ADSORPTION OF INORGANIC AND ORGANIC ARSENIC COMPOUNDS BY ALUMINUM-LOADED CORAL LIMESTONE

Coral limestones were treated with an aqueous solution of aluminium su lfate and thereby aluminium-loaded coral limestones (AI-CL) were prepa red, By use of AI-CL as an adsorbent, the adsorption of inorganic arse nic compounds (arsenate [As(V)] and arsenite [As(III)] and of organic arsenic compounds (methylarsonic acid, dimethylarsinic acid, and arsen obetaine) was examined, The adsorption ability of Al-CL is superior to that of iron(III)loaded coral limestone (Fe-CL) for As(V), Bs(PII), m ethylarsonic acid and dimethylarsinic acid, The adsorption of As(V) an d As(III) is almost independent of the initial pH over a wide range (2 or 3 to 11). The addition of other anions, such as chloride, nitrate, sulfate and acetate, in the solution does not affect the adsorption o f As(V) and As(III), whereas the addition of phosphate greatly interfe res with the adsorption, Arsenic adsorption is effectively applied to a column-type operation and the adsorption capability for As(V) is 150 mu g/g coral limestone.