Malachite green adsorption onto modified pine cone: Isotherms, kinetics and thermodynamics mechanism

In this study, the pine cone was activated using NaOH solution and used in the adsorption of malachite green. The effects of initial pH, temperature, initial concentration, and contact time on the adsorption process were evaluated. Functional groups of active pine cone were characterized using Fourier Transform Infrared (FT-IR). Surface tissue images were obtained using Scanning Electron Microscopy (SEM). Isotherm studies were performed by analyzing data at the equilibrium. The compatibility of the experimental data with Langmuir, Freundlich, and Temkin isotherms was tested and results revealed that the data fits well to Langmuir type 2. Adsorption capacity is 111.1 mg/g and high adsorption value. Pseudo-first order and pseudo-second order kinetic model equations were used to analyze the kinetic data of the adsorption process. The pseudo-second order kinetic model was found to fit very well. The adsorption process was found to be endothermic, spontaneous and physical process according to thermodynamic parameters (Delta G(0), Delta H-0, Delta S-0).