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Abstract: In this study, a novel composite inorganic–organic coagulant was prepared by polyferric chloride (PFC) and polydimethyldiallylammonium chloride (PDMDAAC). The variations of size and specific surface area with respect to pH for composite polyferric chloride-polydimethyldiallylammonium chloride (PFC-PDMDAAC) were investigated, and the coagulation efficiency of PFC-PDMDAAC was studied by Jar–test, and Photometric Dispersion Analyzer 2000 (PDA 2000) was used to investigate floc aggregation process of PFC-PDMDAAC. The results show that the average size and specific surface area of PFC-PDMDAAC are larger than that of PFC. The coagulation efficiency of PFC-PDMDAAC is higher than that of PFC and PDMDAAC. The floc aggregation process shows that kaolin particles may be aggregated to micro-flocs by Fe(III) species in PFC-PDMDAAC at first, and then the micro-flocs are bridged together to form large flocs by organic coagulants in PFC-PDMDAAC. The soluble dye is aggregated initially to insoluble dye micro-compound by the reaction of PDMDAAC, and then the insoluble dye micro-compound is aggregated to large flocs by Fe(III) polymers in PFC-PDMDAAC. [Copyright &y& Elsevier]

Abstract: In this study, a new composite coagulant, which was prepared by ployferric chloride (PFC) premixed with polydimethyldiallylammonium chloride (PDMDAAC), was adopted to treat the simulated dye water and the actual textile wastewater. The effect of coagulant dosage and pH of dye water on the color removal was examined. And the color removal results treated by the composite coagulant (PFC–PDMDAAC) were compared with those treated by PFC, PDMDAAC and PFC followed by PDMDAAC (PFC/PDMDAAC), respectively. The following results are discovered. Synergy between PFC and PDMDAAC increases zeta potential of PFC–PDMDAAC and reduces the effect of pH on zeta potential and Fe(III) species of PFC–PDMDAAC. Treatment with PFC–PDMDAAC is very effective in removing disperse blue HGL (98%) and reactive blue STE (86%). And small changes in the color removal efficiency of PFC–PDMDAAC are observed in all pH range. The color removal efficiency for disperse blue HGL and reactive blue STE is higher than 96% and 98% in the pH range 7.5–10.5, respectively. Furthermore, PFC–PDMDAAC is shown to be more effective in removing dye than that of PFC/PDMDAAC. Finally, the treatment of the actual textile wastewater has shown that PFC–PDMDAAC is a more effective coagulant. [Copyright &y& Elsevier]