CO2 and CO Capture on the ZnO Surface: A GCMC and Electronic Structure Study.

The amount of polluting gases released into the atmosphere has grown drastically. Among them, it is possible to cite the release of CO2 and CO gases on a large scale as one of the products of the complete and incomplete combustion of petroleum-derived fuels. It is worth noting that the production of energy by burning fossil fuels supplies the energy demand but causes environmental damage, and several studies have addressed the reduction. One of them is using materials with the potential to capture these gases. The experimental and theoretical studies have significant contributions that promote advances in this area. Among the materials investigated, ZnO has emerged, demonstrating the considerable potential for capturing various gases, including CO2 and CO. This work used density functional theory (DFT) and Grand Canonical Monte Carlo Method (GCMC) to investigate the adsorption of CO2 and CO on the surface of Zinc oxide (ZnO) to obtain adsorption isotherms and interaction energy and the interaction nature. The results suggest that CO2 adsorption slightly changed the angle of the O-C-O to values less than 180°. For the CO, its carbon atom interacts simultaneously with Zn and O of the ZnO surface. However, CO interactions have an ionic character with a lower binding energy value than the CO2 interaction. The energies calculated using the PM6 and DFT methods generated results compatible with the experimental values. In applications involving a mixture of these two gases, the adsorption of CO2 should be favored, and there may be inhibition of the adsorption of CO for high CO2 concentrations.

GCMC and electronic evaluation of pesticide capture by IRMOF systems.

Environmental contamination by pesticides is a recurrent problem, and a way to minimize its impacts and provide the reduction of contaminants already in the environment is a challenge. In this context, porous materials such as metal-organic frameworks (MOFs) have gained prominence. MOFs can carry the pesticide when physically or chemically interacting with its pore sites, enabling pesticide capture. However, evaluating the best MOF to maximize the process is an important step that can be performed under computer simulation. This work used grand canonical Monte Carlo simulations to assess the interaction between glyphosate, atrazine, acephate, and dichlorodiphenyltrichloroethane pesticides with the structures of IRMOF-1, IRMOF-8, IRMOF-10, and IRMOF-16. These MOFs present several organic unit types, which generate different pore volumes with similar chemical environment. For glyphosate, atrazine, and acephate, a direct relationship was shown between the pore volume and the amount of captured pesticide, which is a direct contribution from the strong interaction between the pesticides. Higher pore volumes maximize glyphosate, atrazine, and acephate capture. Otherwise, for dichlorodiphenyltrichloroethane, the larger the pore volume, the smaller the amount of pesticide is loaded. The interaction between all pesticides and IRMOFs is mainly governed by van der Waals contribution, being more pronounced for glyphosate, atrazine, and acephate molecules.