A solid-state chemical method for synthesizing MgO nanoparticles with superior adsorption properties.

As a traditional and effective adsorbent, MgO is a low-cost, eco-friendly, nontoxic, and economical material for wastewater treatment. However, multistep processing and the use of organic agents result in high costs and lead to environmental pollution, strongly inhibiting the practical application of MgO. Herein, a simple solid-state chemical route has been used to prepare small-sized MgO nanoparticles with a large specific surface area of 213 m 2 g -1 without using liquid solvents, template agents, or surfactants. This facile method is a green strategy that is suitable for large-scale production, avoiding complex preparation processes and serious environmental pollution. The obtained small-sized MgO nanoparticles showed a superior adsorption capacity of 2375 mg g -1 towards Congo red, originating from the large specific surface area and surface features (hydrogen bonds and electrostatic interactions). The adsorption behavior obeyed a pseudo-second-order rate equation and the Langmuir isotherm adsorption model. This study provides a route for the synthesis of oxides with large specific surface areas and obtained an adsorbent with superior adsorption capacity.