REMOVAL OF AS(III) AND AS(V) IN AQUEOUS SOLUTION

摘要

There are toxic arsenical species such as As(III) and As(V), and arsenious species have speciallyrnstrong toxicity. The strong toxicity causes contamination of groundwater and water pollution for thernsemiconductor production process. This study is concerned with the removal of As(III) and As(V)rnwith various kinds of Mg/Al layered double hydroxides (LDH) containing CO_3~(2-), SO_4~(2-), Cl~- and NO_3~- as interlayer anionic species.rnThe anion exchange property is different from the kind of layered double hydroxides and the Mg-rnAl-NO_3~-LDH is superior in the anion exchange property of As(III) and As(V) due to the nature ofrnnitrate ion existing in the interlayer. The pH condition suitable for As(V) removal is 7.1 or more. Ifrnthe initial conditions such as 10mg/dm~3 of As(V) concentration, 7.1 of pH, 1 m~3 of amount of solutionrnand 99 per cent of removal are fixed, the required amount of Mg-Al-NO_3~-LDH is 0.27kg for two stepbatchrnoperations. The As(III) is suitable to oxidize to As(V) before the removal processing.