Eco-Friendly Adsorptive Treatment of Methylene Blue in Aqueous Media with Agricultural Waste

This research focuses on assessing the potential of raw artichoke waste powder as an economical and sustainable biosorbent for the removal of methylene blue (MB) from aqueous solutions. The prepared artichoke waste powder was characterized using FT-IR and XRD, confirming the presence of functional groups (hydroxyl, carboxyl, carbonyl) and a largely amorphous structure favorable for adsorption. Batch experiments were conducted to evaluate the effects of solution pH, adsorbent dosage, initial dye concentration, and contact time on MB removal. Optimal adsorption was observed at alkaline pH (10–12) and an adsorbent dosage of 0.6–1 g/L, achieving nearly complete dye removal. Adsorption isotherms were fitted using Langmuir, Freundlich, and Sips models, with the Sips model showing the lowest sum of squared errors (SSE = 156.9), indicating predominantly monolayer chemisorption with slight surface heterogeneity. Kinetic studies showed that the pseudo-second-order model (SSE = 31.41) accurately described the adsorption process, highlighting the importance of chemical interactions between MB molecules and the functional groups on the adsorbent surface. These findings demonstrate that raw artichoke waste powder is an effective, eco-friendly, and economical adsorbent for cationic dye removal from water.