the kinetic and thermodynamic study of the removal of cr(vi) ion from aqueous solution by human hair waste

The removal of cr(vi) ions from aqueous solution by human hair waste is investigated by using uv–vis spectrophotometer technique. the morphological analysis of the human hair was also investigated by the scanning electron microscopy, fourier transforms infrared spectroscopy and x-ray photoelectron spectroscopy. the influence of various physicochemical effective parameters such as ph, ionic strength, adsorbent amount, contact time, initial concentration of metal ion on removal of cr(vi) ions by human hair process was also studied. the optimum conditions for this adsorption process were obtained at ph = 2 and contact time of 150 min while the highest cr(vi) uptake is recorded for 0.5 g of the adsorbent per 100 ml of solution. three isotherms models including langmuir, freundlich and temkin were applied to describe the equilibrium data. it was found that the experimental data were well described by freundlich isothermal model. the maximum adsorption capacity was found to be 11.64 mg g−1.the thermodynamic study data showed that the adsorption process of cr(vi) on human hair is an endothermic, spontaneous and physisorption reaction. the kinetics of the adsorption process was studied using three kinetics models including lagergren-first-order, pseudo-second-order and elovich model. the obtained data are indicated that the adsorption processes of cr(vi) over human hair could be described by the pseudo-second-order kinetic model.