Degradation of toxaphene by zero-valent iron and bimetallic substrates

The pesticide, toxaphene, is a major environmental concern and has been reported to be harmful, especially via skin contact, ingestion, or inhalation. Although now banned, it persists in nature. The results of this research showed that toxaphene in an aqueous solution was degraded by dechlorination when contacted with Fe and bimetallic substrates. This degradation displayed a power-law relationship with a decrease of toxaphene concentration over time. Toxaphene contacted with Fe produced a degradation rate value, -k(ToX) [ln(h)](-1), of 0.088 for a solution-to-mass ratio of 4:1 and 0.113 for a 2:1 ratio. Doubling the initial concentration of toxaphene for a volume-to-mass ratio of 4:1 decreased the degradation rate and resulted in a -k(Tox) value of 0.061. Bimetallic substrates including nickel-plated Fe and copper-plated Fe had degradation values of 0.219 and 0.245, respectively. A chloride mass balance indicated that nearly all of the toxaphene in the solution had been dechlorinated; as the chloride concentration in the solution increased over time, the toxaphene concentration decreased. The increase of chloride ions in the solution displayed a logarithmic relationship over time for all of the substrates contacted with toxaphene.