Adsorption of Malachite Green Dye Using Pinus Sylvestris: Isotherm, Kinetics and Thermodynamics Studies

Abstract

In this study Pinus sylvestris shavings powder (PiSP) was utilized as an adsorbent for the removal of Malachite Green (MG) which is one of the common basic dyes, from aqueous solution. The adsorption experiments were carried out in a batch system and effects of initial dye concentration, interaction time and temperature were investigated. Langmuir, Freundlich and Temkin adsorption isotherms have been used to model equilibrium data. Freundlich isotherm model becomes more convenient option compared with Langmuir and Temkin models. Freundlich model coefficients are raise as the temperature rises, showing that the adsorption process becomes favorable higher temperature. Kinetic parameters were determined by pseudo first order (PFO), pseudo second order (PSO) and intraparticle diffusion (IPD) models. Results indicated that experimental and calculated qe values close to each other explained that this process fits PSO kinetic model with higher R-2 values than other two models. Kinetic constants become closer to both temperatures and initial concentrations and qe values are increases with increasing concentration of MG. Initial dye concentration elevates from 10 to 60 mg/L, dye adsorption capacity onto PiSP from 3.28 to 22.88 mg/g, 3.58 to 24.06 mg/g and 3.88 to 25.78 mg/g for 298, 308 and 318K, respectively. Thermodynamic parameters for instance free energy (Delta G), enthalpy (Delta H) and entropy (Delta S) of this separation process are determined from -2757,7 J/mol, 6550,68 J/mol and 12,73 kJ/cool, respectively. The negative values of Delta G degrees showed that this separation process was endothermic and natural. The research results demonstrate that PiSP may be an alternative material than costly adsorbents for dye removal.