PEG assisted P/Ag/Ag2O/Ag3PO4/TiO2 photocatalyst with enhanced elimination of emerging organic pollutants in salinity condition under solar light illumination

Abstract In this study, the effect of salinity on degradation of model environmental pollutants (organic dyes and E. coli) was investigated using polyethylene glycol (PEG) assisted P/Ag/Ag2O/Ag3PO4/TiO2 photocatalyst. The photocatalyst was firstly synthesized with structure modifier PEG to determine the optimum molecular weight by sol-gel method, and was characterized by XRD, UV-Vis, PL, SEM, TEM, EDS, and photocurrent experiment. The PEG300 modified P/Ag/Ag2O/Ag3PO4/TiO2 photocatalyst was found to be the optimal molecular weight which exhibited small crystalline size, narrow band gap, better absorption ability, smaller particles size, large photocurrent density, low recombination rate and higher photocatalytic activity among other PEG modified photocatalyst. The PEG300-P/Ag/Ag2O/Ag3PO4/TiO2 photocatalytic degradation of emerging organic pollutants such as rhodamine B, methyl orange, and methylene blue was significantly higher at aqueous NaCl (2.6 and 3.2 wt%) and artificial salinity (25 and 35‰) compared to freshwater under simulated solar light illumination. Furthermore, the elimination of organic dyes under different environmental factors such as initial pH, light intensity, reaction temperature showed substantial degradation in real environmental conditions at salinity. Moreover, PEG300-P/Ag/Ag2O/Ag3PO4/TiO2 photocatalyst demonstrated high practicability on complete inactivation of E. coli, simultaneous degradation of organic dyes, and high stability in seawater. Superoxide anion (•O2-) radicals was found to be the dominant reactive species, and subsequent formation of Cl• and free chlorine oxidative agents further improved the photocatalytic purification process. The PEG300-P/Ag/Ag2O/Ag3PO4/TiO2 photocatalyst showed great potential in treating environmental organic pollutants at salinity condition under solar light illumination.