Graphene membranes for water desalination

Abstract

Extensive environmental pollution caused by worldwide industrialization and population growth has led to a water shortage. This problem lowers the quality of human life and wastes a large amount of money worldwide each year due to the related consequences. One main solution for this challenge is water purification. State-of-the-art water purification necessitates the implementation of novel materials and technologies that are cost and energy efficient. In this regard, graphene nanomaterials, with their unique physicochemical properties, are an optimum choice. These materials offer extraordinarily high surface area, mechanical durability, atomic thickness, nanosized pores and reactivity toward polar and non-polar water pollutants. These characteristics impart high selectivity and water permeability, and thus provide excellent water purification efficiency. This review introduces the potential of graphene membranes for water desalination. Although literature reviews have mostly concerned graphene's capability for the adsorption and photocatalysis of water pollutants, updated knowledge related to its sieving properties is quite limited. NPG Asia Materials (2017) 9, e427; doi:10.1038/am.2017.135; published online 25 August 2017 INTRODUCTION Currently,~1.2 billion people around the world are suffering from a shortage of water and its adverse consequences on health, food and energy. 1,2 On one hand, population growth, increased industrialization and greater energy needs and, on the other hand, loss of snowmelt, shrinkage of glaciers and so on will worsen this situation in upcoming years. As estimated by the world water council, the number of affected people will rise to 3.9 billion in the coming decades. 2,3 One of the most promising approaches to alleviate the water shortage, desalination can increase the water supply beyond what is available from the hydrological cycle. 4 Seawater desalination indeed provides an infinite, steady supply of high-quality water that does not harm natural freshwater ecosystems.Seawater comprises a vast supply of water (97.5% of all water on the planet). Thus, the growth of the installation of seawater desalination facilities in the past decade to circumvent water shortage problems in water-stressed countries has progressed quickly. In 2016, the global water production by desalination was estimated to be 38 billion cubic meter per year, that is, two times higher than that in 2008. 5 So far, seawater desalination has been mainly performed via multistage flash distillation and reverse osmosis (RO). 6 Mostly in the arid Persian Gulf countries, desalination plants perform based on heating and then condensing seawater. This kind of desalination plant consumes large amounts of thermal and electric energy, thus emitting greenhouse gases extensively. 7 In addition to this non-economical and non-ecofriendly version of desalination plants, the main type of desalination plants constructed in the past two decades, as well as future planned ones, are based on RO technology (Figure 1). 8

Water on graphene: review of recent progress

“…Water transport through graphene opens up new opportunities for multiple applications of graphene-based membranes in molecular sieving [18], [38], [39], water filtration [40], purification and desalination of water [17], [41], [42].…”

Graphene synthesized in atmospheric plasmas—A review

“…Future research should investigate the performance of GSG in applications for graphene powder. RGO has been used in a myriad of applications, such as high-strength nanocomposites, 117,118 energy storage, 20,24 water purification, 119,120 and drug delivery. 121 However, it is currently unknown if the pure and highly ordered nature of GSG will enhance the mechanical properties of nanocomposites, increase the energy storage capabilities of batteries, or improve the tribological properties of lubricants.…”

An Overview of the Water Remediation Potential of Nanomaterials and Their Ecotoxicological Impacts

“…A membrane is a selective barrier located between two homogenous phases that splits a feed water stream into a retentate and a permeate fraction. The pressure difference between the feed and permeate sides acts as the driving force for the membrane's action and passes water through the Water 2020, 12, 1150 6 of 23 membrane [25]. As a result, based on charge, size, and shape, solutes and particles are discriminated ( Figure 4a).…”