Reductive dehalogenation of a chloroacetanilide herbicide in a flow electrochemical cell fitted with Ag-modified Ni foams

BACKGROUND: The aim of this work is to adapt the electrochemical reduction of Alachlor™, using Ag-modified Ni foam electrodes to environmental applications. In this context, preparative electrolyses of Alachlor™ were performed in a flow electrochemical cell in different electrolytic media. RESULTS: The highest catalytic activity for the reduction of Alachlor™ was obtained in 0.05 mol L-1 NaOH, with a conversion yield of 93%. The dechlorination yield of Alachlor™ estimated from the Cl- concentration was 77%, significantly lower than its conversion yield, but higher than the yield of deschloroalachlor (69%), the main dehalogenated by-product, indicating the presence of other by-products. CONCLUSIONS: Total reduction of Alachlor™ was achieved in conditions adapted to environmental applications, showing that this process can be used for dechlorination treatment of Alachlor™ in aqueous media. Although a high dechlorination yield was obtained, biodegradability estimated from BOD5 measurements remained low, showing that the C–Cl bond is not the only functional group that is responsible for the biorecalcitrance of Alachlor™. © 2017 Society of Chemical Industry.