Evaluation of adsorptive capacity of natural biosorbent for dye removal as a contribution to environmental protection: effect of various parameters

In this study, natural bentonite was prepared and tested for the removal of diazo dye throughthe adsorption process. Investigated biosorbent was characterized using XRD, N-2 sorption, XRF, total surface area using methylene blue method and TEM techniques. The effect of major parameters, such as initial dye concentration, adsorbent dosage, pH, contact time and temperature were investigated and discussed.Resultsshow that studied bentonite after purification exhibited high adsorption capacity toward acid dyes. Maximum adsorption of Congo red dye(CR)was achieved between pH 4 and 5. Kinetic study revealed that the adsorption profile is well fitted by the pseudo-second-order kinetic model and chemisorption process was proposed.Isotherm data were investigated according to Langmuir and Freundlich equations. Thermodynamic study showed the spontaneous nature of adsorption with endothermic process.Removal of lead heavy metal was investigated by adsorption into Congo red loaded purified bentonite and results show a high % removal (98.83 %).