Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification

Abstract

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and thus achieving stable water permeability through membranes over time. Here, we report a facile method to prepare hydrogels based on zwitterions for membrane applications. Freestanding films can be prepared from sulfobetaine methacrylate (SBMA) with a crosslinker of poly(ethylene glycol) diacrylate (PEGDA) via photopolymerization. The hydrogels can also be prepared by impregnation into hydrophobic porous supports to enhance the mechanical strength. These films can be characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to determine the degree of conversion of the (meth)acrylate groups, using goniometers for hydrophilicity and differential scanning calorimetry (DSC) for polymer chain dynamics. We also report protocols to determine the water permeability in dead-end filtration systems and the effect of foulants (bovine serum albumin, BSA) on membrane performance.

Membranes with Surface-Enhanced Antifouling Properties for Water Purification

“…Therefore, zwitterions can be more hydrophilic than PEG [58,62]. A study of copolymer hydrogels prepared from PEGDA and zwitterionic monomer, such as sulfobetaine methacrylate (SBMA), exhibit greater hydrophilicity than those from PEGDA [61,63,64]. Similar to PEG, zwitterionic chains have elastic forces against foulants when they compress the chains, which also contributes to antifouling properties [65].…”

Zwitterionic Hydrogel-Impregnated Membranes with Polyamide Skin Achieving Superior Water/Salt Separation Properties

“…Figure presents the effect of the PEGDA concentration in the prepolymer solutions on A w and the Na 2 SO 4 rejection ( R S ) in s IM x samples. Increasing the PEGDA concentration in the prepolymer solution from 20 to 40 wt % decreases the A w of the IMs from 0.5 ± 0.1 to 0.03 ± 0.01 LMH/bar but increases the Na 2 SO 4 rejection from 22 ± 7 to 97 ± 2%, which can be ascribed to the increased cross-linking density. ,, …”

“…Increasing the PEGDA concentration in the prepolymer solution from 20 to 40 wt % decreases the A w of the IMs from 0.5 ± 0.1 to 0.03 ± 0.01 LMH/bar but increases the Na 2 SO 4 rejection from 22 ± 7 to 97 ± 2%, which can be ascribed to the increased cross-linking density. 32,36,37 The addition of the PA skin has a negligible effect on A w (see Figure 5a) but increases the Na 2 SO 4 rejection (see Figure 5b) for sIM20 and sIM30. For example, sIM30 shows A w of 0.14 ± 0.03 LMH/bar and Na 2 SO 4 rejection of only 49 ± 10%, while sIM30-NF2 exhibits A w of 0.11 ± 0.02 LMH/bar and Na 2 SO 4 rejection of 84 ± 7%.…”

“Nonstick” Membranes Prepared by Facile Surface Fluorination for Water Purification

“…Pure-water permeance ( A W ) was determined using dead-end filtration cells. , The membranes were mounted in the cells and kept in DI water for at least 24 h before the measurement. The water permeance ( A W ) can be calculated using the equation below: where Δp (bar) is the transmembrane pressure (TMP), A m is the active membrane area (m 2 ), and V is the volume of water permeated (L) over t (h).…”

“…Pure-water permeance (A W ) was determined using dead-end filtration cells. 31,32 The membranes were mounted in the cells and kept in DI water for at least 24 h before the measurement. The water permeance (A W ) can be calculated using the equation below:…”