Marjan Tanzifi; Mohsen Jahanshahi; Majid Peyravi; Soodabeh Khalili
Abstract
Dye-containing wastewater is a major pollutant that can irreversibly damage the environment. Ultrafiltration membrane technology combined with photocatalysis is used for treatment of dye-containing solutions. To remove dye pollution, Methylene blue (MB) and Congo red (CR), graphitic carbon nitride (CNG) ...
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Dye-containing wastewater is a major pollutant that can irreversibly damage the environment. Ultrafiltration membrane technology combined with photocatalysis is used for treatment of dye-containing solutions. To remove dye pollution, Methylene blue (MB) and Congo red (CR), graphitic carbon nitride (CNG) and its zirconium dioxide nanocomposite (CNGZ) were used in the photocatalytic dynamic membrane system in both self-forming and pre-coated modes under household LED light. The filtration results of the self-forming membrane showed that the pure CNG- and nanocomposite-based photocatalytic membrane systems were more efficient for MB and CR dyes removal than the photocatalytic system in batch mode. In addition to improving dye molecule removal efficiency, adding the photocatalyst to the PES membrane also significantly increased water flux. Moreover, the respective MB and CR rejection rates were 29% and 47% for the pure PES membrane and 89% in 120 min and 100% in 80 min for the CNGZ-based photocatalytic membrane. This suggests that the photocatalytic membrane system is a more effective dye pollution remover than the pure PES. For comparison, the pre-coated dynamic membrane system used for MB dye removal was good for removing 98.6% within 20 min. The results suggest that CNGZ-based photocatalytic dynamic membrane is a promising technology for increasing dye molecules removal efficiency and flux in remediation of dye-containing wastewater.
Soodabeh Khalili; Mohsen Jahanshahi
Abstract
The objective of this work is to develop a cost-effective carbonaceous CO2 adsorbent. N-doped porous carbon (NDC) with nano- pore size was synthesized by KOH activation of nano polyaniline (PANI). PANI synthesized in this work has thin nanofibrillar morphology with different lengths and diameters. The ...
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The objective of this work is to develop a cost-effective carbonaceous CO2 adsorbent. N-doped porous carbon (NDC) with nano- pore size was synthesized by KOH activation of nano polyaniline (PANI). PANI synthesized in this work has thin nanofibrillar morphology with different lengths and diameters. The activation process was carried out at 800 °C with KOH/precursor ratio of 2. This adsorbent of carbon exhibits high CO2 adsorption capacity of 1.9 mmol/g at 25 °C under atmospheric pressure. The morphology of PNCs is investigated through different technical methods, such as scanning electron microscopy (SEM), N2 adsorption isotherm at 77 K and Fourier transform infrared spectroscopy (FTIR). The CO2 adsorption experiments were done at three different temperatures (298, 308, and 318 K) and pressures up to 10 bar, and correlated with the Langmuir, Freundlich, and Sips models. The Sips isotherm model presented the best fit to the experimental data. Small values of isosteric heat of adsorption were evaluated based on Clausius–Clapeyron equation showed the physical nature of adsorption mechanism. The high amount of CO2 capture by nano- pore size NDC renders it as a promising carrier for practical applications such as gas separation.
Soodabeh Khalili; Ali Asghar Ghoreyshi; Mohsen Jahanshahi; Behnam khoshandam
Abstract
Multiwalled carbon nanotubes (MWCNT) were found to be an effective separation media for purifing CO2 from O2. Significant uptakes of CO2 and O2 were measured at 288 K, 298K and 308 K over the pressure range of 1 to 40 bar using volumetric method in dual sorption vessels. The same shape of isotherms ...
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Multiwalled carbon nanotubes (MWCNT) were found to be an effective separation media for purifing CO2 from O2. Significant uptakes of CO2 and O2 were measured at 288 K, 298K and 308 K over the pressure range of 1 to 40 bar using volumetric method in dual sorption vessels. The same shape of isotherms introduced a common mechanism of adsorption but the amount of CO2 adsorbed on MWCNT is 2 times higher than O2 adsorption. The mass uptake of CO2 and O2 by MWCNT was found to increase with increasing pressure and decreasing temperature. The experimental data was well fitted by the Langmuir and Freundlich model isotherms considering the values of regression correlation coefficients. Following a simple acidic treatment procedure, CO2 and O2 adsorption was increased over range of pressure. The adsorbents was characterized by N2 adsorption isotherm at 77 K, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The effect of temperature and pressure on selectivity obtained from IAST demonstrated that maximum selectivity over the pressure and temperature ranges p = 0.5-5 bar and T = 298–308 K was achieved at 308 K and 5 bar.