Study on the hydrolysis-polymerization process of aluminum in polyaluminum silicate chloride(PASC) flocculant
高浓度聚硅氯化铝(PASC)中铝的水解-聚合特性研究

Using NaAlO2 as basification agent, the high-concentration (about 2.0 (mol·L-1)) flocculants polyaluminum silicate chloride (PASC) with different Si/Al molar ratio were prepared by feeding the alkali slowly. The species distribution and transformation were detected by Ferron timed complexation spectrophotometry. And the hydrolysis-polymerization process of aluminum in PASCsolution was investigated by NaOHtitration method. And the interaction between hydrolyzed aluminum species and polysilicic acid in PASCwere studied by IRmeasurements. It was found that the kinetics curve of Al-Ferron timed complexation accorded with At=A0+A11-exp(-k-b1t]+A2-exp(-kb2t)] equation. It was also found that there were interactions between polysilicic aid and hydrolyzed aluminum species in PASC, and these interactions could partially affect the hydrolysis-polymerization processes and the aluminum species distribution. The aluminum species could change from low polymer into high polymers easily when NaAlO2 was used as basification agent. The higher the Si/Al ratio was, the more the polymerize aluminum species were.