Removal of Cr(III) Using Humic Acid-Modified Attapulgite

A novel modified attapulgite has been developed. The method is based on the modification of attapulgite with humic acid, and its application is for the removal of Cr(III) in different conditions. It is characterized using Fourier-transformed infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET). Then, the adsorption behaviors of as-prepared product are evaluated by static adsorption of Cr(III) from wastewater. The effect of pH, contact time, temperature, concentration, and adsorbent dosage on adsorption of Cr(III) is discussed. The results indicate that adsorption amount of Cr(III) on modified attapulgite is better than that of natural attapulgite. The temperature of the Cr(III) solution is found to have a significant influence on the adsorption amount. The Langmuir isotherm is used to describe well the equilibrium adsorption data, and the enthalpy change is evaluated by the Van't Hoff equation. The thermodynamic analysis indicates that the adsorption is an exothermic and spontaneous process. Finally, the adsorption kinetic conformed to the quasi-first-order and quasi-second-order ratio equations.