Chemical modification of plant raw materials aimed at obtaining new valuable products and materials is described. Methods of preliminary treatment and modification of biopolymers (cavitation, microwave irradiation, and application of cross-linking and delignification reagents) making it possible to reduce decomposition of all major components are considered. Modified products can be used as sorbents of heavy metal salts, additives to drilling fluids in drilling of oil and gas wells, in the construction industry etc.