Using Lignin Waste of Pulp & Paper Industry – Ksenia Antokhina, St Petersburg Mining University

Lignin is one of the main waste products of the pulp and paper industry. It is an amorphous, complex, natural polymer composed of heterogeneous phenylpropane units, that does not have a specific primary structure. It is known that: • Lignin is the main non-carbohydrate part of wood and a binding material for plant cell walls • It protects plants against mechanical, chemical and biological effects. • It makes up 30% of all non-fossil carbon on the Earth. Deciduous wood contains 18-25% of lignin, conifers – 23-50%, cereal straw – 12-20% by mass. Technical lignins are produced as by-products during chemical processing of wood. There are two types of these lignins: alkaline lignins or lignosulfonates (make up 85% of all lignins) and hydrolysis lignins. Application prospects of lignin. Many useful properties of lignin, that can be used in the future, have been investigated. Some of its main properties are mentioned below: • Due to its natural polymer structure and a wide range of ionogenic groups lignin can be used as a sorbent for treatment of wastewater from various pollutants. • Dispersing properties of lignosulfonates and their capability to bind metal ions make it possible to use lignin for preparation of drilling mud for oil wells. • Wood waste is rich in various vitamin complexes, and therefore it can be used as a raw material for the production of animal feeds. • Hydrolysis lignin improves agrophysical, agrochemical and biochemical soil characteristics, so it has positive influence on soil fertility and plant nutrition. • Modern technology allows to replace limestone mineral powder for lignin-containing polymers suggests its application for production of asphalt concrete mixtures without reducing quality. Thus, lignin is a valuable resource and has various applications. One of the most promising areas is production of bioplastics from lignin-containing waste, which, on the one hand, can solve the problem of recycling of waste from the pulp and paper industry in Russia, and, on the other, to significantly reduce the amount of plastic produced from hydrocarbons and the use of natural resources.