Highly Sensitive Adsorption and Detection of Iodide in Aqueous Solution by a Post-Synthesized Zirconium-Organic Framework

Effective methods of detection and removal of iodide ions (I(−)) from radioactive wastewater are urgently needed and developing them remains a great challenge. In this work, an Ag(+) decorated stable nano-MOF UiO-66-(COOH)(2) was developed for the I(−) to simultaneously capture and sense in aqueous solution. Due to the uncoordinated carboxylate groups on the UiO-66-(COOH)(2) framework, Ag(+) was successfully incorporated into the MOF and enhanced the intrinsic fluorescence of MOF. After adding iodide ions, Ag(+) would be produced, following the formation of AgI. As a result, Ag(+)@UiO-66-(COOH)(2) can be utilized for the removal of I(−) in aqueous solution, even in the presence of other common ionic ions (NO(2)(−), NO(3)(−), F(−), SO(4)(2−)). The removal capacity as high as 235.5 mg/g was calculated by Langmuir model; moreover, the fluorescence of Ag(+)@UiO-66-(COOH)(2) gradually decreases with the deposition of AgI, which can be quantitatively depicted by a linear equation. The limit of detection toward I(−) is calculated to be 0.58 ppm.