Kinetic and thermodynamic studies adsorption of Methylene Blue (MB) in aqueous solution on a bioadsorbent from Cucumeropsis mannii Naudin waste seeds

Abstract

The aim objectives of present study were to prepare a bioadsorbent from the seeds of Cucumeropsis mannii Naudin (BCM) and to examine its effectiveness in the removal of methylene blue (MB) from aqueous solution by adsorption process. The process of adsorption of MB onto BCM was optimizing by varying different parameters such as contact time, initial dye concentration, and temperature. The kinetic of adsorption was analyzed using pseudo-first-order and pseudo-second-order kinetic models. The experimental equilibrium data were examined using Langmuir and Freundlich isotherms. Thermodynamics parameters were also determined. The results show that the maximum adsorption percentage is 89% and the maximum adsorption capacity is 47 mg g^-1 at 308 K. Isotherms studied showed that Freundlich model is the best model to describe adsorption of BCM onto MB. Kinetic studies show that the adsorption process follows pseudo second-orderkinetic model. The thermodynamic study indicated a negative value of ΔH° (-41 kJ mol^-1) and shows that adsorption of MB on BCM is exothermic and essentially a chemical process. BCM is a potential bioadsorbent for the removal of MB from aqueous solution and can therefore be used for water purification process.

Keywords: Cucumeropsis mannii Naudin, methylene blue, adsorption, bioadsorbent, isotherms, kinetics and thermodynamics.