The emission of CO2 from power plants that burn fossil fuels is the major cause of the accumulation of CO2 in the atmosphere. The separation of CO2 from CO2/air mixtures can play a key role in alleviating this problem. This separation can be carried out by using suitable adsorbents, such as carbon molecular sieves. In this work, a CMS was prepared by deposition of polyfurfuryl alcohol polymer on activated carbon. After deposition of the polymer, the material was carbonized at 800ºC for 2 hours. This material was used to separate O2/N2 mixtures and CO2 in a fixed bed at room temperature. Experimental breakthrough curves obtained were fitted to theoretical models in order to establish the main mechanisms of mass transfer. The breakthrough curves showed that it is possible to separate O2, N2 and CO2. The shape of the breakthrough curves was not influenced by the total flow, indicating that the gas contact for the gas mixture was good. The experimental data were fitted to theoretical models and it was established that the main mechanism of mass transfer was intraparticle diffusion.

The thermodynamics and kinetics of adsorption of reactive dyes on high-ash char was studied. Equilibrium data were obtained using the static method with controlled agitation at temperatures in the range of 30 to 60ºC. The Langmuir isotherm model was used to describe the equilibrium of adsorption, and the equilibrium parameters, R L, in the range of 0 to 1 indicate favorable adsorption. The amount of dye adsorbed increased as temperature increased from 30 to 40ºC, but above 40ºC the increase in temperature resulted in a decrease in the amount of dye adsorbed. The kinetic data presented are for controlled agitation at 50 rpm and constant temperature with dye concentrations in the range of 10 ppm to50 ppm. The film mass transfer coefficient, Kf, and the effective diffusivity inside the particle, De, were fitted to the experimental data. The results indicate that internal diffusion governs the adsorption rate.

The use of nonconventional adsorbents, particularly those that can be easily regenerated, to replace activated carbon in the removal of color from dye wastewaters has been recently proposed. This work shows a thermodynamic and kinetic study of the adsorption of reactive dyes (yellow monochlorotriazine and yellow dichlorotriazine), in liquid phase, on commercial alumina. The basic thermodynamic data were obtained using the static method, with a thermostatic bath at four different temperatures (30, 40, 50 and 60oC) and different pH values. The kinetic data were obtained by adding a known quantity of adsorbent to a dye solution at a constant temperature and under controlled stirring conditions. It was possible to draw the uptake curves, using the effects of the stirring on the adsorption rate. The intraparticle effective diffusivity was estimated using the film and pore diffusion model. The results were compared with the data obtained using a commercial activated carbon.