Synthesis of zero valent iron nanoparticles and application to removal of arsenic(III) and arsenic(V) from water

Environmental and Analytical Chemistry Division, School of Advanced Sciences, VIT University,

Vellore-632 014, Tamilnadu, India

E-mail : badalmandal@vit.ac.in

Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan, ROC

Nanobio-medicine Research Group, School of Biotechnology, Chemical & Biomedical Engineering,

VIT University, Vellore-632 014, Tamilnadu, India

Department of Physics, Sri Venkateswara University, Tirupati-517 502, Andhra Pradesh, India

Solid Sate and Structural Chemistry Unit, Indian Institute of Science, Bangalore-560 012, India

Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad-500 607, India

Manuscript received 13 September 2011, accepted 16 December 2011

Recently nano scale zero valent iron particles (nZVI) have been considered as smart adsorbent for environmental and groundwater remediation. Although several synthetic methods are available for the preparation of nZVI, air stable nZVI are not available for remediation works. Further, challenges demand synthesis of nZVI without stabilizers and capping agents. A modified methodology for the synthesis ~f air stable nZVI has been developed without any capping agents and characterized by powder X-Ray Diffraction (XRD), Scanning Electron Microscopy Energy-dispersive X-Ray (SEM-EDS), Transmission Electron Microscopy (TEM) and X-Ray Photoelectron Spectroscopy (XPS). The results of the present study suggest that the synthetic nZVI are air-stable over a period of one year and consists of particles of 30-40 nm in diameter. Although a layer of less than 3 nm thick oxide/hydroxide is observed by TEM and XPS, it appears to be due to oxidation of outer surface during analysis. Adsorption study has shown that the synthetic nZVI are more effective adsorbent than the commercial nZVI and can remove simultaneously arsenite [As^lll] and arsenate [As^V] from water without prior reduction of As v to As111 . The removal process is adsorptive rather than precipitative and the removal of As^lll is greater than that of As^V