Preparation of new composite membranes for water desalination using electrodialysis

The use of polyethersulfone (PES), an excellent but highly hydrophobic thermoplastic, as a matrix material for ion-exchange membranes was investigated. To make PES ion-exchangeable, sulfonate groups were introduced to the polymer chains by sulfonation reaction with chlorosulfonic acid. The degree of sulfonation of sPES was estimated to be 21%. Preliminary experiments investigated the effect of polyethylene glycol (PEG) and Pluronic F127 as fillers to improve the hydrophilicity of the membranes. Moreover, a lab scale electrodialysis cell has been designed and set up to evaluate the performance of these novel membranes compared to the benchmark of commercial membranes. The results show promising properties of ion-exchange capacity, water uptake, conductivity and hydophilicity from blended membranes, comparable to commercial membranes, though the performance of the prepared membranes did not exceed the commercial one. Further characterization of the transport properties of ion-exchange membranes need to be investigated to be able to understand the effects of the fillers on the performance of the membranes in ED application

Zr(HPO4)(2) based organic/inorganic nanohybrids as new proton conductors

In this study, sulfanilic acid was intercalated into an alpha-Zr(HPO4)(2) with the aim to enhance the proton conductivity via the acidic -SO3H groups. TGA results suggest that intercalation really takes place and a four-day reaction leads to the intercalation of 0.72 guest molecules (sulfanilic acids) per alpha-Zr(HPO4)(2). We find that the hybrid material undergoes three-step decomposition pathways: dehydration (40-150 degrees C), decomposition of benzene ring (150-470 degrees C), and finally de-SOx (470-1000 degrees C). The sulfanilic acid/alpha-Zr(HPO4)(2) hybrid shows a proton conductivity of 2.80 x 10(-3) S/cm, one order higher than the original alpha-Zr(HPO4)(2) (2.04 x 10(-4) S cm(-1)) measured at a relative humidity of 100% and 22 degrees C. The conductivity is strongly dependent on the relative humidity, and sharply increases at over 80% relative humidity. The activation energy for the proton transport in the hybrid is 0.33 and 0.15 eV at 60% and 100% relative humidity, respectively, in the temperature range of 22-100 degrees C, further reflecting the influence of humidity on the proton conduction