Adsorption of Methylene Blue Dye from aqueous solution using low cost adsorbent: Kinetic, Isotherm Adsorption and Thermodynamic Studies

Abstract

Abstract Fig leaf as an environmentally friendly byproduct of fruit plants, has been used for the first time to treatment of methylene blue dye. The fig leaf activated carbon (FLAC) was prepared successfully and used for adsorption of methylene blue dye (MB) purpose. The adsorbent was characterized by the Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM) and the specific surface area by the Brunauer-Emmett-Teller (BET). In the present study, initial concentrations, contact time, temperatures, pH, carbon dose, volume solution and activation agent were covered. However, the initial concentration of MB was investigated at different concentrations 20, 40, 80, 120 and 200 mg/L. pH value was examined at these values (pH3, pH7, pH8 and pH 11). When pH is 11, the adsorption efficiency of MB retains at 84.3%. To determine how well FLAC removed MB, adsorption temperatures were changed at 20, 30, 40, and 50 °C. The adsorption capacity of FLAC was determined to be 22.7 mg/g for 0.08 g and 54.9 mg/g for 0.02 g. This adsorption inclined toward the Langmuir isotherm model (R2>0.95), where the adsorption created a monolayer covering the surface of the adsorbent, based on the curve-fitting using the Freundlich and Langmuir isotherm models. Additionally, it was discovered that the maximum adsorption capacity (Qm) was 69.93 mg/g and the Langmuir affinity constant (KL) was 0.08 L/mg. The FLAC as low-cost adsorbents for methylene blue dye has shown good cationic dye adsorption performance.