Effect Of Evaporation Time Research Articles

Inducing the Skinned-oriented Asymmetrical Nanofiltration Membranes via Controlled Evaporation Times in Dry/Wet Phase Inversion Process

The effect of evaporation time on the fabrication of fine skinned asymmetric polyethersulfone nanofiltration membrane was studied. Nanofiltration experiment and modeling data revealed that the variation of the evaporation time during dry/wet phase inversion process was found to significantly affect the membrane performance and properties. The evaporation times (5 to 25 s) were found to improve the performance and characteristics of the membrane. As good separation performance was achieved, modeling data and morphological analysis discovered that the optimum evaporation time was found to be at 20 s. At these optimal settings, the fabricated membranes demonstrated the finest structural details and morphologies, and the best key properties (rp, Δx/Ak and ζ), which were within the ranges of commercial nanofiltration membranes.

Optimization of the Asymmetric Cellulose Acetate Membrane Synthesis Variables for Porosity and Pure Water Permeation Flux Using Response Surface Methodology: Microfiltration Application

Membranes play a vital role in membrane-based water treatment processes. Thus, improvement in the membrane fabrication stage can greatly affect the overall performance of these technologies. Accordingly, this study focuses on optimizing the fabrication process of a microfiltration cellulose acetate membrane prepared using a pore-templating method. The effects of synthesis variables and their interactions were investigated using face-centered composite design through response surface methodology (RSM). Calcium carbonate (CaCO3) and glycerin concentrations in the casting solution in addition to evaporation time and hydrochloric acid (HCl) bath time were selected as the independent variables, while the membrane porosity and pure water flux were considered as the response variables. Significant increase in both responses was observed by increasing CaCO3 and glycerin concentrations (P value < 0.05). However, the effect of evaporation time was found to be statistically insignificant on both responses. The effect of the HCl bath time was found to significantly affect the membrane porosity but not the pure water flux. RSM models for both responses were statistically evaluated in terms of the coefficient of determination (R2), and the estimated values (96.74% for the porosity model and 83.85% for the flux model) indicated good fit of the model to the experimental values. Multiple response optimization was employed, and the membrane produced at optimum conditions proved to have good agreement with the predicted values (16.2% error in flux and 3.66% error in porosity). The membrane was successfully applied for paint pigment rejection and oil emulsion rejection, and rejection efficiencies of 95.6% and 80% were achieved for color and oil, respectively, confirming the applicability of the membrane produced at the obtained optimum condition for wastewater treatment.

Brine Treatment by Solar Energy: Case Study in Tor-Sinai - Egypt

The absence of scalable, low energy requirement for brine treatment present a real threat and coming disaster for future generations targeting RO desalination. Brine with a certain concentration was evaporated with different solar concentrators and the effect of evaporation time on liquid concentration by variation in concentrator’s volume. The effect of different concentrator’s volume on the recovered condensate fresh water and weight of precipitated salts was showed. The thermal solar efficiency was found to exceed 90% for the different applied capacities. The concentrator volume was largely affecting the rate of evaporation in the closed and exposed ones. The excellent morphology and purity of precipitated salts with full characterization with the designed closed solar concentrator when compared with the exposed ones was shown. This morphology as spherical, agglomerated particle having a variety of particle size distribution, i.e., distinguished crystals for solar concentrator compared with continuous distribution for solar ponds. The ease of concentrator’s design and the adverse effect of volume enlargement on operability for incident solar energy 300 W/m2, makes the implementation of multilayer small capacity solar concentrator is an alternative.

Miscible-blend polysulfone/polyimide membrane for hydrogen purification from palm oil mill effluent fermentation

The biogas produced from the anaerobic fermentation of palm oil mill effluent (POME) contains equal amount of H2 and CO2, in which the biohydrogen (bioH2) is a prospective source of renewable energy. Therefore, the determination of an efficient H2 purification technique has been a major concern. Membrane separation technology is highly recommended due to its excellent purification performance with high permeation of H2 and H2/CO2 selectivity. Polymer blending is a favourable approach due to its simplicity to refine membrane inner structural properties by combining different polymers with complementary features. In this study, the synthesized polysulfone-polyimide (PSf/PI) membrane is an alternative polymeric membrane practicable for H2/CO2 separation due to its outstanding permeation properties, enhanced membrane properties as well as improved tolerance to plasticizing gases. The effect of evaporation time on PSf/PI membranes was further investigated and was thoroughly characterized by FTIR, TGA, DSC and SEM. The miscibility of the PSf/PI blending was proven by DSC with the detection of only single glass transition temperature value. The highest permeability of both H2 and CO2 gas were presented by PSf/PI-60 membrane with 348 GPU and 86 GPU, respectively, H2/CO2 selectivity of 4.4 and H2 purification efficiency of 80%. Hence, PSf/PI membrane is a high potential candidate with inherent properties for H2/CO2 separation from POME fermentation.

