Bentonites with Immobilized Organophosphorus Complexing Ligands as Adsorbents for the Removal of Toxic Metals from Natural Water L.S. Kostenko†, I.I. Tomashchuk‡, T.V. Kovalchuk†, O.A. Zaporozhets†, V.N. Zaitsev§*
	* Corresponding authors † Taras Shevchenko National University of Kyiv, 01033, Kyiv, Lva Tolstoho Street, 12, Ukraine; ‡ Université de Bourgogne Franche-Comté, 12 rue de la Fonderie, 71200 Le Creusot, France; § Pontifical Catholic University of Rio de Janeiro, 38097, Rio de Janeiro, Marquês de Sao Vicente Street, 225, Brazil; *e-mail: vnzaitsev@gmail.com
	Methods Objects Chem. Anal., 2018, 13(1), p. 35-43 https://doi.org/10.17721/moca.2018.35-43
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Abstract

The article deals with synthesis of bentonite-based materials with covalently immobilized organophosphorus complexing agents: N-methylpropylamino (Bnt-MAPA) and propylaminodi- (Bnt-ADPA) methylenephosphonic acids. The organo-bentonites were characterized by powder X-ray diffraction, FTIR, and ³¹P NMR spectroscopy. It is demonstrated that interlayer spacing in bentonites is increased upon silanization up to 51% that essentially improved filtration properties of the adsorbents. The concentration of immobilized chelating groups was found from pH-potentiometric titration as 0.35 and 0.60 mmol/g for Bnt-MAPA and Bnt-ADPA, respectively. In the pH range 3-8, the organo-bentonites adsorb up to 0.19 mmol/g of Fe(III), Pb, Cu, Zn and Cd ions during 15 minutes. All studied ions (except Cd) can be completely removed from water solution with pH > 6.5. The metal adsorption on the organo-bentonites is completely reversible and allows the adsorbent multiple utilization, with the metal recovery 90-95%. The organo-bentonites were used for purification of water samples from Lybid river (Kiev region). Complete removal (> 97%) of Pb and significant decrease (59-65 %) of Cu and Zn ions was achieved upon simple filtration. X-ray fluorescence analysis showed an increase in the content of Ca, Pb, Cu, Zn, Mn, and Sr in the phase of adsorbent after its utilization for filtration.

Keywords: organo-bentonites, adsorption, water treatment, organophosphorus complexones, immobilized ligands

Article language: Ukr