New coagulant agents from tannin extracts: Preliminary optimisation studies

Among the multiple uses of tannins, the production of coagulant agents is considered one of the most interesting one. The synthesis of tannin-derived coagulants is studied through a factorial design in order to evaluate the possible combinations between two types of tannin extracts (Acaciamearnsii de Wild and Schinopsisbalansae) under three commercially-available products (Clarotan, WeibullBlack and Quebrachocolorado) and three types of amine compounds (ammoniumchloride, glycidyltrimethylammoniumchloride and diethanolamine). After several reproducibility verifications, the optimum product was found to be the one from Clarotan and diethanolamine, which was very effective if tested with surface river water, dye or surfactant-polluted wastewater. Real surface water was clarified with low coagulant dosages (ca. 10 mg L−1), while dye concentration was reduced from 100 to 8 mg L–1 and surfactant concentration decreased from 50 to 7.5 mg L−1 with coagulant dosage of ca. 150 mg L−1.