Facile preparation of hydroxyl‑rich mesoporous magnesium silicate with excellent adsorption performance

The pollution of heavy metal ions and dyes in water pose a significant threat to the ecological environment and organismal health, and the development of effective adsorbents has attracted greatly attention. In the present work, hydroxyl‑rich mesoporous magnesium silicate (HMMS) with a high specific surface area of 472.9 m2/g was synthesized by a facile microwave-assisted solvothermal method for adsorption of Pb(II) ions and cationic dye methylene blue (MB) from water. HMMS particles were formed by the stack of nano-sized crystal and dense pores were formed between them. Adsorption experiments showed that HMMS exhibited fast adsorption speed and excellent adsorption capacity for Pb(II) ions (449.8 mg/g) and MB (467.3 mg/g). After six cycles, the adsorption performance of HMMS still remained above 92%. The adsorption data of HMMS for Pb(II) ions and MB were both well-fitted by the Langmuir isotherm model and pseudo-second-order kinetic model. Adsorption carried out at different initial pH values and FTIR analysis demonstrated that the adsorption mechanism of HMMS for Pb(II) ions and MB was the synergistic effect of electrostatic attraction and hydroxyl bonding. This work demonstrated that HMMS has significant potential in practical wastewater treatment.