This work analyzes the degradation of toxic perchlorate from wastewater and its conversion to non-toxic chloride ion through nano-scale zero valent iron (nZVI) coating. To prevent its agglomeration and to provide the required stabilization and more removal efficiency, it was coated with various coating agents which are co-friendly (green agents) and inexpensive. At first, nZVI was synthesized using green method. Thereafter, it was used for the removal of perchlorate. NZVI was characterized by X-ray diffraction (XRD), dynamic light scattering (DLS) and transmission electron microscopy (TEM) techniques. Data show that nZVI coated with starch had the size range of 20 to 60 nm and spherical morphology and thickness of about 60 nm. Analysis results of UV-Spectrophotometry and ion chromatography showed that perchlorate was removed with more efficiency (up over 90%) under optimal conditions, and for one week, it was coated with nZVI using starch. Also, the parameters of the removal efficiency include temperature, time reaction, pH and amount of nZVI. Activation energy (Ea) of 16.77 kJ mol-1 and constant rate (k) of 0.0242 min-1 were obtained from the removal of perchlorate under optimal conditions. The study shows that the obtained results improved more than previously.
Key words: Degradation of perchlorate, green method, nanoscale zero valent iron, mechanism, kinetic of process.
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