聚硅酸铁的碱解实验及混凝效能研究

Alkalization experiment and coagulation performance of poly-silicic-ferric coagulant

采用共聚法制备不同Si/Fe比的聚硅酸铁(PSF)混凝剂(PSF0.5、PSF3分别指Si/Fe摩尔比为0.5、3),并对PSF进行碱解实验以及PSF对松花江水、哈尔滨市南岗区生活污水的混凝实验。结果表明,通过碱解实验可以得到有关混凝剂内部形态变化以及各原料反应过程的一些辅助信息。碱解实验可以进一步较准确验证PSF的反应机制:共聚初期,低Si/Fe比生成以Si-O-Fe-O-Fe-O-Si键络合的物种,随共聚时间的增加可能导致易断裂的Fe-O-Fe键断裂;而高Si/Fe比在共聚初期,铁和聚硅酸还没有络合或络合很少,随共聚时间的增加,主要生成以Si-O-Fe-O-Si-O-Si键络合的物种。Fe-O-Fe键稳定性比Si-O-Fe或Si-O-Si键差。综合浊度、UV254和COD的去除效果,PSF0.5、PSF3对松花江水的最佳投药量分别为8.5mg/L、10.5mg/L,对哈尔滨市南岗区生活污水的最佳投药量分别为70mg/L、100mg/L。PSF3的除浊再稳投药量低于PSF0.5,而PSF0.5去除UV254、COD的再稳投药量却低于PSF3。

Poly-sihcic-ferric （PSF） coagulant with various Si/Fe mtios（PSF 0.5 and PSF 3 represent Si/Fe molar ratios of 0.5 and 3, respectively）, was prepared by co-pelymerization. The alkalization experiments of PSF and coagulation performance of PSF in treating surface water collected from the Songhua River and sewage water from Nangang district in Harbin were investigated. The results showed that some information-assisted the reaction mechanism between Si and Fe and the species transformation could be captured by the alkalization experiment. The alkalization experiment further improved validation of the Si-Fe reaction mechanism： much larger morphology based on Si-O-Fe-O-Fe-O-Si bond was immediately formed and then the unstable Fe-O-Fe bond breaks with increasing of the co-polymerization time in lower ratios of PSF （such as PSF 0.5） at initial co-pelymerization stage. While for higher ratios of PSF （ such as PSF 3）, only a small amount of Fe3＋ participates in eomp｜exation with PS at the initial co-polymerization stage, and species based on the Si-O-Fe-O-Si-O-Si bend was formed. The optimum doses of PSF 0.5 and PSF 3 are 8.5 mg/L and 10.5 mg/L for surfaces water and are 70 mg/L and 100 mg/L for sewage water according to the removal of turbidity, UV254 and COD, respectively. PSF 3 gave a lower re-stabihzation dose for turbidity removal titan PSF 0.5, while the contrary was true for UV254 and COD removal.