Arsenic removal was investigated by nanoscale zero valent iron (NZVI) under CO2-air bubbling system. The measure of gas bubbling was to acidify the solution and oxygenate NZVI adsorbent. Effects of carbonation and aeration periods were studied in four different scenarios. The most favorable condition was as follows; pretreatment step: CO2 bubbling (300 mL/min for 5 min) and air bubbling (300 mL/min for 10 min), and treatment step: Continuous air bubbling (300 mL/min). In the condition of having an initial concentration of 1000 mu g/L, As(III) and As(V) could be removed by 78 and 99%, respectively. When we applied this conditions to the field groundwater spiked with arsenic, the removal efficiency was a little higher than the system both without gas- and acidic chemical-pretreatment. The X-ray absorption near edge spectroscopy (XANES) suggested the apparent valence states of the activated NZVI to be 2(+) and 3(+). (C) 2014 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Journal of The Taiwan Institute of Chemical Engineers, v.47, pp.182-189