Measurement and correlation of liquid - Liquid equilibria of three imidazolium ionic liquids with acetone and cyclohexane

Ionic liquids (ILs) can be recycled as extractants for their low vapor pressure and volatility. More and more applications are applied to the separation of industrial organic matter. The industrial production of ILs has gradually been realized, which also widens the way for the application of ILs. In this work, the liquid-liquid extraction of cyclohexane-acetone azeotropic mixture with different ILs {1-butyl-3-methylimidazolium bis(trifluormethylsulfonyl), 1-butyl-3-methylimidazolium trifluoromethansulfonate and 1-butyl-3-methylimidazolium dicyanamide} is studied. The extraction mechanism is discussed based on the molecular scale. The relationship between hydrogen bond donor and acceptor between ILs and acetone is analyzed by COSMO-SAC. The interaction between molecules is optimized and calculated by Materials Studio 7.0. The extraction ability of ILs is analyzed by radial distribution function, and the experimental results are verified. The liquid-liquid equilibrium test is carried out at 298.15 K. Distribution and selectivity are indices used to judge the extraction efficiency of ILs. The NRTL model and UNIQUAC model are adopted to correlate the liquid-liquid equilibrium data. The results show that all of the two models can well correlate the experimental.This work is supported by the National Natural Science Foundation of China (No. 21776145), National Natural Science Foundation of China (No. 21676152)

Design and Control of a Middle Vessel Batch Distillation Process for Separating the Methyl Formate/Methanol/Water Ternary System

The middle vessel batch distillation process for separating the methyl formate/methanol/water ternary system was simulated using Aspen Plus and Aspen Plus Dynamics. The composition control structure (CCS) and temperature control structure (TCS) were studied in a dynamic simulation based on the results of a steady-state simulation. Two temperature control structures, one the traditional TCS and the other TCS with high selectors, show better control performances than CCS. The two control structures can stably control the product purities and liquid holdups in the product vessels at the end of the batch. The results show that TCS with high selectors is better than traditional TCS in terms of the liquid holdups. The performance of the TCS with high selectors is assessed, and controllability is demonstrated

Effect of Solvent Flow Rates on Controllability of Extractive Distillation for Separating Binary Azeotropic Mixture

The mixture of <i>n</i>-heptane and isobutanol creates a minimum-boiling azeotrope under atmospheric conditions. Extractive distillation was used for separating <i>n</i>-heptane and isobutanol. A sequential iterative optimization procedure optimized the steady state extractive distillation process to obtain a minimal total annual cost (TAC). The dynamic control of the optimal extractive distillation process showed poor controllability. It was found that the dynamic control performance could be improved if the solvent flow rate was increased properly with a small increase in TAC. Hence, the choice of the optimal extractive distillation process for separating a binary azeotropic mixture should be considered from the perspectives of both TAC and the dynamic control performance

Control of a Ternary Extractive Distillation Process with Recycle Splitting Using a Mixed Entrainer

Dynamic control of the ternary extractive distillation process is complex, due to the relatively high number of operating parameters and interactions between multiple azeotropes. In this research, the control structures of the ternary extractive distillation using dimethyl sulfoxide and a mixed solvent of dimethyl sulfoxide and ethylene glycol, as the entrainer, were explored for separating tetrahydrofuran/ethanol/water. A composition with a ratio of reboiler duty to mole feed flow rate control structure was proposed to obtain good dynamic responses for the ternary extractive distillation process with dimethyl sulfoxide and mixed entrainer. Moreover, control comparisons of the ternary extractive distillation with dimethyl sulfoxide and mixed entrainer demonstrated that the dynamic performances of the extractive distillation with mixed entrainer were better compared with the process using dimethyl sulfoxide. These studies contribute to the development of controllability for ternary extractive distillation processes for separating ternary or multicomponent azeotropic mixtures

Computer-Aided Screening of Ionic Liquids As Entrainers for Separating Methyl Acetate and Methanol via Extractive Distillation

