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Mikel Duke - One of the best experts on this subject based on the ideXlab platform.

  • Direct contact membrane distillation of dairy process Streams
    Membranes, 2011
    Co-Authors: Angela Hausmann, Peter Sanciolo, Elankovan Ponnampalam, Nohemi Quispe-chavez, Mike Weeks, Todor Vasiljevic, Mikel Duke
    Abstract:

    Membrane distillation (MD) was applied for the concentration of a range of dairy Streams, such as whole milk, skim milk and whey. MD of a pure lactose solution was also investigated. Direct contact MD (DCMD) mode experiments were carried out in continuous concentration mode, keeping the warm feed/retentate and cold Permeate Stream temperatures at \n54 °C and 5 °C respectively. Performance in terms of flux and retention was assessed. The flux was found to decrease with an increase of dry-matter concentration in the feed. Retention of dissolved solids was found to be close to 100% and independent of the dry-matter concentration in the feed. Fourier Transform Infrared Spectroscopy (FTIR) of the fouled membranes confirms organics being present in the fouling layer.

  • Performance of cobalt silica membranes in gas mixture separation
    Journal of Membrane Science, 2009
    Co-Authors: Scott Battersby, Mikel Duke, Tsutomu Tasaki, Simon Smart, Bradley P. Ladewig, Victor Rudolph, João C. Diniz Da Costa
    Abstract:

    In this work we investigate the performance of cobalt silica membranes for the separation of gas mixtures at various temperatures and partial pressures. The membranes were prepared by a sol–gel process using tetraethyl orthosilicate (TEOS) in ethanol and H2O2 with cobalt nitrate hexahydrate (Co(NO3)26H2O). The membranes complied with molecular sieving transport mechanism, delivering high single gas selectivities for He/N2 (4500) and H2/CO2 (1000) and high activation energy for the smaller gas molecules (He, H2) whilst a negative activation energy for larger molecules (CO, CO2 and N2). Molecular probing results strongly suggest membranes with a narrow pore size distribution with an average pore size of 3 A. The effect of gas composition on the membrane operation was studied over both binary and ternary gas mixtures, and compared with the single gas permeance results. It was found in both cases feed concentration had a large impact on both selectivities and flow rates. These followed a trade off inverse relationship, as increasing H2 feed concentration led to a higher flow rate but a lower H2 selectivity, though H2 purity in the Permeate Stream increased. The use of sweep gas in the Permeate Stream to increase the driving force of gas permeation was beneficial as the H2 flow rate and the H2 recovery rate increased by a factor of 3. It is noteworthy to mention that though the ternary feed flow had only 27% H2 concentration, the Permeate Stream delivered CO and CO2 at very low concentrations, 0.8 and 0.14%, respectively. It was observed that the membrane selectivity in gas mixtures were 10–15% of the single gas selectivity, while permeation decreased with the gas composition (Single > Binary > Ternary). Nevertheless, increased temperature and sweep flow rate allowed the membrane to deliver a Permeate Stream in excess of 99% H2 purity and a lower CO concentration of 700 ppm, indicating the quality of these membranes for gas mixture separation.

  • Flowfields on feed and Permeate sides of tubular molecular sieving silica (MSS) membranes
    Journal of Membrane Science, 2007
    Co-Authors: Madhat Abdel-jawad, Mikel Duke, S Gopalakrishnan, Michael N. Macrossan, P. Smith Schneider, J. C. Diniz Da Costa
    Abstract:

    We present a novel computational fluid dynamic approach to integrate diffusion through inorganic molecular sieve silica (MSS) membranes and continuum flows on the feed/retentate and Permeate sides of these membranes. In this approach, we model the membrane by creating a bounded region separating the feed/retentate side from the Permeate side in which only the phenomenological equations of the activated gas transport model apply. Continuum flows on both sides of this region are described by the Navier–Stokes equations and gas-through-gas diffusion is modelled using the Stefan–Maxwell model only. The phenomenological equations are applicable exclusively to diffusion through the membrane. By coupling these equations we obtain complete flowfields on the feed/retentate and Permeate sides of MSS membranes. The complete model characterises the flow of CO, CO2, He, H2, and N2 and gas mixtures of CO2 and H2 on both sides of tubular MSS membranes and is validated by comparing flow rates with single gas experiments. We found that partial pressure axial distributions in the feed/retentate and Permeate Streams of the membrane are constant. In the Permeate Stream, the radial variation of axial velocity across the flow is nearly the same for all axial locations. There is a linear increase of axial velocity (and total flow rate) with axial coordinate.

