Degradation Characteristics of Carbon Tetrachloride by Granular Sponge Zero Valent Iron

Granular sponge zero valent iron (ZVI) was employed to degrade carbon tetrachloride (CCl₄). The effects of acidic washing, initial solution pH, and ZVI dosage on CCl₄ degradation were investigated. Results showed that CCl₄ was effectively removed by ZVI and approximately 75% of CCl₄ was transformed into chloroform through hydrogenolysis. The rate of chloroform transformation was slower compared to that of CCl₄, resulting in chloroform accumulation. CCl₄ degradation was a pseudo first-order process. The observed pseudo first-order reaction rate constant (k) for CCl₄ and chloroform were 0.1139 and 0.0109 h^-1, respectively, with a ZVI dosage of 20 g/L and an initial CCl₄ concentration of 20 mg/L. Surface acidic washing had a negligible effect on CCl₄ degradation with ZVI. The k for CCl₄ degradation increased linearly with increasing ZVI dosage and the optimal dosage of ZVI was 20 g/L based on the surface area-normalized rate constants. The negative relationship between k and the solution pH indicated that the degradation of CCl₄ by ZVI performed better under weakly acidic conditions.