Investigating adsorption of aqueous heavy metals through isotherms and kinetics with Zn-Co-Fe/LDH for remarkable removal efficiency

Abstract

Abstract Heavy metals can be extracted from aqueous solutions by using the Zn-Co-Fe/LDH adsorbent (2:2:1 M), which was made by coprecipitation. Many of analytical methods, inclusive the scanning electron microscope (SEM), X-ray diffraction (XRD), and infrared spectroscopy (FTIR), were applied to evaluate the produced adsorbent. The impact of adsorption factors consisting adsorbent dosage, time, initially adsorbate concentration, and solution pH was estimated. The Zn-Co-Fe/LDH material’s crystal structure is verified by X-ray diffraction investigation of the sample. As 3+ , Pb 2+ , and Hg 2+ ions were successfully removed from the watery solution using the Zn-Co-Fe/LDH adsorbent. At pH range from 3 to 9, the maximal removal of As 3+ ions reached 74%, whereas that of Pb 2+ and Hg 2+ ions reached 100%. The maximum adsorption capacity of LDH was determined by utilizing five model isotherms, the best model was Langmuir–Freundlich model and the maximum adsorption capacity was 529.63 mg/g, 2741.5 mg/g, and 1852.9 mg/g, respectively. The temperature experiments were conducted at 25, 35, 45, and 55 °C to investigate the thermodynamic parameters $$\Delta$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Δ</mml:mi> </mml:math> H o , $$\Delta$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Δ</mml:mi> </mml:math> S o , and $$\Delta$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Δ</mml:mi> </mml:math> G o . The calculated values show exothermic and non-spontaneous adsorption processes. The results revealed that heavy metals removal mechanisms involved physical and chemical adsorption. The reuse of adsorbent study was performed and discussed. In regard to this study, Zn-Co-Fe/LDH is a material that shows promise for treating industrial wastewater by effectively removing heavy metals from aqueous solutions.