新型固体聚硅硫酸铁混凝剂的制备及结构表征

The Preparation and Characterization of a New Solid Coagulant:Polymeric Ferric Silicate Sulfate

聚硅酸基混凝剂是重要的水处理剂之一,在混凝过程中扮演重要的作用,但易于产生自聚反应、形成硅胶、失去稳定性。因此,制备稳定的聚硅酸基混凝剂受到广泛关注。为获得一种稳定的聚硅酸基混凝剂,提出一种新型稳定的固体硅酸基混凝剂(PSPF)的制备方法。采用红外光谱与扫描电镜表征PSPF的结构与形貌;Ferron逐时络合比色分光光度法分析PSPF中Fe的形态;通过微污染源水的处理评估PSPF的混凝性能。以硫酸亚铁、硅酸钠、磷酸二氢钾、碳酸钠等为原料,确定硅铁摩尔比(n_(Si)/n_(Fe))、磷铁摩尔比(n_p/n_(Fe))与碱化度(n_(OH)/n_(Fe))对PSPF的制备影响。结果显示在60℃水浴30 min条件下,PSPF最优合成条件为:n_(Si)/n_(Fe)为1:4,n_P/n_(Fe)为1:6与n_(OH)/n_(Fe)为1:10。表征分析显示,PSPF是一种高分子聚合物,含有的新基团键(例如,Si—O—Si与Fe—O—Si),其有助于增大PSPF分子量与分子链与增强PSPF的混凝性能;PSPF形貌团簇,呈网状结构,有助于吸附架桥和网捕卷扫;Si含量增加提高了PSPF中Fe(b)和Fe(c)的含量,增强了PSPF的聚合度与固化效果。PSPF的混凝性能受PSPF投加量与水环境pH影响显著;在pH为6与投加量为8 mg·L^(-1)时,残余浊度和UV254去除率分别可达0.33 NTU与58.6%。实验研究显示,混凝剂多因素(Si,Fe与P)调控对增强固体聚硅酸基混凝剂的固化效果、稳定性以及混凝性能具有良好的效果。

As one of the most important water treatment agents,polysilicate coagulant,has been playing an important role in coagulation- flocculation,but it is prone to lose stability due to self-polymerization and the forming of silica gel.Therefore,research on the preparation of stable polysilicate coagulant has attract great attention.A new method to prepare a stable polysilicate coagulant（PSPF）,was proposed in this paper.Its structure and morphology were characterized by using Fourier transform infrared（FTIR） spectroscopy and scanning electron microscopy（SEM） respectively.Fe species in PSPF was analyzed via FeFerron complexation timed spectrophotometric method The performance of PSPF was assessed by measuring micro-polluted water treatment efficiency.Primary chemicals,such as ferrous sulfate,sodium silicate,potassium dihydrogen phosphate,sodium carbonate,were used.The influence of those parameters affecting the preparation of PSPF,such as n（Si）/n（Fe）,n）P/n（Fe） and n（oh）/n（Fe）molar ratios were examined.The results showed that n（Si）/n（Fc） of 1：4,nP/n（Fe） of 1：6 and n（OH）/n（Fe） of 1：10 under 60 ℃ water bath for 30 min was the optimum condition for preparation.The FTIR spectrum indicated that PSPF was a kind of high molecular polymer,containing new groups（e.g.,Si—O—Si and Fe—O—Si）,which could increase the molecular weight,molecular chain and coagulation-flocculation efficiency.PSPF presented a cluster appearance similar to a network structure,which was conductive to adsorption-bridging capacity and precipitation sweeping.The increase of Fe（b） and Fe（c） as a result of Si increasing in PSPF improved the polymerization and solidification.The coagulation behaviors of PSPF that were largely affected by the coagulant dosage and pH,indicated that for pH and dosage at 6 and 8 mg·L^-1,respectively,the residual turbidity and UV254 removal efficiency could achieve 0.33 NTU and 58.6%,respectively.