Coordination configurations of cupric tartrate in electronic industry wastewater

Abstract

The coordination structure of cupric tartrate (Cu—TA) complex was investigated by ultraviolet—visible (UV–Vis) and liquid chromatography/mass spectrometer (LC–MS) firstly; furthermore, effective coordination configurations and electronic properties of Cu—TA in aqueous solution were systematically revealed by density functional theory (DFT) calculations. Consistently, Job plots show the possible existence of [Cu(TA)] and [Cu(TA)2]2– at 230 and 255 nm based on UV–Vis results. LC–MS results confirm the existence of the single and high coordination complexes [Cu2(TA)2]+, [Cu(TA)2]+ and [Cu2(TA)3(H2O)2(OH)2]2+. DFT calculation results show that carboxylic oxygen and hydroxyl oxygen of tartaric acid (TA) are preferred sites for Cu(II) coordination. [Cu(TA)] (1H, 3H sites O of TA coordinated with Cu(II)), [Cu(TA)2]2– (two 1C, 2H sites O of TA coordinated with Cu(II)), and [Cu(TA)3]4– (three 2H, 3H sites O of TA coordinated with Cu(II)) should be dominant coordination configurations of Cu—TA. The corresponding Gibbs reaction energies are –170.1, –136.2, and –90.2 kJ/mol, respectively.