Search

Abstract: Sulfonated poly (ether ether ketone) (SPEEK) membrane with degree of sulfonation (DS) of 63% was modified by adding various amounts of Cloisite15A® clay. The effect of clay loading on the physical properties of SPEEK nanocomposite membranes was investigated. SPEEK mixed with 2.5wt.% of Cloisite15A® (SP63/2.5Cl) has been identified as the best composite formulation in this study. Subsequently, various amounts of 2,4,6-triaminopyrimidine (TAP) were further incorporated into SP63/2.5Cl formulation. The effect of TAP incorporation on the physical and performance properties of the membranes was studied. Nanometer scale distribution of Cloisite15A® in the SPEEK polymer matrix has been achieved by the assistance of TAP, as observed by the field emission scanning electron microscopy (FESEM). A complete exfoliated nanocomposite structure of SP63/2.5Cl/5.0TAP was confirmed by X-ray diffraction (XRD). The increase of Cloisite15A® content in the SPEEK membrane has dramatically improved the swelling behavior and barrier properties towards methanol. The SP63/2.5Cl/5.0TAP polymer–clay nanocomposite membrane served as a promising alternative proton exchange membrane (PEM) for DMFC applications with superior DMFC performance compared to commercial Nafion®112. [Copyright &y& Elsevier]

Abstract: Sulfonated poly (ether ether ketone) (SPEEK)/Cloisite 15A® nanocomposite membranes were fabricated by incorporating 2,4,6-triaminopyrimidine (TAP) as compatiblizer and characterized for DMFC application. The SPEEK-nanocomposite membranes were prepared via solution intercalation method. The membranes were then characterized based on their thermal and physical properties as a function of Cloisite 15A® and TAP loading. The characteristics of the SPEEK nanocomposite membranes were then compared with the parent SPEEK membrane and the commercially available Nafion 112 membrane. The XRD confirmed that intercalation took place in the SPEEK nanocomposite membranes. The membrane stability, i.e. the liquid uptake in water and in the aqueous methanol solution, as well as the mechanical and thermal stability significantly were improved with the Cloisite 15A® and TAP loadings into the SPEEK polymer matrix. The barrier performance of SPEEK/Cloisite 15A®/TAP was significantly enhanced to compete with the expensive Nafion 112 membrane. Higher proton conductivity of 3.87×10−3 Scm−1, which is higher than that of the parent SPEEK membrane, was also attained. [Copyright &y& Elsevier]

Abstract: Realizing that one of the most important challenges in the forward osmosis (FO) membrane is internal concentration polarization (ICP), thin film nanocomposite (TFN) membranes were prepared by incorporating different loadings of titanium dioxide (TiO2) nanoparticles (ranging from 0 to 0.90wt%) into the polysulfone (PSf) substrate in order to reduce ICP. The nanocomposite substrates prepared were characterized with respect to hydrophilicity, overall porosity, surface roughness and cross-sectional morphology by different methods. Results revealed that both hydrophilicity and porosity of the substrate were increased upon addition of TiO2 nanoparticles. Moreover, a large number of finger-like macrovoids were developed by increasing the loading of TiO2 nanoparticles, leading to enhancement in water permeability. As for the FO performance tested at AL-FS orientation and with DI water as feed and 0.5M NaCl as draw solution, the TFN membrane prepared using PSf substrate embedded with 0.60wt% TiO2 nanoparticles (designated as TFN0.60) exhibited the most promising result by showing water flux of 18.81L/m2 h, i.e. 97% higher than the control TFC membrane prepared by substrate without TiO2 incorporation (designated as TFC), with no significant change in reverse solute flux. Compared to the control TFC membrane, the FO water flux of TFN0.60 was also reported to increase significantly from 4.2 to 8.1L/m2 h (AL-FS orientation) and from 6.9 to 13.8L/m2 h (AL-DS orientation) when seawater was used as feed solution and 2M NaCl was used as draw solution. The increase in water flux can be attributed to the decrease in structural parameter (S value=0.39mm), mainly due to the formation of finger-liked macrovoids that connect the top and bottom layer of the substrate and reduce the tortuosity, resulting in decreased ICP. Although further increasing TiO2 nanoparticles loading to 0.90wt% could increase membrane water permeability, the FO performance was compromised by a significant increase in reverse solute flux. To the best knowledge of the authors, this is the first report on TFN membrane using PSf-TiO2 nanocomposite substrate for FO applications. [Copyright &y& Elsevier]