Thermodynamic and Kinetic Study for Removal of MB and CR from Aqueous Solution Using of SD and SD/MgO -Nanoparticles as Biosorbents

Abstract

Thermodynamic study for investigation of the biosorbent from Pine trees, sawdust (SD) and sawdust veneered with magnesium oxide (MgO), (SD/MgO) Nanoparticles for removal of Cationic (Methyl blue, MB) and anionic (Congo Red CR) dyes in a batch process. Characterizations for each biosorbents were done by FTIR, SEM, and XDR. Various parameters for batch equilibrium experiments preformed to examine the affinities for adsorption process for each dyes on each adsorbents. The data results in the kinetics study are used to fit with the Pseudo-first order and Pseudo-second order rate law, and intra particle diffusion models. The Freundlich, Langmuir, and Temkin, were applied as isothermal models to describe the adsorption convergence. The Data revealed that MB and CR dyes adsorption onto SD and SD/MgO has a good agreement with pseudo-second order and Freundlich.  The K_F values for MB and CR dyes adsorption onto SD and SD/MgO varied between [31.88-67.19, 44.05-46.63, 276.3-864.6, and 57.74-170.69]mlg^-1, while K_L values varied between [0.008-0.004, 0.012 -0.008, 0.012-0.005, and 0.009-0.032]mlg^-1 at the three temperatures respectively. The values of thermodynamic parameters (ΔG, ΔH, ΔS) were calculated at 25, 35, 45 ±1ºC. The negative values for ΔG means that the adsorption processes spontaneous and has endothermic nature which proved by the positive value of ∆H that control the chemisorption adsorption in spite of increasing temperature, while the randomness at the surface of the adsorabt on the adsorbent surface due to the positive of the ∆S.