Separations Technology

A packed column distillation process experiment was conducted with the goal of understanding the operation of vapourliquid separation, analyzing the sample for the top and bottom product by refractometer to obtain the refractive index (RI) in order to determine their respective composition and also to obtain the time when the vapourliquid separation is nearly finish. In this experiment 30 litres of 10% v/v (volume/volume) mixture of Ethanol in water was prepared and filled in a reboiler vessel. The mixture was allowed to boiled until almost all component with low boiling point has been vaporized from the mixture.

Developing a lithium mining project is a complex challenge which requires a careful planning, involving a multidisciplinary team. Each stage needs to be considered in planning, including resource exploration, production process design, basic and detailed engineering, financing, over to construction, commissioning, personnel training and process performance verification.

The objectives of the reviews are the collection, concise description, comparison and evaluation of the various chromatographic technologies except liquid chromatography using natural and modified cyclodextrins for the increase the seperation capacity of various chromatographic separation systems.

Abstract We propose a complementary pressure swing adsorption (CPSA) process consisting of four beds for separating air into enriched oxygen and nitrogen. Simulation results showed that the CPSA process performed better than either the oxygen process or ...

The widespread use and high solubility nature of glyphosate posed a significant threat to water contamination. Glyphosate is a non-selective herbicide for weed control in various agricultural applications. Electrocoagulation method was thus proposed to coagulate this pollutant, and a magnetic treatment was introduced to shorten settling time and to assist sedimentation of suspended solids. The effects of operational variables such as initial glyphosate concentration, electrolysis time and applied voltage towards removal of glyphosate, chemical oxygen demand (COD) and total suspended solids (TSS) were explored to broaden the core understanding of settling velocity and ferromagnetic effects of magnetic fields. The combination of electrocoagulation and the magnetic field was designed and setup into batch laboratory experiment and static mode with two parallel iron (Fe) plates for both anode and cathode. This design used permanent magnets namely NdFeB of 0.55 T and the magnetic exposure time was 6 hours. Results showed that the increment in both applied voltage and treatment time and the reduction in initial glyphosate concentration were beneficial for improving glyphosate, COD, and TSS removal efficiencies. An initial glyphosate concentration of 25 mg/L, applied voltage of 30 V and treatment time of 40 min, were obtained as optimum experimental conditions. Respective glyphosate, COD and TSS removal efficiencies of 95.84%, 71.43%, and 79.08% were observed in experiments conducted in optimum conditions. As a conclusion, magnetic field strongly encouraged electrocoagulation process in obtaining better results due to a ferromagnetic mechanism in aqueous solutions.

This study was intended to compare the performance of electrocoagulation process using aluminium and iron electrodes for glyphosate removal in aqueous solution. The effects of initial glyphosate concentration, electrocoagulation time and distance between electrodes, were discussed in detail. An electrocoagulation tank of 500mL with two metal plates electrodes, same in dimensions and metal types, was set up to perform batch mode laboratory experiment and the glyphosate in white powder was first diluted with deionized water. Production of metal cations showed an ability to neutralize negatively charged particles, which then encouraged to bind together to form aggregates of flocs composed of a combination of glyphosate and metal hydroxide. Compared with iron electrodes, aluminium electrodes were more effective for glyphosate removal, with a removal efficiency of over than 80%. This study revealed that electrocoagulation process using aluminium electrodes is reliable, especially designed for initial concentration 100 mg/L, electrocoagulation time 50 min, and distance between electrodes 6 cm. Finally, it can be concluded that electrocoagulation process using aluminium electrodes is efficient for glyphosate removal from aqueous environments.

In general, dewatering of plant tissues (such as vegetables) and food materials is achieved by heating. In order to prevent the degradation of biologically active components in plant materials, the dewatering process should be carried out at low temperature. Therefore, in the present study, we attempted to develop a simple protocol for dewatering cryo-preserved plant tissues using liquefied dimethyl ether (DME). Prior to dewatering from frozen plant materials, we have examined the efficiency of liquefied DME for cryogenic removal of water from ice cubes. Here, lemon peel residue (consisting of flavedo and albedo) was chosen as the model plant material for dewatering and concomitant extractions of water-soluble components such as ascorbate and citric acid and hydrophobic components, chiefly, essential oils (EOs). By focusing on the exploitation of unused resources after food processing, the juice extraction residues from lemon fruits (lemon peels) were used as the starting materials. The yield of vitamin C (VC) extracted from the peel tissues derived from a single lemon fruit exceeded the amount of VC found in the manually press-extracted juice from a single lemon fruit. The major components in DME-extracted crude lemon EOs were determined and quantified with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC-FID) to be limonene (40.4%, w/w), β-pinene (10.4%, w/w), and γ-terpinene (6.9 %, w/w).

