Silica-based Materials for Mercury Detection and Removal: A Chelation-Free Solution

In this study, we introduce a chelation-free approach to the dual-functional detection and removal of Hg²⁺ ions using two novel silica-based materials, AnSiO₂ and PySiO₂, functionalized with anthracene and pyrene, respectively. These materials were synthesized via a two-step process involving the direct condensation of triethoxyvinylsilane onto silica gel surfaces, followed by Heck coupling with 9-bromoanthracene and 1-bromopyrene, respectively. They exhibit strong fluorescence emission in aqueous solutions, particularly at pH 6. Upon exposure to Hg²⁺ ions, both materials undergo significant fluorescence quenching, enabling sensitive and selective detection of Hg²⁺. PySiO₂ demonstrated superior performance compared to AnSiO₂, with a lower detection limit (0.29 μM) and a higher Stern-Volmer constant (2×10⁶ M^-1). Additionally, PySiO₂ shows a higher adsorption capacity for Hg²⁺, reaching 54.04mg/g, as confirmed by ICP-MS analysis. The sensing mechanism involves charge-dipole and π-electron interactions, supported by spectroscopic analyses. Reusable for four cycles, PySiO₂ effectively removes Hg²⁺ from aquaculture water, showcasing its potential for scalable, cost-effective, and simultaneous detection and remediation of mercury in real-world applications.