Industrial grade multiwalled carbon nanotubes (IG-MWCNTs) were functionalized with polyethylenimines (PEIs) for CO2 capture from simulated flue gas. Ethylenediamine end-capped PEI (PEI-EC) impregnated IG-MWCNTs was found to exhibit a significantly higher adsorption capacity than other branched PEIs impregnated IG-MWCNTs. The PEI-EC impregnated IG-MWCNTs were characterized with various experimental methods including N2 adsorption/desorption isotherms, X-ray diffraction, and thermogravimetric analysis. The CO2 adsorption behavior of the PEI-EC impregnated IG-MWCNTs is influenced by PEI loading and adsorption temperature. The PEI-EC impregnated IG-MWCNTs exhibit a CO2 adsorption capacity as high as 2.538 mmol/g at 343 K, and can be completely regenerated higher than 403 K. The CO2 adsorption/desorption kinetics of the PEI-EC impregnated IG-MWCNTs was investigated with Avrami’s fractional order kinetic model. The activation energy of the CO2 adsorption/desorption was calculated from Arrhenius equation and used to evaluate the performance of the adsorbent.

Ultraviolet (UV) light with a wavelength of 254 nm was applied to a double dielectric barrier discharge (DDBD) system to decompose of gaseous xylene. The results show that a significantly synergistic effect can be achieved with the introduction of UV light into the DDBD system. When UV light is applied, the system show a 21.8 % increase in its removal efficiency for xylene at 35 kV with an ozone concentration close to 971 ppmv. The COx (x = CO2 and CO) selectivity of outlet gas rises from 6.54 to 76.2 %. The optimal synergetic effect between UV light and DDBD can be obtained at a peak voltage of 30 kV. The system is robust for humidity, which only slightly reduces the xylene removal efficiency at a high peak voltage (30–35 kV). With the increase of gas flow rate, the removal efficiency for xylene decreases due to a reduced residence time. In addition, the products of xylene degradation were also analyzed. The major products of the degradation were found to be CO2 and H2O while byproducts such as O3 and HCOOH were observed as well.

Fe(II)EDTA is an effective absorbent for the integrated chemical absorption–biological reduction system in removing nitric oxide (NO) from flue gas. However, this absorbent is subject to some defects, such as oxidation by oxygen. In order to overcome this drawback, instead of using Fe(II)EDTA solely, a mixed absorbent containing both Fe(II)EDTA and Fe(II)Cit (Cit = citrate) is employed to absorb NO from simulated flue gas. The mixed absorbent not only shows a high NO absorption capacity similar to a Fe(II)EDTA absorbent, but also exhibits high NO absorption rate and good resistance to oxidation in simulated flue gas. This mixed absorbent can maintain 80% NO removal efficiency at 323 K for more than two hours at an inlet NO concentration of 670 mg·m–3, which is almost as effective as the Fe(II)EDTA absorbent at the same Fe(II) concentration. The oxidation rate constant of Fe(II) in the mixed absorbent is also slower than that in the Fe(II)EDTA absorbent. The optimal molar ratio of Fe(II)Cit to Fe(II)EDTA in the mixed absorbent was found to be 3:1. The effects of several key factors for NO removal, such as the inlet concentrations of NO (200–670 mg·m–3), O2 (1–6.5%), and SO32– (0–43 mg·L–1) and the pH of the mixed absorbent, have been studied. Interestingly, results seem to suggest that SO32– is beneficial for the removal of NO in the system. These findings provide fundamental data for the design of NO removal system for industrial applications with mixed Fe(II)EDTA/Fe(II)Cit absorbent.