Abstract <p>The use of cellulose obtained from processing flax straw, a by-product of agricultural production, as a sorption material for water purification has demonstrated insufficient structural stability, which complicates technological operations and reduces the level of water purification. The results of the experimental studies conducted within the framework of this work formed the basis for the development of a technology for producing a sorption material with improved performance characteristics determined by the introduction of an impregnating additive based on silicon oxide into flax cellulose, delignified by exposure to a peroxide–alkaline solution. This additive improves the structural composition of the base material, thereby increasing efficiency and simplifying sorption processes during water purification from benzene and aniline impurities.</p>