Degradation of trichloroethylene by zero-valent iron immobilized in cationic exchange membrane

Abstract

Zero-valent iron (ZVI) immobilized in cationic exchange membrane (CEM) was investigated for the degradation of trichloroethylene (TCE). Using a commercial CEM as a support, it was possible to immobilize ZVI conveniently. According to the surface analysis, the nanoparticles were formed on the surface of CEM after immobilization and the size of them was 30-40 nm. The ZVI-immobilized CEM (Fe(0)-CEM) contained 75 mg Fe/m(2) membrane. The removal of TCE was accomplished by sorption on the membrane matrix and degradation by the immobilized ZVI. About 36.2 mg/L of TCE was removed within initial 2 h and the observed rate constant was 0.44 h(-1). The value of surface area normalized rate constant (k(SA)) of Fe(0)-CEM was 35.77 L h(-1) m(-2). The obtained k(SA) was higher than other studies on the nanoparticles or the membrane-immobilized nanoparticles by 1-3 orders of magnitudes. The higher k(SA) resulted from low metal loading (ca. 6.5 mg/L) in this test. Moreover the released iron concentration to aqueous phase was very low (0.1-0.3 mg/L), In conclusion, the Fe(0)-CEM proposed in this study was effective in the TCE removal. And it would be possible to reuse the Fe(0)-CEM repeatedly after re-reducing it.