Preparation of low carbon impact lignin nanoparticles with controllable size by using different strategies for particles recovery
Λεωνίδας Μάτσακας, Milena Gerber, Liang Yu, Ulrika Rova, Paul Christakopoulos
Abstract
Lignin still remains an underutilized plentiful resource whose conversion to high-added value products is a cornerstone towards establishing a viable biomass biorefinery. Bio-materials in the form of nanoparticles represent promising high-value products with numerous downstream applications. The aim of the current work was to develop a method that would allow controlling the size of (birch and spruce) lignin nano- and micro-particles for their subsequent recovery into a solid product. We tested different two-step and one-step isolation processes and demonstrated that particle size could be easily controlled to meet different ranges (<100 nm, <500 nm, and>1 μm). In general, two-step isolation methods, i.e. a step of decrease of solvent concentration followed by isolation of lignin particles, were better for the isolation of well-defined spherical particles. In particular, the rate at which ethanol concentration was decreased played a significant role in determining the size of lignin particles. Moreover, when lignin concentration was increased from 1 % to 5 % and 10 % (w/v), particle size and homogeneity decreased slightly, but productivity augmented. The present study demonstrates that different isolation methods can be applied to obtain renewable, customarily sized, lignin spherical micro- and nano-particles.