RESUMO
Ionic liquids (ILs) are considered to be potential material devices for CO2 capturing and conversion to energy-adducts. They form a cage (confined-space) around the catalyst providing an ionic nano-container environment which serves as physical-chemical barrier that selectively controls the diffusion of reactants, intermediates, and products to the catalytic active sites via their hydrophobicity and contact ion pairs. Hence, the electronic properties of the catalysts in ILs can be tuned by the proper choice of the IL-cations and anions that strongly influence the residence time/diffusion of the reactants, intermediates, and products in the nano-environment. On the other hand, ILs provide driving force towards photocatalytic redox process to increase the CO2 photoreduction. By combining ILs with the semiconductor, unique solid semiconductor-liquid commodities are generated that can lower the CO2 activation energy barrier by modulating the electronic properties of the semiconductor surface. This mini-review provides a brief overview of the recent advances in IL assisted thermal conversion of CO2 to hydrocarbons, formic acid, methanol, dimethyl carbonate, and cyclic carbonates as well as its photo-conversion to solar fuels.
RESUMO
An alternative activated biochar was developed from barley malt bagasse (BMB) through pyrolysis followed by CO2 activation. The materials BMB, biochar and activated biochar (CO2-biochar) were characterized and tested as adsorbents for the removal of methylene blue (MB) from aqueous solutions. Adsorption kinetics, equilibrium and thermodynamics were studied. It was found that BMB and biochar presented surface area values lower than 1â¯m2 g-1, while CO2-biochar was a typical mesoporous material with surface area around 80â¯m2 g-1. As consequence, the adsorption potential for methylene blue was in the following order CO2-biocharâ¯â«â¯biocharâ¯>â¯BMB. Adsorption kinetics of MB on CO2-biochar followed the pseudo-second order model. Langmuir presented the best fit with the equilibrium adsorption isotherms. The maximum adsorption capacity was 161â¯mgâ¯g-1. MB adsorption on CO2-biochar was spontaneous, favorable and exothermic. Pyrolysis followed by CO2 activation was a suitable route to produce an alternative mesoporous adsorbent from barley malt bagasse.