Morphology-engineered porous MgO for efficient CO2 capture and ciprofloxacin removal.

The adsorption properties of MgO are predominantly determined by its structure and morphology. A porous structure endows MgO with high specific surface area and porosity, thereby enhancing mass diffusion and adsorption. However, conventional synthesis methods for porous MgO are usually expensive, noxious, or time-consuming, and typically lack precise modulation over the porous structure. Consequently, developing a facile and cost-effective approach for fabricating porous MgO is of critical importance. In this study, porous flower-like (F-MgO) and hexagonal flake MgO (NP MgO) were synthesized via a simple and efficient microwave-assisted hydrothermal method using cheap inorganic reagents for adsorbing CO2 and ciprofloxacin (CIP). Meanwhile, MgO structures were precisely regulated and analyzed through various characterization methods. Compared with NP MgO, F-MgO exhibited a higher specific surface area, smaller crystallite size, and more abundant active sites, thus showing a higher CO2 capture capacity and CIP removal efficiency. Moreover, F-MgO showed a CO2/N2 selectivity exceeding NP MgO and featured a high cycling stability. The adsorption of CO2 capture and CIP by F-MgO and NP MgO followed pseudo-first and pseudo-second-order kinetic models and the Freundlich isotherm model. The existence states of CO2 and CIP on MgO were confirmed by in situ and conventional Fourier transform infrared spectroscopy, suggesting that the adsorption of CO2 and CIP on both MgO structures was mainly dominated by chemisorption, supplemented by physisorption. This study provides a strategy for designing and preparing cost-effective and efficient porous MgO adsorbents, offering significant advantages for practical environmental remediation.