Electrochemical Degradation of Ethyleneamines Contained in Galvanic Baths on a BDD Electrode

Abstract

Ethylenediamine (EDA), diethylenetriamine (DETA) and N,N,N',N'-tetrakis (2-hydroxypropyl) ethylenediamine (THPrED) are used relatively often in galvanic processes. Tetra-substituted derivatives, such as N, N, N ', N'-tetrakis (2-hydroxyethyl) ethylenediamine, (THEtED) are quite biologically stable and hardly degradable. In recent years, much attention has been devoted to electrochemical oxidation, using anodes with a high over-potential of O2 evolution, such as the boron-doped diamond (BDD). DETA and THPrED electrochemical treatment using a BDD anode was herein studied. The degradation efficiency of the amines was evaluated under different current intensities and reaction times. To determine the products formed in the oxidation process, ion chromatography (IC) was used. A high decrease in the current between the first and the second CV scan indicated the polymer film formation on the BDD electrode surface. Hydroxyl radicals formed at a potential of about 2 V and higher caused further oxidation of the electrode reaction products. It was found that NH4, CH3-COOH, N2, EDA, CO2 and NO3were formed in a short reaction time, and at low current intensity. The mineralization occurred during substrates electrolysis, due to rapid DETA and THPrED decomposition. After 180 min of reaction, αTOC and αN values for DETA were 94% and 18%, respectively. For THPrED, αTOC was 98.6% and αN was 43.6%. Therefore, the electrochemical approach was considered a very promising method in practical application for the treatment of wastewater containing amines.