Isotherm, Kinetic and Thermodynamic Studies on Methylene Blue Biosorption from Aqueous Solution onto Mulberry tree (Morus nigra L) roots powder

Abstract

In this study, batch adsorption experiments were conducted for the adsorption of Methylene Blue (MB) onto ground Morus Nigra L roots powder (MNLRP) surface from aqueous solution. The Physico-Chemical characteristics of MNLRP were studied. The results showed that the pH value was 7.24, the bulk density value was 0.638 g /cm3, the internal surface area (microspores) was 627.08 mg/g using the iodine number, and ash content (metal compounds content) was 0.129%. The effects of different parameters on adsorption processes were studied. The maximum adsorption capacity, qmax , was found to be 32.63 mg/g at 45oC. The adsorption process was very fast initially and reached the equilibrium at 15 minutes. The removal percentage increased with increasing adsorbent dosage, pH solution, initial concentration, and temperature. Among the all isotherms tested in this study, Langmuir isotherm model gave the best fit with R2 and Chi square. The adsorption process was found to be physisorption process due to the calculated mean energy of adsorption calculated form Dubunin-Radushkevich (D-R) isotherm model ranged from 1.24 to 1.71 KJ/mol. Adsorption kinetics data were modeled with different kinetic models. The results revealed that the pseudo-second order model was the best fitting model. The results from thermodynamic parameters showed that the adsorption process was spontaneous and endothermic processes and increased randomness at the solid/liquid interface. Therefore, this study demonstrates that MNLRP could be used to remove MB dyes from aqueous solutions.