Adsorption of arsenite and selenite using an inorganic ion exchanger based on Fe–Mn hydrous oxide

• Published in: Journal of colloid and interface science 2012, Vol.365 (1), p.213-221
• Main Authors: Szlachta, Małgorzata, Gerda, Vasyl, Chubar, Natalia
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Adsorptivity; Anion exchanging; anions; arsenic; Arsenite; arsenites; Arsenites - chemistry; Carbonates - chemistry; Chemistry; Exact sciences and technology; Ferric Compounds - chemistry; Fe–Mn hydrous oxide; Fourier transform infrared spectroscopy; General and physical chemistry; Inorganic ion exchanger; ion exchange; Ion exchangers; iron; Manganese - chemistry; manganese carbonate; Manganese Compounds - chemistry; oxidation; Oxides; Oxides - chemistry; Selenite; selenites; selenium; Sodium Selenite - chemistry; Surface physical chemistry; urea; X-ray photoelectron spectroscopy
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2011.09.023

[Display omitted] ► Inorganic mixed adsorbent is based on Fe(III)–Mn(III) hydrous oxides and MnCO 3. ► Material was synthesised using a hydrothermal precipitation approach. ► Adsorbent had a high selectivity and adsorptive capacity towards As(III) and Se(IV). The adsorption behaviour and mechanism of As(III) and Se(IV) oxyanion uptake using a mixed inorganic adsorbent were studied. The novel adsorbent, based on Fe(III)–Mn(III) hydrous oxides and manganese(II) carbonate, was synthesised using a hydrothermal precipitation approach in the presence of urea. The inorganic ion exchanger exhibited a high selectivity and adsorptive capacity towards As(III) (up to 47.6 mg/g) and Se(IV) (up to 29.0 mg/g), even at low equilibrium concentration. Although pH effects were typical for anionic species (i.e., the adsorption decreased upon pH increase), Se(IV) was more sensitive to pH changes than As(III). The rates of adsorption of both oxyanions were high. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) studies showed that the ion exchange adsorption of both anions took place via OH − groups, mainly from Fe(III) but also Mn(III) hydrous oxides. MnCO 3 did not contribute directly to As(III) and Se(IV) removal. A higher adsorptive capacity of the developed material towards As(III) was partly due to partial As(III) oxidation during adsorption.