2, 4-Dichlorophenol (2, 4-DCP) has been extensively applied for chemical and pharmaceutical production, resulting in severe environmental pollution. In this paper, the sulfided nanometer zero-valent iron (S-nZVI) was synthesized and applied to remove 2, 4-DCP. The experimental tests displayed that when the sulfur iron mole ratio was 0.129, the elimination rate for 2.4-DCP was 91.9%, and the removal rate declined when the sulfur-to-iron proportion increased. As the initial concentration of 2, 4-DCP improved from 10 to 40mgL-1, the elimination rate of 2, 4-DCP declined from 92.6% to 65.3%. The elimination effect of S-nZVI on 2, 4-DCP increased with rising temperature. The removal rate of 2, 4-DCP varied under various pH conditions. The removal efficiencies were reduced from 75.5% to 48.8% when the initial pH ranged from 5 to 3. When pH is 11, the removal rate is 97.9%. Kinetics of degradation reaction of 2, 4-DCP under different conditions were conducted. The process for removing 2, 4-DCP was in accord with the pseudo-first-order kinetics model. The initial pH and sulfur mole ratio played a decisive role, which determined the removing rate of 2, 4-DCP. The findings can guide more efficient S-nZVI reactivity towards the target contaminants in water remediation.
In this study, two-step methods were used to prepare sulfide nano-zero valent iron and the morphology, elemental composition, surface charge, crystal structure and elemental valence were characterised. The influence factors (S/Fe ratio, initial pH and initial concentration of Cr(VI)) and the mechanism of Cr(VI) removal was determined. The results revealed that the sulphide modification could increase the removal rate of chromium. The maximum removal rate of chromium was 81 mg/g, achieved at an S/Fe ratio of 0.1. The Cr(VI) removal process by S-nZVI0.1 is a multistep process, starting with strong adsorption to the surface of the particles by adsorption, followed by reduction of Cr(VI) to Cr(III), and finally fixing the contaminants on the S-nZVI0.1 surface by co-precipitation. This study has great significance for preparing a remediation material that could be efficiently used for repairing of Cr(VI) contaminated sites.
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