Toshinori Tsuru - One of the best experts on this subject based on the ideXlab platform.

  • Catalytic membrane reactors for SO3 decomposition in Iodine–Sulfur thermochemical cycle: A simulation study
    International Journal of Hydrogen Energy, 2015
    Co-Authors: Lie Meng, Masakoto Kanezashi, Toshinori Tsuru
    Abstract:

    Abstract The possibility of applying a catalytic membrane reactor (CMR) to SO 3 decomposition in a low-temperature range was theoretically evaluated with the purpose of producing CO 2 -free hydrogen in an Iodine–Sulfur thermochemical cycle. A one-dimensional, isothermal and plug-flow model was developed for a cocurrent membrane reactor with selective permeation from the reactant Stream to the Permeate Stream. Simulation results have revealed that CMRs can greatly reduce the reaction temperature for SO 3 decomposition from the conventional 1200–1400 K to about 900 K. We predicted that porous inorganic membranes with a high O 2 permeability and with selectivities of more than 50 for O 2 /SO 3 and less than 10 for O 2 /SO 2 had the potential to effectively improve SO 3 conversion. CMRs were simulated to carry out SO 3 decomposition at different catalyst weights, reaction temperatures, and SO 3 feed flow rates as well as pressures in feed and Permeate Streams. SO 3 conversion at 900 K was increased to 0.93 beyond the equilibrium conversion of 0.28 due to a shift in thermodynamic equilibrium.

  • Methylcyclohexane dehydrogenation for hydrogen production via a bimodal catalytic membrane reactor
    Aiche Journal, 2015
    Co-Authors: Lie Meng, Xin Yu, Takuya Niimi, Hiroki Nagasawa, Masakoto Kanezashi, Tomohisa Yoshioka, Toshinori Tsuru
    Abstract:

    The dehydrogenation of methylcyclohexane (MCH) to toluene (TOL) for hydrogen production was theoretically and experimentally investigated in a bimodal catalytic membrane reactor (CMR), that combined Pt/Al2O3 catalysts with a hydrogen-selective organosilica membrane prepared via sol-gel processing using bis(triethoxysilyl) ethane (BTESE). Effects of operating conditions on the membrane reactor performance were systematically investigated, and the experimental results were in good agreement with those calculated by a simulation model with a fitted catalyst loading. With H2 extraction from the reaction Stream to the Permeate Stream, MCH conversion at 250°C was significantly increased beyond the equilibrium conversion of 0.44–0.86. Because of the high H2 selectivity and permeance of BTESE-derived membranes, a H2 flow with purity higher than 99.8% was obtained in the Permeate Stream, and the H2 recovery ratio reached 0.99 in a pressurized reactor. A system that combined the CMR with a fixed-bed prereactor was proposed for MCH dehydrogenation. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1628–1638, 2015

  • Equilibrium shift of methylcyclohexane dehydrogenation in a thermally stable organosilica membrane reactor for high-purity hydrogen production
    International Journal of Hydrogen Energy, 2013
    Co-Authors: Gang Li, Takuya Niimi, Masakoto Kanezashi, Tomohisa Yoshioka, Toshinori Tsuru
    Abstract:

    Abstract A high-performance organosilica membrane was prepared via sol–gel processing for use in methylcyclohexane (MCH) dehydrogenation to produce high-purity hydrogen. The membrane showed a high H2 permeance of 1.29 × 10−6 mol m−2 s−1 Pa−1, with extremely high H2/C3H8 and H2/SF6 selectivities of 6680 and 48,900, respectively, at 200 °C. The extraction of hydrogen from the membrane reactor led to the MCH conversion higher than the thermodynamic equilibrium, with almost pure hydrogen obtained in the Permeate Stream without considering the effect of carrier gas and sweep gas in the membrane reactor, and the organosilica membrane reactor was very stable under the reaction conditions employed.

