Selective detection and quantification of Co2+ Ions by mesoscopic engineering silica-monolithic based circular optical strips

The presence of Co 2+ ions in water streams can pose severe health risks to humans due to their health impacts at high concentrations. As a result of its weak interaction with existing adsorbents, selective detection and removal of Co 2+ are challenging. To meet the global challenge, we engineered a mesoscopic silica monolithic architecture of hexagonal mesopores that can detect and remove Co 2+ ions from a wide range of water resources. The direct impregnation of the PDBDP azo-Schiff probe on MSM's surface resulted in strong selectivity for Co 2+ ions. Based on various characterization techniques, it was validated that the developed sensor material exhibits a high surface area and uniform pore structure, which can provide a high adsorption capacity and ultrafast sensing kinetics. A clear sensing mechanism was demonstrated using Job's plot, B-H method, and DFT calculation, showing strong interactions between Co 2+ ions and PDBDP imprinted MSM sensor. As a result of optimizing several physicochemical parameters, the naked-eye colorimetric sensing is accompanied by a desirable colour transition from pale yellow to dark red, with LOD and LOQ values of 0.09 & 0.31 ppb, and a linear concentration range of 5.0–150.0 ppb, respectively. Overall, this study provides comprehensive insights into mesoporous materials that remove Co 2+ pollutants from water bodies efficiently.