Lability of Cd, Cr, Cu, Mn and Pb complexed by aquatic humic substances

Abstract

The lability of Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) complexed by humic substances (HSs) was investigated by means of ion exchange on cellulose modified with p-aminobenzoic groups (Cell-PAB), using a batch procedure. The HSs were extracted from water samples using adsorption in a column packed with XAD 8 resin. The metal-HS complexes were prepared by adding solutions containing all the aforementioned metal ions ( Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) ). The results indicated that the distribution coefficients (Kd) of Cell-PAB decreased with the presence of HSs, and that the lability of metal fractions complexed by HSs decreases in pH values > 4.0, complexation time > 10 h and HS concentration > 500 mg L-1. The metal exchange between HSs and Cell-PAB exhibited the following order of metal ion lability: Cd < Pb < Mn <FONT FACE=Symbol>@</FONT> Cr < Cu.

Chromatographic methods for the isolation, separation and characterisation of dissolved organic matter

“…However, despite MS detection providing an additional dimension in achievable resolution, it should be noted that challenges remain in the interpretation of the resulting spectra which are characterised by multitudes of molecular adducts or ions derived from the thousands of compounds characterising DOM. [163][164][165][166][167][168][169] The resulting even m/z complexes stand out in the spectrum and can directly be characterised by molecular formulae assignments or tandem MS experiments. [151][152][153] Following collection of mass spectra, potential elemental formulae are assigned to the acquired monoisotopic mass of each molecular species, within the mass accuracy limits of the instrument used.…”

“…35,162 Additionally, due to the tendency of metal ions to form primarily even-m/z complexes within DOM, and in particular humic substances, Mg 2+ , Be 2+ , Cr 3+ and Mn 2+ have also been used to further simplify mass spectra. [163][164][165][166][167][168][169] The resulting even m/z complexes stand out in the spectrum and can directly be characterised by molecular formulae assignments or tandem MS experiments. 166,[170][171][172] On the basis of previously developed HR-MS methods, 42,156 Stenson et al, targeting humic substances within a Suwannee river fulvic acid standard, 162 presented the separation of DOM isomers through RP-LC-HR-MS. Ions with identical formulae were found within different chromatographic fractions and analysed using the above H/D exchange protocol, providing for isotope differentiation.…”

Fourier transform ion cyclotron resonance mass spectral characterization of metal‐humic binding

“…Refs. 4, 7–9 and references cited therein). The experiments described here do not attempt to repeat or refine these studies; rather they highlight a facile means by which electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FTICR‐MS) can be used to enhance existing knowledge by expanding it from the bulk to individual analytes and by incorporating structural detail.…”

Immobilisation of Humic Substances Using Plasma Modification

“…The interaction of humic substances with metals could play an important role in removing these hazardous substances from the environment [4,[6][7][8][9][10]. Many studies therefore focus on the interaction of heavy metals in wastewater with HSs [3][4][5][8][9][10][11][12]. However, HSs are used mainly in powder form or in a solution, which limits their applications.…”