A Review on Reverse Osmosis and Nanofiltration Membranes for Water Purification

Abstract

Sustainable and affordable supply of clean, safe, and adequate water is one of the most challenging issues facing the world. Membrane separation technology is one of the most cost-effective and widely applied technologies for water purification. Polymeric membranes such as cellulose-based (CA) membranes and thin-film composite (TFC) membranes have dominated the industry since 1980. Although further development of polymeric membranes for better performance is laborious, the research findings and sustained progress in inorganic membrane development have grown fast and solve some remaining problems. In addition to conventional ceramic metal oxide membranes, membranes prepared by graphene oxide (GO), carbon nanotubes (CNTs), and mixed matrix materials (MMMs) have attracted enormous attention due to their desirable properties such as tunable pore structure, excellent chemical, mechanical, and thermal tolerance, good salt rejection and/or high water permeability. This review provides insight into synthesis approaches and structural properties of recent reverse osmosis (RO) and nanofiltration (NF) membranes which are used to retain dissolved species such as heavy metals, electrolytes, and inorganic salts in various aqueous solutions. A specific focus has been placed on introducing and comparing water purification performance of different classes of polymeric and ceramic membranes in related water treatment industries. Furthermore, the development challenges and research opportunities of organic and inorganic membranes are discussed and the further perspectives are analyzed.

A Review of CFD Modelling and Performance Metrics for Osmotic Membrane Processes

“…SWM modules have been used for industrial applications of seawater RO (SWRO) since the 1960s [ 3 ], and their use has been further extended to nanofiltration (NF) in the early 1980s [ 4 ]. For emerging osmotic membrane processes such as forward osmosis (FO) and pressure retarded osmosis (PRO), the development of SWMs is still at an early stage and is only limited to lab-scale studies [ 5 , 6 , 7 , 8 ].…”

The Recent Progress in Modification of Polymeric Membranes Using Organic Macromolecules for Water Treatment

“…In general, the filtration membranes have been divided into four categories: microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) with reduced pore size in order to reject various size substances and effluences [46]. Among these pressure-driven membrane technologies, RO has gained great global interest and one of the promising large-scale processes due to the simplicity in plant design with low energy cost [47,48]. RO technology, which consists of only four major processes, offer high performance of semi-permeable membrane that leads to superior water permeability and salt rejection [49][50][51][52].…”

Ion separations with membranes

“…Polymeric membranes play vital roles in various industrial applications, such as water treatment, [1,2] gas separations, [3][4][5] food processing, [6,7] and energy production and storage. [5,8] These wide-ranging processes exploit membrane structures and materials that range from dense to porous, composite to free-standing, and singlecomponent to mixed-matrix.…”

“…A number of reviews describe the history of membranes and their applications. [1][2][3][4][5][6][7][8][10][11][12][13][14][15][16][17][18] This paper focuses on a less explored membrane process, separation of different cations and anions. In contrast to reverse osmosis, which removes essentially all ions from solution, this paper focuses on allowing selective passage of only certain ions.…”