We demonstrate an extensible flat-histogram Monte Carlo simulation methodology for studying the adsorption of multicomponent fluids in flexible porous solids. This methodology allows us to easily obtain the complete free energy landscape for the confined fluid-solid system in equilibrium with a bulk fluid of any arbitrary composition. We use this approach to study the adsorption of a prototypical coarse-grained binary fluid in “Hookean” solids, where the free energy of the solid may be described as a simple spring. However, our approach is fully extensible to solids with arbitrarily complex free energy profiles. We demonstrate that by tuning the fluid-solid interaction ranges, the inhomogeneous fluid structure inside the pore can give rise to enhanced selective capture of a larger species through cooperative adsorption with a smaller one. The maximum enhancement in selectivity is observed at low to intermediate pressures and is especially pronounced when the larger species is very dilute in the bulk. This suggest a mechanism by which the selective capture of a minor component from a bulk fluid may be enhanced.

Experimental studies and them1odynamic modeling for the separation of aromatic compounds from a complex mixture of hydrocarbons have been carried out. The sample used in this work is the main material for producing lubricating oils, and the solvent used for extraction of aromatic components is a new selective solvent which has unique specifications in comparison with conventional solvents such as furfural. This modeling is based on the method of Ruzicka for making model molecules. The parameters required for modeling were obtained. and then liquid-liquid equilibrium calculations were done ;rnd compared with the experimental data. These calculations were also carried out using published parameters for the vapor-liquid equilibria of the components involved in the mixture. The results have been compared with the previous calculations as well as with the experimental data, and good agreement was found.

The objectives of the reviews are the collection, concise description, comparison and evaluation of the various chromatographic technologies using natural and modified cyclodextrins for the increase the separation capacity of various chromatographic separation systems

Abstract Crystallization of potassium chloride from an aqueous solution cosaturated with sodium chloride was studied in a 1-L continuous mixed-suspension mixed-product cooling crystallizer. Various operating temperature and feed temperature combinations were employed to investigate the effect of these variables and the resulting supersaturation on the crystallization kinetics. Significant polycrystals formation was observed in all cases. The population balance theory with the inclusion of aggregation process was used to develop empiric correlations for the nucleation rate, growth rate, and aggregation frequency. In view of the large supersaturation measured experimentally, very high nucleation rates were observed compared with the data published by other workers. The measured growth rates in this study include growth owing to the individual molecules as well as growth owing to the aggregation process.

In this paper, an analytical solution of the coupled heat and mass transfer process in a cross-flow liquid-desiccant dehumidifier/regenerator is developed. By the use of reliable assumptions, the government equations for the system are solved by an analytical method. The results of the present analytical solution are compared with experimental data from the literature, and they show good agreement. The maximum error produced by the presented analytical solution is less than 12 %. The effect of the operating parameters is considered using the presented analytical solution. The results show that air inlet humidity, air flow rate, desiccant inlet temperature, and desiccant inlet concentration have more influence on the moisture removal rate in the cross-flow dehumidifier. Also, air inlet humidity, desiccant inlet temperature, desiccant inlet concentration and desiccant flow rate have more effect on the moisture removal rate in the cross-flow regenerator. The effect of the Lewis number on the performance of the dehumidifier/regenerator is investigated. As the results show, by the use of Le = 1.08 in the dehumidification process and Le = 0.96 in the regeneration process, instead of the value of unity, better results are obtained. The benefit of the present study is a simplified application for the evaluation of the outlet parameters of the cross-flow air dehumidifier/regenerator.

We use Monte Carlo simulations to investigate the thermodynamic behavior of soft porous crystal (SPC) adsorbents under the influence of an external barostat. We consider SPCs that naturally exhibit polymorphism between crystal forms of two distinct pore sizes. In the absence of barostatting, these crystals may be naturally divided into two categories depending on their response to stress applied by the adsorbate fluid: those which macroscopically deform and change the volume of their unit cell (" breathing ") and those which instead undergo internal rearrangements that change the adsorbate-accessible volume without modifying the unit cell volume (" gate-opening "). When breathing SPCs have a constant external pressure applied, in addition to the thermodynamic pressure of the adsor-bate fluid, we find that the free energy difference between the crystal polymorphs is shifted by a constant amount over the entire course of adsorption. Thus, their relative stability may be easily controlled by the barostat. However, when the crystal is held at a fixed overall pressure, changes to the relative stability of the polymorphs tend to be more complex. We demonstrate a thermodynamic analogy between breathing SPCs held at a fixed pressure and macroscopically rigid gate-opening ones which explains this behavior. Furthermore, we illustrate how this implies that external mechanical forces may be employed to tune the effective free energy profile of an empty SPC, which may open new avenues to engineer the thermodynamic properties of these polymorphic adsorbents, such as selectivity. [http://dx.doi.org/10.1063/1.4983616]

... Extractive separations using hydrotropes Mamta Agarwal and Vilas G. Gaikar Department of Chemical Technology, University of Bombay, Matunga, Bombay, India Hydrotropes, such as sodium toluate, sodium toluene sulfonate, sodium cymene sulfonate ... '2 Mahapatra et al.'3 ...