Adsorption Performances of Naked and 3-Aminopropyl Triethoxysilane-Modified Mesoporous TiO2 Hollow Nanospheres for Cu2+, Cd2+, Pb2+, and Cr(VI) Ions

Mesoporous hollow TiO2 nanospheres composed of anatase TiO2 nanoparticles were prepared by the sacrificial template method using methyl acrylic acid/styrene latex as the template. The mesoporous hollow TiO2 nanospheres were modified with 3-aminopropyl triethoxysilane (APTES) through the Ti-O-Si bonding. The adsorption of Cu2+, Cd2+, and Pb2+ ions on the naked and APTES-modified hollow TiO2 nanospheres followed the pseudo-second-order adsorption kinetics. According to the Langmuir adsorption isotherms, the maximum adsorption capacities of APTES-modified hollow TiO2 nanospheres for Cu2+, Cd2+, and Pb2+ ions were 12.7, 17.5, and 1.8 times those of naked hollow TiO2 nanospheres, respectively. When Cr(VI) was adsorbed on the surface of the APTES-modified hollow TiO2 nanosphere, the oxidation property of Cr(VI) decayed its adsorption.