Mass Ratio Of Solution Research Articles

Mass transfer during the osmotic dehydration of West Indian cherry

The main purpose of this work was to study water loss, solids gain, and weight and moisture reduction during the osmotic dehydration process of the West Indian cherry (Malpighia punicifolia). The diffusion coefficient of West Indian cherry was estimated by the inverse method using average moisture contents. Osmotic dehydration was examined for 12 h in a 65°Brix solution at temperature of 27 °C, without agitation, using a fruit:solution mass ratio of 1:4, 1:10, and 1:15. The kinetics and internal changes occurring during the osmotic dehydration of West Indian cherry are reported. The product’s drying kinetics was simulated using the diffusion model, and two optimization methods, Levenberg–Marquardt and Differential Evolution algorithm, were used to predict the diffusion coefficient. The results indicated that the two optimization methods performed similarly in estimating the diffusion coefficient adequately. The average calculated diffusion coefficient was 1.663 × 10−10 m2s−1, which is consistent with values reported in the literature.

Preparation of monolithic polylaurylmethacrylate column and its application in capillary electrochromatographic separation of myoglobin digests

The monolithic polylaurylmethacrylate column was prepared in a single step using the monomer solution containing lauryl methacrylate (LMA), ethylene dimethacrylate (EDMA), and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), with the ternary porogenic solvent consisting of 1-propanol, 1,4-butanediol and H2O. The effects of AMPS content and the ratio of monomer solution to porogenic solvent were investigated. The optimal mass ratio of monomer solution to porogenic solvent was 35:65, the monomer solution was composed of 59.5% (w/w) LMA, 40% (w/w) EDMA and 0.5% (w/w) AMPS, and the porogenic solution was composed of 60% (w/w) 1-propanol, 30% (w/w) 1,4-butanediol and 10% (w/w) H2O. The prepared monolithic column was successfully applied in the capillary electrochromatographic (CEC) separation of myoglobin digests under the optimized mobile phase.

Dielectric and Piezoelectric Properties of PZT Composite Thick Films with Variable Solution to Powder Ratios

The use of PZT films in sliver-mode high-frequency ultrasonic transducers applications requires thick, dense, and crack-free films with excellent piezoelectric and dielectric properties. In this work, PZT composite solutions were used to deposit PZT films >10 μm in thickness. It was found that the functional properties depend strongly on the mass ratio of PZT sol-gel solution to PZT powder in the composite solution. Both the remanent polarization, P(r), and transverse piezoelectric coefficient, e(31,) (f), increase with increasing proportion of the sol-gel solution in the precursor. Films prepared using a solution-to-powder mass ratio of 0.5 have a remanent polarization of 8 μC/cm(2), a dielectric constant of 450 (at 1 kHz), and e(31,) (f) = -2.8 C/m(2). Increasing the solution-to-powder mass ratio to 6, the films were found to have remanent polarizations as large as 37 μC/cm(2), a dielectric constant of 1250 (at 1 kHz) and e(31,) (f) = -5.8 C/m(2).

Extraction and isolation of indole alkaloids from Tabernaemontana catharinensis A.DC: Technical and economical analysis

In the present work, the technical and economical analysis of extraction and isolation of indole alkaloids from Tabernaemontana catharinensis is presented. The extraction was carried out using supercritical CO 2 as solvent and ethanol as cosolvent (5%, v/v). The global yield isotherms were determined at 35 and 45 °C for pressures of 150–350 bar. The mass transfer rate for the constant extraction rate period (CER), the duration of the CER period, and the mass ratio of solute in the fluid phase at the bed outlet were calculated. The extraction curves were adjusted by Crank, Goto et al. and Esquível et al. models. The economical analysis was carried out considering that the cost of manufacturing can be obtained in terms of the costs of investment, operational labor, raw material, waste treatment and utilities. The higher global yields were obtained at 350 bar (1.30 × 10 −2 and 1.54 × 10 −2 kg/kg, at temperatures of 35 and 45 °C, respectively). The Goto's model was able to quantitatively describe the experimental data. The cost of manufacturing the extracts obtained at 350 bar, 45 °C, using 5% (v/v) of ethanol was US$ 79.35 kg −1 of extract. Using previous experimental data obtained at 300 bar, 55 °C, using 10% of ethanol (v/v), the cost of manufacturing for the fractionation process to obtain a rich alkaloidal fraction (AF) was US$ 440.31 kg −1 of alkaloids.

