Fouling Resistance and Physicochemical Properties of Polyamide Thin‐Film Composite Membranes Modified with Functionalized Cyclodextrins

Abstract

Thermal and mechanical properties and fouling resistance of polyamide thin-film composite (PA-TFC) membranes modified with amino-cyclodextrins and diethylamino-cyclodextrins are investigated. It was found that the decomposition temperatures of the modified membranes were 500°C and were not significantly different with those of the unmodified membranes. Differential scanning calorimetry (DSC) studies showed that the modified membranes with heating melting temperatures in the range 112.5-113.8°C were more crystalline than the unmodified membranes due to the presence of cyclodextrin derivatives on the interfacial layer. The crystallization temperatures (T c ) were found to range between 128.75 and 129.03°C and the glass transition temperatures (T g ) ranged between 78.67 and 79.33°C. The modified PA-TFC membranes were found to have comparable ultimate tensile strengths (UTS) to the unmodified membranes, except for the membranes modified with amino-b-CDs, with a UTS of 20.00 AE 0.50 MPa. The PA-TFC membranes had a lower water uptake percentage due to their enhanced crystallinity. However, these materials had a higher water permeate flux due to the hydrophilic nature of the modified membranes enhanced by the rich hydroxyl groups on the CDs. The modified PA-TFC membranes also exhibited high MgSO 4 salt rejection and fouling resistance capacities compared to unmodified membranes. Different pH levels resulted in different fouling resistance patterns of the membranes. Therefore, the membranes modified with functionalized CDs were thermally and mechanically stable, had enhanced crystallinity, high divalent salt rejection and fouling resistance under different pH conditions.

Antifouling Properties of Silver-Zinc Oxide Polyamide Thin Film Composite Membrane and Rejection of 2-Chlorophenol and 2,4-Dichlorophenol

“…The procedure followed in the fabrication of PA-TFC membranes using interfacial polymerization was adapted from Mbuli et al (2017) [19]. Aqueous solutions of piperazine and nanocomposites of Ag-ZnO (0 to 2 wt%), and the organic phase of TMC and hexane were prepared according the quantities shown in Table 1.…”

“…Used membranes were cleaned with deionized water for 10 min to remove the foulant molecules loosely deposited on the surface of the membranes. The membranes were re-assessed to obtain flux of the cleaned membranes ( J wc ) [18,19]. Water recovery ratio (FRR) were determined using Equation (3); FRR(%)= JwcJw0 where J w 0 , J wt , and J wc are the water fluxes of pure water, 2-CP/2,4-DCP solutions, and cleaned membranes, respectively.…”

“…The disadvantage of the phase inversion method is the easy desorption of NPs from the membranes. Interfacial polymerization is one of the suitable methods for fabrication of thin film membranes (e.g., PA-TFC) [19]. The structure of the thin film membranes consists of three layers namely; the ultra-thin surface layer, microporous interlayer, and polyester porous layer (support).…”

Cyclodextrin-Based Nanofibers and Membranes: Fabrication, Properties and Applications

“…TFC membranes include reverse osmosis (RO) and ultrafiltration (UF) membranes prepared by interfacial polymerization. The unique structure of TFC membranes that consists of a UF support, a nonwoven support and a polymer membrane brings advantages such as low operation pressure, high retention of multivalent ions or salts, low maintenance cost and high permeation flux [86,92,93]. This type of membranes is mostly used in water treatment for the production of drinking water from wastewater, seawater and brackish water [94].…”

“…Other areas of application include organic solvent nanofiltration and pharmaceuticals and biochemical industries [86,93]. The layers of TFC membranes can be modified independently for maximum preferred properties such as water uptake, fouling resistance, chemical resistance, thermal stability, hydrophilicity and mechanical strength [92]. The excellent properties of TFC membranes are due to modifying agents such as CDs and their derivatives.…”