固体聚硅硫酸铁混凝剂的表面形貌及混凝效能

以水玻璃、硫酸亚铁及氯酸钠为原料,采用共聚法制备不同Si/Fe摩尔比的聚硅硫酸铁(PFSS)混凝剂,通过两种方式固化:(1)将未稀释的PFSS经自然干燥制成凝胶状样品;(2)将不同聚合反应时间的PFSS稀释后干燥制成粉末状样品.用扫描电镜及X射线衍射仪对其表面形貌及成分进行观察和分析,对比粉末状固体PFSS与液体PFSS的混凝性能.结果表明,两种固化手段制备的PFSS表面形貌完全不同,其中凝胶状样品没有孔隙、连接紧密,而粉末状样品是松散的片状或晶须状结构,Si/Fe摩尔比对样品的表面形貌有很大影响.PFSS不是原料的简单复配,而是"硅铁反应的共聚物".反应时间对固体PFSS混凝性能的影响小于对液体PFSS的影响,制备液体和固体混凝剂需要不同的反应时间.与液体PFSS相比,固体PFSS的除浊性能随Si/Fe摩尔比的增加逐渐下降,而除UV254的性能却逐渐升高.延长沉淀时间有利于固体PFSS混凝性能的提高.

EXTERIOR SHAPES AND COAGULATION PERFORMANCE OF SOLID POLY-FERRIC-SILICIC SULFATE

Poly-ferric-silicic sulfate(PFSS)with different Si/Fe molar ratios was prepared using water glass,ferrous sulfate and sodium chlorate by co-polymerized method,and was solidified with the two following ways:(1)gel samples were made by aging at room temperature without dilution;(2)powder samples were made after drying dilute from different reaction time.The exterior shapes and constitutes of solid PFSS were observed and analyzed with scanning electron microscope(SEM) and X-ray Diffractionmeter(XRD),respectively.The results indicate that exterior shapes of solid PFSS are completely different due to the difference of the preparation method: gel samples are a type of compact structure without holes,while powder samples are incompact structure with many holes and are made of curl slice or crystal palpus with different Si/Fe molar ratios,and Si/Fe molar ratio has great influence on the exterior shapes of PFSS.PFSS is not a simple mixture of raw materials but a complexation formed by polymerizing Si,Fe molar and other ions.Influence of reaction time on the performance efficiency of solid PFSS is more obvious than that of liquid PFSS,so different time is needed in preparing solid PFSS compared with that in liquid PFSS.Compared to liquid PFSS,turbidity removal by solid PFSS decreases as the increasing of Si/Fe molar ratio,in comparison with the increase in removing UV_(254),so different Si/Fe molar ratio should be selected to be solidified in treating different waters.The coagulation performance of solid PFSS can be improved with the increasing of the precipitation time.