Study On Phosphorus Removal From Water By Magnetic Lanthanum Modified Ca-montmorillonite And Its Recovery

It is reported that about 30 to 50 percent of the world's water resources are facing the problem of eutrophication due to excessive phosphorus emissions.At the same time,phosphorus is a scarce and non-renewable resource and an indispensable element of human life.Therefore,it is of great significance for environmental treatment and cost reduction to remove and recycle phosphorus from wastewater and the recyclability of adsorbents.?1?Lanthanium modified Ca-montmorillonite?Ca-MMT@La?was successfully prepared by SEM-mapping,FTIR and XRF.The optimal adsorption conditions of Ca-MMT@La were as follows:pH=6,adsorption temperature was 20°C,initial concentration of lanthanum solution was 500 mg/mL,and adsorption time was 2 h.The Langmuir isotherm adsorption equation inferred that its adsorption belonged to monolayer adsorption.?2?Ca-MMT had no phosphorus adsorption effect.The phosphorus removal efficiency of Ca-MMT after lanthanum modification was significantly improved.The optimal phosphorus removal conditions for Ca-MMT@La were as follows:pH=3,the initial phosphorus concentration was 100 mg/L,and the adsorption time was 7 h.The phosphorus removal rate increased with the increase of lanthanum content.Langmuir isothermal adsorption equation deduced that adsorption belonged to single molecular layer adsorption.?3?The Fe₃O₄ particles with an average size of about 10 nm were successfully loaded onto the Ca-MMT@La by XRD,SEM-mapping,FTIR and XRF.When Fe₃O₄content was 42.86%and initial phosphorus concentration was 50 mg/L,Ca-MMT@La@Fe3O4 had a maximum adsorption capacity of 4.89 mg/g,with phosphorus removal rate of 97.80%and good magnetic properties.?4?The optical phosphorus removal condition were as follows:at pH=2,the initial PO₄^3--P concentration was 200 mg/L,adsorption time was 12 h.The adsorption process of phosphate by Ca-MMT@La@Fe₃O₄ could be described by a quasi-secondary kinetic model.The Langmuir isotherm adsorption equation was inferred to be a monolayer adsorption.?5?2 mol/L NaOH solution was selected as the desorbent.After six cycles,Ca-MMT@La@Fe₃O₄ still remained high adsorption and desorption capacity.This study resolves such problems of traditional adsorbent as lower adsorption capacity,poor reusability and difficult separation.It has potential application value for the removal and recycling of phosphate in aqueous solution.