Highly charged cellulose-based nanocrystals as flocculants for harvesting Chlorella vulgaris.

Dries Vandamme, Samuel Eyley, Guy Van den Mooter, Koenraad Muylaert, Wim Thielemans

Index: Bioresour. Technol. 194 , 270-5, (2015)

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Abstract

This study presents a novel flocculant for harvesting Chlorella vulgaris as model species for freshwater microalgae based on cellulose nanocrystals (CNCs), thus synthesized from a renewable and biodegradable resource. Cationic pyridinium groups were grafted onto CNCs by two separate one-pot simultaneous esterification and nucleophilic substitution reactions. Both types of modified CNCs were positively charged in the pH range 4-11. Both reactions yielded CNCs with a high degree of substitution (up to 0.38). A maximum flocculation efficiency of 100% was achieved at a dosage of 0.1 g g(-1) biomass. In contrast to conventional polymer flocculants, cationic CNCs were relatively insensitive to inhibition of flocculation by algal organic matter. The present results highlight the potential of these new type of nanocellulose-based flocculants for microalgae harvesting.Copyright © 2015 Elsevier Ltd. All rights reserved.