Microwave assisted preparation and characterization of biopolymer-clay composite material and its application for chromium detoxification from industrial effluent

The microwave assisted preparation and characterization of chitosan-surfactant modified NaMMT clay composite material is discussed, followed by its interesting application to detoxify heavy metal chromium. Cr(VI) could be effectively adsorbed in a weakly acidic medium (pH 5) from a large sample volume. The composite material before and after the adsorption of chromium was scrupulously characterized using FT-IR, SEM, XRD and EDX techniques. The XRD study revealed the crystalline nature of the composite material with sharp and symmetric peaks. The bichromate ion forms an ion-pair with the protonated amine group in chitosan and this is reflected in the appearance of a Cr=O peak at 916 cm -1 in IR study. The surface hydroxyl groups in clay can be protonated and this could also serve as a source of electrostatic interaction with the bichromate oxyanion. The material exhibited a superior adsorption capacity of 133 mg g -1 and the adsorption data fitted well with Langmuir and Freundlich isoth