in natural water.To this end,magnetic composite P-removal agent in terms of phosphate removal efficiency and magnetic separability was developed.This agent has both high phosphate removal efficiency and magnetic P-containing insoluble materials produced can be magnetically separated out of the natural water,thereby the eutrophication of natural water is avoided.In this study,the orthogonal experiment was designed to determine the experimental conditions for magnetic composite P-removal agent.The optimal experimental conditions include effects of reaction time,reaction temperature,and amount of metal salt on the phosphate removal efficiency were studied.The optimal reaction conditions to produce the magnetic composite P-removal agent with higher phosphate removal agent were obtained.The agent was prepared under a reaction time of 4 h,reaction temperature of 65°C,and metal salt content of 12.96 mmol.Then,under the optimal preparation conditions,nine types of magnetic composite P-removal agent were prepared by changing the types of metal salt.Afterwards,the optimal agent was selected according to the respective phosphate removal efficiency as La³⁺/poly?acrylamide-co-acryloyloxyethyl thimethylammonium chloride?/Fe₃O₄[La³⁺/CPAM/Fe₃O₄].The phosphate removal efficiency of La³⁺/CPAM/Fe₃O₄to phosphate reached 90.07%.The morphology,element and chemical bond composite,structure and magnetic response of the optimal magnetic composite phosphate removal agent have been investigated.The agent successfully combined with phosphate and had good magnetic response,satisfying the requirement of magnetic separation.The influence of different experimental conditions on the performance of magnetic composite P-removal agent were further studied.The results showed that the magnetic composite P-removal agent had a strong pH dependence and has a high phosphate removal efficiency in the presence of competitive anions.The phenomenon also showed that the magnetic composite P-removal agent has good affinity for phosphate in natural water.In addition,when the initial phosphate concentration is 50 mg·L^-1and the pH 7,the amount of the magnetic composite P-removal agent is 3.75 g·L^-1,the phosphate removal efficiency reached 90.07%.