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Membrane Technology (membrane + technology)
Selected AbstractsMembrane Technology for Water TreatmentCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2010Th. Peters Abstract Membrane processes have become very important tools in water management and water related environmental engineering, because their efficiency has been proven from a technical and economical, as well as an ecological, point of view. This situation is partially based on results obtained during the operation of reverse osmosis systems that were developed in the early days of this technology for the desalination of seawater. Details regarding the theoretical background of these pressure driven membrane processes, examples of their application in water treatment, limiting factors, operational data and results for the purification efficiency are considered as the basis for the discussion of decision-supporting criteria for the selection of these technologies for possible applications, and as basis for the evaluation of future developments. [source] Reformer and membrane modules plant to optimize natural gas conversion to hydrogenASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009M. De Falco Abstract Membrane technology may play a crucial role in the efficient production of hydrogen from natural gas and heavy hydrocarbons. The present work assesses the performance of a hydrogen production plant utilizing by reformer and membrane modules (RMM), by which the hydrogen produced in reaction units is separated by Pd-based membranes. A major advantage of RMM architecture is the shift of chemical equilibria favoring hydrogen production due to the removal of hydrogen through membranes at each reaction step, thus improving hydrogen yield while simultaneously allowing methane conversion at temperatures below 650 °C. Lower operating temperatures allow location of the modules downstream of a gas turbine, achieving an efficient hybrid system producing electric power and hydrogen with a significant reduction in energy consumption of approximately 10% relative to conventional systems. Fundamental concepts are analyzed and integrated into a process scheme. Effects of variables including reactor temperature outlet, steam-to-carbon ratio and recycle ratio throughout pinch and sensitivity analysis are described. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Renewable resources , green biorefinery: separation of valuable substances from fluid,fractions by means of membrane technologyBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 1 2009Senad Novalin Abstract The aim of this study is to emphasize the potential of membrane technologies and the specific performance-limiting borders of pressure-driven (microfiltration, ultrafiltration, nanofiltration, reverse ssmosis) as well as electro-membrane (electrodialysis, electrodialysis using bipolar membranes) techniques for the separation of valuable substances from silage press-juice obtained in green biorefineries. Depending on the product, nanofiltration can be considered a partially fractionating technique with great future potential. Electrodialysis turns out to be a suitable separation technique for removing huge amounts of salt and isolating individual valuable substances. However, residual impurities must be taken into account for subsequent separation steps. In any case, further separation processes (e.g. chromatography) must be integrated in future green biorefinery production plants. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd [source] Novel Polymer Electrolyte Membranes for Automotive Applications , Requirements and Benefits,FUEL CELLS, Issue 4 2004C. Wieser Abstract During the past few years, the feasibility of using polymer electrolyte fuel cells in automotive power trains at an impressive performance level has been proven repeatedly. However, current fuel cell stacks are still largely based on decade-old polymer electrolyte membrane technology thus limiting performance, durability, reliability, and cost of the fuel cell systems. The major challenge for membrane R&D constitutes the demand for polymer electrolytes that allow for system operation at higher temperatures and lower water management requirements without increased conduction losses. None the less, demanding automotive requirements will not compromise on other properties such as mechanical and chemical stability and gas permeability. [source] Milk sugars and minerals as ingredientsINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 2 2001Matti Harju Lactose is the natural carbohydrate source and prebiotic compound found in the milk of mammals, but large variations in lactase activity in the small intestines of adult populations can cause problems with its use. The value of lactose can be increased by hydrolysis, but even more valuable products can be made by changing the structure of lactose and preventing its absorption in the gut. Some of these nonabsorbable lactose derivatives are already used in medical and functional food applications. Calcium phosphate precipitation to the heat-transfer surfaces is one of the oldest problems of the dairy industry, but if precipitation is carried out in controlled conditions, the precipitate can be further processed to form milk calcium powder. Milk calcium can be used as a natural source of calcium in