Other affiliations: Universiti Teknologi Malaysia
Bio: Takeshi Matsuura is an academic researcher from University of Ottawa. The author has contributed to research in topics: Membrane & Membrane distillation. The author has an hindex of 85, co-authored 540 publications receiving 26188 citations. Previous affiliations of Takeshi Matsuura include Universiti Teknologi Malaysia.
Papers published on a yearly basis
TL;DR: In this paper, the use of activated carbon, oxidation, activated sludge, nanofiltration and reverse osmosis membranes, and their efficiencies in removal of these pollutants, are reviewed.
Abstract: The occurrence of emerging or newly identified contaminants in our water resources is of continued concern for the health and safety of consuming public. The existing conventional water treatment plants were not designed for these unidentified contaminants. The endocrine disrupting chemicals (EDCs) comprise pharmaceuticals, personal care products, surfactants, various industrial additives and numerous chemicals purported to be endocrine disrupter. These have become a threat to our water supply network. The current wastewater treatment system is not effective in elimination of these different classes of emerging contaminants as these have not been monitored due to the absence of stringent regulation specific to these contaminants. These undesirable compounds are being released, knowingly or unknowingly, into the aquatic environment that affect the whole living organism. The paper discusses adverse effects of these emerging contaminants to water consumers and discusses the potential removal processes. The use of activated carbon, oxidation, activated sludge, nanofiltration and reverse osmosis membranes, and their efficiencies in removal of these pollutants, are reviewed. In particular, the nanofiltration removal mechanism is emphasized because of its utmost importance in eliminating micropollutants.
TL;DR: In this paper, the molecular weight cut-off (MWCO) of the nanofiltration membranes studied were found to be between 3500 and 98,000 Daltons, and the mean pore size (μp) and the geometric standard deviation (σp) around mean ranged from 0.7 to 11.12 µm and 1.68 to 3.31 µm.
Abstract: Various ultrafiltration and nanofiltration membranes were characterized by solute transport and also by atomic force microscope (AFM). The molecular weight cut-off (MWCO) of the membranes studied were found to be between 3500 and 98,000 Daltons. The mean pore size (μp) and the geometric standard deviation (σp) around mean ranged from 0.7 to 11.12 nm and 1.68 to 3.31, respectively, when calculated from the solute transport data. Mean pore sizes measured by AFM were about 3.5 times larger than calculated from the solute transport. Pore sizes measured by AFM were remarkably fitted to the log-normal probability distribution curve. Pore sizes of the membranes with low MWCO (20,000 Daltons and lower) could not be measured by AFM because of indistinct pores. In most cases, the pore density ranged from 38 to 1291 pores/μm2. In general, the pore density was higher for the membrane having lower MWCO. Surface porosity was around 0.5–1.0% as measured from the solute transport and was 9.5–12.9% as obtained from AFM images. When membranes were coated with a thin layer of sulfonated polyphenylene oxide, mean pore sizes were reduced for all the membranes. Surface roughness was also reduced on coating.
TL;DR: In this paper, the performance studies of mixed matrix membrane (MMM) for gas separation were critically reviewed, and the materials selection and the preparation techniques of MMM were also discussed.
Abstract: Development of polymeric gas separation membranes is one of the fastest growing branches of membrane technology. However, polymeric materials are somewhat deficient in meeting the requirements of current membrane technology. Mixed matrix membrane (MMM), comprising rigid permeable or impermeable particles, such as zeolites, carbon molecular sieves, silica and carbon nanotubes, dispersed in a continuous polymeric matrix presents an interesting approach for improving the separation properties of polymeric membranes. In this approach, using properties of both the organic and inorganic phase, a membrane with good permeability, selectivity, mechanical strength, and thermal, chemical stability and processibility can be prepared. In this paper the performance studies of MMM for gas separation were critically reviewed. In addition, the materials selection and the preparation techniques of MMM were also discussed. Methodology in improving the interface defects in the MMM and its effect on the separation performance have also been reviewed. The models for predicting the performance of MMM for gas separation have been discussed in details and the future direction of research and development to fully exploit the potential usage of MMM was shown.
TL;DR: In this paper, a review of the fundamental concepts that have to be considered to prepare various types of MMMs, including considerations for the design novel MMMs that will eventually surpass the Robeson's trade-off upper bound.
