Detection and adsorption of Hg2+ by new mesoporous silica and membrane material grafted with a chemodosimeter

Abstract

A novel organic–inorganic silica material (MCM-3T), prepared by covalent immobilization of the 2,1,3-benzothiadiazole-based chemodosimeter 3 and thiol group to the mesoporous silica material (MCM-48 type), was characterized by several spectroscopic methods. The MCM-3T shows excellent optical properties with a detection limit of ca. 8.0 × 10⁻⁶ M under optimized conditions and exclusively distinguishes the Hg²⁺ ion from other metal ions in aqueous solution. The MCM-3T can detect Hg²⁺ ion in a large pH range from 5.0 to 11.0, indicating its convenience for practical application. The MCM-3T is also an outstanding adsorbent for the removal of Hg²⁺ ion from aqueous solution. The adsorption process of Hg²⁺ ion on the MCM-3T is well described by the Freundlich isotherm equation and the equilibrium adsorption capacity is 234.88 mg g⁻¹. Furthermore, a new multifunctional silica membrane was synthesized on an alumina ceramic tube and characterized by SEM. The color and emission color of the membrane changed obviously and 90.7% of Hg²⁺ ion relative to the initial feed was removed after aqueous Hg²⁺ ion solution permeated through the membrane. This simple synthetic strategy, the economical starting materials, and the considerable signal changes exhibit a promising application of the MCM-3T and multifunctional silica membrane for the simultaneous detection and separation of Hg²⁺ ion in environmental and industrial fields.