Lignin materials for adsorption: Current trend, perspectives and opportunities

Lignin is a highly aromatic low value biomass residue, which can be utilized for chemicals, fuels and materials production. In recent years significant attention has focused on adsorbent materials from lignin. However, only 5% of available lignin is exploited worldwide, thus significant opportunities still exist for materials development. This review summarizes recent research advances in lignin-based adsorbents, with a particular emphasis on lignin, its modification and carbon materials derived from this abundant feedstock. Lignin derived activated carbons have been utilized for air pollutant adsorption (e.g. CO₂, SO₂ and H₂S), while modified lignin materials have been developed for the removal of organic dyes and organics (like methylene blue, Procion Blue MX-R and phenols), heavy metals (such as Cu, Zn, Pb and Cd), or recovery of noble metals (e.g., Pd, Au and Pt). Future perspectives highlight how green chemistry approaches for developing lignin adsorbents can generate added value processes.