Chapter 4 - Lignin Chemicals and Their Applications

Abstract

Lignin is an excellent raw material for preparing chemicals because of its rich sources and low price. It also contains a variety of active functional groups, including hydroxyl, methoxy, carbonyl, carboxyl, and benzene. According to researches, the two main types of lignin are alkali lignin and lignosulfonate. Products modified by lignin and further chemicals, such as reducing agents and fluid loss agents, have been applied successfully in the fossil fuels field. By reducing the loss of drilling fluid, the introduction of lignin reduces the cost of production, which improves the efficiency of crude oil production. Lignin can reduce the viscosity of coal-water mixture, giving it good liquidity as the slurry dispersant in the coal industry. This feature effectively reduces the condensation between the grains of coal-water slurry, improving the combustion efficiency. Lignin also can be used as dye dispersion agents and tanning agents in light industry. The activity groups of lignin, like sulfonic acid and amino groups, are used to disperse dye particles uniformly in water, which makes dyeing more uniform by reacting with collagen active groups. This feature improves the softness of the leather's grain and reduces the use of chrome tanning agents. It furthermore reduces the degree of pollution of the environment. Lignin also can be used in the field of building materials, as a water-reducer of concrete and the grinding agent of cement. By increasing the strength of concrete, lignin can delay concrete-setting and improve the water-retention properties of concrete, which can increase its ability to meet the requirements in construction. By improving the powder-grinding efficiency of cement particles, lignin can make the size of concrete particles more uniform and reduce the energy consumption in the process of cement grinding. Lignin also has been applied in agriculture, such as with sustained-release drugs, fertilizers, and soil conditioners. Through the effective load of pesticide molecules and control of their release, the utilization rate of pesticide can increase and the amount of pesticide can decrease. Lignin-based fertilizers have three main properties: slow dissolution, controlled-release, and nonvolatility. These properties reduce the loss of fertilizer and improve the utilization rate of fertilizer. Lignin also has been used in the field of medicine, including as antiinflammatory agents, anticancer agents, and virus inhibitors. It needs further development and exploration.