Fe-exchanged nano-bentonite outperforms Fe3O4 nanoparticles in removing nitrate and bicarbonate from wastewater

Raj Mukhopadhyay; Tapan Adhikari; Binoy Sarkar; Arijit Barman; Ranjan Paul; Ashok K Patra; Parbodh C Sharma; Parveen Kumar

doi:10.1016/j.jhazmat.2019.05.025

Fe-exchanged nano-bentonite outperforms Fe₃O₄ nanoparticles in removing nitrate and bicarbonate from wastewater

J Hazard Mater. 2019 Aug 15:376:141-152. doi: 10.1016/j.jhazmat.2019.05.025. Epub 2019 May 13.

Authors

Raj Mukhopadhyay¹, Tapan Adhikari², Binoy Sarkar³, Arijit Barman¹, Ranjan Paul⁴, Ashok K Patra², Parbodh C Sharma¹, Parveen Kumar¹

Affiliations

¹ ICAR-Central Soil Salinity Research Institute, Karnal 132001, India.
² ICAR-Indian Institute of Soil Science, Bhopal 462038, India.
³ Department of Animal and Plant Sciences, The University of Sheffield, Sheffield, S10 2TN, UK. Electronic address: b.sarkar@sheffield.ac.uk.
⁴ Division of Soil Resource Studies, ICAR-National Bureau of Soil Survey and Land Use Planning, Nagpur 440033, India.

PMID: 31128393
DOI: 10.1016/j.jhazmat.2019.05.025

Abstract

Nitrate (NO₃^-) and bicarbonate (HCO₃^-) are harmful for the water quality and can potentially create negative impacts to aquatic organisms, crops and humans. This study deals with the removal of NO₃^- and HCO₃^- from contaminated wastewater using Fe-exchanged nano-bentonite and Fe₃O₄ nanoparticles. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, surface area measurement and particle size analysis revealed that the adsorbents fall under the nano-scale size range with high specific surface area, and Fe was successfully exchanged in the nano-bentonite clay. The kinetics of adsorption was well defined by pseudo-first order and pseudo-second order kinetic models for both NO₃^- and HCO₃^-. The Fe-exchanged nano-bentonite was a better performing adsorbent of the oxyanions than Fe₃O₄ nanoparticles. According to the Sips isothermal model, the Fe-exchanged nano-bentonite exhibited the highest NO₃^- and HCO₃^- adsorption potential of 64.76 mg g^-1 and 9.73 meq g^-1, respectively, while the respective values for Fe₃O₄ nanoparticles were 49.90 mg g^-1 and 3.07 meq g^-1. Thus, inexpensiveness and easy preparation process of Fe-exchanged nano-bentonite make it attractive for NO₃^- and HCO₃^- removal from contaminated wastewater with significant environmental and economic benefits.

Keywords: Nano-bentonite; Nitrate pollution; Oxyanion adsorption; Wastewater treatment; Water alkalinity.