HW Models Research Articles

Crystallization separation of Na2CO3 and Na2MoO4 from the high-salinity ash slag produced by production process of Na2MoO4 based on the theory of phase equilibrium

High-salinity ash slag containing Na2CO3 and Na2MoO4 produced from the production process of Na2MoO4 brings about the resource waste and environmental pollution issues. To realize the resource utilization of these high-salinity ash slag, the phase equilibrium data of the ternary Na2CO3–Na2MoO4–H2O system at 298.15 K and 323.15 K were determined using the isothermal dissolution equilibrium method, and the equilibrium solid phase was determined by X-ray diffraction. By comparing the phase diagrams of the ternary Na2CO3–Na2MoO4–H2O system at 298.15 K, 323.15 K, and 353.15 K, the change rules of the crystallization region were analyzed. The Pitzer and HW models were used to calculate the ionic interaction parameters of θMoO4–CO3 and ψNa–MoO4–CO3, which could be further used to predict the solubility curves of the ternary Na2CO3–Na2MoO4–H2O system. The calculation results were in good agreement with the experimental results. Furthermore, the phase diagrams of the ternary Na2MoO4–Na2CO3–H2O system at 298.15 K and 353.15 K were selected to design a process for the highly-efficient recovery of Na2MoO4·2H2O and Na2CO3·H2O from the high-salinity ash slag. The experimental results showed that the one-way recovery rate of Na2CO3 could reach 92.55%, with a purity of 99.62%, and that of Na2MoO4·2H2O is 45.61%, with a purity of 99.14%. These results were almost consistent with the theoretical calculation results. After multiple cycles, Na2CO3 and Na2MoO4 could be completely recovered.

Phase equilibria in the quaternary KBr–MgBr2–K2SO4–MgSO4–H2O system at (323.15 and 348.15) K

Aiming to utilize the bromine resource in bittern comprehensively, the phase equilibria in the quaternary KBr–MgBr2–K2SO4–MgSO4–H2O system at (323.15 and 348.15) K were researched by the isothermal dissolution equilibrium method. The solubilities and equilibrium solid phases were determined, and the corresponding phase diagrams were plotted. The phase diagram at 323.15 K comprises six invariant points, thirteen univariant curves, and eight crystallization areas corresponding to KBr, K2SO4, MgSO4·H2O (Kie), MgSO4·4H2O (Tet), MgSO4·6H2O (Hex), MgBr2·6H2O (Mb), K2SO4·MgSO4·4H2O (Leo) and KBr·MgBr2·6H2O (Car-Br), respectively. The phase diagram at 348.15 K consists of five invariant points, eleven univariant curves, and seven crystallization areas corresponding to KBr, K2SO4, Kie, Mb, Leo, K2SO4·2MgSO4 (Lan) and Car-Br, respectively. With the Pitzer and HW models, the solubilities of the quaternary KBr–MgBr2–K2SO4–MgSO4–H2O system at (323.15 and 348.15) K were calculated, and the results are essentially consistent with the experimental data.

Solid-liquid equilibria in the ternary NaBr-Na2CO3-H2O system at (298.15, 323.15 and 368.15) K and its application

To comprehensively utilize the waste residue produced in pure terephthalic acid (PTA) production, the ternary NaBr-Na2CO3-H2O system at (298.15, 323.15 and 368.15) K were investigated by using the isothermal dissolution equilibrium method, and the corresponding equilibrium phase diagrams were plotted. There are six invariant points, nine univariant curves, nine single salt crystallization regions and six cocrystallization zones in total in the diagrams. Pitzer and HW models were combined with experimental data to fit out the ion interaction parameters θBr-CO3 and ψNa-Br-CO3 at different temperatures. There is an excellent agreement between the calculated and experimental solubilities. The purity of sodium bromide in the waste residue was increased to 97.67% using the ternary NaBr-Na2CO3-H2O system at 368.15 K, and then a small amount of sulfuric acid was added. With the ternary NaBr-Na2SO4-H2O system at 308.15 K, the purity of the obtained NaBr production could reach 99.48%, which met the superior product requirement of HGT 3809–2006. Meanwhile, Na2CO3 obtained in this separation process can be reused in PTA production with a recovery of 99.46%.

