Iron hydroxides are good adsorbents for uncomplexed metals, some metal-ligand complexes and many metal oxyanions.
However, their adsorption properties of these precipitations are not fully exploited in wastewater treatment operations because of difficulties associated with their separation from the aqueous phase.
This study describes experiments in which iron hydroxides were coated onto the surface of ordinary adsorbents(Sea sand) that are very resistant to acids, The coated adsorbents were used in adsorption of oxyanionic metals.
The process was successful in removing some anions such as SeO3(-Ⅱ) over a wide range of metal concentrations and sorption of oxyanionic metals increased with decreasing pH.
Formation of two surface complexes for oxyanionic metals adsorption on iron hydroxides comprise (1) complexation of the free anion by a positively charged surface site, and (2) protonation of the adsorbed anion (or alternatively adsorption of a protonated form from solution)
The coated adsorbents are inexpensive to prepare and could serve as the basis of a useful oxyanionic metal removal.

• 박상원(계명대학교 환경과학대학) | Sang Won Park
• 강혜정(계명대학교 환경과학대학) | Hye Jung Kang