This study was designed to prepare functionalized multiwalled carbon nanotubes (MWNTs-COOH) incorporated chitosan membrane for separation of ethanol/water mixtures by pervaporation. The pristine MWNTs were treated by mixed acid and then functionalized by diisobutyryl peroxide. The structure and property of the functionalized MWNTs were characterized by Fourier transform infrared and Raman spectroscopies and transmission electron microscopy. A series of functionalized MWNTs incorporated chitosan membranes were prepared by solution blending method. The swelling degree of the resulting membranes in ethanol/water mixtures was 6 times that of the pristine chitosan membrane. The permeation flux of the membranes increased significantly with increasing functionalized MWNTs content in blend membrane matrix in pervaporation. On the basis of the experiments of sorption equilibrium, the solubility and the diffusion coefficient of membranes in water, ethanol, and 90% ethanol/water mixtures were obtained. Compared with the calculated diffusion coefficient (D 90 ), the measured diffusion coefficient (D 90 T ) in 90% ethanol/water mixtures was higher, taking M(2) for an example, D 90 was 0.193 × 10 -6 m 2 /s, and D 90 T was 0.41 × 10 -6 m 2 /s, which indicated the functionalized MWNTs were more prone to increased water permeation when ethanol and water penetrated into the membrane simultaneously. In addition, effects of MWNTs content in the membrane matrix and operating temperature on pervaporation performances were investigated. After introducing functionalized MWNTs, the Arrhenius activation parameters for the total permeation decreased from 28.15 to 12.91 kJ/mol, which indicated that the carbon nanotubes filled membranes were easier to penetrate and exhibited higher flux performance than a pristine membrane.

2011) Preparation of high-flux thin film nanocomposite reverse osmosis membranes by incorporating functionalized multi-walled carbon nanotubes, Desalination and Water Treatment,[19][20][21][22][23][24] To link to this article: http://dx. A B S T R AC TTo enhance the water fl ux of reverse osmosis membranes, thin fi lm nanocomposite reverse osmosis membranes are prepared by incorporating functionalized multi-walled carbon nanotubes (MWNTs). The functionalized MWNTs are obtained by the treatment of pristine MWNTs with the mixed acid of H 2 SO 4 and HNO 3 (3:1 v/v). The MWNTs are analyzed by Fourier transform infrared spectrometry (FTIR). The surface morphology and structure of membrane are characterized by scanning electronic microscopy (SEM), transmission electron microscopy (TEM) and contact angle measurement, respectively. Those results show that modifi ed MWNTs yielded some hydrophilic groups, such as -COOH and -OH, which make acidifi ed MWNTs disperse more evenly in the aqueous solution. The SEM and TEM results demonstrate that the functionalized MWNTs penetrated through the polyamide layer, and might play the role of water channel. Compared with the bare polyamide membrane, the MWNT-polyamide thin fi lm nanocomposite membranes have more hydrophilic surface, and the water fl ux of MWNT-polyamide membranes improve dramatically. For 2000 ppm NaCl, the water permeability increases from 26 l/m 2 h without MWNTs to 71 l/m 2 h at the acidifi ed MWNTs loading of 0.1% (w/v), while NaCl rejection of MWNT-polyamide membranes decreases obviously compared to bare polyamide membrane. However, for 200 ppm purifi ed terephthalic acid (PTA) solution, the pure water fl ux increases from 19 l/m 2 h up to 49 l/m 2 h, while PTA rejection is all higher than 98%. The experimental results reveal that the modifi ed MWNTs well dispersed in the polyamide thin fi lm layer, and hence improve the water permeation.