SeO23- -selective properties of inorganic materials synthesized by the soft chemical process

Three groups of inorganic materials were studied with a view to finding adsorbents selective for selenium from aqueous solution in competitive conditions: (A) divalent-cation-substituted bismutite-type compounds (Bi1-x, M-x)(2)(O1-x, (OH)(x))(2)CO(3)(.)nH(2)O, (B) hydrotalcites [M1-x2+Nx3+ (OH)(2)](+x)(CO32-)(x/2)(.)nH(2)O and (C) amorphous titanic acid TiO(2)(.)nH(2)O. The first group of materials was synthesized by hydrolyzing mixed solution of M(NO3)(2) and Bi(NO3)(3) with Na2CO3 solution at Na2CO3/(M+Bi)=20 on a molar basis at room temperature. Other materials were prepared by the soft chemical process according to our previous reports. These materials were identified using powder X-ray diffraction (XRD), FTIR spectra, and TG/DTA. Amorphous titanic acid and bismutite-type compounds showed excellent selectivity for SeO3. Divalent oxyanions were CO32- exchanged with 3 in the bismutite-type compounds and hydrotalcites through the ion-exchange mechanism. Selenite-selective properties of these materials found in the present study will be useful for its removal from contaminated aqueous effluents. (C) 2002 Elsevier Science B.V. All rights reserved.