Experimental measurement and modeling of ion exchange equilibrium and kinetics of cadmium(II) solutions over microporous stannosilicate AV-6

authors	Cardoso, SP; Azenha, IS; Lin, Z; Portugal, I; Rodrigues, AE; Silva, CM
nationality	International
journal	CHEMICAL ENGINEERING JOURNAL
author keywords	Cadmium; Ion exchange; Mass action law; Maxwell-Stefan; Microporous stannosilicate AV-6; Nernst-Planck
keywords	LANTHANIDE SILICATE EU-AV-20; MAXWELL-STEFAN APPROACH; EXCESS GIBBS ENERGY; TITANOSILICATE ETS-4; AQUEOUS-SOLUTION; STRUCTURAL-CHARACTERIZATION; MASS-TRANSFER; METAL-IONS; REMOVAL; SYSTEMS
abstract	Microporous stannosilicate AV-6 was investigated for cadmium(II) removal from aqueous solutions in batch experiments. Ion exchange equilibrium of the Cd2+/K+/AV-6 system was modeled using the mass action law combined with activity coefficient models for the solution (ideal, Debye-Htickel and Pitzer equations) and for the solid (Wilson equation) with absolute average relative deviations (AARDs) between 6.56% and 6.75%. It was concluded that the system embodies strong intraparticle non-idealities, namely solid activity coefficients between 0.2602 and 0.7180 for Cd2+. The kinetics of cadmium(II) sorption was analyzed measuring removal curves and modeling the data with pseudo-first and pseudo-second order expressions, commonly adopted in the literature, and with Maxwell-Stefan (MS) and Nernst-Plank (NP) based models. The best results were achieved by MS and NP approaches, for which AARD was 3.74% and 3.71%, respectively. The kinetic performance of the ion exchange was also discussed taking into account structural aspects of the AV-6 material. (C) 2016 Elsevier B.V. All rights reserved.
publisher	ELSEVIER SCIENCE SA
issn	1385-8947
year published	2016
volume	295
beginning page	139
ending page	151
digital object identifier (doi)	10.1016/j.cej.2016.03.007
web of science category	Engineering, Environmental; Engineering, Chemical
subject category	Engineering
unique article identifier	WOS:000375507300016