External mass transfer studies during the adsorptions of some dyestuffs and p-nitrophenol onto chitosan from aqueous solution

The effect of temperature on the adsorptions of some dyestuffs (orange 11 (O-II), crystal violet. (CV) and reactive blue 5 (RB5)] and an ideal adsorbate p-nitrophenol (PNP) by chitosan (Sigma C 36,46) from aqueous solution was investigated. The experimental data related to adsorption isotherms were applied to linear forms of the equations that they fitted, and isotherm constants were calculated. Since the isotherm curves obtained for the adsorptions of O-II and CV by chitosan fitted the Langmuir adsorption isotherm, the Langmuir constants (q(m) and b) related to the adsorption isotherms of these dyestuffs together with their kinetical data at different temperatures were applied to the equation of McKay et, al., and external mass transfer coefficients (k(f))(1) at these temperatures were calculated. In addition. kinetic data obtained for each dyestuff and PNP at different temperatures were applied to a further equation developed by Weber-Mathews, and (k(f))(2) Constants at these temperatures were calculated.