The article is devoted to the synthesis of sorption materials based on agricultural waste and testing the effectiveness of the synthesized materials. As a result of the activity of the agricultural sector of Ukraine, a large amount of organic waste is generated every year, the main method of disposal of which is incineration, which is not ecological due to the increase in carbon dioxide emissions, which, in turn, increases the greenhouse effect in the atmosphere. The processing of such waste into sorption material that can be used for wastewater treatment and soil remediation is particularly relevant in the context of significant soil contamination with heavy metals as a result of military operations. Biochar was obtained from agricultural waste (corn leaves, corn cobs, potato straw, nut shells, etc.) by their heat treatment at a temperature of 350 °C for 1 h. The obtained biochar was impregnated with a solution of FeCl3, dried and again heated without access of air at the temperature of 350 °C for 1 h. Modification significantly increased sorption efficiency of materials.