Eco-friendly removal of hexavalent chromium from aqueous solution using natural clay mineral: activation and modification effects

Inexpensive and naturally abundant clay mineral is investigated as a non-toxic and environmentally friendly adsorbent. The clay adsorbent prepared from natural clay (NC) by drying and milling then treated with diluted HCl before calcination to 600 degrees C. The structural and morphological properties of this modified clay are investigated by Fourier-transform infrared spectroscopy and scanning electron microscope. NC and modified clay at 600 degrees C (MC600) were applied for hexavalent chromium, Cr(VI), removal from aqueous media via batch adsorption facility. According to the experimental results, the adsorption capacity for chromium removal was calculated (14.3 mg g(-1)) with a removal efficiency reached to 66% after 90 min of equilibrium time. The sorption matrix indicated that Cr(VI) removal is following the pseudo-second order kinetic model. The experimental data are well fitted with Freundlich isotherm model and the adsorption process is suggested to follow a chemisorption and favourable uptake. The clay reusability was also tested and the outcomes suggested that MC600 had good potential as an economic adsorbent for chromium removal from contaminated water. According to this finding, modified NC is an effective adsorbent for direct Cr(VI) removal from aqueous media and the clay material is signified as an efficient treatment technology can also be adapted to heavy metal removal in wastewater treatment applications and could replace the commercially available adsorbents.