Characterization of humic acid reactivity modifications due to adsorption onto α-Al 2O 3
KAUST DepartmentBiological and Environmental Sciences and Engineering (BESE) Division
Environmental Science and Engineering Program
Water Desalination and Reuse Research Center (WDRC)
Permanent link to this recordhttp://hdl.handle.net/10754/562103
MetadataShow full item record
AbstractAdsorption of purified Aldrich humic acid (PAHA) onto α-Al 2O 3 is studied by batch experiments at different pH, ionic strength and coverage ratios R (mg of PAHA by m 2 of mineral surface). After equilibration, samples are centrifuged and the concentration of PAHA in the supernatants is measured. The amount of adsorbed PAHA per m 2 of mineral surface is decreasing with increasing pH. At constant pH value, the amount of adsorbed PAHA increases with initial PAHA concentration until a pH-dependent constant value is reached. UV/Visible specific parameters such as specific absorbance SUVA 254, ratio of absorbance values E 2/E 3 and width of the electron-transfer absorbance band Δ ET are calculated for supernatant PAHA fractions of adsorption experiments at pH 6.8, to have an insight on the evolution of PAHA characteristics with varying coverage ratio. No modification is observed compared to original compound for R≥20mgPAHA/gα-Al2O3. Below this ratio, aromaticity decreases with initial PAHA concentration. Size-exclusion chromatography - organic carbon detection measurements on these supernatants also show a preferential adsorption of more aromatic and higher-sized fractions. Spectrophotometric titrations were done to estimate changes of reactivity of supernatants from adsorption experiments made at pH ≈6.8 and different PAHA concentrations. Evolutions of UV/Visible spectra with varying pH were treated to obtain titration curves that are interpreted within the NICA-Donnan framework. Protonation parameters of non-sorbed PAHA fractions are compared to those obtained for the PAHA before contact with the oxide. The amount of low proton-affinity type of sites and the value of their median affinity constant decrease after adsorption. From PAHA concentration in the supernatant and mass balance calculations, "titration curves" are experimentally proposed for the adsorbed fractions for the first time. These changes in reactivity to our opinion could explain the difficulty to model the behavior of ternary systems composed of pollutants/HS/mineral since additivity is not respected. © 2011 Elsevier Ltd.
CitationJanot, N., Reiller, P. E., Zheng, X., Croué, J.-P., & Benedetti, M. F. (2012). Characterization of humic acid reactivity modifications due to adsorption onto α-Al2O3. Water Research, 46(3), 731–740. doi:10.1016/j.watres.2011.11.042
- Colloidal α-Al2O3 Europium(III) and humic substances interactions: a macroscopic and spectroscopic study.
- Authors: Janot N, Benedetti MF, Reiller PE
- Issue date: 2011 Apr 15
- Using spectrophotometric titrations to characterize humic acid reactivity at environmental concentrations.
- Authors: Janot N, Reiller PE, Korshin GV, Benedetti MF
- Issue date: 2010 Sep 1
- Effects of pH and phosphate on the adsorptive fractionation of purified Aldrich humic acid on kaolinite and hematite.
- Authors: Hur J, Schlautman MA
- Issue date: 2004 Sep 15
- Binding of ionic surfactants to purified humic acid.
- Authors: Koopal LK, Goloub TP, Davis TA
- Issue date: 2004 Jul 15
- Surface charge and adsorption from water onto quartz sand of humic acid.
- Authors: Jada A, Ait Akbour R, Douch J
- Issue date: 2006 Aug