Environmentally Benign Adsorption Materials for Removing Arsenic from Aquatic Environment

摘要

Adsorptive removal of arsenic using adsorption gels prepared from orange and apple juice residues was reviewed by summarizing the authors’ previous papers. Orange and apple juice residues contain a large amount of pectin, partly methyl-esterified pectic acid, which exhibits high affinity for high-valent metal ions such as iron(III), rare earths(III) and zirconium(IV). Anionic species of arsenic(III, V) are effectively and selectively adsorbed on pectic acid gel via loading these high-valent metal ions. Raw orange juice residue was saponified using calcium hydroxide to improve the loading capacity for these metal ions. It was found that zirconium(IV) exhibits the most suitable adsorption behaviors for arsenic(III, V). Similar result was obtained also for apple juice residue. An actual sample of acid mine drainage from the Horobetsu mine which contained a high concentration of iron and low concentration of arsenic, was tested using the adsorption gel prepared from orange juice residue and the results were compared with those from the current treatment process based on coprecipitation with iron hydroxide. The new process using the above- mentioned adsorption gel was proposed for treatment of such acid mine drainage.