Electro-filtration efficient oxidation of herbicide atrazine by Sb, Ce co-doped SnO2 membranes

Herein, we reported using nontoxic Ce for co-doping to reduce the dopant amount of highly toxic Sb, resulting in a boost to the ability of SnO2 reactive electrochemical membrane (REM) in the oxidation of refractory herbicide atrazine (ATZ). The study found that co-doping Ce causes the expansion of SnO2 crystal and yields numerous defects on the SnO2 crystal surface, creating more reactive sites and significantly enhancing the catalytic activity of Sb-doped SnO2 REM. A single-pass through the Sb, Ce co-doped SnO2 REM system could reduce ATZ in a real groundwater sample from a 10 & mu;g & BULL;L-1 of feed concentration to steadily below the EAP regulatory maximum contaminant level of 14 nM. The addition of high concentrations of chloride and natural organic matters greatly inhibits the oxidation of ATZ, whereas solution pH and bicarbonate have less effect. Quenching experiments demonstrate that hydroxyl radical (& BULL;OH) plays the key role in ATZ oxidation. The degradation by-products of ATZ were identified using high-resolution mass spectrometry, and possible degradation pathways, including & BULL;OH-induced de-alkylation and & BULL;OH de-chlorination processes, were proposed based on the by-products' concentration changes. Biological toxicity tests using freshwater green algae Chlorella vulgaris demonstrated that the toxicity of ATZ effluent was greatly eliminated.