PNIPAm grafted amino-functionalized mesoporous silica for thermo-responsive chromium elimination

In this study, the effective elimination of Cr(VI) was achieved by thermo-responsive polymergrafted amino-functionalized mesoporous silica (MS@APTES@PNIPAm) in aqueous solution. The MS@APTES@PNIPAm was successfully synthesized by the coupling of 3-MOP and N-isopropyl acrylamide (NIPAm) in 3-aminoproyltriethoxysilane (APTES) grafted mesoporous silica surface. The thermoresponsive elimination of Cr(VI) was demonstrated at various pH levels and at room temperature and 40 degrees C, respectively. The characterization of the synthesized materials was achieved by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and nitrogen (N-2) adsorption-desorption. The maximum adsorption of hexavalent chromium on MS@APTES@PNIPAm in aqueous solution was 123.8 mg g(-1) at 40 degrees C in pH 2.5. Furthermore, the results of isotherm and kinetic experiments demonstrated that the adsorption behavior of Cr(VI) on MS@APTES@PNIPAm was well fitted to a Langmuir plot with a pseudo-second-order and intra-particle diffusion model. (C) 2017 Elsevier B.V. All rights reserved.