JOURNAL OF SEPARATION SCIENCE AND ENGINEERING
Year:2018 | Volume:10 | Issue:2 |Papers Count:9

In recent years, the waste energy in cooling water of power plants has been applied for the production of water from saline waters. In this research, the effect of using the cooling water of a power plant located on the Persian Gulf coast, as a feed of a reverse osmosis unit was investigated on the separation of salt from seawater, the quality of the final product and water recovery. By increasing the feed water temperature from 20 to 45 ° C, although the flow of the produced water increased about twice (from 7. 5 to 14 L/m2h), it decreased the membrane salt rejection and salt separation by the membrane. As a result, the electrical conductivity of the produced water increased to about 700 to 1200 μ S/cm. This change is due to enhanced membrane permeability to water and salt at higher water temperatures. Increased water flux saved energy for water production, but reduced the desirability of drinking water, although it remained within the world health organization (WHO) standards.

A sub-critical centrifuge was fed with a 53%-47% (w/o) mixture of “ Freon-12-Freon-22” to survey tail scoop distance from rotor wall effect and feed flow rate effect on gas hold up and rotor wall temperature. In this case, 20 experiments in four tail scoop distances (6. 12, 5, 4, and 3mm) and five feed flow rates (10, 15, 25, 35, and 40 g/h), were designed. The results showed that, rotor wall temperature distribution in vertical direction was decreasing from top cap to bottom cap. Temperature of all points of rotor wall increased monotonously with feed flow rate increment due to uniform raise of gas hold-up and number of gas molecule-rotor wall impacts, while temperature difference between top cap and bottom cap was invariant. Temperature of top of rotor wall raised with tail scoop distance decreasing, due to increasing of drag force exerted on the gas by tail scoop, which causer to increase temperature difference between top cap and bottom cap. Temperature difference between top cap and bottom cap was only dependent to physical characteristic of gas centrifuge like tail scoop position. Highest and lower rotor wall temperature was respectively 316 and 305 k at 3 and 6. 12 mm tail scoop distance and 40 and 10 g/h feed flow rate.

Bleaching using bleaching earth is one of the essential processes in edible oil refineries. The spent bleaching earth containing 20-40 % oil, therefore it is ready for rapid oxidation and flammability. To prevent the environmental problems, it is necessary to have a proper treatment on spent bleaching earth before disposal in the earth. The main objective of this study is to examine the removal percent of oil from spent bleaching earth using supercritical extraction process. Experiments were designed based on the central composite design of four parameters and the results were analyzed and optimized using response surface methodology. According to the results of the proposed mathematical model, the best operating conditions were determined at pressure of 200 bar, temperature 44 ° C, solvent flow rate 0. 04 mL/s and time 90 minutes. The amount of extraction was 3. 26 % under the obtained optimum conditions which had been an appropriate compliance with the predicted value by related model (3. 49 %).

Nodaway, membrane methods such as ultrafiltration have been considered to separating pollutions from fluids. The governing equations indicate the role of cartridge geometry on the separation process. The present study is carried out to investigate the effect of cartridge geometry on the separation performance of a hollow fiber ultrafiltration system. Numerical Modeling are divided into three categories, include circle, square, and triangle. The region including fibers is considered as a porous medium. Results show in the same conditions, the use of square and triangular geometry reduce transemembrane pressure, cake thickness and consequently the cake resistance and the membrane resistance compared to circle. Also, triangle geometry has shown better performance under changes in inflow and packaging density and the time to reach the same thickness of the cake is more than the other two geometries.

In this study, the continuous separation of hexane and water in micro-systems was investigated. For this purpose, two dimensional glass microfluidic chips were fabricated using laser ablation and thermal bonding method. The chips comprised of a main microchannel and few lateral micro channels. It was aimed to exit hexane and water from the, respectively, main and lateral micro channels. It was found that decreasing the width and increasing the number of the lateral micro channels, and increasing the flow rate of water result in increased separation. Also, increasing the flow rate of hexane and increasing the length of the lateral micro channels result in the reduction of the separation. In order to increase the operating flow rate of the capillary separation, three-dimensional microfluidic chips were fabricated by parallelization of four microscale capillary separators. With the three-dimensional microfluidic chips, the separation efficiency of up to 60% was achieved at the operating flow rate of 1. 5 mL min-1.

In this paper, a two-dimensional mathematical model was presented for the removal of CO2 and H2S in a polypropylene hollow fiber membrane contactor in the presence of MEA. Modeling was performed in both axial and radial directions under the dry condition for countercurrent gas-liquid flow arrangement. To evaluate the model, the results of this modeling were compared with experimental data of removal of CO2 in the presence of water physical solvent and MEA chemical solvent. The results showed that the CO2 and H2S removal efficiency increased with the increase of the liquid flow rate, number of fibers, membrane length, and solvent concentration, but, decrease by increasing gas flow rate because of lower hold up time. It was also found that in low amine discharges, hydrogen sulfide is completely removed. Finally, the results showed that by increasing the wetting, the removal of these gases is reduced.

Absorption and separation of carbon dioxide and hydrogen sulfide from biogas by the metal organic framework MIL-47 have been investigated by using the Monte Carlo method. The simulation results have a good agreement with the available experimental data. At first, the adsorption isotherm of pure, binary and ternary blend of methane, carbon dioxide, and hydrogen sulfide gases were studied. The simulation results show that the gas adsorption increases by decreasing and increasing in the temperature and pressure, respectively, and the pure absorption of hydrogen sulfide gas in the MIL-47 is higher than the other gases. The selectivity of carbon dioxide and hydrous sulfide relative to methane gas calculates 0. 2 and 2. 9 at ambient temperature and pressure, respectively. Therefore, the metal organic framework MIL-47 is not suitable for the absorption and separation of carbon dioxide gas, but it is good able to separation of hydrogen sulfide from biogas.

In recent years, the aqueous two phase systems (ATPS) are applied for separation of biological products as a new method. In this research, the ATPS based on poly (ethylene glycol) 2000 and magnesium sulfate are applied for separation of-amylase. The binodal curve is firstly obtained by using cloud point method at 23 and is correlated by the Merchuk equation. Also, partitioning of-amylase in two phase region at various working points is investigated and tie lines, partition coefficients and recovery are obtained. The results show that the bimodal curve is fitted with the Merchuk equation well. After partitioning of-amylase enzyme in the ATPS,-amylase tends to the top phase and the average of the partition coefficients the extraction recoveries are 1. 15 and 71%, respectively. Also, the partition coefficient of-amylase is increased with increasing concentration of polymer (at constant concentration of salt) and concentration of salt (at constant concentration of polymer). The values of Gibbs free energy of-amylase show that partitioning process is spontaneously toward top phase.