Electrodialysis for the concentration of ethanolamine salts

Monoethanolamine (MEA) is currently produced from oil-based chemicals in an energy intensive process. Fermentative MEA production from renewable sources is considered to be a more sustainable process option. In such a process MEA is likely to be produced in a relatively low concentration in protonated form. Monopolar membrane electrodialysis can be applied to obtain a concentrated MEA solution of 10–18 wt% MEA from this dilute stream. The outlet concentration strongly depends on the applied current density. At low current densities (100 A m−2) the concentration is relatively low (10 wt% MEA) due to diffusive water transport. At higher current densities (1000 A m−2) the concentration is higher (18 wt% MEA). Other variables such as inlet concentration and temperature have little influence on the outlet concentration. Current utilization is around 80% and seems independent of current density, diluate conductivity and temperature. On the other hand, cell potential strongly depends on these variables and especially on diluate conductivity. For typical electrodialysis conditions the power consumption is 0.35 kWh/kg MEA.