In the production of poly­(vinyl alcohol), the raw materials methyl acetate (MeOAc) and methanol (MeOH) exist as a homogeneous azeotropic mixture. Twenty-five kinds of ionic liquids, composed of five types of cations and five types of anions, were studied using the COSMO-SAC method. The σ-profile data for each component and the selectivity at infinite dilution (<i>S</i>^∞) were calculated and analyzed, respectively. 1-Hexyl-3-methylimidazolium chloride ([HMIM]­[Cl]) and 1-butyl-3-methylimidazolium chloride ([BMIM]­[Cl]) were selected as suitable entrainers based on the COSMO-SAC method. The binary interaction parameters of the NRTL model of the MeOAc/ionic liquid and MeOH/ionic liquid systems were regressed. The conceptual design for the separation of MeOAc and MeOH using ionic liquids as entrainers was investigated. The comparison of two processes using two entrainers was carried out from an economic perspective. The total annual cost (TAC) of the process using [HMIM]­[Cl] as an entrainer can be reduced by 16.5% compared with that of the process using [BMIM]­[Cl]. The results indicated that the COSMO-SAC method is feasible for screening ionic liquids as optimal entrainers. This work could provide theoretical instruction for further industrial applications using ionic liquids as solvents via COSMO-SAC computer-aided screening

Liquid–Liquid Extraction of Butanol from Heptane + Butanol Mixture by Ionic Liquids

Selection of a suitable solvent is the key for the extraction process. In this work, four ionic liquids were selected as solvent for extracting butanol, the ternary liquid–liquid equilibria (LLE) data for systems of heptane + butanol + {[HMIM]­[BF₄] (1-hexyl-3-methylimidazolium tetrafluoroborate), [OMIM]­[BF₄] (1-octyl-3-methylimidazolium tetrafluoroborate), [HMIM]­[OTf] (1-hexyl-3-methylimidazolium trifluoromethansulfonate), and [HMIM]­[NTf₂] (1-hexyl-3-methylimidazolium bis­((trifluoromethyl)­sulfonyl)­imide)} were measured at 298.15 K and atmospheric pressure. The extraction capacity of four ILs in the separation of butanol from heptane + butanol mixture was estimated by the selectivity (<i>S</i>) and solute distribution ratio (β), and the influence of the structure and anion of IL on the extraction efficiency was investigated. The experimental LLE data were correlated by using NRTL and UNIQUAC models

Preparation, Characterization and Pharmacokinetics of Tolfenamic Acid-Loaded Solid Lipid Nanoparticles

The clinical use of nonsteroidal anti-inflammatory drugs is limited by their poor water solubility, unstable absorption, and low bioavailability. Solid lipid nanoparticles (SLNs) exhibit high biocompatibility and the ability to improve the bioavailability of drugs with low water solubility. Therefore, in this study, a tolfenamic acid solid lipid nanoparticle (TA-SLN) suspension was prepared by a hot melt&ndash;emulsification ultrasonication method to improve the sustained release and bioavailability of TA. The encapsulation efficiency (EE), loading capacity (LC), particle size, polydispersity index (PDI), and zeta potential of the TA-SLN suspension were 82.50 &plusmn; 0.63%, 25.13 &plusmn; 0.28%, 492 &plusmn; 6.51 nm, 0.309 &plusmn; 0.02 and &minus;21.7 &plusmn; 0.51 mV, respectively. The TA-SLN suspension was characterized by dynamic light scattering (DLS), fluorescence microscopy (FM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared (FT-IR) spectroscopy. The TA-SLN suspension showed improved sustained drug release in vitro compared with the commercially available TA injection. After intramuscular administration to pigs (4 mg/kg), the TA-SLN suspension displayed increases in the pharmacokinetic parameters Tmax, T1/2, and MRT0&ndash;&infin; by 4.39-, 3.78-, and 3.78-fold, respectively, compared with TA injection, and showed a relative bioavailability of 185.33%. Thus, this prepared solid lipid nanosuspension is a promising new formulation