A highly sensitive and selective sensor for trace uranyl (VI) ion based on a graphene-coated carbon paste electrode modified with ion imprinted polymer

Abstract Uranium is a kind of natural radionuclide, when the human body is exposed to higher uranium radioactive conditions, it will cause adverse effects on their health. Therefore, the analysis and detection of uranyl ions in the environment is a vital prerequisite for preventing uranium pollution. A bipolar bidentate ligand isophthalaldehyde-tetrapyrrole (IPTP) was first synthesized and a study was characterized by its structure and spectral properties. In the present work, an innovative electrochemical sensor by using IPTP as a ligand for uranyl (VI) ion (UO22+), α-methacrylic acid as functional monomer and uranyl (VI) ion as a template, a relatively stable structure was constructed by stirring at 35°C. Then, the polymer sol-gel was acquired by combining sol-gel processing under alkaline conditions, which was added dropwise to the surface of a carbon paste electrode (CPE) which had been modified with graphene (GR). The introduction of graphene allowed the reduction peak current of uranyl ions to be increased significantly. Under the optimum experimental conditions (pH=5 and the adsorption time=20 minutes), the ion-imprinted sensor was designed by adopting differential pulse voltammetry (DPV) for the sensing of uranyl (VI) ions. The detection technique successfully achieved the determination of uranyl ion in the concentration range 1.0 × 10−10 mol L−1 to 1.0 × 10−7 mol L−1, in practical soil samples with excellent repeatability and recovery (97.3%-102.9%).