Abstract
The study aims to develop effective biomass-based adsorbents for the removal of methylene blue from aqueous media. The study presents a comparative analysis of activated carbons derived from barley straw (AC-BS), wheat straw (AC-WS) and wheat bran (AC-WB), synthesised by chemical activation using KOH. The resulting materials are characterised by a well-developed porous structure with a specific surface area of 1866–2036 m²/g. The structural and textural properties of the samples were investigated using SEM, BET, FTIR and Raman spectroscopy. It was shown that the formation of a micro-mesoporous structure and the presence of oxygen-containing functional groups play a key role in adsorption. Methylene blue was used as a model contaminant. It was found that the adsorption process depends significantly on the solution pH, initial concentration and contact time. The maximum removal efficiency reached 99.7% for AC-BS and 90.7% for AC-WB at pH 9, whereas the AC-WS sample demonstrated high efficiency over a wide pH range (95.7–100%). The highest adsorption capacity was 493.3 mg/g for AC-WS. The results obtained show that differences in the morphology of the source biomaterial determine the textural characteristics of the adsorbents and their efficiency. This work demonstrates the potential for using agro-industrial waste to create highly efficient adsorbent materials for water treatment.