Distillation of Ethanol-Water Solutions in the Presence of Potassium Acetate

Abstract

Complete separation of ethanol-water mixtures through salt addition has been demonstrated in a continuously operated single sieve-plate-column including salt recycling. The effect of salt concentration as well as reflux ratio on the separation are outlined based on experimental data. The results clearly indicate that distillation in the presence of salts is an economical alternative to more conventional processes.     

Correlative models for perovskites with rock salt B-site ordering

Empirically derived predictive models describing synthesis-structure relationships have the potential to significantly improve and guide future research in a more cost-effective and timely manner; however, few of these models exist for cation ordering in perovskites. In this study, four compositions within the AZn_0.5Ti_0.5O₃ system (A = Nd, Sm, Nd_0.5La_0.5, Nd_0.5Gd_0.5) were synthesized using a conventional solid-state mixed-oxide method. X-ray diffraction data show evidence of long-range 1:1 rock salt cation ordering on the B site for all compositions. Additional data for other rock salt B-site ordered compositions were mined from literature. Correlative models for the B-site shrinkage (Δr_B) have been derived for each B-site ordered system, and a general model has been developed for rock salt B-site ordering from these specific models. This general model allows for the prediction of the room-temperature volume shrinkage resulting from rock salt B-site ordering using only published ionic radii data.     

Xanthan Precipitation from Solutions and Fermentation Broths

Abstract

Precipitation of xanthan from solutions and fermentation broths is studied. The effects of different precipitating agents, initial xanthan concentrations, and salt additions on xanthan solutions are examined. The effect of sodium and calcium chloride concentrations added to isopropanol (IPA) is studied for xanthan solutions. Xanthan precipitation from fermentation broths has been carried out, and the effect of salt addition to IPA is considered.     

Assessment and validation of a hygroscopic growth model with different water activity estimation methods

Abstract

Hygroscopic growth models are currently of interest as aids for targeting the deposition of inhaled drug particles in preferred areas of the lung that will maximize their pharmaceutical effect. Mathematical models derived to estimate hygroscopic growth over time have been previously developed but have not been thoroughly validated. For this study, model validation involved a comparison of modeled values to measured values when the growing droplet had reached equilibrium. A second validation process utilized a novel system to measure the growth of a droplet on a microscope coverslip relative to modeled values when the droplet is undergoing the initial rapid growth phase. Various methods currently used to estimate the water activity of the growing droplet, which influences the droplet growth rate, were also compared. Results indicated that a form of the hygroscopic growth model that utilizes coupled-differential equations to estimate droplet diameter and temperature over time was valid throughout droplet growth until it reached its equilibrium size. Accuracy was enhanced with the use of a polynomial expression to estimate water activity relative to the use of a simplified estimate of water activity based on Raoult’s Law. Model accuracy was also improved when constraining the film of salt solution surrounding the dissolving salt core at saturation.

Copyright © 2020 American Association for Aerosol Research     

PARTITIONING OF AROMATIC MOLECULES IN AQUEOUS BIPHASIC SYSTEMS

ABSTRACT

Aqueous biphasic systems (ABS) may be suitable for the separation of aromatic molecules in industrial and environmental settings; hence it is invaluable to have predictive models of partitioning behavior in these systems for design and evaluation purposes. In a continuing study of the partition of small aromatic organic molecules, the distribution of several relatively hydrophilic substituted benzene species is reported. The partitioning behavior of five charged substituted benzene species (phthalic acid, 4-hydroxybenzoic acid, benzoic acid, salicylic acid, and p-toluic acid) and one uncharged species (1,3-dinitrobenzene) has been studied in ABS prepared from stock solutions of 40% (w/w) PEG-2000 and increasing concentrations of four water-structuring salts [K₃PO₄, K₂CO₃, (NH₄)₂SO₄, and NaOH]. Comparison has been made with published data on the partitioning of these solutes in 1-octanol/water biphasic systems. In general, the partition of these species may be understood in terms of the free energy of hydration of the salt forming the ABS and the dissociation of the charged groups of the distributed solutes.     

