Degradation of chelating Cu(II)-ethylenediaminetetraacetic acid wastewater and its reaction mechanism by tourmaline/H2O2 system

The treatment of wastewater containing Cu(II)-ethylene diamine tetraacetic acid (EDTA) was investigated. The degradation process and mechanism were discussed as well. The results show that tourmaline has higher treatment efficiency compared with elbaite. The decreasing rates of the chemical oxygen demand and the removal rate of Cu2+ ions increase with the increase of tourmaline addition and the decrease of the particle size. The largest removal rate is found at pH=3. Ultraviolet-visible spectra show that the structure of chelating Cu(II)-EDTA decomposes to low-molecular organic material. The tourmaline and degradation products of EDTA chelate in the degradation manifest as a color change of the wastewater. The reaction of tourmaline/H2O2 is similar to the Fenton reaction. Additionally, the generation of dissolved oxygen and control of the pH are both key factors of degradation.