Detection of Cr(III), prometryn, and ibuprofen by hybrid Eu(III)–dipicolinate kaolinite luminescent sensor

Europium (III) was complexed on solids prepared by kaolinite functionalization with pyridine 2–carboxylic and pyridine 2,6–dicarboxylic acids; the luminescent properties of the obtained solids were analyzed for evaluating their application as luminescent sensors of prometryn, ibuprofen and chromium (III). The luminescent hybrid materials were characterized through powder X–ray diffraction, infrared absorption spectroscopy, thermal analysis, scanning electron microscopy, ultraviolet/visible absorption spectroscopy, energy dispersion and photoluminescence spectroscopy (excitation and emission) and lifetime measurements of the excited state. The materials proved to be promising, with quantum efficiencies of 31.16% and 45.18% for the samples functionalized with picolinic and dipicolinic acids, respectively. For the contaminant adsorption tests, the solid with picolinic acid showed better detection efficiency in a lower concentration range for chromium (III) than solids with dipicolinic acid, while both showed similar ranges for the organic contaminants.