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.