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4732149 
Journal Article 
The solubility of maleic acid in various inorganic salts and organic solvents: Thermodynamics model and parameters 
Wongkaew, K; Mohdee, V; Sotak, T; Hronec, M; Pancharoen, Ura; Arpornwichanop, A 
2017 
Yes 
Fluid Phase Equilibria
ISSN: 0378-3812 
ELSEVIER SCIENCE BV 
AMSTERDAM 
450 
75-85 
English 
WOS:000411552600009 
has retraction 4815113 (Retraction of Vol 450, Pg 75, 2018)
This paper concerns the solubility of maleic acid, using inorganic salts and organic solvents. Several types of organic solvents were investigated such as methyl isobutyl ketone (MIBK), n-butanol, toluene, ethyl acetate and ethyl methyl ketone. Results showed that the solubility of maleic acid increased as follows: n-butanol > ethyl methyl ketone (EMK) > methyl isobutyl ketone (MIBK) > ethyl acetate (EA) >toluene. The effect of inorganic salts on the solubility of maleic acid was also investigated and was found accordingly: LiC1 > NaC1 > KCl > CaCl2 > MgCl2> BaCl2 > ZnCl2. In order to investigate thermodynamics parameters, temperatures ranging from 303.15 to 333.15 K were explored. As temperature increased, the efficiency of solubility of maleic acid increased. Correlations, based on the Gibbs Helmholtz equation and the Van't Hoff equation, were used to calculate Gibbs energy, enthalpy and entropy and to explain the thermodynamic properties for the solution process. The positive value of enthalpy and the negative value of Gibbs free energy were endothermic and nonspontaneous, respectively for the dissolution process of maleic acid. In order to predict the experimental data, thermodynamic models, such as the Buchowski Ksiazaczak lambda h model, the modified Apelblat model and NRTL, were investigated. NRTL proved to be the most suitable for predicting the solubility behavior of maleic acid with temperature exhibiting low values of RAD and RMSD. (C) 2017 Elsevier B.V. All rights reserved. 
Solubility data; Maleic acid; Inorganic salts; Organic solvents; Thermodynamics parameters; Model