  • Photocatalytic Membrane Reactor Using Porous Titanium Oxide Membranes
    Journal of Chemical Engineering of Japan, 2003
    Co-Authors: Toshinori Tsuru, Tomohisa Yoshioka, Terutaka Toyosada, Masashi Asaeda
    Abstract:

    A photocatalytic membrane reactor, in which permeation of solutes through a membrane and a photocatalytic reaction occur simultaneously, that is, a photocatalytic membrane reactor, is described. Using trichloroethylene (TCE), a decomposition ratio in excess of 95% in the Permeate Stream to that in the feed Stream was achieved by means of porous titanium oxide (TiO 2 ) membranes, when approximately 1 ppm TCE solution was fed to the TiO 2 membranes under irradiation by a blacklight. The decomposition ratio, defined as the concentration ratio of the Permeate to the feed Stream, decreased with applied pressure and the feed concentration. A proposed photocatalytic reaction model where a photocatalytic reaction in the outer reaction zone and in the inner reaction zone under membrane permeation conditions is consistent with the observed experimental data.

  • Photocatalytic membrane reactors using nanoporous titanium oxide membranes
    membrane, 2003
    Co-Authors: Toshinori Tsuru
    Abstract:

    A TiO2 photocatalytic membrane reactor, in which permeation of organic molecules through a membrane and a photocatalytic reaction occur simultaneously, is reviewed for liquid phase as well as gas-phase reactions. The advantages of the system are (1) the forced transport of reactants by convection to the TiO2 membranes, (2) the oxidation reaction on the outer and inner surface of the porous TiO2 membranes where high concentrations of OH radicals would be expected, (3) the potential for obtaining a Permeate Stream oxidized with OH radicals after a one-pass permeation through the TiO2 membranes, and (4) improved selectivity combined with the molecular sieving mechanism. For the liquid phase reactions of trichloroethylene (TCE), a decomposition ratio in excess of 95% in the Permeate Stream to that in feed Stream was achieved by a TiO2 photocatalytic membrane reactor, when approximately 1 ppm TCE solutions was fed under blacklight irradiation. For the case of gas-phase reactions, photocatalysis with membrane permeation resulted in a large decomposition rate and the formation of a large amount of intermediate products, compared to photocatalysis without membrane permeation.

Javier Miguel Ochando-pulido - One of the best experts on this subject based on the ideXlab platform.

  • On the optimization of a flocculation process as fouling inhibiting pretreatment on an ultrafiltration membrane during olive mill effluents treatment
    Desalination, 2016
    Co-Authors: Javier Miguel Ochando-pulido, Marco Stoller, Luca Palma, Antonio Martínez-Ferez
    Abstract:

    In this work, a simple and cost-effective pretreatment upStream an UF membrane operation for the purification of the main olive mill effluent Streams (OME) is examined. The raw wastewater was processed by a pH-temperature (T) flocculation process formerly studied at lab scale in previous work. In the present paper, modelization and optimization of the pretreatment process are addressed at pilot scale. Statistical multifactorial analysis showed both pH and T remarkably influence the suspended solids concentration removal efficiency (p-value practically equal to zero), confirming a statistically significant relationship between the variables considered at 95% confidence level. Moreover, the pH exhibits a deeper influence than the T, according to the p-values withdrawn from the analysis, and the squared effects are significant too, but more significant in the case of the pH. Contour plots and response surface support the previous results, and the optimized parameters were 21.4 °C and pH equal to 2.2, yielding 98.4 − 98.6% TSS reduction and 90.5% v/v recovery of clarified water. Finally, a boundary flux value of 9.7 L/hm2and a significant reduction of the fouling index (3.4·10− 2min− 1) were ensured, and a Permeate Stream reusable for irrigation, boosting the cost-efficiency of the integral process.

