Thermodynamic model for equilibrium solubility of gibbsite in concentrated NaOH solutions

The thermodynamic properties of the most important NaOH-NaAI（OH）4-H20 system in Bayer process for alumina production were investigated. A theoretical model for calculating the equilibrium constant of gibbsite dissolved in sodium hydroxide solution was proposed. New Pitzer model parameters and mixing parameters for the system NaOH-NaAI（OH）4-H20 were yielded and tested in the temperature range of 298.15-373.15 K. The results show that the proposed model for calculating the equilibrium constant of gibbsite dissolution is applicable and accurate. The obtained Pitzer model parameters of β（0）（NaAl（OH）4）、β（1）（NaAl（OH）4）和CΦ（NaAl（OH）4）,Al（OH）4 for NaAI（OH）4, the binary mixing parameter of θ（OH-Al（OH）4-） with OH-, and the ternary mixing parameter of ψ（Na＋OH-Al（OH）4-） for AI（OH）4- with OH- and Na＋ are temperature-dependent. The prediction of the equilibrium solubility of gibbsite dissolved in sodium hydroxide solution was feasible in the temperature range of 298.15-373.15 K.

Experimental measurement and thermodynamic modeling of binary and ternary solid–liquid phase equilibrium for the systems formed by L-arabinose,D-xylose and water

Solid–liquid phase equilibrium data for binary(L-arabinose–water) and(D-xylose–water) systems at temperatures from(269.85–298.05) K and ternary(L-arabinose–D-xylose–water) system at temperatures of 273.85 K,278.85 K and 284.45 K were measured at atmospheric pressure.The ternary phase diagrams of the systems were constructed on the base of the measured solubility.Two pure solid phases were formed at given temperatures,including pure L-arabinose and pure D-xylose,which were con firmed and determined by the method of Schreinemakers' wet residue.At the same temperature,the crystallization region of L-arabinose was larger than D-xylose's.The acquired solubility data were then correlated using the NRTL model,Wilson model and Xu model.The calculated solubility with the three models agreed well with the experimental values.

Syntheses,Crystal Structures and Theoretical Studies of Three Novel Salts of Vortioxetine and the Investigation of Their Solubility

Three new vortioxexine （VOT） salts with salicylic acid （SA）, 5-fluorouracil （FU） and （p-nitrophenyl）-acetic acid （PA） have been synthesized and characterized in detail. In VOT-SA（1：1）, the protonated VOT and deprotonated salicylic anion form a tetrameric unit with the R4 4（12） synthon via N（1）–H（1）…O（1）^a （a： x–1, y, z） and N（1）–H（2）…O（2）^b （b： –x, –y, –z＋1） hydrogen bonds. However, in VOT–FU（1：2）, the protonated VOT and deprotonated 5-fluorouracil anion feature an R4 4（16） ring motif via N（1）–H（1）…O（2）^c （c： –x＋1, –y＋1, –z＋1） and N（1）– H（2）…O（1）^d （d： x, y–1, z） hydrogen bonds. The neutral FU extends the R4 4（16） ring to form a two-dimensional structure through R2 2（8） N–H…O and N（6）–H（4）…N（4）……e （e： –x＋1, y–1/2, –z＋1/2） hydrogen bonds. In VOT-PA（1：1）, PA molecules are linked through N（1）–H（1）…O（1）f （f： –x＋1, y＋1/2, –z＋1） and N（1）–H（2）…O（2）, which forms a right-handed helical structure. Furthermore, components of the crystalline phase have also been investigated in terms of their corresponding Hirshfeld surface, and the salification improves the equilibrium solubilities and dissolution rates of VOT in three salts at 25 ℃ in water.

Studies on Stability of a Novel Cathode Material for MCFC

The stability of NiO and oxidized nickel niobium surface alloy electrode under various molten carbonate fuel cell(MCFC) cathode conditions were investigated by determination of equilibrium solubility of nickel ions in the carbonate melt of the two electrode materials.It is found that under MCFC cathode conditions the stability of NiO electrode is improved significantly by the deposition of niobium.As far as stability is concerned,oxidized nickel niobium alloy electrode can be considered as a candidate for cathode material of MCFC.

Predictions of equilibrium solubility and mass transfer coefficient for CO_(2) absorption into aqueous solutions of 4-diethylamino-2-butanol using artificial neural networks

In the present work,artificial neuron network(ANN)based models for predicting equilibrium solubility and mass transfer coefficient of CO_(2) absorption into aqueous solutions of high performance alternative 4-diethylamino-2-butanol(DEAB)solvent were successfully developed.The ANN models show an outstanding predictive performance over the predictive correlations proposed in the literature.In order to predict the equilibrium solubility,the ANN model were developed based on three input parameters of operating temperature,concentration of DEAB and partial pressure of CO_(2).An outstanding prediction performance of 2.4%average absolute deviation(AAD)can be obtained(comparing with 7.1–8.3%AAD from the literature).Additionally,a significant improvement on predicting mass transfer coefficient can also be achieved through the developed ANN model with 3.1%AAD(comparing with 14.5%AAD from the existing semi-empirical model).The mass transfer coefficient is considered to be a function of liquid flow rate,liquid inlet temperature,concentration of DEAB,inlet CO_(2) loading,outlet CO_(2) loading,concentration of CO_(2) along the height of the column.