Enhanced coagulation for TiO2-NPs removal by using a hybrid flocculant

A hybrid flocculant, PAC-CA, with the advantages of inorganic and organic flocculants, was prepared, and the coagulation behavior and floc characteristics of PAC-CA for removing titanium dioxide nanoparticles (TiO 2 -NPs) under different conditions were studied. The effects of monomer mass ratio, initiator concentration, hydroxyl aluminum ratio, reaction temperature, and polymerization time on the coagulation performance for TiO 2 -NP removal were studied. PAC-CA was characterized through SEM, FT-IR, TG-DSC, XRD, XPS, and Ferron complex colorimetric characterization. The characterization results showed that PAC-CA was successfully copolymerized using AlCl 3 , carboxymethyl chitosan, and acrylamide. The high content of Alb in PAC-CA helped improve the coagulation performance. When the dosage was 30 mg/L, the pH was 8, the stirring intensity was 200 s −1 , and the settling time was 30 min, the optimal removal rates for TiO 2 -NPs and turbidity were 87.30% and 91.72%, respectively. Kaolin could effectively improve the TiO 2 -NP removal efficiency and promote the density and particle size of flocs. Humic acid exerted an inhibitory effect on coagulation efficiency with loose and small flocs.