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Synthesis, characterisation of ternary layered double hydroxides (LDH) for sorption kinetics and thermodynamics of Cd²⁺

Author:
Abasi, Cyprian Y., Ejidike, Ikechukwu P., Dikio, Ezekiel D.
Source:
TheInternational journal of environmental studies 2019 v.76 no.3 pp. 441-455
ISSN:
1029-0400
Subject:
adsorption, cadmium, heat production, hydroxides, ions, kinetics, models, probability, temperature
Abstract:
Kinetic and thermodynamic studies were carried out on the sorption of Cd²⁺ on three synthesised and characterised layered double hydroxides, namely: Ni-Co-Ti, Ni-Co-La and Mn-Ni-Al-CO₃. Sorption kinetics were investigated through time-dependent studies. Thermodynamics were determined by the effect of temperature on adsorption. Kinetic modelling of the adsorption of Cd(II) ions on the LDHs was determined using the first-order, pseudo-first order, pseudo-second order and Elovich kinetic models, as well as additional diffusion models. The results showed that the pseudo-second-order model best correlated the adsorption data with R² values of 1.000, 0.998 and 1.000 for NiCoTi, NiCoLa and MnNiAl-LDH respectively. Diffusion of the adsorbate was best correlated by the Weber-Morris intraparticle diffusion model with R² values of 0.9753, 0.8472 and 0.9412 for NiCoTi, NiCoLa and MnNiAl-LDH respectively. Thermodynamic studies showed that the adsorption was spontaneous and exothermic with a high probability of sticking.
Agid:
6400314