Enhanced Adsorption of Methylene Blue by Chemically Modified Materials Derived from Phragmites australis Stems

In this study, the biomass of Phragmites australis was chemically modified using NaOH and subsequently citric acid to produce an effective adsorbent named SA-RPB. The absorbent was characterized using XRD, SEM, BET, and FT-IR methods. The study's findings indicated that the adsorbent existed mainly as cellulose crystals, contained micropores with an average diameter of 15.97 nm, and had a large number of hydroxyl and carboxyl groups on the surface. The adsorption process of SA-RPB was evaluated through the adsorption of methylene blue (MB) dye in aqueous solution. Adsorption kinetics showed that the pseudo-second-order model well described the adsorption process. The adsorption isotherm process satisfactorily fitted with the Langmuir model with the maximum adsorption capacity of 191.49 mg/g at 303 K. These findings show that MB may be efficiently removed from aqueous solutions using the adsorbent made from the raw biomass of Phragmites australis treated with NaOH and then citric acid.