Nanoclays‐Incorporated Thin‐Film Nanocomposite Membranes for Reverse Osmosis Desalination

Abstract

produce a TFC membrane with both high water permeability and salt rejection as there is a trade-off relationship between them. [5,6,[11][12][13] Up to now, various methods, such as monomer alteration, [14][15][16] surface modification, [17,18] and posttreatment, [19] have been attempted to improve the membrane performance.The rapid progress in nanomaterials has brought new possibilities to break through the bottleneck. Thin-film nanocomposite (TFN) membranes, a new type of nanotechnology-enhanced membranes, are studied as a promising candidate for desalination purposes. [5,6,[20][21][22] Many nanoparticles, such as zeolites, [6,[23][24][25] silica, [26,27] metal-organic frameworks− covalent-organic frameworks (MOFs− COFs), [28][29][30] carbon nanotubes, [31,32] and carbon−graphene oxide quantum dots, [33][34][35] have been incorporated into the polyamide matrix of TFN membranes to increase membrane hydrophilicity and provide additional water pathways. [36] Nevertheless, most of the nanoparticles used are produced in laboratory scale and the yield is relatively low, which is difficult to scale up for commercialization when taking economic viability into account.Of the nanomaterials available in the market, nanoclays of abundant sources from nature are potential to be the nanofillers in TFN membranes. [37] Ghanbari et al. incorporated halloysite nanotubes into polyamide layers for brackish water desalination. [38] Dong et al. used montmorillonite as nanofillers to enhance fouling resistance. [39] Hebbar et al. utilized functionalized bentonite to improve nanofiltration performance in removal of heavy metals and humic acids. [40] However, most of the nanoclays reported have relatively low dispersity in solvents, which have to undergo long-time activation or complicated surface modifications prior to be dispersed in water or organic solvents. [38][39][40] Laponite (Na +0.7 [Si 8 Mg 5.5 Li 0.3 O 20 (OH) 4 ] 0.7− ) nanoclays (NC-LAP), a type of synthetic nanoclays, have been discovered and commercialized for decades, and commonly used as a film-forming agent, emulsifier, and gelling agent. [41,42] Owing to its excellent aqueous dispersity, small size and nontoxicity, Laponite can be a good candidate as nanofillers in TFN membranes, which requires no complicated pretreatment when being blended with the aqueous monomer solution for interfacial polymerization.Herein, new TFN membranes with incorporation of commercialized Laponite nanoclays were fabricated via conventional interfacial polymerization (illustrated in Figure 1). The influence of nanoclays on membrane morphology and separation A series of thin-film nanocomposite (TFN) membranes with incorporation of Laponite nanoclays (NC-LAP) is prepared and demonstrated for brackish water and seawater desalination. It is the first attempt to use poly(ethylene glycol) 200 (PEG200) assisted Laponite as nanofillers to improve the performance of TFN membranes for reverse osmosis (RO) seawater desalination. The influence of NC-LAP loading and PEG200 as the dispersant on membrane ...

Studying the Effect of Shortening Carbon Nanotubes via Ball Milling on Cellulose Acetate Nanocomposite Membranes for Desalination Applications

“…The structure and properties of nanocomposite membranes depend on different variables such as the types of polymer matrices (e.g., polyamides, cellulose acetate), types of solvents (e.g., dimethylformamide, acetone), and the introduction of different additives, particularly nanofillers (e.g., graphene, nanoclays). Each variable can affect the porosity, surface, and cross section morphology of the membranes, thus creating mixed matrix membranes for different applications [ 9 , 10 , 11 , 12 , 13 , 14 ]. One of the most widely investigated types of nanofillers involves carbon nanotubes (CNTs), and investigations have aimed at understanding their effects on filtration performance, mechanical stability, and morphology changes.…”

Anisotropic Evaporator with a T‐Shape Design for High‐Performance Solar‐Driven Zero‐Liquid Discharge

“…[ 12,13 ] ZLD not only enables the recovery of freshwater but also the solid salt, thus representing an ideal method for wastewater management. At present, the ZLD strategy involves (1) concentrating wastewater by reverse osmosis (RO) or membrane filtration, [ 14 ] and (2) separating the salt as a solid by thermal evaporative crystallization. [ 15 ] However, the membranes for RO are expensive and need frequent replacement.…”

Assessing the Performance of Thin-Film Nanofiltration Membranes with Embedded Montmorillonites

“…With the rapid advancement of nanotechnology, researchers focus on developing nanoparticles to improve the TFC membranes. These nanoparticles are silica [29,31], silver [30,32], graphene or graphene oxide [33,34], zeolites [35,36], nanoclays [37][38][39][40][41][42][43], quantum dots [44,45], and carbon nanotubes [46,47]. TFC membranes with embedded nanoparticles are called thin-film nanocomposite (TFN) membranes [48,49].…”

“…MMTs also have ions that may undergo ionic substitution, capable of producing useful new materials for various applications [53]. For the membrane applications, several scholars [37][38][39][40][41][42][43] attempted to embed different types of nanoclay in a polyamide matrix. Recently, Li et al [37], modified a synthetic nanoclay-laponite by functionalizing it with different metal ions.…”

“…They improved both the flux and antifouling properties of the polyamide membrane prepared using m-phenylenediamine (MPD), and trimesoyl chloride (TMC). Zhao et al [38] used PEG 200 to assist in the dispersion of laptonite in an aqueous MPD solution. In their study, the flux of TFN membrane increased while maintaining NaCl rejection.…”