Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification

Summary

This paper reports practical methods to prepare hydrogels in freestanding films and impregnated membranes and to characterize their physical properties, including water transport properties.

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.

Introduction

There is a great need to develop low cost and energy efficient technologies to produce clean water in order to meet the increasing demand. Polymeric membranes have emerged as a leading technology for water purification due to their inherent advantages, such as their high energy efficiency, low cost, and simplicity in operation¹. Membranes allow pure water to permeate through and reject the contaminants. However, membranes are often subjected to fouling by contaminants in the feed water, which can be adsorbed onto the membrane surface from their favorable interactions^2,3. The fouling can....

Protocol

1. Preparation of the Prepolymer Solutions

1. Preparation using water as a solvent
   1. Add 10.00 g of deionized (DI) water to a glass bottle with a magnetic stir bar.
   2. Measure 2.00 g of SBMA and transfer it to the glass bottle containing the water. Stir the solution for 30 min, until the SBMA is completely dissolved.
   3. In a separate bottle, add 20.00 g of PEGDA (M_n = 700 g/mol).
   4. Add 20.0 mg of 1-hydroxycyclohexyl phenyl ketone (HCPK), a photo-initiator, to the PEGDA solution. Let the solution stir for at least 30 min.
   5. Using a disposable pipette, transfer 8.00 g of the PEGDA-HCPK solu....

Results

Freestanding films prepared with the prepolymer solutions specified in steps 1.1 and 1.2 are referred to as S50 and S30, respectively. Detailed information is shown in Table 1. The prepolymer solution specified in step 1.2 was also used to fabricate impregnated membranes, which are denoted as IMS30. Because the porous support is made of hydrophobic polyethylene, only the prepolymer solution containing ethanol can be impre.......

Discussion

We have demonstrated a facile method to prepare freestanding films and impregnated membranes based on zwitterionic hydrogels. The disappearance of three (meth)acrylate characteristic peaks (i.e., 810, 1,190, and 1,410 cm^-1) in the IR spectra of the obtained polymer films and impregnated membrane (Figure 2) indicates the good conversion of the monomers and crosslinker^4,19,21. Additionally, the.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Poly(ethylene glycol) diacrylate                  Mn = 700 (PEGDA)	Sigma Aldrich	455008
1-Hydroxycyclohexyl phenyl ketone, 99% (HCPK)	Sigma Aldrich	405612
[2-(Methacrloyloxy)ethyl dimethyl-(3-sulfopropyl) ammonium hydroxide, 97%	Sigma Aldrich	537284	Acutely Toxic
Ethanol, 95%	Koptec, VWR International	V1101	Flamable
Decane, anhydrous, 99%	Sigma Aldrich	457116
Solupor Membrane	Lydall	7PO7D
Micrometer	Starrett	2900-6
ATR-FTIR	Vertex 70
DSC: TA Q2000	TA Instruments
Rame’-hart Goniometer: Model 190	Rame’-hart Instruments
Ultraviolet Crosslinker: CX-2000	Ultra-Violet Products		UV radiation
Permeation Cell: Model UHP-43	Advantec MFS
Deionized Water: Milli-Q Water	EMD Millipore