Compositional Analysis of Nickel(II)-Aminopolycarboxylic Acids Using UV-Vis Spectrophotometry

Chelating agents, particularly aminopolycarboxylic acids (APCAs) such as ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and nitrilotriacetic acid (NTA), are extensively employed across various industries, including agriculture, metallurgy, food processing, pharmaceuticals, and nuclear sectors. This is largely due to their exceptional ability to bind metal ions, effectively reducing their reactivity. However, this strong affinity also poses significant environmental challenges, including the potential for persistent contamination in aquatic systems. When used for chelating radioactive contaminants, the resulting complexes exhibit notable stability, potentially leading to prolonged environmental presence and radiological pollution risks. This study employs UV-Vis spectrophotometry to investigate the speciation of Ni-APCA complexes across different concentrations and pH levels, revealing insights into their structural dynamics and interactions. We found that while Ni-EDTA complexes are highly stable across a wide pH range, Ni-NTA and Ni-DTPA complexes exhibit significant structural variability. Understanding these dynamics is crucial for developing effective nuclear waste management strategies and enhancing analytical methods for APCA quantification. This research offers foundational knowledge to optimize APCA applications in decontamination processes.