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Updated: Jan 19, 2026

Quantification of Humic and Fulvic Acids in Humate Ores, DOC, Humified Materials and Humic Substance-Containing Commercial Products
Published on: March 18, 2022
Sorption of Nb(V) on pyrolusite (β-MnO2): Effect of pH, humic acid, ionic strength, equilibration time and
Madhusudan Ghosh1, P S Remya Devi2, K K Swain1
1Analytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, India.
Abstract:
The sorption of Nb(V) on pyrolusite has been studied and the effect of pH, ionic strength, humic acid, temperature and equilibration time were also investigated in a series of batch equilibrium experiments. The sorption was found to be affected by solution pH, ionic strength and humic acid. The sorption was high in neutral/near neutral pH (~96 %) but lower sorption was observed both in acidic (~55 %) and basic (~85 %) media. Sorption was decreased in acidic pH with increase of ionic strength and reverse effect was seen in basic pH although the effect is less prominent. Presence of humic acid causes enhancement of sorption in acidic pH whereas sorption declined in basic pH. The sorption process is endothermic in acid medium and exothermic in basic medium. In acid medium the sorption is entropy driven process. Kinetics of the sorption study was found to follow pseudo first order in acidic pH whereas pseudo second order in basic pH.
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