Regeneration of activated carbon adsorbed EDTA by electrochemical method
(1. School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China;
2. National Engineering Research Center for Pollution Control of Heavy Metals, Changsha 410083, China;
3. Hunan Research Academy of Environmental Sciences, Changsha 410004, China;
4. China Machinery International Engineering Design & Research Institute Co., Ltd., Changsha 410007, China;
5. Changsha Nonferrous Metallurgy Engineering and Research Institute, Changsha 410011, China)
2. National Engineering Research Center for Pollution Control of Heavy Metals, Changsha 410083, China;
3. Hunan Research Academy of Environmental Sciences, Changsha 410004, China;
4. China Machinery International Engineering Design & Research Institute Co., Ltd., Changsha 410007, China;
5. Changsha Nonferrous Metallurgy Engineering and Research Institute, Changsha 410011, China)
Abstract: Activated carbon after saturated adsorption of EDTA was used as particle electrode in a three-dimensional electrode reactor to treat EDTA-containing wastewater. Electrochemical method was used to regenerate activated carbon after many times of electrolysis. Based on the analysis of infrared spectra of activated carbon after adsorption and repeated electrolysis, EDTA was degraded into glycine, and then non-catalytic activated associated complex was formed with N—H bond on the activated carbon. The catalytic ability of the activated carbon vanished and the EDTA degradation efficiency was dropped. Activated carbon could be effectively regenerated by electrochemical method in the three-dimensional reactor. Effects of electric current, conductivity and pH on activated carbon regeneration were investigated, and the optimum conditions were concluded as follows: 100-300 mA of current intensity, 1.39 mS/cm of electric conductivity, 60 min of electrolysis time and pH 6.0-8.0. Under the optimized conditions, the activity of the activated carbon can be recovered and the residual total organic carbon (TOC) was below 10 mg/L (the initial TOC was 200 mg/L) in the three-dimensional electrode reactor.
Key words: activated carbon; electrochemical regeneration; three-dimensional electrode; EDTA