Equilibrium ion exchange studies of Zn2+, Cr3+, and Mn2+ on natural bentonite

Marinos A. Stylianou, Vassilis J. Inglezakis, Maria Loizidou, Agapios Agapiou, Grigorios Itskos

2016

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DOI 10.1080/19443994.2016.1235153

Data confidence 70 medium

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Abstract

Bentonite is a clay mineral often used in ion exchange processes due to its high ion exchange capacity. In the present study, a commercially available in Greece market bentonite was obtained and characterized by XRD, XRF, FTIR, BET, and TG/DTA analysis. Monmorillonite was the main component of bentonite sample (>80%). Ion exchange equilibria of Zn2+, Cr3+, and Mn2+ on bentonite was examined by use of batch equilibrium isotherms, distribution coefficients, and maximum exchange levels (MELs) under the same normality for all metals (0.01 N) at 25 ± 2°C. The equilibrium isotherms for the metals studied exhibit a favorable-type isotherm. Selectivity series deduced from equilibrium isotherms are Cr3+ > Zn2+ > Mn2+, and the same occurs for MELs. The Langmuir and Freundlich models were applied and fitted the equilibrium data for the metal ion uptake. A detailed literature review on heavy metals-bentonite equilibrium is provided.