Mesoporous hollow silica shells modified with functional diamine groups show high-performance absorption capacity and selective colorimetric response to copper ions in aqueous solutions

High-performance measurement and removal of copper ions is highly desirable in both clinical and environmental applications. Herein, an efficient, reliable and recyclable functional material was prepared to adsorb and determine Cu2+ using N-[3-(trimethoxysilyl) propyl] ethylenediamine modified mesoporous hollow shells (HMS-NHs). By stepwise coating with mesoporous silica at highly mono-dispersed PS spheres, removal of template materials, and modification with functional diamine groups, higher absorption capacity of about 138.58 mg/g was obtained. After optimization of PS template size, thickness of SiO2 layers, pore size of the shell, and etc, as-prepared HMS-NHs gave clear colorimetric response after color development using cupron solution. Selectively measure Cu2+ in a wide concentration ranges from 0.025 to 49 μΜ was observed with a detection limit around 0.025 μΜ (3δ). More importantly, the functional absorbent can be regenerated by treatment with hydrochloric acid and maintains high efficiency upon repeated use for at least 10 times. Extensive investigation demonstrated that the HMS-NHs can serve as not only high-performance absorption materials but also sensitive sensor for Cu2+, thus offering a good alternative for potential removal and detection of copper ions in real applications.