In North Carolina, researchers at North Carolina State University have developed a simple, effective and relatively inexpensive technique for removing lignin from the plant material used to make biofuels, which may drive down the cost of biofuel production.
The researchers began by making a number of liquid salts called “protic ionic liquids” or PILs. These PILs are fairly inexpensive to prepare, because they are made by mixing together an acid, such as acetic acid (more commonly known as vinegar), and a base (a chemical class of materials called amines). As part of the pretreatment process, one of the PILs is mixed with biomass and then heated and stirred. The lignin dissolves into the PIL, leaving the cellulose behind as a solid. The cellulose, which is now much easier to process, is then easily filtered from the mixture for use in the next biofuel production steps.
The remaining PIL-lignin liquid mixture can then be heated to distill (or vaporize) the PIL, leaving the lignin behind as a black powder. The vapors from the PIL are collected and cooled to recover the liquid PIL so that it can be re-used. The lignin is also valuable, because it can be used to manufacture polymers or other chemical products which could supplement the cost of running the biofuel production facility.
