Rational design of hierarchical macroporous–mesoporous magnesium silicate for highly efficient removal of organic dye and Pb2+

Abstract

A facile hydrothermal strategy has been developed to fabricate the hierarchical macroporous–mesoporous magnesium silicate (HMMgS) using macroporous siliceous foams (MOSF) as the silicon precursor and sacrificial template. The macroporous structure of HMMgS with a large surface area (565 m² g⁻¹) and high pore volume (0.94 cm³ g⁻¹) is reproduced from the template MOSF, which can provide various active sites for the adsorption of pollutants. The mesopores stem from the stacking of magnesium silicate nanosheets on the scaffold of MOSF, facilitating the mass transportation of contaminants to the interfaces. Consequently, the usage efficiency of active sites on the surface can be greatly enhanced. Therefore, HMMgS exhibits the excellent adsorption capacities of 602 mg g⁻¹ for methylene blue (MB) and 253 mg g⁻¹ for Pb²⁺. Besides, HMMgS also demonstrates extraordinary recyclability with easy separation by sedimentation, showing its promising potential in practical wastewater treatment.