Interaction between Diethyldithiocarbamate and Cu(II) on Gold in Non-Cyanide Wastewater

A surface-enhanced Raman scattering (SERS) detection method for environmental copper ions (Cu(2+)) was developed according to the vibrational spectral change of diethyldithiocarbamate (DDTC) on gold nanoparticles (AuNPs). The ultraviolet-visible (UV-Vis) absorption spectra indicated that DDTC formed a complex with Cu(2+), showing a prominent peak at ~450 nm. We found Raman spectral changes in DDTC from ~1490 cm(−1) to ~1504 cm(−1) on AuNPs at a high concentration of Cu(2+) above 1 μM. The other ions of Zn(2+), Pb(2+), Ni(2+), NH(4)(+), Mn(2+), Mg(2+), K(+), Hg(2+), Fe(2+), Fe(3+), Cr(3+), Co(2+), Cd(2+), and Ca(2+) did not produce such spectral changes, even after they reacted with DDTC. The electroplating industrial wastewater samples were tested under the interference of highly concentrated ions of Fe(3+), Ni(2+), and Zn(2+). The Raman spectroscopy-based quantification of Cu(2+) ions was able to be achieved for the wastewater after treatment with alkaline chlorination, whereas the cyanide-containing water did not show any spectral changes, due to the complexation of the cyanide with the Cu(2+) ions. A micromolar range detection limit of Cu(2+) ions could be achieved by analyzing the Raman spectra of DDTC in the cyanide-removed water.