Modified wool as adsorbent for the removal of Cr(III) from aqueous solution: adsorption properties, isotherm and kinetics

Waste wool was modified by maleic anhydride, and modified wool was prepared by optimizing the conditions such as pH, temperature, and time. The adsorption isotherm, as well as the kinetics of the modified wool, were studied. The results showed that modified wool was effective in removing Cr(III) in wastewater. The maximum adsorption was reached when the pH was about 4.5, the time was 120 min, and the temperature was 30 °C. The experimental results were fitted using Langmuir and Freundlich equations. The results indicate that the Langmuir isotherm is better at describing the adsorption process. Two kinetic models, the pseudo-first-order and pseudo-second-order, were used for analyzing the kinetic data, and the latter was shown to describe the adsorption behavior better.