Coordination-complex polymer as an organic conductor for organic light-emitting diodes

A coordination complex of poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT-PSS) is used to enhance the performance of organic light-emitting diodes. Use of the coordination complex formed by copper results in more than doubling the device lifetime when the complex is used as the hole injection layer (HIL) in place of the usual HIL of PEDOT-PSS that is not treated. Of the possible coordination complexes of PEDOT-PSS, the coordination complex formed with copper gives the best performance. The optimal mass ratio of CuSO4 and PEDOT-PSS solution in forming the complex is found to be 0.533. Surface morphology of the organic film formed and conductivity enhancement are the main factors that determine the optimal mass ratio.

An experimental study of fluidized-bed coating: influence of operating conditions on growth rate and mechanism

This study investigates the influence of fluidizing gas velocity, atomizing air, and liquid flow rates, liquid concentration, initial bed mass, and particle size on the mechanism of growth of sand particles in a batch fluidized-bed coater. An aqueous solution of NaCl was used as the coating liquid and sprayed in the bed by means of a pneumatic atomizer. The results showed that for a given particle size, the fluidizing air velocity was the most important factor affecting the coating kinetics and stability. The dominant mechanism was the onion-ring layering, especially at excess gas velocities higher than 0.27 m/s. For a fixed value of the mass ratio of solute introduced in the bed to the initial particle mass, binder concentration, liquid flow rate, and the initial bed weight had no effect on the growth mechanism. The deposition quality was found to be affected by the droplet size. A decrease of droplet size resulting from increasing the atomizing air flow rate permitted homogenous coating of the solid surface.

ENERGY STORAGE FOR DESICCANT COOLING SYSTEMS COMPONENT DEVELOPMENT

Liquid desiccant cooling systems are especially suitable for solar energy applications. The liquid desiccants can be regenerated at temperatures below 80°C and the concentrated and diluted desiccants can easily be stored to provide a high energy storage capacity for air dehumidification and cooling. Special absorption processes are necessary to achieve an optimal air dehumidification and simultaneously a high energy storage capacity. The dominating effects on the absorption process are discussed in detail. For efficient dehumidification the temperature of the absorption process and the inlet concentration of the salt solution are of major importance. For a high energy storage capacity a high air to solution mass ratio is required to achieve great differences between salt inlet and outlet concentrations. A high mass ratio corresponds to a small desiccant flow. New dehumidifiers have been developed and tested, to achieve an efficient air dehumidification and high storage capacity. They dehumidify air by a very small flow of a hygroscopic aqueous salt solution, e.g. LiCl–H 2O in an internally cooled absorption process. Experimental results of air dehumidification and storage capacities are reported. Mass transfer coefficients, used in numerical models, have been identified by absorption experiments and enable the reliable sizing of dehumidifiers.

Mass transfer model for osmotic dehydration of fruits and vegetables—I. Development of the simulation model

A mathematical model based on mass transfer in plant tissues was developed with the aim of finding a simple predictive model which was easy to use and yet had a broad application scope in the osmotic dehydration of foods. The model takes into account the capacity of each constituent to diffuse within tissue by using a diffusion coefficient and a transmembrane mass transfer coefficient. The model also depends on the mass ratio of osmotic solution to product, on the initial chemical composition of the product and solution, and on the product shape. The application of the model to apple dehydration with polyethyleneglycol (PEG) solutions allowed us to quantitatively simulate the time evolution of cellular and extracellular volumes which was observed previously in histological sections under the microscope. By using experimental data obtained during potato dehydration in mixed solutions of sucrose and salt, mass transfer and apparent diffusion coefficients were fitted in order to evaluate product behavior under different process conditions. A good quantitative agreement was obtained between the experimental and calculated results. The model presented in this paper allows the main variables of osmotic dehydration to be estimated using a low number of fitting parameters, and interprets, through a simple algorithm, the complex phenomena of the main mass transfer mechanisms in plant tissues.