聚硅酸铁(PSF)混凝剂硅铁反应过程研究

以水玻璃、硫酸亚铁及氯酸钠为原料,用共聚法制备不同Si/Fe比的聚硅酸铁(PSF)混凝剂(PSF0.5、PSF1、PSF3分别指Si/Fe摩尔比为0.5、1、3),同时监测制备过程中pH的变化,并就不同共聚反应时间的样品,分别采用X-射线衍射法(XRD)、紫外吸收(UVA)扫描法、透射电镜法(TEM)、光子相关光谱法(PCS)及红外光谱法(IR)对其反应过程的微观品质进行多方面表征.结果表明,PSF是硅铁反应的共聚物,而不是简单的原料复配.不同Si/Fe比的PSF具有不同的硅铁成键速度、成键方式及成键稳定性,低Si/Fe比主要生成以Si—O—Fe—O—Fe—O—Si键络合的物种,而高Si/Fe比主要生成以Si—O—Fe—O—Si—O—Si键络合的物种,Fe—O—Fe键的形成速度快并且与Si—O—Fe键的形成可能有相互促进作用,而Si—O—Si键(硅酸聚合)形成速度慢并且与Si—O—Fe键的形成可能有相互阻碍作用,Fe—O—Fe键的稳定性比Si—O—Fe或Si—O—Si键差.对于PSF中硅铁不同成键模式的分析为合成高性能、高稳定性的硅酸铁类混凝剂以及为优势形态控制提供了一定的理论基础.

Analysis of Reaction Process Between Si and Fe in Poly-Silicic-Ferric Sulfate (PSF) coagulant

A new inorganic polymer coagulant, poly-silic-ferric sulfate (PSF) with various Si/Fe ratios (PSF0.5, PSF1 and PSF denote Si/Fe molar ratios of 0.5, 1 and 3, respectively), was prepared using water glass, ferrous sulfate and sodium chlorate by co-polymerization, and pH value was measured during the preparation process. The influence of both Si/Fe ratio and reaction time (polymerization time) on the complexation process (bonding mode) between Si and Fe was explored with many analytical methods (such as X-ray diffraction (XRD), ultraviolet/visible absorption (UVA) scanning, transmission electron microscope (TEM), photon correlation spectra (PCS) and infrared spectrum (IR) using PSF samples taken from different reaction time at different Si/Fe ratios. The results show that the characteristics of PSF are largely influenced by both reaction time and Si/Fe ratios. PSF is found to be a complexation compound of Si, Fe and many other ions, instead of a simple mixture of raw materials. The complexation process between Si and Fe may be different from various Si/Fe ratios, namely, the bonding rate, bonding mode and the stability of the bond between Si and Fe are different from various Si/Fe ratios: the polymer based on Si-O-Fe-O-Fe-O-Si bond may be formed at low Si/Fe ratio, in comparison with that based on Si-O-Fe-O-Si-O-Si bond at high Si/Fe ratio; the formation rate of Fe-O-Fe bond is rapid and there may be a mutual acceleration between Fe-O-Fe bond and Si-O-Fe bond, while the formation rate of Si-O-Si is slow and maybe there is a mutual retardation between Si-O-Fe bond and Si-O-Si bond; the stability of Fe-O-Fe bond is weaker than that of Si-O-Fe or Si-O-Si bond.