Arsenic adsorption was carried out on simple materials such asgoethite and amorphous iron hydroxide, and more complex matricessuch as clay pillared with titanium(IV), iron(III), and aluminum(III). These matrices were synthesized from a bentonitewhose montmorillonitic fraction was pillared according to optimizedparameters. These sorbents were characterized by variousmethods: XRD, FTIR, BET, DTA/TGA, surface acidity, and zetametry.Elimination of arsenite and arsenate as a function ofpH was studied. Arsenate elimination was favored at acidic pH,whereas optimal arsenite elimination was obtained at 4For pH values above 10, the pillared clays were damaged and eliminationdecreased. Equilibrium time and adsorption isotherms werealso determined for arsenite and arsenate at each matrix autoequilibriumpH. Amorphous iron hydroxide had the highest adsorptioncapacities both towards arsenate and arsenite. Adsorptioncapacities of goethite and iron- and titanium-pillared claystoward arsenate were similar, but those toward arsenite were different.Desorption experiments from the various matrices were carriedout. Iron- and titanium-pillared clays showed a desorption capacityabove 95% and around 40% respectively, but no desorption ratecould be obtained for iron (hydr)oxides as they were damaged duringthe process.
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