  • The effect of Permeate recirculation on the depuration of pretreated olive mill wastewater through reverse osmosis membranes
    Desalination, 2012
    Co-Authors: Javier Miguel Ochando-pulido, S. Rodriguez-vives, Antonio Martínez-férez
    Abstract:

    Abstract Still scarce are the studies addressing the depuration of olive mill wastewater (OMW) by means of membrane technology, encountering severe fouling problems related to ineffective pretreatments. In addition, they focus only on meeting irrigation standards. The target of this investigation was to experimentally evaluate the improvement driven by recirculating a fraction of the Permeate Stream in the performance of a thin-film composite reverse osmosis membrane (polyamide/polysulfone) for purification of OMW previously pretreated by means of chemical oxidation based on Fenton's reagent, coagulation–flocculation and filtration through olive stones. For this purpose, Permeate flux and rejection of pollutants under increasing Permeate recirculation fraction, additionally to fouling on membrane surface, were examined and found to be improved. Similarly, influence of operating temperature was as well investigated. Operating in a diafiltration mode, instead of the batchwise common to most OMW depuration processes, attempted semicontinuous production and lower rate of increase of pollutants concentration. Upon recirculation of a fraction of the Permeate Stream above 10%, high and stable Permeate flux was provided ensuring no significant steady-state flux decline. Under these conditions, 100% suspended solids, phenols and iron removal was achieved, in addition to around 99.4% and 98.2% overall COD and conductivity rejection efficiencies respectively.

  • Fouling inhibition upon fenton-like oxidation pretreatment for olive mill wastewater reclamation by membrane process
    Chemical Engineering and Processing: Process Intensification, 2012
    Co-Authors: Javier Miguel Ochando-pulido, G. Hodaifa, Antonio Martínez-férez
    Abstract:

    In this study, olive mill wastewater (OMW) treatment by membrane operations was conducted to achieve the quality to recirculate the final effluent to the manufacture process or at least to the olives washing machines to finally close the loop. An efficient and novel pretreatment method for the OMW was performed to preserve the membranes from the deleterious fouling phenomena commonly encountered in all membrane facilities. This pretreatment consisted of Fenton-like advanced oxidation, flocculation-sedimentation and filtration through olive stones subsequently. One nanofiltration (NF) and two rather different reverse osmosis (RO) polymeric membranes were tested for the ulterior OMW purification. Upon the adopted strategy, near-zero fouling occurred on the NF membrane. Also, the composite RO membrane suffered minimum flux decay which rapidly reached a plateau. This was not the case of the asymmetric RO membrane, which yielded higher initial but not sustainable productivity. Both RO membranes provided COD and conductivity values in the Permeate Stream below standards for reuse in the production process (COD

Azmi Mohd Shariff - One of the best experts on this subject based on the ideXlab platform.

  • Effect of recycle ratio on the cost of natural gas processing in countercurrent hollow fiber membrane system
    Journal of Industrial and Engineering Chemistry, 2015
    Co-Authors: S. S.m. Lock, K. K. Lau, Azmi Mohd Shariff
    Abstract:

    The separation of the countercurrent hollow fiber membrane module has been characterized adapting a "Multi-component Progressive Cell Balance" approach and incorporated within the Aspen HYSYS process simulator. The simulated data is found to exhibit good accordance with published experimental result. The study of the double staged membrane module with Permeate recycle system, which was proposed to be the optimum configuration in previous works, has been extended by altering the recycle ratio of the Permeate Stream to study the process economics. Parameter sensitivities of typical membrane selectivity and CO2feed concentration adapted in industrial application have been conducted. The study of high CO2content is highlighted since it represents the future expansion of natural gas extraction considering that most of the remaining fields contain high concentration. It is observed that the recycle ratio is an important parameter to be considered in the industrial design process since it affects the gas processing cost significantly. Increasing the recycle ratio is proposed to increase the membrane area and compressor power while improving the hydrocarbon recovery, with substantial impact observed at low selectivity membrane and high CO2feed concentration. A tradeoff must be determined among these parameters for determination of the optimal recycle ratio configuration.

