Experimental and theoretical studies of sodium acetyldithiocarbamate for the removal of Cu²⁺ and Ni²⁺ from aqueous solution

With the continuous worsening of water pollution, the use of various collectors to remove heavy metal ions from aqueous solutions has attracted widespread attention. In this work, an acid-resistant collector, sodium acetyldithiocarbamate (ADTC) that combines acetamide with carbon disulfide was proposed for heavy metal removal. The structure of ADTC was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectrometer (NMR). Flame atomic absorption spectrophotometry (FAAS) was used to detect the concentration of metal ions in the solution before and after the treatment of the chelating agents. The chelation removal efficiency are compared for different chelating agents for Cu²⁺ and Ni²⁺ in acidic aqueous solution with pH = 1–7, and compared to the chelation removal efficiency of sodium diethyldithiocarbamate (DDTC) and sodium ethyl xanthate (SEX) chelating agents. The experimental results suggest the order of the chelating ability is ADTC > DDTC > SEX for Cu²⁺ and Ni²⁺. The chelating ability of ADTC to Ni²⁺ is stronger than that of Cu²⁺. The chelating ability of the collector is greatly affected by the pH value. The ADTC has a good chelating ability in the pH range of 3–7. The molecular orbital distribution, charge and electrostatic potential surfaces in quantum chemistry are used to explore the main active sites of the chelating agent are the S atom. The results of high resolution mass spectrometry showed that the ADTC is coordinated with the positive divalent metal ion in the ratio of 2:1. According to the results, the dithioamino (–NHCSS⁻) groups are coordinated with the positive divalent metal ion in a 2:1 ratio. Molecular dynamics simulation is used to explore the adsorption energy and binding strength of the chelating agent on the metal surface.