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The electrochemical reduction of hexachlorobenzene (HCB) has been studied in micellar aqueous solutions using Triton-SP 175 which, unlike conventional surfactants, is acid-labile. At pH <3, the hydrophobic residue cleaves from the hydrophilic chain, leaving a solution without surface-active properties and allowing recovery of the electrolysis products from the solution. A micellar solution containing 0.1% v/v Triton-SP 175 and 1% v/v heptane as cosolvent was indefinitely stable in the presence of 0.05 M sodium sulfate as an environmentally friendly supporting electrolyte. Electrolytic dehalogenation to less chlorinated benzenes was studied at a wide variety of cathodes; in all cases a quantitative material balance of phenyl residues was achieved. Lead was the preferred cathode in terms of both the degree of dechlorination achieved and the current efficiency.

Electrolysis has been studied as a possible method to treat DDT wastes. In methanol, the major process was dehydrochlorination to DDE followed by further reduction. In an aqueous emulsion containing 1% heptane and 0.1% Triton SP-175®, DDT was reduced at a deposited lead electrode with sodium sulphate as the supporting electrolyte by sequential hydrodechlorination of the aliphatic chlorine atoms. An excellent material balance was achieved, but the current efficiency was poor, even at low current densities. Electrooxidation of DDT was also investigated; in aqueous solutions or emulsion, little oxidation occurred because of competing oxidation of water at the highly positive potentials needed to oxidize DDT. In acetonitrile, electrooxidation occurred with high current efficiency by way of "electrochemical combustion" of DDT and its intermediate oxidation products to CO2. We conclude that development of an electrolytic technology for destroying DDT wastes is unlikely.Key words: electroreduction, electrooxidation, voltammetry, surfactant media.

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