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

Abstract 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 Ag 2 SNPs' environmental risks. Herein, this study on the basis of electrospray 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 μg/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 μg/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.