Rosemary particle as a new green additive to improve polysulfone membrane separation performance in removal of organic pollutants

This study used rosemary particles to make PSf nanofiltration membranes with antifouling properties, for medicinal pollutants and Azo dyes removal. The extract of rosemary plant was extracted using the Soxhlet process. Then homogeneous rosemary particles were embedded in the PSf membrane matrix as a green additive using the NIPS method. Characterization of the structure and morphology of rosemary particles and membranes was performed by FTIR, XRD, UV–Vis, FE-SEM, STA, DLS, ATR-FTIR, SEM, AFM, Zeta potential and TGA analyses. The results indicated the formation of homogeneous, hydrophilic, and spherical particles with a negative surface charge as well as physical stability in aqueous solutions and high thermal stability with a particle size of about 229 nm. Adding the optimal amount of rosemary particles increased the hydrophilicity (reduced water contact angle from 60.55° to 52.15°) and porosity (increased from 69.3 to 91.7%). Also, by adding 1 wt% of rosemary particles, the permeability of the membrane increased by 3.5 times. The increase in mean pore radius (from 4.77 to 6.08 nm), smoother surface of modified membranes and negative charge on the membrane surface proved this improvement. Therefore, the amount of 1 wt% caused the best flux performance of pure water (from 126 to 359 LMH) and BSA solution (from 104.5 to 202.3 LMH). Moreover, RE/PSf membranes showed a high rejection for azithromycin: 81.98%, cefixime: 58.07%, O II: 71.75, RY 160: 81.71 and RB 5: 93.69%.