Degradation of 1, 4-dioxane by hydroxyl radicals produced from clay minerals

[Display omitted] •Fe(II) oxidation in clays produces OH in neutral pH and dark environment.•Degradation of 1,4-dioxane was correlated with Fe(II) oxidation and OH production.•Nontronite represents a renewable catalyst for 1,4-dioxane degradation. 1,4-Dioxane is causing a general concern as an emerging contaminant in groundwater environment. Traditional remediation methods can be either inefficient or costly. In this study, we present a cost effective method for possible in situ remediation of 1,4-dioxane. Hydroxyl radicals (OH) produced from oxygenation of structural Fe(II) in ferruginous clay minerals significantly degraded high concentrations of 1,4-dioxane (up to 400μmol/L) within 120h under circumneutral pH and dark condition. The amount of 1,4-dioxane degradation was positively correlated with the amount of OH. The major degradation product of 1,4-dioxane was formic acid. Different clay mineral types, initial Fe(II) concentration, and buffer composition all affected OH production and 1,4-dioxane degradation efficiency. Nontronite, an iron-rich smectite, was a reusable and effective material for sustainable production of OH and 1,4-dioxane degradation, through regeneration of Fe(II) either biologically or chemically. The non-selectivity and strong oxidative power of OH make it a promising agent for remediating various kinds of organic contaminants in aqueous environment.