Biosorption of methylene blue from aqueous solutions by a waste biomaterial: hen feathers

Biosorption potential of hen feathers (HFs) to remove methylene blue (MB) from aqueous solutions was investigated. Batch experiments were carried out as function of different process parameters such as pH, initial dye concentration, biosorbent dose and temperature. The optimum conditions for removal of MB were found to be pH 7.0, biosorbent dose = 1.0 g, and initial dye concentration = 50 mg L −1 . The temperature had a strong influence on the biosorption process. Experimental biosorption data were modeled by Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherms with the Langmuir isotherm showing the best fit at all temperatures studied. The maximum monolayer sorption capacity was determined as 134.76 mg g −1 at 303 K. According to the mean free energy values of sorption ( E ) calculated using the D–R isotherm model, biosorption of MB onto HFs was chemisorption. Kinetic studies showed that the biosorption of MB followed pseudo second-order kinetics. The activation energy ( E a ) determined using the Arrhenius equation confirmed that the biosorption involved chemical ion-exchange. Thermodynamic studies showed that the biosorption process was spontaneous and exothermic. To conclude, HFs is a promising biosorbent for MB removal from aqueous solutions.