Removal of lead ions from aqueous solutions by insolubilized Iraqi humic acid

Humic acid from Adhamiya clay soil was extracted and converted to insolubilized humic acid (INaHA). It was characterized by Fourier-transform infrared spectroscopy, elemental analysis, thermal gravimetric analysis, X-ray diffraction, differential scanning calorimetry, and scanning electron microscop...

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Bibliographic Details
Published in:Desalination and water treatment 2020-12, Vol.206, p.286-296
Main Authors: Baker, Hutaf M., Khalili, Fawwaz I., Aldulaimy, Baraa Ibraheem Abass
Format: Article
Language:English
Subjects:
Insolubilized humic acid
Isotherm models
Kinetic models
Lead ions
Removal
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Summary:Humic acid from Adhamiya clay soil was extracted and converted to insolubilized humic acid (INaHA). It was characterized by Fourier-transform infrared spectroscopy, elemental analysis, thermal gravimetric analysis, X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy. Adsorption of Pb(II) ions by INaHA was studied using the batch technique at different temperatures (25.0°C, 35.0°C and 45.0°C) and at different pH values (3.0, 4.0 and 5.0), The solutions adjusted to pH 4 were found to be the optimum media for the removal Pb(II) ions. Pseudo-second- order kinetic model was used to understand the mechanism for adsorption, the maximum capacity of the uptake of lead ions was achieved after 24 h. The rate constant k2 of the pseudo-second-order sorption was used to calculate the activation energy (Ea) of (20.26 kJ/mol), which gives evidence that the physisorption process took place. Isotherm equilibrium models were investigated, Langmuir, Freundlich and Dubinin–Radushkevich) were applied to the data acquired at different temperature values 25.0°C, 35.0°C and 45.0°C. It was found that the Langmuir isotherm is the best model to describe this adsorption depending on the R2. The energy E which is determined from the Dubinin– Radushkevich isotherm model was taken the range 1.16 to 1.03 kJ/mol. The experimental thermodynamic functions, ΔG°, ΔH° and ΔS° are –4.5 kJ/mol, 9.23 kJ/mol and 46.13 J/mol.K, respectively. The %uptake of lead was determined using a continuous column experiment and was found to be 93.91%. The recovery of desorbed Pb(II) using 1 M of HNO3 is higher than using 1 M of HCl.
ISSN:1944-3986
1944-3986
DOI:10.5004/dwt.2020.26352