Home – Home – Jornals – Siberian Journal of Forest Science 2025 number 4

Scots pine ( Pinus sylvestris L.) sawdust is highly promising as a raw material for wood carbon sorbents. However, the prospect of using pine sawdust as adsorption materials to extract toxic metals from aqueous solutions depends heavily on the composition of active surface functional groups. The purpose of the study is to assess the sorption properties and the degree of change in the composition of oxygen-containing functional groups of carbon sorbents. The modification was made with solutions of one-, two- and polybasic carboxylic acids to promote large-scale woodworking waste as real alternative sorption materials. 1 % carboxylic acids of different basicity (acetic, succinic, tartaric, citric) were used as chemical modifiers for both initial sawdust and sawdust thermally treated at 300 ± 10 °C. Chemical modification was carried out at a temperature of 80 °C for 5 hours. To quantify functional groups in the composition of modified carbon sorbents, the Boehm titrimetric method was used. Impregnation of carboxylic acids of different basicity has increased the total acidity of the resulting carbon sorbents due to increasing in the number of hydroxyl groups in their composition, which were not previously present in initial pine sawdust. The sorption behavior of chemically and thermochemically modified carbon sorbents was investigated in relation to Cu (II) and Zn (II) ions and a positive effect of the modification has been established only in the case of copper extraction from aqueous solutions. The calculated thermodynamic parameters indicate the spontaneous physical sorption occurs without the formation of stable chemical bonds, and the sorption of Cu (II) ions on the original sawdust proceeds in accordance with the Dubinin-Radushkevich model, and extraction by modified samples occurs according to the Langmuir model. Pine sawdust sorbents modified chemically and thermochemically with 1 % citric acid (sorption capacity 16.96 and 12.20 mg/g, respectively) has shown good potential for effective extraction of copper iones.