Effective adsorption of Cr(VI) from aqueous solution by Mg-Fe LDH supported on orange peel activated carbon: isotherm, kinetic, thermodynamics and mechanism studies

Uttam Kumar Sahu; Swagatika Tripathy; Hari Sankar Mohanty; Prativa Kar

doi:10.1080/15226514.2024.2427388

Effective adsorption of Cr(VI) from aqueous solution by Mg-Fe LDH supported on orange peel activated carbon: isotherm, kinetic, thermodynamics and mechanism studies

Int J Phytoremediation. 2024 Nov 12:1-14. doi: 10.1080/15226514.2024.2427388. Online ahead of print.

Authors

Uttam Kumar Sahu¹, Swagatika Tripathy², Hari Sankar Mohanty³, Prativa Kar¹

Affiliations

¹ Department of Chemistry, Gandhi Institute of Engineering and Technology University, Gunupur, India.
² Department of Chemistry, Veer Surendra Sai University of Technology, India.
³ Department of Physics, Gandhi Institute of Engineering and Technology University, Gunupur, India.

PMID: 39530456
DOI: 10.1080/15226514.2024.2427388

Abstract

The toxic Cr(VI) contaminating water released from the metallurgical, dyeing, and electroplating industries is getting worse day by day and is extremely hazardous to human health. Thus, the development of a cost-effective, quick, and efficient adsorbent is highly essential for the Cr(VI) decontamination from wastewater. Herein, a microwave-assisted carbon-based composite called Mg-Fe LDH@OPAC was prepared by assembling Mg-Fe LDH onto orange peel-activated carbon (OAPC). Prior to investigating deeply into the adsorption behavior of the composite, the Mg-Fe LDH@OPAC formation was confirmed by using instrumental techniques like FESEM, EDS, Zeta potential, XRD, FTIR, Raman, XPS, and BET analyzer. The material had a high surface area of 143.9 m²/g and showed a good monolayer Langmuir uptake capacity of 118.36 mg/g. Under ideal circumstances, the maximum amount of Cr(VI) was removed within just 120 min and showed high efficiency in the presence of other coexisting anions respectively. The adsorption was accounted by pseudo-second-order kinetics and spontaneous in nature. Ultimately, a possible adsorption mechanism was suggested, confirmed by XPS studies; which showed that oxidation-reduction, electrostatic interaction, and surface complexation reaction were responsible for Cr(VI) adsorption on Mg-Fe LDH@OPAC surface.

Keywords: Activated carbon; Cr(VI; LDH); adsorption and removal.

Plain language summary

Environmental contaminants like Cr(VI) in drinking water are highly toxic, and their long-term persistence in the water environment causes mutagenic effects on human beings. We present a novel material for the first time (yet not been reported) by intercalating activated carbon (from a low-cost wedge of orange peel) into Mg-Fe layered double hydroxide (abbreviated as Mg-Fe LDH@OPAC), which has superior hazardous hexavalent chromium metal uptake capability. With the order of SO₄^2->F^->CO₃^2->I^->PO₄^3->NO₃^- the as-prepared Mg-Fe LDH@OPAC exhibits strong selectivity toward Cr(VI) in the presence of varied competing ions with a modest drop in removal effectiveness. The combined properties of AC and LDH make Mg-Fe LDH@OPAC potentially efficient adsorbent to remove Cr(VI) from the different water sources and potentially applied in wastewater treatment.