calcium-fortified dairy products. The mineral and salty taste of whey has reduced its use as a food ingredient. The use of modern membrane technology offers a means of producing whey salt as a by-product of whey demineralization. These otherwise wasted minerals can then be used as a natural mineral salt. Especially interesting is the possibility of recycling the whey salt into cheese, improving its nutritional status. [source] Liquid membrane technology: fundamentals and review of its applicationsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2010M. F. San Román Abstract OVERVIEW: During the past two decades, liquid membrane technology has grown into an accepted unit operation for a wide variety of separations. The increase in the use of this technology owing to strict environmental regulations and legislation together with the wider acceptance of this technology in preference to conventional separation processes has led to a spectacular advance in membrane development, module configurations, applications, etc. IMPACT: Liquid membrane technology makes it possible to attain high selectivity as well as efficient use of energy and material relative to many other separation systems. However, in spite of the known advantages of liquid membranes, there are very few examples of industrial applications because of the problems associated with the stability of the liquid membrane. APPLICATIONS: Liquid membrane technology has found applications in the fields of chemical and pharmaceutical technology, biotechnology, food processing and environmental engineering. On the other hand, its use in other fields, such as in the case of hydrogen separation, the recovery of aroma compounds from fruits, the application of ionic liquids in the membrane formulation, etc., is increasing rapidly. Copyright © 2009 Society of Chemical Industry [source] Recovery of cadmium from a zinc hydrometallurgical leachate using reactive emulsion liquid membrane technologyJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2004Jianzhang Fang Abstract A new emulsion liquid membrane process using 3,5-diisopropylsalicylic acid (DIPSA) and triisobutylphosphine sulfide (TIBPS) as carriers, and ammonium sulfide (NH4)2S as precipitant is described. The reactive nature of sulfide ions with extracted cadmium ions in the internal aqueous phase significantly increases cadmium recovery and minimizes zinc impurities. The new process is applied to the enrichment of a low concentration of cadmium ions from a solution containing a high concentration of zinc ions. Under optimum operating conditions, a single stage process produced a cadmium recovery of 98% at a cadmium sulfide content of 99.6%. The results are encouraging for potential applications in zinc hydrometallurgy for recovery of cadmium from sulfuric acid leaching solution of zinc ores. Copyright © 2004 Society of Chemical Industry [source] CLARIFICATION OF WATERMELON (CITRULLUS LANATUS) JUICE BY MICROFILTRATIONJOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2008Ch. CHHAYA ABSTRACT Microfiltration of watermelon juice was conducted using stirred membrane cell in continuous mode. The experiments were conducted at operating pressures of 136.5, 204.7 and 276 kPa, and stirring speeds 1,200 rpm (Re = 1.40 × 105), 1,400 rpm (Re = 1.63 × 105) and 1,600 rpm (Re = 1.87 × 105). Permeate flux decline was analyzed using a first-order kinetic model, and correlations were developed for the steady-state polarized layer resistance with the operating conditions, e.g., transmembrane pressure difference, Reynolds number and membrane resistance. The permeate flux was calculated based on the developed correlation, and found to be in good agreement with the actual experimental flux. The change in quality parameters of clarified juice was marginal compared to that of original juice. PRACTICAL APPLICATIONS The application of membrane technology is one of the emerging areas in food industry. The major application includes fruit juice clarification and concentration. Because of the nonthermal nature of membrane separation, the juice can be clarified at room temperature and packed aseptically for a longer shelf life without the loss of its initial quality parameters. The major problem during clarification is decline in permeate flux of fruit juice with time. Identification of causes for flux decline is essential for designing of membrane modules to make the clarification process commercially viable. The quality of juice during storage is vital, and therefore, determination of variation of its physicochemical properties during storage is also important. [source] Remediation with cyclodextrin: Recovery of the remedial agent by membrane filtrationREMEDIATION, Issue 3 2007Thomas B. Boving Cyclodextrin-enhanced flushing of contaminants from the subsurface is a promising innovative remediation technology. It will become more economically viable at more sites if methods can be developed to recover and reconcentrate the cyclodextrin solution after it has been flushed through an aquifer. The goal of this study was to determine if membrane technology is capable of meeting that need. Five membranes with different material properties were tested for this purpose in the laboratory. The results of these tests indicate that there are large differences both in the efficiency of these membranes to extract