Effect of evaporation time on cellulose acetate membrane for gas separation

Throughout this decades, membrane technology has been the desirable option among the others gas separation technologies. However, few issues have been raised regarding the membrane gas separation application including the trade-off between its permeability and selectivity and also its effects towards environment. Therefore, for this research, a biopolymer membrane for gas separation application will be developed with reasonably high on both permeability and selectivity. The main objective of this research is to study the effect of solvent evaporation time on the flat sheet asymmetric membrane morphology and gas separation performance. The membranes were produced by a simple dry/wet phase inversion technique using a pneumatically controlled casting system. The dope solution for the membrane casting was prepared by dissolving the cellulose acetate (CA) polymer in N-Methyl-2-pyrrolidone (NMP) and the solvent evaporation time was varied. Permeability and selectivity of the membrane was performed by using pure gases of carbon dioxide, CO2 and methane, CH4. The increase in solvent evaporation time had improved the membrane morphologies as the porosity of the membrane surface decrease and formation of a more mature skin layer. The gas permeation tests determined that increasing in solvent evaporation time had increased the selectivity of CO2/CH4 but reduce the permeability of both gases

Effect of Solvent Evaporation Time on CO&lt;sub&gt;2&lt;/sub&gt;/CH&lt;sub&gt;4 &lt;/sub&gt;Gas Performance for Poly(Lactic) Acid Membranes

Membrane technology in gas separation application was commercialized approximately 30 years ago because of a number of advantages offered compare to the conventional technique. The use of poly (lactic acid) (PLA), a biodegradable polymer, as a membrane material would assist the reduction of depending to petroleum-based polymer. This study investigated the effect of evaporation time to the gas separation performance of PLA membrane. Membrane prepared from polymer solution consist of PLA and dicholoremethane (DCM) as solvent was fabricated using pneumatically controlled casting system with dry/wet phase inversion method. Permeation test was conducted using pure carbon dioxide and methane gas. The results revealed that as the evaporation time increased, the pore size and surface porosity decreased, while the skin layer thickness increased. Although the morphology of the prepared membranes showed the desirable structure, the gas separation performance of the membrane prepared with polymer concentration of 15wt% and 60s evaporation time was found to be promising but not yet commercially ready.

Study on Preparation and Performance of Modified Polyvinyl Chloride-co-vinyl Acetate Microfiltration Membranes

In this paper, flat-sheet microfiltration membranes were prepared from modified polyvinyl chloride-vinyl acetate (VC-co-VAc) material with hydroxyl group, VC-co-VAc-OH, by phase inversion technique. The influences of casting solution composition (polymer concentration, additive types, and content) and preparation conditions (coagulation temperature, evaporation time of solvent, and the relative humidity in the environment) on pure water flux, retention, and pore size distribution were discussed. The results showed that casting solution composition and the membrane preparation conditions all have significant impacts on the performances of the membrane: on the one hand, in order to prepare membranes with high flux, either decrease the polymer concentration, or increase the PEG molecular weight or the coagulation temperature or the relative humidity can achieve it; on the other hand, with the increase of additive content, the pure water flux increased quickly, then decreased dramatically, while the effect of evaporation time were the opposite. And these results were confirmed by the SEM images. Furthermore, the microfiltration membranes, which were prepared under optimized conditions, were used to treat synthetic oilfield polymer-flooding wastewater, and good experimental results were obtained.

Morphological Characterization of Cellulose Acetate Based Reverse Osmosis Membranes by Atomic Force Microscopy (AFM)-Effect of Evaporation Time

The surface structures of asymmetric cellulose acetate membranes prepared by the phase inversion method were investigated by the atomic force microscopy (AFM). The differences in the surface morphology have been expressed in terms of four types of roughness parameters such as; roughness average (Sa), root mean square roughness (Sq), surface skewness (Ssk), and surface kurtosis (Sku). The association of the roughness characteristics with the salt rejection performance has also been investigated. The results show that the increase in the evaporation time, results in the change of the membrane morphology and rejection efficiency. За допомогою атомно-силової мікроскопії (АСМ) досліджено структуру поверхні асиметричних мембран з ацетату целюлози приготовлених методом фазової інверсії. Відмінності в морфології поверхні були виражені чотирма типами параметрів шорсткості, таких як: середня шорсткість (S„), середньоквадратична шорсткість (Sq), поверхнева асиметрія (Ssk) та поверхневий ексцес (розподіл) (Sku). Встановлено взаємозв'язок між шорсткістю та видаленням солі. Показано, що збільшення часу випаровування призводить до зміни морфології мембран і ефективності.

Preparation of UF and NF poly (phthalazine ether sulfone ketone) membranes for high temperature application

The ultrafiltration (UF) and nanofiltration (NF) membranes have been prepared successfully from poly (phthalazine ether sulfone ketone) (PPESK), a proprietary chemical of excellent thermal, chemical and mechanical stability. The effects of PPESK concentration, the type and concentration of additives in the casting solution on membrane permeation flux and rejection were evaluated by using orthogonal array of the design of experiments in separation of polyethyleneglycol (PEG). It is shown that PPESK concentration and the additive in the casting solution is the dominant factor on the rejection and permeation flux, respectively. The membrane performance is consistent and agrees with the theoretical analysis. The membranes were applied in the dye separation with the effects of evaporation time, heat treatment and the type of dye studied. The separation of a variety of dyes of 600–900 Da can be accomplished by the PPESK membranes properly prepared. Over 98% dye rejections were obtained for seven typical dyes. The permeation flux increases greatly by raising operation temperature and pressure without significant change of rejection.

