Yongli Wang

The solubilities of dexamethasone sodium phosphate in different solvents were measured using a synthetic method. The laser monitoring observation technique was used to determine the disappearance of the solid phase in a solid + liquid mixture. The solubility data were correlated with Apelblat equation.

In this work, a facile oxidation strategy was developed to prepare novel tungsten disulfide/tungsten trioxide (WS2/WO3) heterostructures for adsorbing organic dyes efficiently by combining the hydrophilic property of WO3 and the superior dye affinity of WS2. The structural and elemental properties of the synthesized hybrid materials were systematically investigated, and the results demonstrated the retained flower-like morphology of the primitive WS2 and the successful introduction of WO3. Furthermore, surface properties such as a superior hydrophilicity and negative-charged potential were also demonstrated by a water contact angle characterization combined with a Zeta potential analysis. The performance of the obtained WS2/WO3 hybrid materials for removing Rhodamine B (RhB) from wastewater was evaluated. The results showed that the maximum adsorption capacity of the newly synthesized material could reach 237.1 mg/g. Besides, the adsorption isotherms were also simulated by a statistical physics monolayer model, which revealed the non-horizontal orientation of adsorbates and endothermic physical interaction. Finally, the adsorption mechanism and the recyclability revealed that the partial oxidation strategy could contribute to a higher adsorption capacity by modulating the surface properties and could be applied as a highly efficient strategy to design other transition metal dichalcogenides (TMDs) heterostructures for removing organic dyes from wastewater.

The solubility data of two polymorphs of 2,3,5-trimethyl-1,4-diacetoxybenzene (TMHQ-DA) in ethanol, 1-propanol, 2-propanol, and 1-butanol at various temperatures were experimentally measured using gravimetrical method and correlated by the modified Apelblat model and the van’t Hoff equation, respectively. Differential scanning calorimetry (DSC) and thermogravimetry (TG) analyses were performed to investigate the thermodynamic stability and the transition of the two forms of TMHQ-DA. An enantiotropic relationship was found between TMHQ-DA Form A and TMHQ-DA Form B, and the transition point between them was experimentally determined to be 314.50 ± 1 K. A thermodynamic model for estimation of the transition point was also derived, and the estimated results are satisfactorily consistent with the experimental values. Finally, the accuracy of the transition point obtained in this research was validated by the polymorphic transformation experiments monitored using Raman spectroscopy.

The crystallization process of vanillin in a 1-propanol/water system was investigated. It was found that liquid–liquid phase separation, also termed oiling out, will happen under some conditions. To fully understand this process, the oiling out as well as the following nucleation and crystal growth of this compound were investigated by using series of in situ tools such as FBRM, ATR-FTIR, and PVM. The phase diagram, including the solubility curve and the liquid–liquid separation curves, was determined experimentally. Meanwhile, the influence of oiling out on the properties of the final crystalline product was analyzed. It was proposed that crystallization mechanisms of vanillin might be significantly different depending on the position of the crystallization profile in the phase diagram. By using the fundamental data of phase diagram, control and optimization of solution crystallization of vanillin could be achieved to avoid or suppress the oiling out and to get products with high purity and ideal crystalline properties.