Photocatalytic remediation of gamma-hexachlorocyclohexane contaminated soils using TiO2 and montmorillonite composite photocatalyst.

TiO2 and montmorillonite composite photocatalysts were prepared and applied in degrading gamma-hexachlorocyclohexane (gamma-HCH) in soils. After being spiked with gamma-HCH, soil samples loaded with the composite photocatalysts were exposed to UV-light irradiation. The results indicated that the photocatalytic activities of the composite photocatalysts varied with the content of TiO2 in the order of 10% < 70% < 50% < 30%. Moreover, the photocatalytic activity of the composite photocatalysts with TiO2 content 30% was higher than that of the pure P25 with the same mass of TiO2. The strong adsorption capacity of the composite photocatalysts and quantum size effect may contribute to its increased photocatalytic activities. In addition, effect of dosage of composite photocatalysts and soil pH on gamma-HCH photodegradation was investigated. Pentachlorocyclohexene, trichlorocyclohexene, and dichlorobenzene were detected as photodegradation intermediates, which were gradually degraded with the photodegradation evolution.