Author
Vassilis Gekas
Other affiliations: Technical University of Crete, Lund University
Bio: Vassilis Gekas is an academic researcher from Cyprus University of Technology. The author has contributed to research in topics: Membrane & Ultrafiltration. The author has an hindex of 34, co-authored 83 publications receiving 4364 citations. Previous affiliations of Vassilis Gekas include Technical University of Crete & Lund University.
Topics: Membrane, Ultrafiltration, Osmotic dehydration, Mass transfer, Osmosis
Papers published on a yearly basis
Papers
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TL;DR: In this paper, the authors present an overview of an Environmental Impact Assessment of solar energy systems and assess the potential environmental intrusions in order to ameliorate them with new technological innovations and good practices in the future power systems.
669 citations
TL;DR: In this article, a critical review on the mass transfer correlations under turbulent duct flow, as they appeared in the literature ( 1934-1984), and a discussion on the factors influencing mass transfer during membrane operations (reverse osmosis and ultrafiltration), like porosity and roughness of the membrane wall and change of viscosity and diffusion coefficient due to the strong concentration gradient.
358 citations
TL;DR: In this article, the prediction of activity coefficients of fifteen natural phenols (tyrosol, hydroxytyrosols, oleuropein, caffeic, cinnamic, pcoumaric, ferulic, gallic, p-hydroxyphenyl acetic, protocatechuic, rosmarinic, sinapic, syringic, and vanillic acid) in seven solvents (water, ethanol, methanol, acetone, dichloromethane, ethyl acetate, and dieth
Abstract: The current study denotes the prediction of activity coefficients of fifteen natural phenols (tyrosol, hydroxytyrosol, oleuropein, caffeic, cinnamic, p-coumaric, ferulic, gallic, p-hydroxybenzoic, p-hydroxyphenyl acetic, protocatechuic, rosmarinic, sinapic, syringic, and vanillic acid) in seven solvents (water, ethanol, methanol, acetone, dichloromethane, ethyl acetate, and diethyl ether), and three extraction temperatures (298.15, 313.15, and 333.15 K), using the universal functional-group activity coefficient model. Solvents were classified for their ability to dissolve phenols and were compared with experimental data of the literature in order to observe if the solvent extraction of phenols in practice matches with the authors’ theoretical approach. Results indicated the superiority of alcohols and acetone for the recovery of phenols in line with experimental data of previous studies. Furthermore, activity coefficients’ values were found to increase with the increase of temperature. This study provided...
220 citations
TL;DR: In this article, the pressure dependence of water permeability for some flat-sheet ultrafiltration membranes has been found to be a function of the porosity and the membrane structure.
202 citations
TL;DR: In this paper, the authors investigated the clarification of two high-added value products (pectin containing solution and phenol containing beverage) recovered from olive mill wastewater using four types of ultrafiltration (100, 25, 10 and 2 kDa) and one nanofiltration membranes under optimum transmembrane pressure.
187 citations
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TL;DR: Key parameters of an RO process and process modifications due to feed water characteristics are brought to light by a direct comparison of seawater and brackish water RO systems.
2,665 citations
TL;DR: While the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice), and I believe that the Handbook can be useful in those laboratories.
Abstract: There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate
2,493 citations
TL;DR: In this article, a review of membrane characteristics, membrane-related heat and mass transfer concepts, fouling and the effects of operating condition is presented, as well as state-of-the-art research results in these different areas are discussed.
1,973 citations
TL;DR: In this article, a semi-quantitative ranking system was proposed considering projected performance enhancement (over state-of-the-art analogs) and state of commercial readiness, while commercial readiness was based on known or anticipated material costs.
Abstract: Nanotechnology is being used to enhance conventional ceramic and polymeric water treatment membrane materials through various avenues. Among the numerous concepts proposed, the most promising to date include zeolitic and catalytic nanoparticle coated ceramic membranes, hybrid inorganic–organic nanocomposite membranes, and bio-inspired membranes such as hybrid protein–polymer biomimetic membranes, aligned nanotube membranes, and isoporous block copolymer membranes. A semi-quantitative ranking system was proposed considering projected performance enhancement (over state-of-the-art analogs) and state of commercial readiness. Performance enhancement was based on water permeability, solute selectivity, and operational robustness, while commercial readiness was based on known or anticipated material costs, scalability (for large scale water treatment applications), and compatibility with existing manufacturing infrastructure. Overall, bio-inspired membranes are farthest from commercial reality, but offer the most promise for performance enhancements; however, nanocomposite membranes offering significant performance enhancements are already commercially available. Zeolitic and catalytic membranes appear reasonably far from commercial reality and offer small to moderate performance enhancements. The ranking of each membrane nanotechnology is discussed along with the key commercialization hurdles for each membrane nanotechnology.
1,708 citations
TL;DR: In this article, the photovoltaic technology, its power generating capability, the different existing light absorbing materials used, its environmental aspect coupled with a variety of its applications have been discussed.
Abstract: Global environmental concerns and the escalating demand for energy, coupled with steady progress in renewable energy technologies, are opening up new opportunities for utilization of renewable energy resources. Solar energy is the most abundant, inexhaustible and clean of all the renewable energy resources till date. The power from sun intercepted by the earth is about 1.8 × 1011 MW, which is many times larger than the present rate of all the energy consumption. Photovoltaic technology is one of the finest ways to harness the solar power. This paper reviews the photovoltaic technology, its power generating capability, the different existing light absorbing materials used, its environmental aspect coupled with a variety of its applications. The different existing performance and reliability evaluation models, sizing and control, grid connection and distribution have also been discussed. © 2011 Published by Elsevier Ltd.
1,524 citations