Model Time Series untuk Prediksi Jumlah Kasus Infeksi Coronavirus (Covid-19) di Sulawesi Selatan

Since it was declared a pandemic outbreak, the COVID 19 virus has become one of the main focuses of countries in the world in efforts to prevent the spread of the virus, including Indonesia. The areas of greatest severity in Indonesia include Jakarta, East Java, West Java and South Sulawesi. South Sulawesi Province is recorded as the largest area exposed to the COVID 19 pandemic outside Java Island. Predicting the number of COVID 19 cases is an alternative in preventing the spread through making government policies based on predictive data. This article presents a predictive model for the number of COVID 19 cases based on the ARIMA, Holt Winters and Nonlinear Autoregressive Neural Network (NAR-NN) Model. The results of the analysis show that the ARIMA Model (1,1,1) has a better level of prediction accuracy than the HW and NAR-NN models based on the MAPE criteria. Meanwhile, for the RMSE, MAE and MPE criteria, the NAR-NN model is better than others.

Alternative prediction methods in the stock exchanges of Thailand

This paper is conducted to substantially do the two alternatives between the traditional statistical methods such as ARMA and HW models, and artificial intelligence (AI) contains KNN and ELM, respectively. To scope the main object of the paper, SET indexes are collected as the main financial variable, which are 5,472 daily observed days during 9 September 1997 to 11 June 2018. Technically, the cross-entropy (CE) analysis, MSE and RMSE calculations are computationally employed to clarify the resolution of the two computations. The empirical results state that the AI prediction can be a substitution replacing the traditional estimations, and this can strongly confirm that machine learning (ML) algorithms are continuously interested, and they are recently becoming a powerful tool for modern econometric forecasting.

(Solid + liquid) isothermal evaporation phase equilibria in the aqueous ternary system (Li 2SO 4 + MgSO 4 + H 2O) at T = 308.15 K

The solubility and the density in the aqueous ternary system (Li 2SO 4 + MgSO 4 + H 2O) at T = 308.15 K were determined by the isothermal evaporation. Our experimental results permitted the construction of the phase diagram and the plot of density against composition. It was found that there is one eutectic point for (Li 2SO 4 · H 2O + MgSO 4 · 7H 2O), two univariant curves, and two crystallization regions corresponding to lithium sulphate monohydrate (Li 2SO 4 · H 2O) and epsomite (MgSO 4 · 7H 2O). The system belongs to a simple co-saturated type, and neither double salts nor solid solution was found. Based on the Pitzer ion-interaction model and its extended HW models of aqueous electrolyte solution, the solubility of the ternary system at T = 308.15 K has been calculated. The predicted solubility agrees well with the experimental values.

Solubility Prediction of CsCl-Cs2SO4 - H2O System at 298.15K Using the Ion-Interaction Model

The component solubilities of CsCl-Cs2SO4-H2O system at 298.15K were calculated by using Pitzer ion inter- action model and its extended HW models. Excellent agreement with experimental solubilities indicated that the models can be successfully used to calculate the component solubilities. This study affords the necessary parameters for solubility predictions of complicated systems and establishes a theoretical basis for the separation of these valuable metals from salt lake brine. we present the solubility calculation of CsCl-Cs2SO4-H2O at 298.15K by using the Pitzer ion-interaction model. Some mixing ternary parameters derived from this calculation can be used in solubility prediction of more complicated quater- nary or quinary systems constituted by Cs + , Cl - , SO4 2- and

Solubility prediction in the ternary systems NaCl–RbCl–H 2O, KCl–CsCl–H 2O and KBr–CsBr–H 2O at 25 ∘C using the ion-interaction model

The component solubilities in NaCl–RbCl–H 2O, KCl–CsCl–H 2O and KBr–CsBr–H 2O systems at 25 ∘C were calculated by using the Pitzer ion interaction model and its extended HW models. Excellent agreement with experimental solubilities indicated that the models can be successfully used to calculate the component solubilities. This study affords the necessary parameters for solubility predictions of complicated systems containing rubidium and caesium and establishes a theoretical basis for the separation of these valuable metals from salt lake brine.