Microalgae harvesting of Nannochloropsis sp. Using polyethersulphone/lithium chloride/functionalised multiwall carbon nanotube membranes fabricated via temperature induced phase inversion and non-solvent induced phase inversion

Abstract

Microalgae are a promising renewable source especially for producing biofuels and other high value products. Biofuel and biomass production involves several steps from cultivation, harvesting and extraction. Recent technology has used ultrafiltration membrane for microalgae harvesting but are faced with adverse effect of microalgae fouling. In the present study, Nannochloropsis sp. harvesting was performed using an ultrafiltration hybrid membrane made of polyethersulphone (PES) blended with the two additives namely lithium chloride (LiCl) and functionalised multiwall carbon nanotube (F-MWCNT). The membranes were prepared via two methods; non-solvent induced phase separation (NIPS) and temperature induced phase separation (TIPS). The membrane performances were evaluated in terms of membrane flux and fouling for the use of microalgae harvesting. The FESEM analysis showed that the morphology of the hybrid PES-MWCNT-LiCl membranes was very much influenced by the phase separation method. Flux rates of the membranes improved dramatically with increasing amount of additives when prepared using TIPS. A 100% microalgae separation from cultivated solution without major fouling (more than 80% flux recovery) was successfully achieved.