Reductive dechlorination of hexachlorobenzene by Cu/Fe bimetal in the presence of nonionic surfactant

This study investigated the enhancement of nonionic surfactant (TritonX-100, TX-100) on the reductive dechlorination of hexachlorobenzene (HCB) by microscale Cu/Fe bimetal. HCB reduction by Cu/Fe without TX-100, in aqueous TX-100, adsorbed with TX-100 and prepared with TX-100 was compared. Results showed that HCB reduction by Cu/Fe in aqueous TX-100 increased with increasing TX-100 concentration, reached a maximum of 98.6% when aqueous TX-100 concentration attained its critical micelle concentration (CMC), and decreased with the further increase in TX-100 concentration. The mechanism was suggested as the increased HCB mass transport at low TX-100 concentration below CMC and the coverage of reactive sites at high TX-100 concentration above CMC. The greatest reduction was achieved by Cu/Fe in the presence of 0.2 mM TX-100, followed by Cu/Fe adsorbed and prepared with 0.2 mM TX-100. Pentachlorobenzene and tetrachlorobenzene were found as the main dechlorination intermediates. Successive reduction by Cu/Fe in aqueous TX-100 solution could be maintained above 98% for four cycles. It is an alternative to use nonionic surfactants to enhance the reductive dechlorination of hydrophobic polychlorinated aromatic hydrocarbons (PCAH) by Cu/Fe bimetal.