Synergism and Separation Factors in Lanthanide Extraction with Mixtures of Chelating Extractant and Amine Salts in C6H6

Abstract

The solvent extraction of Pr, Gd, and Yb with 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-one (HP) and an amine salt (AmHA) has been studied. The composition of the extracted species has been determined as (AmH)[LnP₄]. The values of the synergistic coefficients and separation factors have been calculated. The effect of the amine salt on the extraction and separation of lanthanides has been discussed.     

Effect of Ionic Strength of Solution on Boron Mass Transfer by Ion Exchange Separation

Abstract

In the present study, batch kinetic tests have been performed for boron removal from model solutions using boron selective ion exchange resins Diaion CRB 02, Dowex (XUS 43594.00) and Purolite S 108. Several kinetic models have been used to evaluate the sorption kinetics of boron by means of a well mixed stirred system, diffusional models, pseudo‐first‐order, and pseudo‐second‐order kinetic models. The mass transfer model, based on a well stirred system including maximum capacity (Q_m, mg/g) and Langmuir constant (b, L/mg) values obtained from Langmuir isotherms, has been used to obtain predictive concentration changes against time. The experimental results have been used to compare with the modelling data for different ionic strength media.     

Modelling of Fish Drying Kinetics Using a Combination of Surface Response Methodology and Diffusional Models

ABSTRACT

Drying is a common fish preservation technique used in developing countries. Analysis of process factors involved in controlled fish drying permits process optimization and assists in design of suitable dryers. Various methodologies, with models of different complexities (analytical, semi–empirical and empirical models), have been used to investigate fish drying kinetics. The original feature of this study is the combined use of surface response methodology and diffusional models. In a limited number of experimetns, this combination allowed development of a predictive tool for assessing fish drying mechanisms and drying time.     

Process Development for the Removal of Zinc and Cadmium from Wastewater Using Slag—A Blast Furnace Waste Material

Abstract

Blast furnace slag, a waste generated in steel plants in India, has been converted into a low cost potential adsorbent. The resulting product has been characterized and used for the removal of zinc and cadmium. The effect of particle size, contact time, and surface loading of zinc and cadmium on the adsorbent for their removal have been studied at the optimum pH (6.0 for Zn²⁺ and 5.0 for Cd²⁺). Kinetic studies were undertaken to show the mechanistic aspects of the process and to obtain the thermodynamic parameters. Sorption data have been correlated with both Langmuir and Freundlich adsorption models. Column operations were also performed in an attempt to simulate industrial conditions. Some feasibility experiments have been performed with a view to recovering Zn²⁺ and Cd²⁺ and for the chemical regeneration of the spent columns without dismantling them.     

Dynamic Models for Drying and Wet-Milling Quality Degradation of Corn Using Neural Networks

ABSTRACT

Non-linear dynamic models of corn drying and wet-milling quality degradation are obtaineddirectly from experimental data. No assumptions about the underlying mechanisms are made. Relative advantages of recurrent versus explicit-time models and technical issues are discussed. This type of model is well suited for very fast on-line simulations, for example in a predictive optimal control algorithm.     

Optimization of solar-powered reverse osmosis desalination pilot plant using response surface methodology

A solar thermal and photovoltaic-powered reverse osmosis (RO) desalination plant has been constructed and optimized for brackish water desalination. The central composite experimental design of orthogonal type and response surface methodology (RSM) have been used to develop predictive models for simulation and optimization of different responses such as the salt rejection coefficient, the specific permeate flux and the RO specific performance index that takes into consideration the salt rejection coefficient, the permeate flux, the energy consumption and the conversion factor. The considered input variables were the feed temperature, the feed flow-rate and the feed pressure. Analysis of variance (ANOVA) has been employed to test the significance of the RSM polynomial models. The optimum operating conditions have been determined using the step adjusting gradient method. An optimum RO specific performance index has been achieved experimentally under the obtained optimal conditions. The RO optimized plant guarantees a potable water production of 0.2 m³/day with energy consumption lower than 1.3 kWh/m³.     

