Salt Transport in Crosslinked Hydrogel Membranes Containing Zwitterionic Sulfobetaine Methacrylate and Hydrophobic Phenyl Acrylate

Abstract

Produced water is a by-product of industrial operations, such as hydraulic fracturing for increased oil recovery, that causes environmental issues since it includes different metal ions (e.g., Li+, K+, Ni2+, Mg2+, etc.) that need to be extracted or collected before disposal. To remove these substances using either selective transport behavior or absorption-swing processes employing membrane-bound ligands, membrane separation procedures are promising unit operations. This study investigates the transport of a series of salts in crosslinked polymer membranes synthesized using a hydrophobic monomer (phenyl acrylate, PA), a zwitterionic hydrophilic monomer (sulfobetaine methacrylate, SBMA), and a crosslinker (methylenebisacrylamide, MBAA). Membranes are characterized according to their thermomechanical properties, where an increased SBMA content leads to decreased water uptake due to structural differences within the films and to more ionic interactions between the ammonium and sulfonate moieties, resulting in a decreased water volume fraction, and Young’s modulus increases with increasing MBAA or PA content. Permeabilities, solubilities, and diffusivities of membranes to LiCl, NaCl, KCl, CaCl2, MgCl2, and NiCl2 are determined by diffusion cell experiments, sorption-desorption experiments, and the solution-diffusion relationship, respectively. Permeability to these metal ions generally decreases with an increasing SBMA content or MBAA content due to the corresponding decreasing water volume fraction, and the permeabilities are in the order of K+ > Na+ > Li+ > Ni2+ > Ca2+ > Mg2+ presumably due to the differences in the hydration diameter.

Phenyl Acrylate-Based Cross-Linked Anion Exchange Membranes for Non-aqueous Redox Flow Batteries

“…To improve the chemical stability, the aliphatic backbone is sometimes replaced by an aromatic backbone. Cross-linking of the polymer matrix is another promising strategy to improve the chemical stability of AEMs. ,,,, N , N -methylene bis acrylamide (MBAA) has been used as a cross-linker in a cross-linked polymerization by many researchers. − Phenyl acrylate (PA)-based polymers were previously prepared for other purposes by different groups because of their appealing chemical and mechanical stability. − Among these, Beckingham et al synthesized PA-based membrane for fuel cells by the thermal polymerization method . Here, the present study describes new AEMs through a simple synthesis method with low-cost materials.…”

Development of Structure–Property Relationships for Ammonium Transport through Charged Organogels

“…While the general structure of Nafion ® is known, the complex morphology of the polymer makes it difficult to develop structure–property relationships, which are needed to guide the development of new membranes [ 22 , 23 ]. Previous work has demonstrated the use of readily tunable (meth)acrylate gels as a platform to understand structure–property relationships in ion exchange membranes [ 24 , 25 , 26 ], with some gels demonstrating improved performance compared to commercial membranes [ 27 ]. Based on these reports, we decided to adopt this tunable chemistry to study the impact of network structure on the transport of ammonium to guide the development of new membranes for NRR cells.…”