Biomimetically synthesized luminescent Tb3+-doped fluorapatite/agar nanocomposite for detecting UO22+, Cu2+, and Cr3+ ions

Abstract

Radionuclides and heavy metal ions have become the main harmful pollutants in the environment. Developing sensitive and rapid methods to detect them from natural water or wastewater is important to reduce their exposure risks. In this study, a novel luminescent Tb³⁺-doped fluorapatite/agar nanocomposite (Tb-FAP/agar) has been synthesized via a facile and green synthetic route through an environmentally friendly biomineralization process using agar as a template. This nanocomposite is the first luminescent fluorapatite for detecting UO₂²⁺, Cu²⁺, and Cr³⁺ ions in water with high selectivity and sensitivity based on luminescence turn-off effects. The detection limits of the Tb-FAP/agar for UO₂²⁺ (7.95 nM), Cu²⁺ (3.94 nM), and Cr³⁺ (1.67 nM) are much lower than the permissible limits in drinking water defined by the United States Environmental Protection Agency (USEPA). Furthermore, the luminescence detection mechanisms for UO₂²⁺, Cu²⁺, and Cr³⁺ ions were speculated. Our study provides insight into developing biodegradable rare earth doped fluorapatite probes for the detection of both radioactive and nonradioactive ions.