Treatment of water contaminated with diphenolic acid by gamma radiation in the presence of different compounds

The elimination of diphenolic acid (DPA) from contaminated water is an urgent challenge. The aim of this study was to investigate DPA degradation by gamma radiation, studying the influence of the dose rate, initial DPA concentration, solution pH, the presence of O2, and the presence of different additives (e.g., Br−, Cl−, CO32-,NO2-,NO3-,andSO42-). A further objective was to study the effect of the water matrix (ultrapure water, surface water, and wastewater) and the variation in total organic carbon and toxicity as a function of absorbed dose. Results obtained showed that: gamma radiation was effective to remove DPA from aqueous solution; the dose constant was slightly dependent on the dose rate; and the solution pH had a major influence on DPA degradation, which was highest at pH 7. DPA degradation was reduced in the presence of Br−, Cl−, CO32-,NO2-,NO3-,andSO42- and was lower with higher concentrations of these species, largely due to their competition with DPA for the reactive radicals generated, especially HO. Lower yield of DPA decomposition were obtained with wastewater and surface water than with ultrapure water due to the presence of organic matter and HCO3-,Cl-,SO42-,andNO3- ions, which react with the reactive radical species (HO, H and eaq-). The TOC and toxicity of the medium decreased during DPA degradation in all water types studied.

► Gamma radiation was effective to remove diphenolic acid (DPA) from aqueous solution.
► The solution pH had a major influence on DPA degradation, which was highest at pH 7.
► DPA degradation was reduced in the presence of Br−, Cl−, CO32-,NO2-,NO3-,andSO42-.
► Lower degradation rate were obtained with wastewater than with ultrapure water.
► Both TOC and toxicity decreased during DPA degradation in all water types studied.