Abstract: Heterogeneous photocatalytic degradation of γ-HCH on soil
surfaces was carried out to evaluate the photocatalytic effectiveness of
α-Fe_2O_3 and
TiO_2 toward degrading γ-HCH on soil surfaces. After
being spiked with γ-HCH, soil samples were loaded with
α-Fe_2O_3 or
TiO_2 and exposed to UV-light irradiation. Different
catalyst loads (0%, 2%, 5%, 7%, and 10% (wt).
α-Fe_2O_3; 0%, 0.5%, 1%, 2% wt).
TiO_2 were tested for up to 7 d irradiation. The effects of
soil thickness, acidity, and humic substances were also investigated. The
obtained results indicated that the γ-HCH photodegradation follows the
pseudo-first-order kinetics. The addition of
α-Fe_2O_3 or
TiO_2 accelerates the photodegradation of γ-HCH, while
the photodegradation rate decreases when the content of
α-Fe_2O_3 exceeds 7%(wt.). The
degradation rate increases with the soil pH value. Humic substances inhibit the
photocatalytic degradation of γ-HCH. Pentachlorocyclohexene,
tetrachlorocyclohexene, and trichlorobenzene are detected as photodegradation
intermediates, which are gradually degraded with the photodegradation
evolution.
