Ligand-modified eggshells for rapid naked-eye detection and removal of trace level Ni²⁺ ions

The global disposal of approximately 8 million tons of eggshell waste each year poses a significant environmental challenge. Nevertheless, this waste can be transformed into novel materials with various industrial applications. Herein, we have prepared a sustainable composite material modified with a ligand dimethyl glyoxime (DMG) by simple immobilization on a porous eggshell surface. The proposed composite material (DMG@ES) demonstrated remarkable Ni2+ ion visual detection by the naked eye with a detection limit as low as 1.7 mu g L-1, while also boasting a swift response time. Importantly, the composite was highly selective towards the detection of Ni2+ ions due to strong affinity between Ni2+ ions and the ligand modified composite material. This stable composite presents a straightforward, efficient, and cost-effective method for sensitive, rapid, and specific optical detection of a wide range of concentrations of Ni2+ ions. Hence, the prepared composite material with tested practical applicability can potentially be up-scaled for commercial purposes, particularly in the field of environmental monitoring.