Transient Response of a Distillation Column Plate. Part II. Model Evaluation from Flow and Mixing Data on a Plate without Two-Phase Mass Transfer

Abstract

The operation of a distillation column plate was simulated by using air for the vapor phase and water for the liquid phase; the turbulent mixing effect in the liquid on the tray and in the downcomers was analyzed by following composition changes of salt (sodium chloride). Composition changes entering the plate and in the downcomer leaving the plate were monitored. The composition–time data was numerically Laplace transformed, and the frequency response form was fit to each of five models: (1) perfect mixing; (2) plug flow; (3) perfect mixing with time delay in the downcomer; (4) dispersion; and (5) dispersion with dead zones on the tray. The composition–time data was reconstructed from each of the best fitting parameters of each of the models, and this data is given for comparison with the experimental data.

The model utilizing dispersion was the best statistical model. The model of perfect mixing on the tray and delay in the downcomer gives a satisfactory fit and is much simpler.     

Dielectric Properties and Optimization of Parameters for Microwave Drying of Petroleum Coke Using Response Surface Methodology

The dielectric properties of petroleum coke at five temperatures between 20 to 100 ^° C, covering different moisture content levels at 2.45 GHz, were measured using an open-ended coaxial probe dielectric measurement system. The effects of drying temperature, duration of drying, and sample mass on the moisture content and dehydration rate of petroleum coke was assessed utilizing the response surface methodology. The dielectric constant, loss factor, and loss tangent were all found to increase nearly linearly with increase in moisture content. Three predictive empirical models were developed to relate the dielectric constant, loss factor, and loss tangent of petroleum coke as a linear function of moisture content from 3–10%. An increase in temperature between 20 to 100 ^° C was found to increase the dielectric properties. The penetration depth was observed to increase linearly with decrease in moisture content in the range of 3 to 10%. A predictive empirical model was developed to calculate penetration depth for petroleum coke. Two mathematical models were established and analyzed using RSM to describe the relationship between the microwave drying conditions and the responses, moisture content, and dehydration rate. Statistical analysis with response surface regression showed that microwave drying temperature, duration of drying, and sample mass were significantly related to moisture content and dehydration rate. Based on the RSM analysis, the optimum process conditions were estimated to be a microwave drying temperature of 75 ^° C, drying duration of 10 sec, and sample mass of 60 g, with the resultant moisture content being 0.34 at a dehydration rate of 2.94 g/min.     

Experimental Investigations on the Performance of a Packed Bed Dehumidifier for Various Climatic Conditions

ABSTRACT

To simulate space cooling or drying systems for various geographical regions (low, moderate, and high humidity regions) a liquid desiccant system consisting of a humidifier and dehumidifier has been designed and constructed. This system consists of two coupled humidifying and dehumidifying packed columns filled with plastic Intalox Snowflake packing material. Experimental measurements of the dehumidifier performance utilizing a new effective liquid desiccant mixture (CELD) total desiccant salt content 40%wt.to 45%wt (salt comprised of equal portions by weight of lithium chloride and calcium chloride ), have. been carried out, The effect of different independent variables such as packing height, air inlet temperature and humidity ratio, and liquid desiccant inlet temperature, flow rate and concentration on the performance of the dehumidifier has been investigated. Experimental results demonstrate that the CELD is a promising desiccant for cooling and drying operations.     

Dehydration modeling of Cordyceps militaris in mid-infrared-assisted convection drying system: Using low-field nuclear magnetic resonance with the aid of ELM and PLSR

Abstract

The changes in moisture content and shrinkage ratio of Cordyceps militaris during mid-infrared-assisted convection drying (MIRCD) with different drying temperatures (40, 50, and 60?°C) and velocities of airflow (1 and 2?ms^?1) were studied. The relationship between low-field nuclear magnetic resonance (LF-NMR) information and moisture content/shrinkage ratio was modeled using partial least-squares regression (PLSR) and extreme learning machine (ELM). Results indicated that the influence of drying temperature was more pronounced than that of air flow velocity. Both types of models showed good predictive ability with R²>0.90. The ELM models exhibited superior predictive performance than that of the PLSR models.     

