Evaluation of a quaternized polyethersulfone membrane enhanced with amine functionalized carbon nanotubes for forward osmosis application

Multiwall carbon nanotubes (CNTs) were quaternized with trimethylamine to form an anionic conductive CNTS (QCNTs) then blended with quaternized polyethersulfone membrane (QPES) by phase invasion method to obtain a composite membrane with higher permeation, improved rejection and enhanced antifouling properties for forward osmosis application. The membranes and QCNTs were characterized using SEM, TGA, NMR, Raman and FTIR. The fabricated composite membranes showed that addition of QCNTs can improve membrane basic properties when compared to commercial polyethersulfone membranes. This observed improvement could be attributed to the incorporated oxygen and amine functionalities in the CNTs. The 0.1 wt % QCNTs showed a contact angle of 64, reverse solute flux of 7.4 and 6.2 Lm-2h-1 for NaCl and MgSO4 respectively compared to an original pure water flux of 8.058 Lm-2h-1. Humic acid was used as a foulant, when the composited was fouled using humic acid, the 0.1wt.% QCNTs showed a reverse solute flux of 5.7 and 5.0 Lm-2h-1 respectively at room temperature.