Formation of anisotropic membranes via thermally induced phase separation

The applicability of the thermally induced phase separation (TIPS) process to the production of anisotropic membranes was investigated. To induce an anisotropic structure, diluent was evaporated from one side of the polymer–diluent melt-blended, thereby creating a concentration gradient in the nascent membrane prior to inducing phase separation. The system used to prepare these membranes was isotactic polypropylene (iPP) in diphenyl ether. The resulting membrane structures showed that this evaporation process was useful in producing anisotropic structures. The effects of evaporation time and initial polymer concentration on the anisotropic membrane structure were investigated. The evaporation process was analysed by solving appropriate mass transfer and heat transfer equations. The agreement between the calculated results and the experimental data on the membrane weight loss and the membrane thickness was satisfactory. The membrane structures are discussed in detail based on the calculated polymer volume fraction profiles in the membranes.

Effect of evaporation time on the pervaporation characteristics through homogeneous aromatic polyamide membranes. II. Pervaporation performances for ethanol/water mixture

Effect of evaporation time on the pervaporation characteristics through homogeneous aromatic polyamide membranes. II. Pervaporation performances for ethanol/water mixture

Effect of evaporation time on the pervaporation characteristics through homogeneous aromatic polyamide membranes. II. Pervaporation performances for ethanol/water mixture

Pervaporation of ethanol/water mixtures through symmetric dense aromatic polyamide membranes was investigated. The membrane structure was controlled by varying the solvent evaporation time before gelation. The membranes were water-selective and the selectivity increased with an increase in the solvent evaporation time. On the other hand, the water flux as well as the ethanol flux decreased with an increase in the evaporation time. These results were consistent with the morphology change of the membrane which takes place with solvent evaporation : the decrease in the channel size. The effects of the downstream pressure on the pervaporation performances were also studied for membranes with different solvent evaporation times. The ethanol concentration in the permeate side increased with an increase in the downstream pressure to certain point, showed a maximum there, then decreased thereafter. The water flux decreased with an increase in the downstream pressure for all membranes studied ; the dependence was expressed by a parabolic curve in the lower pressure range. The ethanol flux also decreased with an increase in the downstream pressure for the membrane with shorter evaporation time, while this flux was slightly affected by the downstream pressure for the membrane with longer evaporation time.

Effect of evaporation time on the pervaporation characteristics through homogeneous aromatic polyamide membranes. I. Pure water permeation and membrane characterization by sorption measurements

AbstractThe pervaporation of pure water through homogeneous aromatic polyamide membranes was investigated. The structure of the prepared membranes was controlled by varying the solvent evaporation times before the gelation step from 5 min to 240 min. The permeation flux of pure water decreased rapidly when the solvent evaporation time increased from 5 min to 30 min, and the decrease was rather moderate at higher evaporation times. Vapor and liquid sorption measurements were used to characterize the membranes. The amount of vapor sorption at a given relative pressure increased with an increase in the solvent evaporation time. The specific surface area of the membranes, calculated from the vapor sorption isotherm, increased with evaporation time up to 30 min, and remained constant thereafter. Liquid sorption volume, on the other hand, decreased monotonically with an increase in evaporation time. The formation of channels in the membrane is used to explain the morphology change during the solvent evaporation. The increase in the solvent evaporation time gradually increases the number of the channels in the membrane and decreases their average size. Good correlation was observed between the average size of the channels (represented by the ratio of specific volume to the specific surface area) and the parameters associated with pervaporation transport. © 1995 John Wiley &amp; Sons, Inc.

Effect of evaporation time on pore size and pore size distribution of aromatic polyamidohydrazide RO/UF membranes

Changement de structure des pores au cours de l'evaporation progressive du solvant (polyethyleneglycol de masse moleculaire moyenne comprise entre 600 et 6000) pendant la formation du film

Transport Properties of Thin Films of SnTe

Epitaxic films of SnTe have been grown on heated NaCl substrates using extremely well controlled source and substrate heaters. As a result, systematic studies were carried out on the effect of evaporation time on the film properties. Without adequate preevaporation, nonuniform films are grown with carrier concentration decaying exponentially from the SnTe-NaCl interface on out. These films show interesting electrical properties. In the thinnest films grown (∼400 Å), the mean free path was somewhat greater than the film half thickness. The mobilities at room temperature and 77 K were in excellent agreement with bulk data. Because of these data, it is concluded that the scattering at the surface is largely specular. Optical data partially confirm the conclusions on the presence of large inhomogeneities.