ABSTRACT This study explores the synthesis, characterization, and adsorption performance of a modified bioadsorbent derived from almond shells for methylene blue removal from aqueous solutions. The raw almond shell, cellulose‐extracted sample and TEMPO‐oxidized derivative were thoroughly characterized using SEM, XRD, FTIR, TGA, BET, DLS, and pH p zc analyses. The MCAS material showed a mesoporous texture, with a specific surface area of 9. 36 m 2 g −1 and an average pore size of 6. 28 nm, and developed a negative surface charge at pH values above neutrality. Batch adsorption experiments confirmed that dye removal was strongly dependent on pH, adsorbent dosage, and contact time, reaching a maximum efficiency of 93% under optimal conditions (pH 8, initial concentration 0. 4 g L −1, contact time 55 min). According to the adsorption kinetics and isotherm studies, the MCAS was found to follow a pseudo‐second‐order kinetic and a Freundlich model indicating a heterogeneous chemisorption mechanism and with a high maximum adsorption capacity of 130 mg g −1. Economic and environmental assessments confirmed low production costs 2. 45/kg, good reusability over three cycles of adsorption‐desorption, and the absence of toxicity in treated effluents, which even promoted plant growth. Overall, MCAS is a sustainable, low‐cost, and effective bioadsorbent for cleaning dye‐contaminated water, highlighting the value of agricultural waste in developing circular and eco‐friendly wastewater treatment methods.
Bahrouni et al. (Wed,) studied this question.