Iron tungstate on nano-γ-alumina as photocatalyst for 1,4-dioxane solar degradation in water

Abstract

Reverse osmosis (RO) does not effectively remove carcinogenic 1,4-dioxane and, consequently, this compound needs to be eliminated from RO-reclaimed water for potable reuse. This work analyzed the 1,4-dioxane mineralization on a solar-driven system using home-made catalysts with iron tungstate (wt%: 1–20%) supported on nano-γ-alumina. Characterization has been conducted using SEM-EDS, N2 adsorption-desorption, XRD, XPS, UV–vis spectra, PL, EIS and transient photocurrent analyses. The BET area of FeW/nAl5 catalyst was close to 200 m2 g−1. XRD and XPS analysis confirmed that iron tungstate was loaded on the support. Mineralization has been checked with catalyst concentration ranging 0.1–0.9 g L−1. More than 90% TOC removal was achieved, with no iron or tungsten leaching after 4 h reaction. Scavenging tests, ESR, ionic chromatography and UPLC-MS analysis confirms that •OH and O2•− radicals were responsible for 1,4-dioxane degradation. Iron promotes •OH formation and 1,4-dioxane photodegradation. Several ring-opening intermediates were identified, whereas condensation byproducts were detected in minor amounts. Based on byproduct identification, reaction pathway was postulated.