复合硅铁混凝剂荷电性及除污染性能与机理

摘要

A new composite polymer,Si-Fe coagulant with various Si/Fe molar ratios,was prepared by using water glass,ferrous sulfate and sodium chlorate by copolymerization.Charged properties of PSF samples taken from different copolymerization times and influence of dilution concentration on PSF Zeta potential were studied with Nano Zetasizer.The pollutants removal by PSF in treating lower temperature and lower turbidity water,and slaughterhouse effluent was explored compared to that by polyferric aluminum（PFA）.Results show that the copolymerization between Si and Fe is not a simple electro neutrality process between positive charge of Fe and negative charge of polysilicic acid（PS）.PSF is found to be a complexation compound of Si,Fe and many other ions,instead of a simple mixture of raw materials.The Zeta potential of PSF at higher concentration tends to be zero,and tends to increase when diluted,up to 11 mV,whereas the average Zeta potential of PFA is 36.1 mV,and slightly increases when diluted.For lower temperature and lower turbidity water,PSF gives higher CODMn removal by 20% than PFA,and for slaughterhouse effluent,PSF has higher turbidity,CODCr and color removal by 60%、66% and 54% than PFA,respectively.The coagulation mechanism of PSF is the cooperation of charge-neutralization /destabilization,bridging and sweeping.%采用共聚法制备不同Si、Fe摩尔比的复合硅铁（PSF）混凝剂,应用Zeta电位分析仪对PSF共聚反应过程的荷电性及稀释浓度对荷电性的影响进行研究,并对比PSF与复合铝铁（PFA）对低温低浊水及屠宰废水的除污染性能,同时分析PSF的混凝机理.结果表明,硅铁共聚反应不是铁盐的正电与聚硅酸的负电的简单电中和过程,也不是简单的原料混合或是各原料单独自聚的产物,而是硅、铁等的共聚产物.PSF浓度较高时,其Zeta电位几乎均在等电点附近,稀释水解后其荷正电量增加,达到11 mV;而PFA的Zeta电位平均值为36.1 mV,稀释后其荷正电量增加很少.对于低温低浊水,PSF对CODMn的去除率比PFA高20%;对于屠宰废水,PSF对浊度、CODCr及色度的去除率比PFA分别约高60%、66%及54%.PSF混凝机理是电中和/脱稳、架桥与卷扫的协同作用.