Abstract
The effects of sepiolite, montmorillonite, and attapulgite on the removal and immobilization of Cr(VI) in water and soil were studied. X-ray diffraction (XRD) characterizations showed that the purities of these three mineral materials decreased in the following order: montmorillonite > attapulgite > sepiolite, and that their surface molecular bond types were similar. The adsorption potential of Cr(VI) in aqueous solutions of the three mineral materials was in the following order: sepiolite > attapulgite > montmorillonite. The adsorption mechanism for attapulgite was consistent with the Freundlich isotherm adsorption model, whereas that for montmorillonite was more consistent with the Langmuir model. Sepiolite had a good fitting effect for both isothermal adsorption models. For montmorillonite and attapulgite, a lower pH corresponded to a higher removal of Cr(VI). For sepiolite, however, the removal efficiency of Cr(VI) from an aqueous solution was the lowest at a pH of approximately 5.0. The results of the soil toxicity characteristic leaching procedure showed that, following the addition of 15% sepiolite, attapulgite, or montmorillonite to the contaminated soil, Cr(VI) concentrations in the leachates decreased by 16.8%, 18.9%, and 15.9%, respectively, and the total Cr concentrations in the leachates were reduced by 21.2%, 29.2%, and 17.6%. Of the three mineral materials, attapulgite demonstrated the highest Cr(VI) immobilization efficiency in soil. This study emphasizes the effect of attapulgite on the immobilization of Cr(VI) in soil and aqueous solutions, thus providing a theoretical basis for the potential application of natural mineral material remediation of Cr(VI)-contaminated aqueous solutions and soils.
Highlights
Chromium is mainly used in the metallurgy, electroplating, printing, textile dyeing, and papermaking industries
Further research on the effects of different mineral materials on the treatment of Cr(VI)-contaminated water and soil is necessary, as mineral materials have a variety of mineral compositions and surface properties
The results show that the order of the specific surface areas of the mineral materials was as follows:
Summary
Chromium is mainly used in the metallurgy, electroplating, printing, textile dyeing, and papermaking industries. Physical methods for the remediation of Cr(VI)-contaminated water and soil mainly immobilize metal ions by adsorption onto the surface or between the layers of an adsorbent (such as illite@carbon nanocomposite or hazelnut shell activated carbon) [23,24]. Further research on the effects of different mineral materials on the treatment of Cr(VI)-contaminated water and soil is necessary, as mineral materials have a variety of mineral compositions and surface properties. Fourier-transform infrared (FTIR) spectra can reflect small molecules or molecular bond stretching vibration on the surface and inside the material These characterization methods are useful to elucidate the properties, composition and structure of materials, and in turn help analyze the differences in the ability of different minerals to adsorb and remove Cr(VI). This study provides guidelines for the use of natural mineral materials in the treatment of Cr(VI)-contaminated environments by achieving the above objectives
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
