Inhibition of disinfection by-product formation in silver nanoparticle-humic acid water treatment

Abstract

Abstract Health risk of disinfection by-products (DBPs) makes the removal of trihalomethanes (THMs) precursors a great concern in water treatment. This study investigated the THMs precursors removal by coagulation with four coagulants, namely TiCl 4 , polymerized titanium chloride (PTC), Al 2 (SO 4 ) 3 , polymerized aluminum chloride (PAC), in silver nanoparticle-humic acid (AgNPs-HA) water treatment. Flocs formed during coagulation process were characterized using a laser diffraction particle-sizing device, and the residual dissolved organic matter (DOM) in coagulated water was characterized using three-dimensional Excitation and emission matrix (3DEEM) fluorescence spectroscopy. Results showed the reduction of THMs by a large margin through coagulation by the four coagulants, and CHCl 3 and CHBrCl 2 were observed as main species. Compared with conventional Al 2 (SO 4 ) 3 and PAC, TiC 4 and PTC achieved efficient AgNPs removal and were superior in terms of DOM removal with improved floc characteristics in terms of floc growth rate and floc size. Analysis of 3DEEM results suggested the fluorescent substance removal ability of TiCl 4 > PTC > Al 2 (SO 4 ) 3 > PAC, and the predominant fulvic acid-like DOM was removed to the largest extent through coagulation. Besides, anatase structured TiO 2 with efficient photocatalytic performance was finally recovered from TiCl 4 and PTC coagulated sludge. The atomic percentage of Ag-doped TiO 2 was TiO 1.82 Cl 0.25 Na 0.29 Ag 0.14 .