A Study of Efficiency of Zero-valent Iron Nanoparticles in Degradation of Trichlorethylene from Aqueous Media

Introduction and The release of chlorinated organic compounds (COCs) is accounted as a danger for public health and environment due to their harmful properties such as carcinogenicity, toxicity, and flammability. Trichlorethylene (TCE) is one of the most famous COCs, which is commonly used as a solvent for dry-cleaning and industrial degreasing and contaminates soil and groundwater. Thus, it is considered as a possible carcinogenic compound (class B2) for humans. Therefore, this study was conducted to evaluate the effect of zero-valent iron nanoparticles (nZVI) in degradation of TCE.
Iron nanoparticles were prepared through the ferric chloride revival method by sodium borohydride. The properties of nanoparticles were determined using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometer. In addition, the effect of pH, concentration of trichloroethylene, iron nano-particle concentration, and contact time were studied on TCE removal efficiency. Box Behnken model was used to investigate the interaction of these variables. Analysis of variance was considered as the statistical method for analysis of responses.
Results on degradation of trichloroethylene with iron nanoparticles showed that the degradation efficiency was equal to 91.23% under optimal conditions (pH=3, the nanoparticles dose of 0.63 g/l, TCE concentration of 11 mg/l, and contact time of 86 min). The results of kinetic studies revealed that TCE degradation by nZVI follows first-order kinetic model.
Based on the obtained results, we can conclude that zero-valent iron nanoparticles have a good efficiency in the degradation of TCE. On the other hand, separation of these nanoparticles is simple due to its magnetism properties, which can improve the use of these nanoparticles.
Keywords: