Abstract:Cationic flocculant 2-hydroxypropyltrimethyl-ammonium chloride chitosan (HTCC) was prepared by the reaction of chitosan (CTS) with 2-hydroxypropyltrimethyl-ammonium chloride (CTA). The optimum synthesis conditions of HTCC was determined according to its turbidity removal efficiency for kaolin suspension as follows: mass ratio MCTS: MCTA: MNaOH =1:2:1.2, reaction temperature was 60℃ and reaction time was 3h. The flocculation experiment showed the turbidity removal efficiency of HTCC was higher, and the applicable pH range of HTCC was broader compared to CTS. The styrene-butadiene rubber wastewater was treated by the composite flocculant HTCC+PAC. The residual turbidity reached under 2 NTU, the removal rates of COD and chromaticity reached to 32.0% and 92.98% respectively. The applicable pH value range for flocculating the sample by HTCC+PAC was from 6.0 to 8.0. This styrene-butadiene rubber wastewater was also treated by composite flocculant HTCC+ PAM (anion). The residual turbidity reached under 3 NTU, and the removal rate of COD was the most high, reaching to 46.0 %, and the dosage was lower. The applicable pH value range for flocculating the sample by HTCC+PAM was wider from 5.0 to 8.9. The use of HTCC combined with PAC or PAM as flocculants in the preceding treatment of styrene-butadiene rubber wastewater would decrease the load of subsequent biochemical treatment and the dosages of PAC or PAM, thus decrease the residual aluminum and residual acrylamide monomer in the treated water.