Abstract: The nano Fe3O4 was modified by gallic acid(GA) and then was mixed evenly with modified chitosan to synthesize a composite magnetic flocculant mCTS@(PGA-Fe3O4), which was used to flocculate the rural black-odorous water. The flocculation effect of mCTS@(PGA-Fe3O4) under different synthetic conditions was investigated. Meanwhile, the flocculation conditions of PAM and mCTS@(PGA-Fe3O4) by response surface method were optimized. Results suggested that the optimized synthetic conditions of mCTS@(PGA-Fe3O4) were: GA dosage 0.3 g, Fe3O4 modified temperature 60℃, AM dosage 3 g, trigger mass 0.03 g and polymerization temperature 60℃. Based on the distribution of response values, the optimum operating conditions were flocculant mCTS@ (PGA-Fe3O4) 0.38 g/L, pH 7.42, and temperature 25.2℃. Under this condition, the removal rates of turbidity, color and COD were 92.0%, 84.2% and 79.9%, respectively flocculation effect was better than that of PAM.In addition, reused experiments results suggested that the flocculant still had good flocculation effect after reusing three times. This work indicated that the mCTS@(PGA-Fe3O4) possessed a good application prospect in the treatment of black-odorous water in future.

Key words: magnetic flocculant, rural black-odorous water, response surface method, flocculating efficiency