Thermodynamics of hyperfiltration (reverse osmosis): criteria for efficient membranes
TL;DR: In this paper, a theory of hyperfiltration based on non-equilibrium thermodynamics is presented, in which authors combine elements of their own previous work with important contributions of other investigators.
About: This article is published in Desalination.The article was published on 1966-12-01. It has received 974 citations till now. The article focuses on the topics: Membrane & Concentration polarization.
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1,167 citations
TL;DR: All SRNF-applications reported so far - in food chemistry, petrochemistry, catalysis, pharmaceutical manufacturing - will be reviewed exhaustively (324 references).
Abstract: Over the past decade, solvent resistant nanofiltration (SRNF) has gained a lot of attention, as it is a promising energy- and waste-efficient unit process to separate mixtures down to a molecular level This critical review focuses on all aspects related to this new burgeoning technology, occasionally also including literature obtained on aqueous applications or related membrane processes, if of relevance to understand SRNF better An overview of the different membrane materials and the methods to turn them into suitable SRNF-membranes will be given first The membrane transport mechanism and its modelling will receive attention in order to understand the process and the reported membrane performances better Finally, all SRNF-applications reported so far – in food chemistry, petrochemistry, catalysis, pharmaceutical manufacturing – will be reviewed exhaustively (324 references)
946 citations
TL;DR: Findings of a comprehensive literature review are reported, targeting membrane rejection mechanisms and factors affecting rejection, and a rejection diagram was proposed, which qualitatively allows prediction of solute rejection if certain solute and membrane properties are known.
942 citations
TL;DR: In pressure-driven membrane processes, a pressure exerted on the solution at one side of the membrane serves as a driving force to separate it into a permeate and a retentate as discussed by the authors.
Abstract: In pressure-driven membrane processes (reverse osmosis, nanofiltration, ultrafiltration, and microfiltration) a pressure exerted on the solution at one side of the membrane serves as a driving force to separate it into a permeate and a retentate. The permeate is usually pure water, whereas the retentate is a concentrated solution that must be disposed of or treated by other methods. Membranes may be polymeric, organo-mineral, ceramic, or metallic, and filtration techniques differ in pore size, from dense (no pores) to porous membranes. Depending on the type of technique, salts, small organic molecules, macromolecules, or particles can be retained, and the applied pressure will differ. This paper reviews the principles behind the different techniques, the types of membranes used, rejection mechanisms, and process modeling. Applications of pressure-driven membrane processes are also considered, including reverse osmosis and nanofiltration for the treatment of wastewater from landfills and composting plants, nanofiltration in the textile industry, and ultrafiltration and microfiltration in drinking water production and wastewater treatment.
Lastly, the paper discusses recent developments, including techniques to prevent membrane fouling by modifications affecting surface roughness or hydrophilicity/hydrophobicity, or by cleaning the membranes, and methods for treating or disposing of the retentate.
822 citations
TL;DR: The cellular components are the key players in restricting solute transport, while the GBM is responsible for most of the resistance to water flow across the glomerular barrier.
Abstract: This review focuses on the intricate properties of the glomerular barrier. Other reviews have focused on podocyte biology, mesangial cells, and the glomerular basement membrane (GBM). However, since all components of the glomerular membrane are important for its function, proteinuria will occur regardless of which layer is affected by disease. We review the properties of endothelial cells and their surface layer, the GBM, and podocytes, discuss various methods of studying glomerular permeability, and analyze data concerning the restriction of solutes by size, charge, and shape. We also review the physical principles of transport across biological or artificial membranes and various theoretical models used to predict the fluxes of solutes and water. The glomerular barrier is highly size and charge selective, in qualitative agreement with the classical studies performed 30 years ago. The small amounts of albumin filtered will be reabsorbed by the megalin-cubulin complex and degraded by the proximal tubular cells. At present, there is no unequivocal evidence for reuptake of intact albumin from urine. The cellular components are the key players in restricting solute transport, while the GBM is responsible for most of the resistance to water flow across the glomerular barrier.
771 citations
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TL;DR: A "translation" of the phenomenological permeability coefficients into friction and distribution coefficients amenable to physical interpretation is presented and a set of equations and reference curves are presented for the evaluation of ω and σ in the transport of polyvalent ions through charged membranes.
Abstract: A "translation" of the phenomenological permeability coefficients into friction and distribution coefficients amenable to physical interpretation is presented. Expressions are obtained for the solute permeability coefficient ω and the reflection coefficient σ for both non-electrolytic and electrolytic permeants. An analysis of the coefficients is given for loose membranes as well as for dense natural membranes where transport may go through capillaries or by solution in the lipoid parts of the membrane. Water diffusion and filtration and the relation between these and capillary pore radius of the membrane are discussed. For the permeation of ions through the charged membranes equations are developed for the case of zero electrical current in the membrane. The correlation of σ with ω and Lp for electrolytes resembles that for non-electrolytes. In this case ω and σ depend markedly on ion concentration and on the charge density of the membrane. The reflection coefficient may assume negative values indicating anomalous osmosis. An analysis of the phenomena of anomalous osmosis was carried out for the model of Teorell and Meyer and Sievers and the results agree with the experimental data of Loeb and of Grim and Sollner. A set of equations and reference curves are presented for the evaluation of ω and σ in the transport of polyvalent ions through charged membranes.
647 citations
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