Preparation and characterization of organic polymer modified composite polyaluminum chloride

Compared with traditional aluminum salts, polyaluminum chloride(PACl) has better coagulation-flocculation performance in turbidity removal. However, i t is still inferior to organic polymers in terms of bridging function. In order to improve the aggregating property of PACl, different composite PACl flocculant s were prepared with various organic polymers. The effect of organic polymer on the distribution of Al(III) species in composite flocculants was studied using 2 7Al NMR and Al-ferron complexation methods. The charge neutralization and surfac e adsorption characteristics of composite flocculants were also investigated. Ja r tests were conducted to evaluate the turbidity removal efficacy of organic pol ymer modified composite flocculants. The study shows that cationic polymer and a nionic polymer have significant influences on the coagulation-flocculation behav iors of PACl. Both cationic and anionic polymers can improve the turbidity remov al performance of PACl but the mechanisms are much different: cationic organic p olymer mainly increases the charge neutralization ability, but anionic polymer m ainly enhances the bridging function.