Thermodynamic study of the effect of concentration and ionic strength on osmotic coefficient of aqueous sulfate and chlo
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ORIGINAL ARTICLE
Thermodynamic study of the effect of concentration and ionic strength on osmotic coefficient of aqueous sulfate and chloride solutions at 298.15 K Seyed Hossein Hashemi1,2 · Mehrdad Bagheri3 · Seyed Abdolrasoul Hashemi4 Received: 24 October 2019 / Accepted: 26 May 2020 © Springer Nature Switzerland AG 2020
Abstract In the present study, 13 aqueous solutions are considered to predict osmotic coefficients of chloride and sulfate aqueous electrolyte systems. For this study (in order to predict osmotic coefficients) the Extended UNIQUAC equation was considered, for AClx=1,2: A = Li, H, Na, K, NH4,Cs, Mg, Ca, Ba (aq) and Bj=1,2SO4: B = Li, Na, K, NH4 (aq) systems. Based on the optimized thermodynamic equation, the effect of concentration and ionic strength on the osmotic coefficient of chloride and sulfate solutions is investigated. According to the results, the osmotic coefficients of the studied systems depend on the ionic strength. For the electrolytic system, the temperature in this study is 298.15 K and pressure is 1 bar. Also, the charge number of cation to anion in this study is 2: 1, 1: 2 and 1: 1. Keywords EUNIQUAC equation · Electrolyte solutions · Osmotic coefficients · Water activity
Introduction The thermodynamic properties of aqueous electrolyte systems such as inorganic ion activity coefficient, water activity, and osmotic coefficients of ions due to electrostatic forces between ions and short-range forces between ions and solvents have an ideal behavior in chemical systems. Therefore, a better understanding of the thermodynamic properties of aqueous electrolyte systems can be helpful in chemical industries such as ion separation from water. However, laboratory data are necessary for the thermodynamic properties of electrolyte systems. But to better understand the intermolecular interaction and better separation of water and ions, thermodynamic models can be of more interest. It is also time-consuming to measure the thermodynamic properties of electrolytic systems (solid–liquid equilibrium systems). * Seyed Hossein Hashemi [email protected] 1
University of Mohaghegh Ardabili, Ardabil, Iran
2
Young Researchers and Elite Club, Shiraz Branch, Islamic Azad University, Shiraz, Iran
3
Petrolium University of Technology, Ahwaz, Iran
4
Gachsaran Oil and Gas Exploitation Company, Kohgiluyeh and Boyer‑Ahmad, Iran
Heretofore, for the investigation of electrolyte systems (due to the mineral cations such as C a2+, Ba2+, Na+, K+ and 2− 2− − Cl , SO4 and CO3 anions),the coefficients of inorganic ions, water activity, ion solubility and inorganic ions saturation index have been studying. In an experimental–computational study, Wang et al. (2015) investigated the solubility of gypsum, hemihydrate, and anhydrates in the electrolytic multipartite system CaSO4 + MSO4 + H2O (M = Mn, Co, Ni, Cu, Zn). In their research, Pitzer thermodynamic model was used to investigate solubility. Based on their results, the solubility of gypsum increases with increasing temperature and
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