Recovery of organics from aspartame effluents with electrodialysis

摘要

In the process for producing aspartame, a great deal of effluents containing sodium chloride and organic acids were discharged. It not only made serious pollution but decreased the yield of aspartame. Recovery of organics from aspartame effluents by removing salt with electrodialysis (ED) is proposed in this paper. The desalinated solution containing few organic reactants could be reused into the synthesis unit. A laboratory-scale electrodialyzer of two compartments with 10 cell pairs was employed. The content of organics in the effluents was determined with total organic carbon (TOC) analyzer. The influences of voltage and flow rate on operation time, energy consumption, current efficiency and organic mass loss were investigated. The ED proved to be an effective method to remove salts from aspartame effluents. The experimental results showed that the optimal operation condition was at 12 V and 20 L/h for the electrodialyzer. During 65 min, the recovery of organics and the salt removal rate were 78 and 98%, respectively. The most efficient time for the laboratory-scale ED process is about 40 min from 10 to 50 min. The diffusion of small organics through ion exchange membranes could be the major reason for the low organics recovery. The current efficiency was 69.9% and the energy consumption was 0.786 kWh/kg. These basic data might be helpful for the large-scale application of ED in treatment of aspartame effluents.