Fabricating lignin-derived flocculants – A review
Weijue Gao, Weibing Wu, Pedram Fatehi
Abstract
The rising water crisis and challenges associated with the use of petrochemicals have resulted in an increased interest in using renewable biopolymer-based materials for decontaminating water and wastewater effluents. Lignin is the second most abundant natural polymer that is produced in large quantities in the pulping and biorefinery industries. Lignin has received a great deal of attention in the last decades for developing lignin-based polymers as effective coagulants and flocculants. This review paper provides a comprehensive overview of the primary research conducted to develop different types of lignin-based flocculants for treating colloidal suspensions and solutions in single and dual polymer systems. The modification strategies, including sulfonation, oxidation , Mannich, carboxymethylation, graft copolymerization , and crosslinking, are reviewed as strategies for altering the physicochemical characteristics of technical lignins for mimicking flocculants. Moreover, the benefits, challenges, and future opportunities related to the preparation and employment of lignin-based flocculants are also discussed.