Adsorption performances of Methylene blue by poly(vinylidene fluoride)/MWCNT membranes via ultrasound-assisted phase inversion method

In this study, poly(vinylidene fluoride) (PVDF)/MWCNT composite membranes were successfully prepared via an ultrasound-assisted phase inversion process. The influences of the ultrasonic power and ultrasonic time on the variation of membrane morphology, hydrophilicity, porosity and adsorption performances to methylene blue (MB) dye were comprehensively investigated. Scanning electron microscope analysis indicated that low ultrasonic power (60 W) and long ultrasonic time (60 s) are in favour of the formation of finger-like pores, causing super water flux, high porosity and large mean pore size of membranes. A maximum adsorption capacity of the ultrasound treated membrane reached up to 4.4 mg/g, which is higher than the untreated membrane (2.4 mg/g). Furthermore, the kinetics and isotherm models studies indicated that the adsorption of MB followed a pseudo-second-order kinetic model and Freundlich isotherm model.