Synthesis of composites from activated carbon based on olive stones and sodium alginate for the removal of methylene blue

The present investigation involves the preparation of activated carbon (AC) from olive stones using a single-step activation process with potassium hydroxide (KOH) as an activating agent. The resulting activated carbon (AC) was used in conjunction with sodium alginate (Alg) to prepare the AC/Alg beads at different ratios (50/50, 60/40, and 80/20) for batch adsorption of methylene blue (MB). Characterization of the materials was conducted using FTIR, SEM, CHNS-O, and TGA-dTG thermal analysis. In batch adsorption studies, the AC/Alg beads were employed to remove MB from aqueous solutions, and various parameters, including contact time, initial pH of the MB solution, and initial MB concentration, were optimized to obtain maximum adsorption efficiency. The experimental results reveal that AC/Alg beads with a ratio of 60/40 exhibit the best adsorption performance. The pseudo-first-order kinetic model and the Langmuir adsorption isotherm, with a maximum adsorption capacity of 586 mg/g, best fit the experimental data.