Adsorption of a hazardous dye, erythrosine, over hen feathers

Erythrosine is a popular dye that is widely used in cosmetics, foodstuffs, medicines, and textiles. It is highly toxic to mankind and can lead to many diseases including carcinogenicity. Removal of erythrosine has been carried out using waste material--hen feathers--as adsorbent. The effects of pH, concentration of the dye, temperature, and adsorbent dosage have been studied. Adsorption of erythrosine over hen feathers has been correlated with Freundlich and Langmuir isotherms and satisfies both models. The adsorption process has been found endothermic in nature and thermodynamic parameters, Gibb's free energy (DeltaG(0)), change in enthalpy (DeltaH(0)), and change in entropy (DeltaS(0)) have been calculated. The paper also includes results on the kinetic measurements of adsorption of the dye on hen feathers at different temperatures. The adsorption follows a first-order kinetics at all the temperatures and values of the rate constant (k(ad)) have been calculated as 0.0179, 0.0177, and 0.0172 s(-1) at 30, 40, and 50 degrees C, respectively. By rate expression and treatment of data it has been ascertained that the adsorption of erythrosine over hen feathers follows a particle diffusion mechanism.