Kinetics and thermodynamics of the adsorption of some dyestuffs from aqueous solution by poplar sawdust

The effect of temperature on the adsorption of metanil yellow (MY) (acidic) and methylene blue (MB) (basic) by poplar sawdust was investigated. In addition, the amounts of NaHCO3, Na2CO3, NaOH and C2H5ONa adsorbed by 1 g of poplar sawdust to determine its surface acidity were also determined. Kinetical data obtained at different temperatures (293 K, 313 K and 333 K) for the adsorption of each dyestuff by poplar sawdust were applied to the pseudo first-order, the pseudo second-order and the intraparticle diffusion equations, and the rate constants of first-order adsorption (k1), the rate constants of second-order adsorption (k2) and intraparticle diffusion rate constants (kp) at these temperatures were calculated, respectively. In addition, isothermal data obtained at different temperatures (293 K, 313 K and 333 K) for the adsorption of each dyestuff by poplar sawdust were applied to thermodynamical equations, and thermodynamical parameters (ΔG, ΔH and ΔS) were also calculated.