聚硅酸钛制备及其助凝特性

采用在活化硅酸制备过程中加入适量TiCl4的方法,试制了一种新型无机高分子助凝剂—聚硅酸钛。研究了不同/条件下制备的聚硅酸钛在固定pH值的水中分散物的粒径和Zeta电位随着活化时间的变化趋势,并与活化硅酸作比较。结果表明,在Si/Ti=20,活化48 h的条件下能制备出较为稳定的聚硅酸钛。与活化硅酸相比,聚硅酸钛在水中的分散物具有较大的粒径和更高的Zeta电位。通过对比制备的活化硅酸和聚硅酸钛的红外图谱发现,聚硅酸钛中有Ti-O-Si键,证明钛离子参与了聚合反应,新生成的化学键提高了它的聚合度和稳定性。采用硫酸铝为混凝剂,聚硅酸钛为助凝剂进行混凝除浊实验。测定了絮凝体的Zeta电位和混凝沉淀后的上清液浊度,研究了硫酸铝投加量和混凝pH对聚硅酸钛助凝效果的影响。结果表明,投加适量的聚硅酸钛助凝剂,明显提高了混凝除浊效果且拓宽了有效混凝pH值的范围。

Preparation of polysilicate-titanium and its performance as coagulant aid

By addition of certain amount of TiCl4 in the process of activation of silicic acid, a new type of inorganic polymeric coagulant aid-polysilicate-titanium was prepared. Under different ratios of Si/Ti, the size and zeta potential of the dispersions of polysilicate-titanium versus reaction time at a fixed pH were investigated, which were also compared with those of the activated silicic acid. The results show that under the conditions of Si/Ti=20 and 48-hour activation time, a relatively stable polysilicate-titanium was formed. Compared with activated silicic acid, polysilicate-titanium has larger particle size and higher zeta potential when it is dispersed in water. By comparison of the IR spectra of activated silicic acid and polysilicate-titanium, the latter possess Ti-O-Si bond, indicating that titanium ions were involved in the polymerization reactions; this chemical bonding increases its polymerization degree and stability. Using Al2(SO4)3 as a coagulant and the polysilicate-titanium as coagulant aid, its effects on turbidity removal were studied. Zeta potential of flocs and supernatant turbidity of coagulated suspensions after sedimentation were measured at different aluminum sulfate dosages and solution pH values.The results show that addition of an appropriate amount of polysilicate-titanium as coagulant aid can significantly improve the turbidity removal efficiency and broaden the effective range of pH.