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The performance of gas-liquid membrane contactor for CO 2 capture was investigated using a novel polysulfone (PSF) flat membrane prepared via non-solvent phase inversion method. Polyvinyl pyrrolidone (PVP) was used as an additive in the dope solution of PSF membranes. Morphological studies by scanning electron microscopy (SEM) analysis revealed that PSF membrane with PVP has a finger-like structure, but the PSF membrane without PVP has a sponge-like structure. Also, characterization results through atomic force microscopy (AFM) and contact angle measurement demonstrated that the porosity, surface roughness and hydrophobicity of the PSF membrane increased with addition of PVP to the dope solution. Mass transfer resistance analysis, based on CO 2 absorption flux, displayed that addition of PVP to the dope solution of PSF membrane decreased membrane mass transfer resistance, and significantly improved CO 2 absorption flux up to 2.7 and 1.8 times of absorption fluxes of PSF membrane without PVP and commercial PVDF, respectively.

The paper reports the first attempt at the method of changing cooling treatment of synthesizing in order to investigate its effect on the physical properties of sol-gel derived nano-bioactive glass-ceramics in the system 58SiO 2 -33CaO--9P 2 O 5 (wt.%). We hypothesized that the method of cooling may affect the properties of nano-bioactive glass-ceramics. To test this hypothesis, two different methods of cooling treatment were applied after calcinations in the synthesis. Both quenched and unquenched nano-bioactive glass-ceramics were soaked in Ringer's solution with bovine serum albumin (BSA) for bioactivity evaluation. The obtained samples were analyzed for their composition, crystallinity and morphology using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), surface electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM images showed that the morphology of nano-bioactive glass-ceramics was completely changed by the quenching process. The results of in vitro bioactivity evaluation revealed that the unquenched sample attained faster apatite formation ability than the quenched sample. Other properties of these two morphologically different nano-bioactive glass-ceramics are discussed.

In this study, adsorption of methane as the main constituent of natural gas was firstly studied on the pristine multi-walled carbon nanotubes (MWCNTs) and then purification and chemical treatments of MWCNTs was performed to enhance the natural gas adsorption capacity. MWCNTs were chemically treated using different methods in this research. The results revealed that chemical treatment of the MWCNTs in presence of H2SO4/HNO3 acidic mixture in 3:1 volume ratio, enhanced considerably natural gas adsorption capacity (an optimal up to 45 mmol/g) at temperature of 298.15 K and the pressure of 50 bar compared to the pristine MWCNTs (about 27 mmol/g) at the same operating conditions. This effect can be attributed to the opening of the nanotubes caps with a major alteration in its structural properties due to chemical treatment. The experimental data of adsorption were almost equally well described by Langmuir, Freundlich and Sips equations to determine the model isotherms. The best fit was obtained by the Sips model isotherm with the r-squared value near to unity. Furthermore, using the experimental data obtained in different temperatures the isosteric heat of natural gas adsorption onto pristine MWCNTs was also calculated in the interested range of pressures and temperatures using the thermodynamic-based Clausius-Clapeyron equation from the Sips isotherm model. The results revealed an energetically heterogeneous surface of MWCNTs in natural gas adsorption. Also the natural gas adsorption process was kinetically studied through pseudo-second order and intra-particle diffusion models which indicated the intra-particular diffusion is rate limiting step in adsorption of methane on MWCNTs

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