hydroxpropyl-,-cyclodextrin (HPCD) and their stability when exposed to trichloroethylene (TCE) at concentrations near aqueous solubility. Not only does the molecular weigh cutoff (MWCO) of a membrane determine if HPCD can be retained, but crucial selection criteria are the membrane's resistance and compatibility with TCE. Of the five membrane materials tested, only two (polymer composite membrane and polysulfone) met both these requirements. The polymer composite membrane (MPF-44) showed reliable and stable HPCD recoveries (>95 percent) even when exposed to high TCE concentrations. The polysulfone membrane showed high HPCD recoveries, 88.5 ± 0.4 percent to 97 percent ±1 percent for ultrafiltration and nanofiltration membranes, respectively. However, membrane swelling and deterioration became a problem at high TCE concentrations (>1,000 mg/L). These problems diminished when the TCE concentration was less than 1 mg/L. Field tests demonstrated that batch mode treatment by ultrafiltration doubled the cyclodextrin concentration from 5 to 10 percent within three hours at a constant operating pressure of 13 psi. Under continuous single-pass treatment conditions, cyclodextrin concentration also increased, although the rate of increase was much smaller than in batch mode. Overall, these tests showed that cyclodextrin recovery is possible under field conditions. © 2007 Wiley Periodicals, Inc. [source] Treatment of Skim Latex Serum Using Gas Sparged UltrafiltrationASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5-6 2005Harunsyah Abstract The major pollutants from a natural rubber processing factory have high organic content and emit an offensive smell due to the biodegradation of the organic matter. In latex concentrate factories, the main sources of effluent are the skim latex serum and washings from all process equipment. This paper presents an application of membrane technology that involves gas sparging for the treatment of skim latex serum. A semi-pilot-scale system using a PVDF vertical tubular membrane (MWCO 100,000) was installed as the experimental setup. Nitrogen gas was bubbled vertically upwards at flowrates ranging from 300 to 500 ml/min. Results obtained thus far show that gas sparging has increased the permeate flux between 1.37% and 146.34% compared to non-gas sparged conditions. In terms of permeate quality, the reductions achieved for suspended solids, total solids, COD, BOD, total nitrogen and ammoniacal nitrogen were 83%, 95%, 67%, 77%, 51%, 74%, respectively, for the gas-sparged condition. Under non gas-sparging conditions, reductions achieved for suspended solids, total solids, COD, BOD, total nitrogen and ammoniacal nitrogen were 92%, 96%, 67%, 72%, 60%, 75%, respectively. [source] Renewable resources , green biorefinery: separation of valuable substances from fluid,fractions by means of membrane technologyBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 1 2009Senad Novalin Abstract The aim of this study is to emphasize the potential of membrane technologies and the specific performance-limiting borders of pressure-driven (microfiltration, ultrafiltration, nanofiltration, reverse ssmosis) as well as electro-membrane (electrodialysis, electrodialysis using bipolar membranes) techniques for the separation of valuable substances from silage press-juice obtained in green biorefineries. Depending on the product, nanofiltration can be considered a partially fractionating technique with great future potential. Electrodialysis turns out to be a suitable separation technique for removing huge amounts of salt and isolating individual valuable substances. However, residual impurities must be taken into account for subsequent separation steps. In any case, further separation processes (e.g. chromatography) must be integrated in future green biorefinery production plants. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd [source] Porphyrin-Functionalized Dendrimers: Synthesis and Application as Recyclable Photocatalysts in a Nanofiltration Membrane ReactorCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2005Suhas A. Chavan Dr. Abstract The convergent synthesis of a series of porphyrin-functionalized pyrimidine dendrimers has been accomplished by a procedure involving the nucleophilic aromatic substitution (NAS) as a key reaction step. The resulting dendritic porphyrin catalysts show high activity in the light-induced generation of singlet oxygen (1O2) from ground-state oxygen. These materials are synthetically useful photosensitizers for the oxidation of various olefinic compounds to the corresponding allylic hydroperoxides. Catalytic activities and regio- and stereoselectivities of the dendritic photosensitizers are comparable to those observed for mononuclear porphyrin catalysts. Recycling of the dendrimer-enlarged homogeneous photocatalysts was possible by solvent-resistant nanofiltration (SRNF) by using an oxidatively stable membrane consisting of a polysiloxane polymer and ultrastable Y zeolite as inorganic filler. Moreover, this membrane technology provides a safe way to isolate the hydroperoxide products under very mild conditions. The membrane showed high retention for the macromolecular catalysts, even in chlorinated solvents, but some oxidative degradation of the porphyrin units of the dendrimer was observed over multiple catalytic runs. [source] | ||||||||||||||||||||||