The Effect Of Silica Speciation On Coagulation Of Kaolin By PACl

In this thesis, the effect of speciation, Si/Al ratio, coagulant dose and pH on coangulation of Kaoling with PAC1 has been investigated in detail base on pre-formed three kinds of Silica and four kinds of PAC1 with typical speciation component. The characterization of Zeta potential, Residual Turbidity (RT), Flocculation Index (FI) and Fractal dimension has been disscussed by using the traditional Jar-test, Turbidity Fluctuation monitoring and the floe struction analysis based on the CCD technique. The process chemistry and mechanism of coagulation has also been disscussed on the aspects of interaction among different species of PAC1 and Silica.By the analysis of the experimental data, the results show that the different speciation of silica have different affection on the coagulation process of the PAC1, under the special condition the coagulation process are well promoted by the formation of hydroxyaluminosilicate (HAS) species, and the HAS can bring about the "sweeping and bridging flocculation"; Due to the difference of silica speciation in the standard water , the characterization of particles' Zeta potentials, Residual Turbidity , and Si/Al ratio or PAC1 dose for the effective coagulation are clearly expressed. The variation of FI is a kind of reflection of particles' aggregation, and to some extends indicates the special coagulation mechanism; The difference of FI produced in given condition are the value, the retard time, the range of variation and the increasing speeds. The fractal dimension also provide insights to the characterization of coagulation; The mechanism of particals' aggregation, speciation of silica and PAC1 all play an important role in the density and the internal structure of floes, as results the characterization of the fractal are clearly obtained.