Removal of methylene blue onto forest wastes: Adsorption isotherms, kinetics and thermodynamic analysis

Abstract

In this study, the removal of methylene blue dye using forest wastes, Salix alba L. (white willow) and Salix babylonica (weeping willow), was investigated by adsorption method. The effects of parameters on the adsorption process such as initial pH (2.8-9.1), initial MB concentration (25-150 mg/L), biosorbent dosage (1-15 g/L) contact time and temperature (15-45 degrees C) were investigated. The suitability of the obtained adsorption data to the Langmuir and Freundlich isotherm models was investigated. The best data for each temperature value were obtained in both langmuir and freundlich isotherms for all adsorbents. The maximum biosorption capacity (q(max)) was found to be 35.46 and 42.74 mg/g for SA and SB, respectively. Kinetics data analyzes were performed using pseudofirst and pseudo-second-order models. For both types of adsorbents, it was determined that the pseudo-second-order kinetics model is the most suitable model. As a result of thermodynamic studies (Delta G degrees, Delta H degrees and Delta S degrees), it was determined that the biosorption process is feasible, spontaneous and exothermic. The results obtained show that both adsorbents are highly effective in MB removal. (C) 2021 Elsevier B.V. All rights reserved.