Abstract
Abstract
This study compares the removal of reactive dyes using natural lignocellulosic adsorbents obtained from spruce, birch, and rapeseed stems. Lignocellulosic sorbents are attractive due to their low cost, availability, and environmental compatibility. Experiments were conducted using Procion Blue H-5R, Reactive Blue 4, and Reactive Red 120 dyes under alkaline-acid treatment at temperatures of 25 °C and 90 °C. The sorption capacities (mg g
−1
) at 25 °C reached 26.96 ± 0.64 (rapeseed) for Procion Blue H-5R, 17.86 ± 0.57 (rapeseed) for Reactive Blue 4, and ∼16.8 ± 0.2 across materials for Reactive Red 120, although commercial activated carbon showed higher capacities. Only minor differences in adsorption capacity were observed between 25 °C and 90 °C under the studied conditions. The results suggest that lignocellulosic agricultural residues, particularly rapeseed biomass, may represent promising low-cost materials for preliminary dye removal applications. However, additional studies involving adsorption kinetics, equilibrium modelling, and advanced surface characterization are necessary for a more comprehensive evaluation of adsorption performance and mechanisms. In addition, the direct comparison of different lignocellulosic biomass under identical experimental conditions provides a useful preliminary perspective on their relative adsorption behaviour.