PPSU dual layer hollow fiber mixed matrix membranes with functionalized MWCNT for enhanced antifouling, salt and dye rejection in water treatment

Loose nanofiltration dual layer hollow fiber membranes (DLHFM) were prepared from polyphenylsulfone (PPSU) with a thin contact mixed matrix membrane (MMM) outer layer containing functionalized multiwalled carbon nanotubes (MWCNT). Two types of MWCNT were used; oxidized MWCNT (OMWCNT) and polyethyleneimine (PEI) functionalized MWCNT (PEI‐MWCNT). Z potential measurements indicate that OMWCNT and PEI‐MWCNT were negatively charged, being OMWCNT most negative. Na2SO4, MgSO4, and methylene blue (MB) rejection was enhanced due to OMWCNT and PEI‐MWCNT incorporation in DLHFM outer layer. Enhanced hydrophilicity and negatively charge mixed matrix DLHFM layer was the key factor for a better mixed matrix DLHFM performance. The best salt and MB rejection was found in those membranes prepared with (OMWCNT) followed by (PEI‐MWCNT) compared with neat PPSU membranes. An increase of 113% and 100% in Na2SO4 and MB rejection respectively was attained in DLHFM with 0.04 wt%, OMWCNT (relative to dope's weight) in comparison with the neat PPSU membrane. Antifouling test for bovine serum albumin (BSA) and MB showed better performance also for the mixed matrix DLHFM containing OMWCNT's. In antifouling tests, a 4.4% and 25% flux recovery increase for MB and BSA respectively was obtained in DLHFM with 0.04 wt% OMWCNT compared with the neat PPSU DLHFM.