Use of modified poly-epoxysuccinic acid as an efficient scale inhibitor to control CaSO4 scaling in NF processes: Performance and mechanisms

The addition of scale inhibitors is one of the effective methods to alleviate membrane fouling on nanofiltration (NF). In this study, two effective poly-epoxysuccinic acid-based scale inhibitors, namely, valine-poly-epoxysuccinic acid (Val-PESA) and histidine-poly-epoxysuccinic acid (His-PESA), were synthesized by grafting copolymerization . Results showed that Val-PESA and His-PESA could significantly retard the formation of CaSO 4 scaling and effectively mitigate membrane fouling . His-PESA had a better scale inhibition effect on CaSO 4 compared to Val-PESA. The inhibition efficiency was maintained at 96.0 % after 20 h operation for Val-PESA and His-PESA. In addition, the inhibition performance of Val-PESA and His-PESA in the batch test was basically the same as in the NF process. Combining the results of the inhibition tests and the relevant characterizations by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, the scale inhibition mechanism was mainly ascribed to enhanced chelation, dispersion and lattice distortion effect. This study sheds light on the designing of novel and efficient scale inhibitors for NF processes.