doi:10.1038/nindia.2013.143 Published online 28 October 2013
Researchers have developed flower-shaped iron oxide hydroxide nanoparticles capable of removing harmful arsenic from contaminated drinking water .
They synthesized iron oxide hydroxide nanoparticles from hydrated ferric sulphate and urea. The nanoparticles had an average size of less than 20 nm. The ability of the nanoparticles to remove arsenic was tested using solutions with varying arsenic concentrations in the presence of negatively charged ions that are usually present in groundwater.
The researchers found that the nanoparticles rapidly adsorbed arsenic during the first 90 minutes. The adsorption subsequently slowed reaching equilibrium after 180 minutes. They also found that arsenic removal increased significantly with increasing nanoparticle concentration. The results indicate that a slightly higher percentage of arsenic is removed from basic solutions than from acidic solutions.
Contaminated drinking water may contain several common anions, such as hydroxyl, sulphate and phosphate ions, which can compete with arsenic during adsorption. However, even in the presence of these interfering anions, the nanoparticles were able to remove arsenic over a broad pH range.
Up to 75 per cent of the arsenic-adsorbed nanoparticles could be regenerated by treating them with dilute acid and alkali. The researchers say that the synthesis of the nanoparticles can be scaled up, making them promising as effective and replicable adsorbents for treating arsenic-contaminated drinking water.