Flocculation Behaviors And Mechanisms Of Organic Polymer Flocculants

The paper focused on the improvement of flocculation performance of cationic organic polymer flocculants (COPF) and inorganic flocculants.Kaolin clay was used as a model suspension. PDA(Photometric Dispersion Analyzer)was set up and applied to monitor the flocculation kinetics,and the floc structure was obtained from image analysis. The flocculation induced by organic polymers as flocculants,flocculant aids. In addition, the optimized coagulation was investigated too in the model suspention of humic acids and kaolin clay. The results were outlined as follows:For lower molecular weight and higher charge density ,polydiallyldimethylammonium chloride (PDADMAC),the flocculation occurs through charge neutralization. The optimum dosage is 0.15mg/l. The lower optimized dosage,the narrower flocculation zone consists with the slower flocculation rate. Accordingly,smaller flocs and more compact floc structure were formed. The floc size at the optimum dosage of PDADMAC was smaller than 100 um and the fractal dimension D2 of the flocs was 1.77 .the polymer bridging was the dominant mechanism for cationic polyacrylamide (C498),higher molecular weights and lower charge densities. The optimum dosage is 0.4mg/l. Its optimized dosage improved,the flocculation zones became broader,and the flocculation rates increased. In addition,the floc structures were more open. The floc size at the optimum dosage of C498 ranged from 100 um to 200 um and the fractal dimension D2 of the flocs were 1.64 .0PF as flocculation aids were the good option for the application of optimum coagulation by organic polymers as flocculants,flocculant aids. Charge density was the key facter for flocculation effect and accordingly PDADMAC had better effect than C498.