Characterisation and coagulation performance of a tannin-based cationic polymer: A preliminary assessment

Laboratory experiments were carried out using a photo-dispersion analyzer (PDA) to evaluate the coagulation performance of TBP at different pH values, and in comparison with alum and polyDADMAC. The results showed that the optimal TBP dose increased with increasing pH, principally because of polymer precipitation, but there was a corresponding increase in coagulation performance. In comparison with alum and polyDADMAC, at optimal doses, the performance of the TBP in treating a kaolin suspension was inferior at neutral pH. However, in higher solution pH conditions the coagulation performance of TBP appears to improve substantially, albeit with a greater dose required, and at pH 9 it was arguably superior to the other two coagulants.