Removal of arsenic from water using the adsorbent: New Zealand iron-sand

Abstract

Adsorption is a technology used to remove arsenic from water contaminated at levels above drinking water standards. In this study, New Zealand Iron-Sand (NZIS), a naturally-available adsorbent was investigated for its efficiency in removing both As (III) and As (V). Several batch tests were conducted with different concentrations of arsenic at different pH conditions. During the batch tests, the maximum adsorption of As (III) occurred at a pH of 7.5, while As (V) adsorption reached its maximum value at a pH of 3. Both Langmuir and Freundlich adsorption models were found to fit with R² values greater than 0.92. From the Langmuir adsorption model, the maximum adsorption capacity of NZIS for As (III) and As (V) were estimated to be 1,250 and 500 μg/g, respectively. These values were substantial enough to consider NZIS a promising new adsorbent for arsenic removal.

Keywords:

• Arsenic
• iron-sand
• adsorption
• groundwater
• New Zealand

Acknowledgments

This research was sponsored by a research grant from the Civil and Natural Resources Engineering Department, the University of Canterbury, Christchurch, New Zealand. The first author is also indebted to NZAID for providing a scholarship to study at the University of Canterbury. Both authors would like to thank Peter McGuigan and David MacPherson for their technical assistance in this project.