Oxyanion Behavior in Alkaline Environments: Sorption and Desorption of Arsenate in Ettringite
Arsenate sorption by ettringite [Ca6Al2(SO4)3(OH)12·26H2O] is examined as adsorption and coprecipitation systems at alkaline pH (10.0−12.5) and for a wide range of As(V) concentration ( 2.0 mM) precipitated new unidentified microcrystalline minerals at the expense of ettringite. Concentrated As(V) solution exposure to coprecipitating ettringite poisoned ettringite crystal growth, with precipitation of some microcrystalline minerals. Sorbed As(V) was also not desorbable in the presence of concentrated sulfate and high ionic strength solutions. Details of As(V) adsorption and coprecipitation systems and inferences on As(V) molecular interactions are proposed.