期刊
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
卷 610, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.colsurfa.2020.125894
关键词
Interpolyelectrolyte complexes; Chitosan; Degradation kinetics; Sorption isotherms
资金
- Brazil's Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)
- Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)
- Pro-Reitoria de Pesquisa da Universidade Federal do Rio Grande do Norte (PROPESQ-UFRN)
Magnetic compounds based on chitosan and poly(sodium 4-styrenesulfate) were prepared for adsorption of cationic and anionic drugs, with sorption occurring in multiple layers and saturation concentrations affected by the nature of the drug. Gibbs free energy of adsorption and thermal degradation kinetics of the composites were studied, showing the impact of magnetite on the activation energy of degradation.
Magnetic compounds, based on magnetite nanoparticles and interpolyelectrolyte complexes (IPEC) were prepared from chitosan (CS) and poly(sodium 4-styrenesulfate) (NaPSS). Two types of composite were obtained: one with positive surface charge and another one with negatively charged surface. The composites were used to adsorb a cationic drug (tetracycline hydrochloride, HTCCl) and an anionic one (sodium cromoglycate, NaCG). Sorption occurred in the form of multiple layers, tending to a saturation value (following Sips isotherm), with saturation sorption concentrations of ca. 0.2 mmol of drug per gram of composite for HTCCl on both positively and negatively charged composites, probably due to the protonation of chitosan by HTCCl. In the case of the anionic drug, it was adsorbed with the same intensity on the composite of opposite charge, while for the composite with negative charge saturation occurred at a value of ca. 0.05 mol per gram of composite. Gibbs free energy of adsorption for dilute solution conditions was estimated, ranging from -17 to -3 kJ/mol, and the analysis of thermal degradation kinetics of composites, using the isoconversional approach, indicated that magnetite decreased apparent energy of activation (with values reaching 400 kJ/mol) for the degradation of the organic phase.
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