Investigation of hexavalent chromium [cr(vi)] removal by carboxymethyl cellulose stabilized zerovalent Iron nanoparticles

The use of zero-valent iron nanoparticles (nZVI) has been gained increasing interest in the area of environmental remediation. Hence the present attempt has been aimed to investigate the removal efficiency of Cr(VI) by adsorption on carboxymethyl cellulose stabilized zero-valent iron nanoparticles (CMC-Feo) from aqueous solutions under different experimental conditions. Nanoparticles were synthesized by reducing Ferrous sulfate heptahydrate (FeSO4.7H2O) using sodium borohydride (NaBH4) in the presence of CMC as a stabilizer. The crystalline size of the respective particles was determined through X-ray diffractogram (XRD) and the size of the particle was found to be 10.77 nm. Morphology of the particles was observed using scanning electron microscopy (SEM). Fourier transform infrared (FTIR) spectroscopy results suggested that stabilizer molecules were adsorbed to iron nanoparticles resulting in a steric layer, and thereby, preventing the nanoparticles from agglomeration. The removal efficiency of Cr(VI) was found to be increased with decrease of Cr(VI) concentration (10 mg/L – 25 mg/L) and pH (3 – 10) and inversely with increase in Feo concentration (0.1 g/L – 0.4 g/L) and temperature (15oC – 45oC). The obtained data revealed that the adsorption of Cr(VI) onto CMC stabilized Feo nanoparticles which were found to fit well by the Freundlich isotherm. The kinetic models were then examined with pseudo first order rate reaction. The correlation coefficient between experimental parameters and time showed that there is a strong positive correlation for Cr(VI) reduction. These results suggest that CMC stabilized Feo nanoparticles could be employed as an effective adsorbent for the removal of chromium (Cr) from contaminated water