Research On Removal Of Antimony From Raw Water By Complexation-ultrafiltration

Antimony compounds may be detected in various raw water bodies,with the rapid development of the industrial sector.It may affect normal operation and water quality of the waterworks.However,the traditional dealing methods of antimony had high cost,large investment,and may cause secondary pollution.Complexation combining ultrafiltration technology in the field of low concentration contaminated water had achieved good effects,which may have certain practical significance.Polyacrylate sodium(PAAS)and polyethylene imine(PEI)were used as complexing agent to remove the over standard antimony(Sb):from raw water by hollow and fiber ultrafiltration membrane.After the principle of removing antimony by complexation ultrafiltration,the effect on removal rate of antimony under pH,different load ratios,initial concentration of antimony,operating pressure,coexisting ions and the volume concentration factor was discussed.The dissociation-whole filtration process was used for recovering antimony and complexing agents.The effect of treatment on regeneration complexing agents was investigated.Chemical cleaning was used to recover ultrafiltration membrane flux.It researched the effects and complex mechanism of complexing agents.Main results of the subject:(1)Interception coefficient of antimony R(Sb)reached 96%when pH=8,L=7.1μgSb/mgPAAS using PAAS as complexing agent.Interception coefficient of antimony R(Sb)reached 98.6%when pH=6,L= 9.5μgSb/mg using PEI as complexing agent.The interception coefficient can achieve good when initial concentration of antimony in the range of 80～160μg/L using PAAS as complexing agent,and it was 100～160μg/L using PEI as complexing agent.Operating pressure had no effect on R(Sb),but it impacted on membrane flux linearly.25kPa was selected as experimental operating pressure.With the volume concentration factor J fell by 5.2%and concentrated ratio reached 3.4 times using PAAS as complexing agent,J fell by 2.9%and concentrated ratio reached 4 times using PEI as complexing agent.Antimony was effectively concentrated,and permeate concentration of antimony Cp reached standards of raw water.When added coexist cations Ca2+ and Mg2+ to raw water,R(Sb)decreased.As Ca2+and Mg2+ concentration increased,R(Sb)greater decreased.(2)The recovery rate of antimony and complexing agent was 98.71%and 96.31%for PAAS-Sb solution by acidification method.It was 99.53%and 99.36%for PEI-Sb solution by basification.Regeneration of PAAS and PEI had a similar effect with the initial.(3)The membrane flux polluted by PAAS-Sb can restore to 96%of the new using HCl solution and the membrane flux polluted by PEI-Sb can restore to 98%of the new using NaOH solution.(4)The effect of complexation ultrafiltration using PEI was better than using PAAS.The reaction kinetics of complexation reaction can be described by a pseudo-first-order equation.Antimony can effectively be removed from the raw water by complexation ultrafiltration process.The concentration of antimony in water can meet "Surface Water Environmental Quality Standard"(GB3838-2002)and "Drinking Water Health Standards"(GB5749-2006),which defines the concentration of antimony limit as 5μg/L.Antimony can be achieved high-times concentrated as well as respectively recovered complexing agents and antimony.