Abstract: The main purpose of research in membrane gas separation is to develop membranes with high permeability and selectivity. Historically, the gas separation performance of polymeric membranes has been constrained to an upper performance limit. Hence, different methods have been investigated to prepare membranes that can exceed this limitation including the incorporation of inorganic materials into polymer matrices. Membranes formed by this method are called mixed matrix membranes (MMMs). The major challenge is to prepare a defect-free polymer/inorganic nanoparticles interfaces with enhanced separation performance and mechanical and thermal stability. For this purpose, various types of nanoparticles have been proposed and examined experimentally. This review is especially devoted to summarize the fundamental concepts that have to be considered to prepare various types of MMMs, including considerations for the design novel MMMs that will eventually surpass the Robeson's trade-off upper bound. In addition, it provides the pros and cons of various factors that affect the MMM preparation especially for CO2 separation processes.
TL;DR: In this article, the authors systematically review the state of the art of biogas upgrading technologies with upgrading efficiency, methane (CH 4 ) loss, environmental effect, development and commercialization, and challenges in terms of energy consumption and economic assessment.
Abstract: Biogas upgrading is a widely studied and discussed topic and its utilisation as a natural gas substitute has gained a significant attention in recent years. The production of biomethane provides a versatile application in both heat and power generation and as a vehicular fuel. This paper systematically reviews the state of the art of biogas upgrading technologies with upgrading efficiency, methane (CH 4 ) loss, environmental effect, development and commercialisation, and challenges in terms of energy consumption and economic assessment. The market situation for biogas upgrading has changed rapidly in recent years, making the membrane separation gets significant market share with traditional biogas upgrading technologies. In addition, the potential utilisation of biogas, efficient conversion into bio-compressed natural gas (bio-CNG), and storage systems are investigated in depth. Two storing systems for bio-CNG at filling stations, namely buffer and cascade storage systems are used. The best storage system should be selected on the basis of the advantages of both systems. Also, the fuel economy and mass emissions for bio-CNG and CNG filled vehicles are studied. There is the same fuel economy and less carbon dioxide (CO 2 ) emission for bio-CNG. Based on the results of comparisons between the technical features of upgrading technologies, various specific requirements for biogas utilisation and the relevant investment, and operating and maintenance costs, future recommendations are made for biogas upgrading.
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …
TL;DR: The empirical upper bound relationship for membrane separation of gases initially published in 1991 has been reviewed with the myriad of data now presently available as mentioned in this paper, which indicates a different solubility selectivity relationship for perfluorinated polymers compared to hydrocarbon/aromatic polymers.
Abstract: The empirical upper bound relationship for membrane separation of gases initially published in 1991 has been reviewed with the myriad of data now presently available. The upper bound correlation follows the relationship P i = k α i j n , where Pi is the permeability of the fast gas, αij (Pi/Pj) is the separation factor, k is referred to as the “front factor” and n is the slope of the log–log plot of the noted relationship. Below this line on a plot of log αij versus log Pi, virtually all the experimental data points exist. In spite of the intense investigation resulting in a much larger dataset than the original correlation, the upper bound position has had only minor shifts in position for many gas pairs. Where more significant shifts are observed, they are almost exclusively due to data now in the literature on a series of perfluorinated polymers and involve many of the gas pairs comprising He. The shift observed is primarily due to a change in the front factor, k, whereas the slope of the resultant upper bound relationship remains similar to the prior data correlations. This indicates a different solubility selectivity relationship for perfluorinated polymers compared to hydrocarbon/aromatic polymers as has been noted in the literature. Two additional upper bound relationships are included in this analysis; CO2/N2 and N2/CH4. In addition to the perfluorinated polymers resulting in significant upper bound shifts, minor shifts were observed primarily due to polymers exhibiting rigid, glassy structures including ladder-type polymers. The upper bound correlation can be used to qualitatively determine where the permeability process changes from solution-diffusion to Knudsen diffusion.
TL;DR: This review provides a summary of the recent occurrence of micropollutants in the aquatic environment including sewage, surface water, groundwater and drinking water.
Abstract: Micropollutants are emerging as a new challenge to the scientific community. This review provides a summary of the recent occurrence of micropollutants in the aquatic environment including sewage, surface water, groundwater and drinking water. The discharge of treated effluent from WWTPs is a major pathway for the introduction of micropollutants to surface water. WWTPs act as primary barriers against the spread of micropollutants. WWTP removal efficiency of the selected micropollutants in 14 countries/regions depicts compound-specific variation in removal, ranging from 12.5 to 100%. Advanced treatment processes, such as activated carbon adsorption, advanced oxidation processes, nanofiltration, reverse osmosis, and membrane bioreactors can achieve higher and more consistent micropollutant removal. However, regardless of what technology is employed, the removal of micropollutants depends on physico-chemical properties of micropollutants and treatment conditions. The evaluation of micropollutant removal from municipal wastewater should cover a series of aspects from sources to end uses. After the release of micropollutants, a better understanding and modeling of their fate in surface water is essential for effectively predicting their impacts on the receiving environment.
