Performance of continuous electrodeionization technique during the purification of the nonaqueous organic solvent N,N-dimethylformamide

This work focused on the use of a continuous electrodeionization (CEDI) device for the purification of the nonaqueous organic solvent N,N-dimethylformamide (DMF). CEDI is mainly used to purify, separate and concentrate hydrous solutions. Its main characteristic is the regeneration of ion-exchange resins by H+ and OH− generated by water splitting. However, for the DMF system, the resins act as channels for ion transfer. DMF cannot be regenerated because it is an anhydrous solution. In this study, the CEDI technique was adopted to remove formic acid (FA), dimethylamine (DMA) and inorganic salts from industrial-grade DMF. Experimental results demonstrated that DMA, FA and salts can be easily removed. Meanwhile, the effects of the voltages and flow rates on the CEDI performance were investigated systematically. This technique is a useful and effective process for the purification of the nonaqueous organic solvent DMF and can be used for the continuous production of high purity DMF.