CTAB-functionalized C@SiO2 double-shelled hollow microspheres with enhanced and selective adsorption performance for Cr(VI)

A novel cetyltrimethylammonium bromide (CTAB)-functionalized C@SiO2 with structure of double-shelled hollow microspheres (F-C@SiO2) was successfully synthesized by hydrolysis of tetraethyl orthosilicate (TEOS) on the carbonaceous hollow sphere (C). The as-prepared F-C@SiO2, C@SiO2 resulting from extracting CTAB from F-C@SiO2, and C were characterized comparatively by XRD, TGA-DSC, SEM, TEM, N-2 adsorption-desorption and zeta potential. Batch adsorption experiments show that the FC@SiO2 with CTAB functionalization presents the fastest adsorption kinetics and the highest adsorption capacity of 202.02 mg g(-1) towards Cr(VI) among the samples (161.81 mg g(-1) for C@SiO2 and 33.16 mg g(-1) for C, respectively). The adsorption mechanisms involving the electrostatic attraction and reduction reaction were also discussed. In addition, coexistence of the ion interference experiments show that the F-C@SiO2 has a highly selective adsorption capacity of 91.11 mg g(-1) towards Cr(VI) under a multiple system of Cr(VI), Cu2+, Cd2+, Zn2+, and Ni2+ with the concentration of 100 mg L-1, respectively. The successful decoration of the CTAB and the SiO2 onto the external surface of the hollow C spheres provides an effective method to develop promising composite for Cr(VI) removal from wastewater. (C) 2018 Elsevier B.V. All rights reserved.