Chemical Stability and Additive Leach Out in Polyethersulfone Membranes Blended with Dragon Blood Resin: An Investigative Study

Abstract

Dragon blood resin (DBR) is an effective bio-based additive for polymeric membrane fabrication. Despite the improved permeability and antifouling properties of the resulting membrane provided by DBR, its weak chemical bond makes it susceptibleto leaching during both fabrication and operation rendering the membrane properties and performances. This study investigates the chemical stability and leaching behavior of polyethersulfone (PES) membranes modified with DBR in an alkaline solution. The study involves immersing two types of PES based membranes, one loaded with 3% DBR (M-3) during the fabrication and one without (M-0), in a 0.01 N NaOH solution for five days. The results show that M-0 had good resistance to high alkaline solution, while M-3 was less stable. The pure water permeability of M-3 increased significantly with immersion time, as well as its surface hydrophilicity. The leaching of DBR from PES membrane matric can be ascribed by its alkali lysis polarity and the breaking of the DBR bonds from reaction of hydroxide ions with the ester bonds and glycosidic linkages in the flavonoids and anthocyanins, causing them to break apart into smaller molecules. The leaching of DBR also left pores that enhanced the membrane pore size. Overall, these findings provide useful information for the optimal design of a bio-based PES membrane.