Application of Modified Bentonites for Arsenite (III) Removal from Drinking Water

Abstract

Four modified bentonites (La(III), Ce(III), Y(III), Fe(III)) were prepared by ion exchange process to remove arsenite (III) ions from water. The modified bentonites were examined with X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD). The rare earth (REE) and Fe(III) ion content in bentonite was higher than the CEC values obtained by ammonium acetate method related to trivalent ions (2.7 x 10-4 mol g-1). The kinetics, equilibrium time, sorption isotherms and desorption experiments were examined. Lanthanum, yttrium and cerium bentonite can bind similar amount of arsenite(III) ions. Iron-bentonite cannot bind significant amounts of arsenite ions. The active sites and the solubilities of the sorption complex were determined. Arsenite (III) ions sorb in the interlayer space as REEAsO3. The solubility of the arsenite complex was two orders of magnitude smaller than that of the phosphate complex. After desorption the eluted amount of arsenite (III) was 55 % related to the sorbed amount of arsenite. The d(001) basal spacing of modified bentonites and that of after sorption and desorption was measured. After the sorption of arsenite ion on lanthanum bentonite, the d(001) basal spacing of montmorillonite was decreased and after desorption an increase in d(001) basal spacing was observed again. Modified bentonites can be used for removing arsenic ions from water.

Badanie z użyciem XPS (roentgenowskiej spektroskopii fotoelektronowej) usuwania jonów z wody za pomocą zeolitów i bentonitów

“…Raw montmorillonite can sorb cations, but not anions, because of the negative charges on the crystal lattice. Therefore, several methods have been investigated in order to sorb anionic pollutants by montmorillonite [7].…”

Use of silver–bentonite in sorption of chloride and iodide ions

“…The sorption of phosphate ion by rare earth cation exchanged bentonites used efficiently against the eutrophication of lakes is mentioned as an example [36]. In our previous three articles, we have successfully used rare earth cation exchanged bentonites for removing phosphate [37] and arsenite ions [38]; and Sn(II), Cr(III)-modified bentonites for removing pertechnetate ions [39].…”