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The treatment of NOx from automotive gas exhaust has been widely studied, however the presence of low concentrations of NOx in confined areas is still under investigation. As an example, the concentration of NO2 can approximate 0.15 ppmv inside vehicles when people are driving on highways. This interior pollution becomes an environmental problem and a health problem. In the present work, the abatement of NO2 immission is studied at room temperature. Three activated carbons (ACs) prepared by physical (CO2 or H2O) or chemical activation (H3PO4) are tested as adsorbents. The novelty of this work consists in studying the adsorption of NO2 at low concentrations that approach real life immission concentrations and is experimentally realizable. The ACs present different structural and textural properties as well as functional surface groups, which induce different affinities with NO2. The AC prepared using water vapor activation presents the best adsorption capacity, which may originate from a more basic surface. The presence of a mesoporosity may also influence the diffusion of NO2 inside the carbon matrix. The high reduction activity of the AC prepared from H3PO4 activation is explained by the important concentration of acidic groups on its surface. [ABSTRACT FROM AUTHOR]

Nickel and copper supported activated carbon (Ni/AC, Cu/AC) prepared by wetness impregnation process were used in the heterogeneous ozonation of nitrobenzene in water. The effect of the preparation conditions on catalysts characteristics was examined in order to optimize the metals content, the temperature and the calcination time. The two catalysts were characterized on the ground of Brunauer-Emmett-Teller adsorption isotherm application, through Fourier transform infrared spectroscopy, temperature programmed-desorption mass spectrometry, Boehm analysis and point of zero charge analysis. It was found that the catalyst properties and the functional surface groups were affected by the operating conditions. The maximum specific surface area of the catalysts was obtained when 12% (w/w) of Cu or 4% (w/w) of Ni were deposited on activated carbon and calcined at 550°C for 2 h. The effect of Cu and Ni addition to the activated carbon on nitrobenzene adsorption capacity was also examined. The results showed that the activated carbon adsorption capacity was improved through impregnation. The tests carried out in a semi-batch reactor showed that the presence of AC, Ni/AC or Cu/AC catalyst enhanced considerably the degradation efficiency in respect to nitrobenzene and improved significantly its mineralization when compared to the process of its ozonation in absence of a catalyst. TOC removal reached 86%, 80%, 69% in the course of ozonation (an ozone flow rate of 30 mg/h) of 20 mg/l nitrobenzene for 60 min oxidation time in the presence of Cu/AC, Ni/AC, AC catalyst, respectively. TOC was 25% in absence of a catalyst. Cu/AC exhibited the highest catalytic activity. [ABSTRACT FROM AUTHOR]

A chemical-activated carbon (CAC) was prepared by phosphoric acid activation of olive stone. The CAC was characterized using various analytical techniques and evaluated for the removal of amoxicillin from aqueous solutions under different operating conditions (initial concentration, 12.5-100 mg L, temperature, 20-25 °C, contact time, 0-7000 min). The CAC characterization indicates that it is a microporous carbon with a specific surface area of 1174 m/g and a pore volume of 0.46 cm/g and contains essentially acidic functional groups. The adsorption tests indicated that 93 % of amoxicillin was removed at 20 °C for 25 mg L initial concentration. Moreover, it was found that adsorption capacity increased with contact time and temperature. Kinetic study shows that the highest correlation was obtained for the pseudo-second-order kinetic model, which confirms that the process of adsorption of amoxicillin is mainly chemisorption. Using the intraparticle diffusion model, the mechanism of the adsorption process was determined. The equilibrium data analysis showed that the Sips and Langmuir models fitted well the experimental data with maximal adsorption capacities of 67.7 and 57 mg/g, respectively, at 25 °C. The chemical-activated carbon of olive stones could be considered as an efficient adsorbent for amoxicillin removal from aqueous solutions. [ABSTRACT FROM AUTHOR]