Studies on the Characteristics of the Methylene Blue Dye Adsorption in Waste Water Using the NaOH Modified Coffee Waste

In this study, It was investigated that the adsorption mechanism of methylene blue on the NaOH modified coffee waste based on the isotherm, kinetics and thermodynamics using the various experiment factor like pH, ionic strength and temperature. When the amount of adsorbent was 20 mg, maximum adsorption amount per unit mass was observed as 13.25 mg/g. Adsorption efficiency was shown to be over 90.6% except under the range of pH 4. In isotherm experiment results, it followed Langmuir isotherm equation more than Freundlich isotherm equation. In kinetic study, it was observed to be pseudo second order equation more than pseudo first order. Adsorption efficiency was decreased as increasing the ionic strength. In the thermodynamics estimation, the adsorption of methylene blue on coffee waste was examined to be physical adsorption since ∆G^o was calculated in the range of-20 to 0 kJ/mol. Also, ∆G^o values were calculated to increase according to temperature. ∆H^o and ∆S^o values were calculated to be-12.554 kJ/mol and-0.010 J/mol K, respectively.