Preparation of aerogel Mg(OH)2 nanosheets by a combined sol–gel-hydrothermal process and its calcined MgO towards enhanced degradation of paraoxon pollutants

The preparation of MgO nanoparticles with relatively small sizes and highly active surface areas is still a great challenge nowadays. The principal objective of this work was to investigate and optimize the calcined conditions of MgO with smaller sizes and higher surface areas, which contributed to its better degradation ability towards paraoxon pollutants. Firstly, the aerogel Mg(OH)2 nanosheets with an increased surface area of 349.0 m2/g was prepared via a combined sol–gel-hydrothermal method. Then the calcined MgO nanoparticles with different morphology, size dimensions, and specific surface areas were obtained at different calcination temperatures from 400 to 800 °C. The optimized average grain size of MgO obtained at 600 °C was achieved to 8.7 ± 3.2 nm with a relatively high surface area up to 231.4 m2/g. Meanwhile, such as-prepared MgO nanoparticles showed an excellent performance towards paraoxon degradation, and the maximum degradation amount of paraoxon-ethyl was up to 57.8 mg/g@90 min at room temperature. The kinetics of degradation was consistent with the pseudo-second-order model (R2 > 0.99). Such excellent degradation capacity was derived from more generations of superoxide radical (•O2−) sites as revealed by using the nitro blue tetrazolium (NBT) as a probe. The results indicated that the MgO nanoparticles reported herein could be an effective candidate for the environmental remediation of organophosphorus toxin pollutants due to their facile scale-up, low cost, eco-friendly characteristic, and high removal efficiency.