Silver-decorated boron carbon nitride nanocomposite for ultra-fast dispersive micro-solid-phase extraction and preconcentration of mercury (II) in environmental waters.

This study presents a silver-decorated boron-carbon-nitride (Ag@BCN) nanocomposite for ultra-rapid dispersive micro-solid-phase extraction (d-µ-SPE) of Hg(II) in diverse water samples, followed by detection using cold-vapor atomic absorption spectrometry (CVAAS). The material integrates the high surface area of a mesoporous BCN support with the high selectivity of Ag nanoparticles (60-75 nm) for Hg(II) through spontaneous amalgamation, addressing the kinetic and environmental limitations of traditional organic chelating agents. The developed D-µ-SPE method reached quantitative extraction equilibrium in just one minute, offering a substantial improvement over most existing D-µ-SPE techniques. The developed method demonstrated excellent analytical performance, with a low LOD (0.067 ng/mL), a high adsorption capacity (54.5 mg/g), and good precision (RSD < 4.6 %) under optimal conditions (pH 4.0, 70 mg of adsorbent). Additionally, the Ag@BCN adsorbent showed recoveries from 94.8 % to 100.0 % even in complex matrices of up to 5 % NaCl, demonstrating its stability in high-ionic-strength matrices like seawater and river water. By combining ultrafast kinetics monitoring, high sensitivity, and a user-friendly interface in a D-µ-SPE format, this work presents an efficient alternative to traditional methods for routine screening and monitoring of mercury in environmental waters.