Alginate fouling reduction of functionalized carbon nanotube blended cellulose acetate membrane in forward osmosis

•The fCNT-CA membrane showed enhanced performance than the bare CA membrane in FO.•The fCNT-CA membrane became more hydrophilic and negatively charged.•Dominant alginate foulant–membrane interaction force was firstly investigated.•The fCNT-CA membrane was more repulsive against alginate foulant via AFM analysis. Functionalized multi-walled carbon nanotube blended cellulose acetate (fCNT-CA) membranes were synthesized for forward osmosis (FO) through phase inversion. The membranes were characterized through SEM, FTIR, and water contact angle measurement. AFM was utilized to investigate alginate fouling mechanism on the membrane. It reveals that the fCNT contributes to advance alginate fouling resistance in FO (57% less normalized water flux decline for 1% fCNT-CA membrane was observed than that for bare CA membrane), due to enhanced electrostatic repulsion between the membrane and the alginate foulant. Furthermore, it was found that the fCNT-CA membranes became more hydrophilic due to carboxylic groups in functionalized carbon nanotube, resulting in approximately 50% higher water-permeated flux than bare CA membrane. This study presents not only the fabrication of fCNT-CA membrane and its application to FO, but also the quantification of the beneficial role of fCNT with respect to alginate fouling in FO.