Reaction mode between Si and Fe and evaluation of optimal species in poly-silicic-ferric coagulant

摘要

A kind of Fe-polysilicate polymer,poly-silicic-ferric(PSF)coagulant was prepared by co-polymerization(hydroxylation of mixtureof Fe3+and fresh polysilicic acid(PS)),in which PSF0.5,PSF1 or PSF3 denotes Si/Fe molar ratio of 0.5,1 or 3,respectively.Theeffects of Si/Fe ratio and reaction time(co-polymerization time or aging time)on the reaction mode between Si and Fe were studies,and the optimal species of PSF was evaluated by pH change during the preparation of PSF and coagulation tests.The results showedthat the characteristics of PSF are largely affected by both reaction time and Si/Fe ratio.PSF is found to be a essential complex of Si,Fe,and many other ions.The reaction mode between Si and Fe differs with various Si/Fe ratios.The pH of PSF0.5,PSF1 or PSF3tended to be stable when reaction time is 10,25 or 55 min,respectively,which is almost consistent with the time reaching the relativestable morphology that is just the optimal species of higher coagulation effciency.The optimal reaction time reaching optimal speciescan be evaluated by measuring the pH change during the polymerization process.