Lignin is an aromatic biopolymer with a heterogeneous structure, which has limited its application potential. Colloidal lignin particles (CLPs) offer a means to disperse lignin homogenously into both water and other media, such as polymers. However, no means thus far have been presented that would allow for a large-scale production of CLPs. Herein we show an industrially scalable closed cycle process of CLP production. In the process, a concentrated solution of lignin in tetrahydrofuran and ethanol is added into the non-solvent water, instantaneously forming CLPs through self-assembly. The organic solvents are recovered and reused in the process. The aqueous CLPs are concentrated by ultrafiltration and the concentrated particles are spray dried, leading to redispersible microclusters.<br/>CLPs can be further functionalized to yield active materials for a variety of applications. We have for example achieved highly spherical silver carboxylate colloidal lignin particles (AgCLPs) with a deprotonation reaction of an organic solution of anhydrous lignin and subsequent ion exchange with silver nitrate. The AgCLPs have high antibacterial activity, which can be retained for days. In addition, CLPs metallized with iron oxide, Pickering emulsions and composite materials applications have been considered.

Closed cycle production of colloidal lignin particles and their functionalization with silver for antimicrobial applications

256th National Meeting (2018)

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