Despite being recognized as a promising technique for treating high salinity water, membrane distillation (MD) has been plagued by the scaling of sparingly soluble salts. The growth of crystals can not only create additional resistance to evaporating water at the feed-membrane interface, but also alter the hydrophobic network to bridge the feed and distillate (i.e., result in the phenomenon of wetting). When recognizing the uncertain behaviors of calcium sulfate (CaSO 4 ) scaling in MD, this study was motivated to ascertain whether the crystal-membrane interactions could be dependent on the variation in crystalline morphology. In particular, optical coherence tomography (OCT) was employed to characterize the scaling-induced wetting via a direct-observation-through-the-membrane (DOTM) mode, which mitigated the effects of developing an external scaling layer on resolving the crystal-membrane interactions. The improved in-situ characterization suggests that the crystalline morphology of CaSO 4 could be effectively regulated by varying the stoichiometry of crystallizing ions; the richness of calcium in the aqueous environment for crystallization would be in favor of weakening the crystal-membrane interactions. The stoichiometry-dependent growth of CaSO 4 crystals can be exploited to develop an effective strategy for preventing the hydrophobic network from being wetted or irreversibly damaged.
Wenbiao Zhi,Yonghong Hu,Mengmeng Liang,Yan Liu,Jiaojiao Li,Jingjing Yin,Ying Shi
In this paper, the solid–liquid equilibrium of 2,5-thiophenedicarboxylic acid in methanol, ethanol, i -propanol, n -butanol, acetic acid, n -hexane, acetonitrile and acetone was explored from 278.15 K to 333.15 K under atmosphere pressure. Modified Apelblat equation and λh equation were adopted to describe and predict the change tendency of solubility. Besides, the thermodynamic properties of the dissolution process, including enthalpy, entropy and Gibbs energy , were calculated by means of van’t Hoff analysis and Gibbs equation. Based on the analysis above, ethanol is considered to be the best solvent in crystallization process of 2,5-thiophenedicarboxylic acid.
In this paper, we focused on solubility and solution thermodynamics of oxytocin. By gravimetric method, the solubility of oxytocin was measured in (acetonitrile + acetone) binary solvent mixtures from 278.15 K to 328.15 K under atmosphere pressure. The solubility data were fitted using modified Apelblat equation, a variant of the combined nearly ideal binary solvent/Redich–Kister (CNIBS/R–K) model and Jouyban–Acree model. Computational results showed that the modified Apelblat equation was superior to the other two equations. In addition, the thermodynamic properties of the solution process, including the Gibbs energy , enthalpy, and entropy were calculated by the van’t Hoff analysis. The experimental results showed that acetonitrile could be used as an effective anti-solvent in the crystallization process.
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