Reverse Osmosis Separation of Nickel from Dilute Solutions

Abstract

Cellulose acetate membranes were characterized in terms of the pure water permeability constant, the solute transport parameter, the mass transfer coefficient, and percent solute separation using a reference system of aqueous sodium chloride solution. The membranes were used in the determination of reverse osmosis characteristics such as product rates and solute separation of dilute nickel salt solutions. The effect of the chemical species present in aqueous nickel salt solution on the degree of separation of nickel has been determined. The results of this study can be used in predicting the general reverse osmosis separation behavior of metals such as Zn, Cu, Pb, Mg, and Mn encountered in acid mine-water samples     

Experimental Determination and Modeling of Sorption Isotherms of Tropical Fruits: Banana,Mango, and Pineapple

Abstract

Sorption isotherms of banana, mango, and pineapple have been experimentally found at 40, 50, and 60°C by use of the salt method for a range of water activities from 0.056 to 0.85. The sorption capacity of these fruits increases with the temperature for a given water activity. The experimental curves have been simulated by the GAB and BET models. The BET model ensures a better representation of the experimental results for water activity lower than 0.35 with maximum deviation of 1.0, 1.5, and 2.0 kgw · kgdm^?1 for respectively banana, mango and pineapple. On the contrary, the GAB model enables the representation of the whole desorption isotherms and the estimation of the water content corresponding to monolayer saturation and of the isosteric heat of sorption. It also takes into account the temperature effect. The isosteric sorption heat of the three studied products are deduced from experimental results and empirical correlations are proposed leading to a satisfactorily representation.     

Diffusion Dialysis. Effect of Membrane Composition on Acid/Salt Separation

Abstract

In order to highlight the relationship between membrane composition and ability to separate acid/salt mixtures by diffusion dialysis, a few anion-exchange membranes were examined. Experiments on solubility/diffusivity phenomena were carried out in contact with hydrochloric acid and sodium chloride solutions (single-and two-solute experiments). Computations using Glueckauf and Tye models have indicated high nonuniformity in the distribution of fixed charges within the membranes and different accessibilities of the internal membrane volumes for the acid and salt. The Neosepta AFN-7 membrane (Tokuyama Soda Co.) has proved effective in differentiating the permeants by sorption (_{k HCl}/k _NaCl ?2) and diffusivity (D _HCl/D _NaCl up to 10). This membrane is also the only one which, when in contact with two-solutes solutions, absorbs the acid preferentially to the salt. For this membrane the perferential sorption and transport of the acid depends not only on the physical structure of the membrane but also on the chemical nature of the polymer which contains pyridine moieties.     

Salt Effects on the Recovery of Phenol by Liquid‐Liquid Extraction with Cyanex 923

Abstract

In this work, the effect of salt addition on the recovery of phenol from a 46 g/L aqueous solution simulating a phenolic resin plant effluent by liquid‐liquid extraction at 298 K has been studied by using an organic phase containing 0.6 M Cyanex 923 extractant in ShellSol T. Addition of sodium sulfate, potassium nitrate, and sodium chloride to the aqueous phase was tested and sodium chloride was selected. Based on the obtained results, a study of phenol recovery process was undergone by taking advantage of the salting‐out effect. Equilibrium curves are presented for liquid‐liquid extraction with and without salt addition to the aqueous phase. An integrated process involving salting‐out and liquid‐liquid extraction was proposed. The stripping concentrates can be reused for phenolic resin production.     

Continuous Dialysis of Protein Solutions on a Large Scale. I. The Influence of Various Factors on the Efficiency of Dialysis

Abstract

Artificial kidneys have been found useful for dialysis of protein solutions in biochemical preparative work. Manufacturer's data for their use in clinics as artificial kidneys could not be adopted directly in the new application. Therefore investigations on the influence of various flow rates on the efficiency of dialysis have been made. In most investigations 1 M salt solutions have been dialyzed against deionized water, and the results are illustrated in three diagrams. A 1 M salt solution with a flow rate of 25 ml/min can be reduced to 0.1 M, which means that this procedure should be of potential value in preparative work for desalting proteins.