Bentonite deposits are widely distributed in different parts of the world associated with volcanic rocks and tuffaceous sediments of Miocene and Oligocene age. Other important minerals are illite, kaolinite and vermiculite. Bentonite mineral is smectite group of minerals having a montmorillonite unit which consists of two tetrahedral silica sheets and one octahedral sheet [1-3]. These come under clay minerals abundant in Rajasthan and Jharkhand. A vast deposit of bentonite occurs in a place Wyoming in U.S.A, Montmorillon in France, Japan and some countries of the world. So, this bentonite has been named after its place known as Wyoming bentonite and montmorillonite has gained its name after its discovery locality at Montmorillon 70 Km NNW of Limoges, France. Natural bentonite is 98% montmorillonite giving positive stain test with benzidine solution [4-6]. Owing to low cost and abundance in nature, a new vistas of research on bentonites has been opened up with a view to remove heavy metals and toxic elements from aqueous medium. Clay minerals have residual charges on the surface due to partial substitution of tetrahedral Si⁴⁺ by Al³⁺ or Al³⁺ or Fe³⁺ by Fe²⁺ or Mg²⁺. Thus, substitution of tetravalent cations by trivalent cations leaves deficit charge on the surface of the clay. Main constituents of clay minerals are SiO₂, Al₂O₃ along with Na₂O, K₂O, CaO and MgO [7]. Characterization of bentonites are done by XRD, FTIR, SEM, TGA, DSC and physico chemical tests. Bentonites of different colour and grade of Rajmahal hills of Jharkhand have been used commercially for various industrial purposes. High swelling power, plastic properties, adsorption potential and cation exchange capacity of bentonite have made it a low cost adsorbent of Cr, Cd, As, F and organic dyes.

References

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Citation

Citation: Ashok Kumar Jha. “Application of Bentonite Mineral in Removal of Heavy Metal". Acta Scientific Agriculture 4.12 (2020): 63-64.

Copyright

Copyright: © 2020 Ashok Kumar Jha. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.