Highly efficient self-template synthesis of porous silica nanorods from natural palygorskite

A simple one-step hydrothermal acid-leaching process was employed to efficiently convert natural Pal to porous silica nanorods with a high SiO2 content and decent length of nanorods. At a lower acid concentration (2.0 mol/L), silica nanorods with the SiO2 content of 97.84% and a rod length equal to original length of Pal nanorods were obtained by this process; while only the products with lower SiO2 content of 79.92% were obtained by a normal acid-bleaching process. Although increasing acid concentration to 8.0 mol/L may enhance SiO2 content to 94.56% in normal acid-leaching process, which led to sharp reduction of length of nanorod. The synthesized porous silica nanorods have a specific surface area of 11939 m(2)/g, average pore size of 7.56 nm, and better whiteness (the L*, a* and b* values are 86.130, 0.131 and 2.801, respectively). This paper provided an effective, universal approach to produce silica nanomaterials from diverse natural clay minerals. (C) 2019 Elsevier B.V. All rights reserved.