  • Removal of CO2 from Natural Gas Using Membrane Separation System: Modeling and Process Design
    Journal of Applied Sciences, 2010
    Co-Authors: Faizan Ahmad, Azmi Mohd Shariff
    Abstract:

    Natural Gas (NG) processing is one of the major industrial separation processes. Membrane process, a relatively new technology among other available techniques, can be used for the removal of impurities like carbon dioxide from NG. Membrane performance has been described by different mathematical models over the decades. In this work, a simple mathematical model has been suggested to be incorporated with ASPEN HYSYS in order to design the membrane system for CO2/CH4 separation. Parameter sensitivities were analyzed by changing the operating conditions, such as feed composition and pressure and membrane properties (including selectivity of the membrane). Moreover, different configurations have been investigated for the optimized design including single stage (with and without recycle) and double stage membrane systems. It is shown that methane recovery can be improved by recycling Permeate Stream as well as by using double stage membrane system.

Kaushik Nath - One of the best experts on this subject based on the ideXlab platform.

  • Separation of ternary sodium chloride/Reactive Black-5 aqueous solutions using two different modules in a nanofiltration pilot plant
    International Journal of Environmental Science and Technology, 2014
    Co-Authors: Tejal M. Patel, Kaushik Nath
    Abstract:

    Nanofiltration of ternary mixtures of sodium chloride and aqueous solutions of Reactive Black-5 was studied in two different modules, namely, flat sheet and spiral wound over a wide range of operating conditions. Hydrophilized polyamide membrane with molecular weight cutoff of 150 was used for the experiments. Combined effect of dye and salt concentration, trans-membrane pressure drop, initial pH of feed solution on the Permeate flux, and observed retention were investigated. Extent of color removal, chemical oxygen demand (COD), total dissolved solid (TDS), and conductivity were determined to assess performance of the membrane. The experimental results showed that both the Permeate flux and observed retention decreased with increase in dye as well as salt concentration in the feed. Permeate fluxes were lower at higher pH values. Substantial removal of color was achieved in the nanofiltration experiments with a marked reduction in COD and TDS. The process allowed the production of Permeate Stream with great reutilization possibilities.

  • Comparative performance of flat sheet and spiral wound modules in the nanofiltration of reactive dye solution
    Environmental Science and Pollution Research, 2012
    Co-Authors: Tejal M. Patel, Harsh Chheda, Abhisek Baheti, Punit Patel, Kaushik Nath
    Abstract:

    Besides the opportunities for reuse, stringent regulations and growing\npublic awareness demand an enhanced quality of effluent from dye\nindustries. Treatment of an aqueous solution of dye (reactive red 198)\nwas carried out in a nanofiltration unit using both flat sheet and\nspiral wound modules to obtain a comparative performance evaluation in\nterms of Permeate flux and quality.\nHydrophilized polyamide membrane with molecular weight cutoff of 150 was\nused for the experiments. Effects of trans-membrane pressure (TMP), feed\nconcentration and addition of salt on Permeate flux were investigated.\nPercent reduction of color, chemical oxygen demand (COD), total\ndissolved solid (TDS), and conductivity were determined to assess\nperformance of the membrane.\nThe maximum flux decline was 16.1% of its initial value at 490 kPa TMP\nwith 50 ppm feed concentration in spiral wound module, whereas the same\nin flat sheet under same conditions was 7.2%. The effect of TMP showed\na quasi-linear increase in flux with increasing pressure. Increased\nPermeate concentration led to the reduction in observed retention of dye\nin the membrane. The average reduction in color, COD, and TDS were\n96.88%, 97.38%, and 89.24%, respectively. The decline in Permeate\nflux was more in case of spiral wound module compared to flat sheet.\nHowever, spiral wound module performed better in terms of color removal,\nCOD reduction, and TDS removal.\nSubstantial removal of color was achieved in the nanofiltration\nexperiments with a marked reduction in COD and TDS. The process allowed\nthe production of Permeate Stream with great reutilization\npossibilities.