Application of Modified Bentonite for Efficient Water Purification: A Case of Cr(VI) Adsorption

Document Type : Research Article

Authors

1 Faculty of Chemical Petroleum and Gas Engineering, Semnan University, Semnan, Iran

2 Department of Chemical Engineering, Faculty of Engineering, University of Garmsar, Garmsar, Iran

Abstract

This study explores the use of acid-activated bentonite as an efficient adsorbent for removing hexavalent chromium (Cr(VI)) from water. Acid activation enhances the surface area and adsorption capacity of bentonite, improving its water treatment efficiency. Various techniques, including BET, FT-IR, XRD, XRF, and SEM, were used to analyze structural and compositional changes after activation. Adsorption experiments showed that under optimal conditions—room temperature, 0.1 ppm Cr(VI), and 1 g of acid-activated bentonite—100% removal was achieved. The adsorption followed the Langmuir isotherm with a maximum capacity of 0.122 mg/g. Kinetic studies confirmed a pseudo-second-order reaction model (R² = 0.99), indicating a chemisorption mechanism. Thermodynamic analysis showed the process is spontaneous and exothermic, requiring no external energy input. Groundwater tests from the Foroomad region (Semnan Province) compared raw and acid-modified bentonite, revealing a 92% Cr(VI) removal efficiency with the modified form, reducing contamination to safe levels. These results highlight acid-activated bentonite as a cost-effective and eco-friendly adsorbent for water purification, demonstrating its real-world potential for ensuring safer drinking water.

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Articles in Press, Accepted Manuscript
Available Online from 12 May 2025
  • Receive Date: 16 March 2025
  • Revise Date: 20 April 2025
  • Accept Date: 08 May 2025