聚硅酸铁及其氧化改性剂的表征与性能分析

Characterization and coagulation performance of poly-silicic-ferric sulfate and its oxidizing modification coagulant

对自制的聚硅酸铁(PSF)进行改性,加入高锰酸钾和稳定剂M,制备出氧化型聚硅酸铁混凝剂(PSF-Ⅰ),并采用光学显微镜及透射电镜、紫外吸收(UVA)扫描、碱解实验、红外光谱及氧化还原电位仪对PSF及PSF-Ⅰ进行性质表征,同时对比研究其对不同水质的混凝性能。结果表明,PSF是由许多链节样物种连接而成的分维数很大的敞开式枝状结构,形态尺寸覆盖范围宽,而PSF-Ⅰ是分布比较均匀、分维数较低、结构紧凑的棕黄色大尺寸稳定形态,不易水解,其氧化还原电位比PSF高出约550 mV。高锰酸钾的加入改变了PSF的微观结构,锰的各种价态可能参与了硅铁的络合,并生成了类似硅氧四面体的结构。对于不同水质,PSF与PSF-Ⅰ的混凝性能均有共同趋势:低投量时PSF-Ⅰ的除浊率比PSF低,但是UV254去除率均比PSF高,最大差值约为17%左右。PSF-Ⅰ是通过混凝吸附和催化氧化功能共同实现对有机物的去除,催化氧化占绝对优势,而PSF仅是通过常规的混凝吸附去除部分有机物,去除机理有本质的区别。

A new type of inorganic coagulant, oxidizing poly-silicic-ferric sulfate（PSF-Ⅰ）, was prepared by adding potassium permanganate and stabilizer M to poly-silicic-ferric sulfate（PSF）. The microproperties of PSF-Ⅰ was characterized with microsoope, transmission electron microsoope（TEM）, ultraviolet/visible aborption（ UVA ） scanning, alkalization experiment, infrared（IR） spectrometer and oxidation-reduction potential （ORP） meter, respectively, in comparison with that of PSF. The coagulation perfommnce of PSF-Ⅰ in treating different water was investigated compared to that of PSF. The results show that the species of PSF is characterized by having multi-branched stmctures with larger size, wider molecular weight and larger fractal dimension. While PSF-Ⅰ is a kind of brown-yellow conglomerate of larger size with lower fractal dimension and almost the similar size of species. The ORP of PSF-Ⅰ is higher 550 mV than that of PSF. The microproperties of PSF have been changed greatly due to the addition of KMnO4, and there exists KMnO4 unattached in PSF-Ⅰ. A kind of tetrahedron structure somewhat like the oonnection of Si-O-Si bonds may be formed by the complexation of Mn （maybe in various valence） with PSF. The coagulation effect has the same trend for various water by PSF, F-Ⅰ and PSF. PSF-Ⅰ has lower turbidity removal than PSF at lower dosage while the tin,oval rate of UV254 by PSF-Ⅰ is higher than that by PSF at entire dosage range with the largest difference of 17%. The removal of dissolved organic matters （DOMs） is caused not only by adsorption/charge-neutralization and co-precipitation but also by oxidization using PSF-Ⅰ as ooagulant, in which catalysis/oxidization is dominant. While to PSF, adsorption/charge-neutralization and co-precipitation is the only coagulation mechanism, so there is an essential distinction in mechanism for removing DOMs by PSF and PSF-Ⅰ.