Study on the effect factors on the separation of N-phosphonomethyliminodiacetic acid (PMIDA) by nanofiltration process

N-phosphonomethyliminodiacetic Acid (PMIDA) is the intermediate product for preparing the herbicide glyphosate. The PMIDA processing industry generally requires significant amount of process water for cleaning, rinsing purposes because of the high chloride and PMIDA content. Nanofiltration membrane separation with high efficiency, ease and economic of operation as one of the most promising technologies have become increasingly attractive for reclamation of solutes. The objective of the study was to investigate on separating the PMIDA from the simulated solution by nanofiltration(NF) under different operating conditions. The results indicated that the NF membrane process performed high efficiency of >95% for PMIDA recovery. The results of the effect of variation of feed circulation pressure, the PMIDA concentration, the pH and the concentration of NaCl conform to the mechanism of separation. Donnan effect and size effect were found to play a major role in the recovery of PMIDA from the simulated solution. The present study shows that nanofiltration is a promising technique for recovery of PMIDA from the simulated solution, which could be used to achieve zero discharge status and solve a major environmental problem.