Mixed matrix heterogeneous cation exchange membrane filled with clay nanoparticles: membranes’ fabrication and characterization in desalination process

Abstract

In this research mixed matrix PVC based-co-clay nanoparticles heterogeneous cation exchange membranes were prepared by solution casting technique. The effect of clay nanoparticles concentration in the casting solution on membrane electrochemical properties was studied. Scanning optical microscopy (SOM) images showed uniform particles distribution and relatively uniform surfaces for the prepared membranes. The membrane water content was improved initially by an increase of additive content ratio up to 1%wt in casting solution and then it began to decrease by more additive concentration. Moreover, swelling was measured less than 5% in thickness and negligible in length and width for the prepared membranes. Membrane potential, transport number and permselectivity were improved by increase of nanoparticles loading ratio. Utilizing Cloisite nanoparticles up to 1%wt in the casting solution also led to an increase in permeability and flux for prepared membranes. The ionic permeability and flux were decreased again by a further increase in additive concentration from 1 to 4%wt. Also, membranes exhibited lower permeability and flux for bivalent ions in comparison with monovalent type. The membrane E-conductivity and mechanical strength was enhanced by an increase of nanoparticles concentration in membrane matrix. The modified membrane containing 1% wt clay nanoparticles showed more suitable electrochemical properties compared to others.

Enhanced selectivity and performance of heterogeneous cation exchange membranes through addition of sulfonated and protonated Montmorillonite

“…As a result, cavities and pores disappeared in modified membranes and a denser structure shows up. Similar observations were found for PVC based ion exchange membranes with added clay nanoparticles [24,25]. Our results this demonstrate that this is a more generic effect, and it is likely that this effected can be replicated with many combinations of clay and polymer.…”

“…5a, a dramatic increase of water content results from adding nanoclay and functionalized nanoclay up to 0.5 wt.% in the casting solution. It is encouraging to compare this figure with that found by Namdari et al [24] and Hosseini et al [25] who found that membrane's hydrophilicity was enhanced up to 1 wt.% nanoclay but then decreased significantly. In our PES based IEMs the increase in water content remains over a much wider range of clay concetrations.…”

“…This leads to improved membrane properties of the prepared membranes, such as a higher ion exchange capacity (IEC), water content, permselectivity, and an lower electrical resistance. While Hosseini et al [25] found an optimal clay concentration of 1%, Namdari et al observed an optimimum at 3%. These works where however limited to a single binder chemistry (PVC).…”

“…Several studies have been carried out using unmodified and sulfonated clay particles in direct methanol fuel cell membranes, such as Nafion, sPEEK, PVA, and PVDF membranes, leading to improvements in proton conductivity and reduced methanol permeability [19][20][21][22][23]. Some work, [24] and [25], has been dedicated to include nanoclay in heterogeneous cation-exchange membranes due to clay's suitable properties, such as easy availability, layered structure, hydrophilicity, low cost, and it's cation exchange capacity. Namdari et al [24] added montmorillonite K10 to PVC/HIPS/ABS blended heterogeneous cation exchange membranes.…”

“…Namdari et al [24] added montmorillonite K10 to PVC/HIPS/ABS blended heterogeneous cation exchange membranes. Hosseini et al [25] focused on mixed matrix PVC based-co-clay nanoparticles heterogeneous cation exchange membranes and studied the effect of clay nanoparticles concentration on membrane electrochemical properties. Both studies showed that the addition of clay lead to a much better distribution of the IEX resin in the polymeric matrix.…”