Effect of silver sulfide nanoparticles on photochemical degradation of dissolved organic matter in surface water

Silver sulfide nanoparticles (Ag(2)SNPs) have shown photocatalytic activity, yet little is known about the effect of Ag(2)SNPs on the photochemical degradation of dissolved organic matter (DOM) in surface water, which seriously impairs understanding of Ag2SNPs' environmental risks. Herein, this study on the basis ofelectrospray ionization coupled with Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) showed for the first time that photodegradation of natural organic matter (NOM, 2R101 N) could be accelerated by both bared and polyvinylpyrrolidone (PVP)-coated Ag(2)SNPs; the NOM with Ag(2)SNPs (e.g., 500 mu g/L) exposed to light irradiation for 96 h showed molecular formulas with lower O/C ratios as compared to the NOM alone. Also, added number of points (ranging from 1 to 2 carboxyl groups) having the same Kendrick mass defect (KMD) (COO) values and higher intensity in smaller Kendrick mass (KM) (COO) values were observed in NOM with Ag(2)SNPs compared to NOM alone. However, negligible effects of Ag(2)SNPs on photodegradation of humic acid (HA, 2S101H) were observed, even when the concentration of Ag(2)SNPs was as high as 5 mg/L. Besides molecular characteristics, a great reduction in organic carbon content of NOM within 96 h was only observed in the presence of Ag(2)SNPs under light condition. More importantly, the enhanced photodegradation of DOM by Ag(2)SNPs even at a concentration of 100 g/L was also validated in surface water. These findings suggest that Ag(2)SNPs have the potential to accelerate the photochemical degradation of DOM in surface water. (C) 2017 Elsevier Ltd. All rights reserved.