Anchored thiol smectite clay-kinetic and thermodynamic studies of divalent copper and cobalt adsorption

Journal Article · Mon Sep 15 00:00:00 EDT 2008 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2008.06.028· OSTI ID:21128477

Airoldi, Claudio ^[1]

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1. Instituto de Quimica, Universidade Estadual de Campinas, Caixa Postal 6154, 13084-971 Campinas, Sao Paulo (Brazil)

A natural smectite clay sample from Serra de Maicuru, Para State, Brazil, had aluminum and zirconium polyoxycations inserted within the interlayer space. The precursor and pillarized smectites were organofunctionalized with the silyating agent 3-mercaptopropyltrimethoxysilane. The basal spacing of 1.47 nm for natural clay increased to 2.58 and 2.63 nm, for pillared aluminum, S{sub Al/SH}, and zirconium, S{sub Zr/SH}, and increases in the surface area from 44 to 583 and 585 m{sup 2} g{sup -1}, respectively. These chemically immobilized clay samples adsorb divalent copper and cobalt cations from aqueous solutions of pH 5.0 at 298{+-}1 K. The Langmuir, Redlich-Peterson and Toth adsorption isotherm models have been applied to fit the experimental data with a nonlinear approach. From the cation/basic center interactions for each smectite at the solid-liquid interface, by using van't Hoff methodology, the equilibrium constant and exothermic thermal effects were calculated. By considering the net interactive number of moles for each cation and the equilibrium constant, the enthalpy, {delta}{sub int}H{sup 0} (-9.2{+-}0.2 to -10.2{+-}0.2 kJ mol{sup -1}) and negative Gibbs free energy, {delta}{sub int}G{sup 0} (-23.9{+-}0.1 to -28.7{+-}0.1 kJ mol{sup -1}) were calculated. These values enabled the positive entropy, {delta}{sub int}S{sup 0} (51.3{+-}0.3 to 55.0{+-}0.3 JK{sup -1} mol{sup -1}) determination. The cation-sulfur interactive process is spontaneous in nature, reflecting the favorable enthalpic and entropic results. The kinetics of adsorption demonstrated that the fit is in agreement with a second-order model reaction with rate constant k{sub 2}, varying from 4.8x10{sup -2} to 15.0x10{sup -2} and 3.9x10{sup -2} to 12.2x10{sup -2} mmol{sup -1} min{sup -1} for copper and cobalt, respectively. - Graphical abstract: A natural smectite clay sample from Serra de Maicuru, Para State, Brazil, had aluminum and zirconium polyoxycations inserted within the interlayer space. The precursor and pillarized smectites were organofunctionalized with the silyating agent 3-mercaptopropyltrimethoxysilane. These chemically immobilized clay samples adsorb divalent copper and cobalt cations from aqueous solutions of pH 5.0 at 298{+-}1 K. The Langmuir, Redlich-Peterson and Toth adsorption isotherm models have been applied to fit the experimental data with a nonlinear approach.

• OSTI ID: 21128477
• Journal Information: Journal of Solid State Chemistry, Vol. 181, Issue 9; Other Information: DOI: 10.1016/j.jssc.2008.06.028; PII: S0022-4596(08)00327-7; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADSORPTION
ADSORPTION ISOTHERMS
ALUMINIUM IONS
AQUEOUS SOLUTIONS
CATIONS
COBALT IONS
COPPER
COPPER IONS
ENTHALPY
ENTROPY
FREE ENTHALPY
OXYGEN COMPOUNDS
PH VALUE
REACTION KINETICS
SMECTITE
SURFACE AREA
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
THIOLS
ZIRCONIUM IONS