Synthesis, characterization and adsorption/sensing applications of novel cadmium(II) based coordination polymer

Abstract

In this study, new luminescent coordination polymers containing cadmium ions, 1,10-phenanthroline and benzene-1,3,5-tricarboxylic acid ligands were synthesised under hydrothermal conditions. The structure of the synthesised Cd(II) CPs was investigated by X-ray diffraction, scanning electron microscope, matrix-assisted laser desorption ionisation mass spectrometry, elemental analysis, thermogravimetric analysis and Fourier transform infrared spectroscopy. In addition, the adsorption and sensing applications of Cd(II) CPs were investigated. The removal of diclofenac, an organic micropollutant, from aqueous systems was investigated for the adsorption application of Cd(II) CPs. The adsorption isotherms fitted the Langmuir model better than the Freundlich model. Adsorption equilibrium was reached after 240 min at pH 6.5 and 298 K, resulting in a maximum adsorption capacity of 1822 mg/g. In the other analytical application of Cd(II) CPs, the detection of Cu2+ and Ni2+ cations in aqueous medium was investigated based on their fluorescence properties. According to the results Cd(II) CPs have better sensitivity and selectivity. The fluorescence intensity of Cd(II) CPs decreased linearly due to the quenching mechanism. The KSV values were calculated to be 1.82 × 108 M−1 for Cu2+ and 8.2 × 108 M−1 for Ni2+. The limits of detection Cu2+ and Ni2+ cations for Cd(II) CPs were calculated to be 2.78 × 10−8 and 6.15 × 10−9 M, respectively. The detection of Cu2+ and Ni2+ ions was performed with a fast response, a wide linear range and a very low detection limit and could be used on real water samples without any matrix interference.