Isolation of Lignin in the Biorefinery Process

Lignocellulosic biomass is structurally complex and not readily degradable and generally requires pretreatment to make its use feasible. In particular, lignin is a natural organic polymer in plant cell walls, usually composed of randomly polymerized aromatic ether unit structures highly cross-linked. In recent years, the exploitation of lignin has become one of the hotspots of research. The chemical properties and structure of lignin are the basis for determining its further application, and the nature of extracted lignin is the prerequisite for lignin to undergo conversion reaction, which is an essential factor affecting the high-value utilization of lignin. Different extraction methods have variable changes in the yields and structures of lignin. This chapter briefly summarizes the feasible strategies for lignin isolation in the biorefinery process. In addition, suggestions and perspectives concerning the industrial improvement of lignin isolation are proposed.