TL;DR: Devising systems that can conduct protons with little or no water is perhaps the greatest challenge for new membrane materials, and new membranes that have significantly reduced methanol permeability and water transport (through diffusion and electro-osmotic drag) are required for automotive applications.
Abstract: Fuel cells have the potential to become an important energy conversion technology. Research efforts directed toward the widespread commercialization of fuel cells have accelerated in light of ongoing efforts to develop a hydrogen-based energy economy to reduce dependence on foreign oil and decrease pollution. Proton exchange membrane (also termed “polymer electrolyte membrane”) (PEM) fuel cells employing a solid polymer electrolyte to separate the fuel from the oxidant were first deployed in the Gemini space program in the early 1960s using cells that were extremely expensive and had short lifetimes due to the oxidative degradation of their sulfonated polystyrene-divinylbenzene copolymer membranes. These cells were considered too costly and short-lived for real-world applications. The commercialization of Nafion by DuPont in the late 1960s helped to demonstrate the potential interest in terrestrial applications for fuel cells, although its major focus was in chloroalkali processes. PEM fuel cells are being developed for three main applications: automotive, stationary, and portable power. Each of these applications has its unique operating conditions and material requirements. Common themes critical to all high performance proton exchange membranes include (1) high protonic conductivity, (2) low electronic conductivity, (3) low permeability to fuel and oxidant, (4) low water transport through diffusion and electro-osmosis, (5) oxidative and hydrolytic stability, (6) good mechanical properties in both the dry and hydrated states, (7) cost, and (8) capability for fabrication into membrane electrode assemblies (MEAs). Nearly all existing membrane materials for PEM fuel cells rely on absorbed water and its interaction with acid groups to produce protonic conductivity. Due to the large fraction of absorbed water in the membrane, both mechanical properties and water transport become key issues. Devising systems that can conduct protons with little or no water is perhaps the greatest challenge for new membrane materials. Specifically, for automotive applications the U.S. Department of Energy has currently established a guideline of 120 °C and 50% relative humidity as target operating conditions, and a goal of 0.1 S/cm for the protonic conductivity of the membrane. New membranes that have significantly reduced methanol permeability and water transport (through diffusion and electro-osmotic drag) are required for portable power oriented direct methanol fuel cells (DMFCs), where a liquid methanol fuel highly diluted in water is used at generally <90 °C as the source of protons. Unreacted methanol at the anode can diffuse through the membrane and react at the cathode, lowering the voltage efficiency of the cell and reducing the system’s fuel efficiency. The methanol is usually delivered to the anode as a dilute, for example, 1 M (or less), solution (3.2 wt %), and relatively thick Nafion 117 (1100 EW, 7 mil ∼ 178 μm thick) is used to reduce methanol crossover. The dilute methanol feed increases the system’s complexity and reduces the energy density of the fuel, while the thick Nafion membrane increases the resistive losses of the cell, especially when compared to the thinner membranes that are used in hydrogen/air systems. The presence of excessive amounts of water at the cathode through diffusion and electro-osmosis * To whom correspondence should be addressed. E-mail: firstname.lastname@example.org. † Sandia National Laboratory. ‡ Case Western Reserve University. § Los Alamos National Laboratory. | Virginia Polytechnic Institute and State University. 4587 Chem. Rev. 2004, 104, 4587−4612
TL;DR: It is shown how a third factor, re-entrant surface curvature, in conjunction with chemical composition and roughened texture, can be used to design surfaces that display extreme resistance to wetting from a number of liquids with low surface tension, including alkanes such as decane and octane.
Abstract: Understanding the complementary roles of surface energy and roughness on natural nonwetting surfaces has led to the development of a number of biomimetic superhydrophobic surfaces, which exhibit apparent contact angles with water greater than 150 degrees and low contact angle hysteresis. However, superoleophobic surfaces-those that display contact angles greater than 150 degrees with organic liquids having appreciably lower surface tensions than that of water-are extremely rare. Calculations suggest that creating such a surface would require a surface energy lower than that of any known material. We show how a third factor, re-entrant surface curvature, in conjunction with chemical composition and roughened texture, can be used to design surfaces that display extreme resistance to wetting from a number of liquids with low surface tension, including alkanes such as decane and octane.