Facile and Green One-Pot Hydrothermal Formation of Hierarchical Porous Magnesium Silicate Microspheres as Excellent Adsorbents for Anionic Organic Dye Removal

Uniform hierarchical porous magnesium silicate (Mg3Si4O10(OH)(2)) microspheres (diameter: 200-350 nm) assembled by ultrathin nanosheets are successfully fabricated through a facile and green one-pot hydrothermal method (140 degrees C, 12.0 h) without the aid of any organic additives or templates, using abundant MgCl2 center dot 6H(2)O, NH4Cl, NH3 center dot H2O, and Na2SiO3 center dot 9H(2)O as the raw materials. The as-formed porous microspheres possess a large specific surface area of 551.08 m(2) g(-1), a pore volume of 0.84 cm g(-1), and a mean pore diameter of 6.12 nm. On the basis of the effects of the hydrothermal parameters, a probable self-sacrificing template assisted formation mechanism of the Mg3Si4O10(OH)(2) microspheres is proposed. When utilized as adsorbents, the adsorption isotherms for methyl blue (MB) and Congo red (CR) are both well-fitted by the Langmuir adsorption model, with the maximum capacities for MB and CR as 1890 and 576 mg g(-1), respectively, superior to most of the referenced adsorbents. Meanwhile, the pseudo-second-order kinetic model and intraparticle diffusion model are also favorable to interpret the kinetic data and adsorption mechanism. Moreover, the recycling performance also indicates the as-formed porous microspheres as excellent adsorbents for removal of MB and CR with satisfactory reusability.