Comparison of UV/PAA and VUV/PAA Processes for Eliminating Diethyl Phthalate in Water

Diethyl phthalate (DEP) is a commonly utilized plasticizer that has gained significant attention due to its widespread occurrence in the environment and its harmful impact on human health. The primary objective of this study was to evaluate and compare several (ultraviolet) UV-(peracetic acid) PAA advanced oxidation processes based on hydroxyl radicals to degrade DEP. The effect of UV-LEDs incorporating PAA at different UV ranges (UV-A, λ = 365 nm; UV-C, λ = 254 nm and VUV, λ = 254 nm) was evaluated. The results demonstrated that DEP was successfully degraded in both the UVC/PAA (removal rate 98.28%) and VUV/PAA (removal rate 97.72%) processes compared to the UVA/PAA process (removal rate of 2.71%). The competitive method evaluated the contribution of R-O•, which were 24.08% and 33.92% in UVC/PAA and VUV/PAA processes, respectively. We also evaluated the effects of peroxymonosulfate (PMS) dosages, UV irradiation, pH and anion coexistence on the removal of DEP. In the UVC/PAA system, DEP degradation was particularly effective (removal rate about 95.52%) over a wider pH range (3–9). As the concentration of HCO3− ions increased, there may have been some inhibition of DEP removal. The inhibitory effect of HA and Cl− ions on DEP removal were negligible. Analysis of the intermediates revealed that DEP degradation primarily occurred via two pathways: hydrolysis and hydroxylation reactions. This study presents a potential mnethod for the removal of phthalates and offers some guidance for the selection of appropriate disinfection technologies in drinking water treatment.