高浓度聚硅氯化铝(PASC)中铝的水解-聚合特性研究

以铝酸钠为碱化剂,采用缓慢滴碱法合成了高浓度(2.0mol.L-1左右)具有不同Si/Al摩尔比的聚硅氯化铝复合混凝剂(PASC).采用Al-Ferron逐时络合比色法、碱式滴定法和红外光谱分析,研究了铝的形态分布、水解-聚合历程及铝硅间的相互作用.实验结果表明,Al-Ferron络合动力学符合At=A0+A11-exp(-kb1t]+A2-exp(-kb2t)];在PASC中,硅酸钠和铝的水解产物间存在着相互作用,这种作用对铝的水解-聚合历程和形态分布有不同程度的影响.用铝酸钠制备PASC时有利于Al的形态由低聚物向中、高聚物转化,且随着PASC中Si/Al比的增加生成多核羟铝配合物的能力逐渐增强.

Study on the hydrolysis-polymerization process of aluminum in polyaluminum silicate chloride(PASC) flocculant

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 A_t=A₀+A₁1-exp(-k-_b1t]+A₂-exp(-k_b2t)] 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.