Experimental determination of partial specific volumes of humic substances in aqueous solutions

Jones, Malcolm N.; Birkett, Jason W.; Wilkinson, A. E.; Hesketh, N.; Livens, Francis R.; Bryan, Nicholas; Lead, Jamie R.; Hamilton−Taylor, John; Tipping, Edward

doi:10.1016/0003-2670(95)00272-2

Cited by 22 publications

(10 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since these species are inhomogeneous mixtures, and often are not separated from other soil components and since they are assumed to be dissolved in the water, the literature usually Published by Copernicus GmbH on behalf of the European Geosciences Union. refers to their partial specific volume (Benedetti et al, 1996;Jones et al, 1995;Reid et al, 1990). In the last decade, the interest of atmospheric sciences in these substances has expanded due to the resemblance of atmospheric HULIS to HS in chemical nature and physical properties (Gelencser et al, 2000;Hoffer et al, 2004;Kiss et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

The density of humic acids and humic like substances (HULIS) from fresh and aged wood burning and pollution aerosol particles

Mentel²,

2006

View full text Add to dashboard Cite

Abstract. Atmospheric aerosols play significant roles in climatic related phenomena. Size, density and shape of particles affect their fluid-dynamic parameters which in turn dictate their transport and lifecycle. Moreover, density and shape are also related to particles' optical properties, influencing their regional and global radiative effects. In the present study we have measured and compared the effective densities of humic like substances (HULIS) extracted from smoke and pollution aerosol particles to those of molecular weight-fractionated aquatic and terrestrial Humic Substances (HS). The effective density was measured by comparing the electro mobility and vacuum aerodynamic diameter of aerosol particles composed of these compounds. Characterization of chemical parameters such as molecular weight, aromaticity and elemental composition allow us to test how they affect the effective density of these important environmental macromolecules. It is suggested that atmospheric aging processes increase the effective density of HULIS due to oxidation, while packing due to the aromatic moieties plays important role in determining the density of the aquatic HS substances.

show abstract

Section: Introductionmentioning

confidence: 99%

The density of humic acids and humic like substances (HULIS) from fresh and aged wood burning and pollution aerosol particles

Mentel²,

2006

View full text Add to dashboard Cite

show abstract

“…The structures proposed, which cover a period from that of Dragunov in 1948 cited by Kononova (1966) to Schulten (1993) and Schulten & Schnitzer (1993). The empirical formulae, molecular masses and estimated partial specific volumes of the various structures are given in Table 2 together with experimental data for humic materials isolated from the same place on two occasions by Reid et al (1990) and Jones et al (1995). The partial specific volumes calculated from the random modelling are also given for the fulvic and humic acids for which we have experimental data.…”

Section: Resultsmentioning

confidence: 99%

“…In practice the difference between V 2 and V,,, is not significant for very dilute solutions. Experimentally values of V2 for humic substances range from 0.46 cm3 g-'-0.71 cm3 g-' (Jones et al, 1995), and whilst some of the variation in V 2 may relate to conditions of measurement it is important to assess to what extent V 2 might reflect variation in the composition and structure of humic materials.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…If the standard error in 112 is a ] , then it follows from the treatment of standard errors of compound quantities that the standard error in M is given by (Jones et al, 1995): (4) from which it follows that a 5% standard error in V 2 will lead to a 15% standard error in M. A knowledge of accurate values of V2 is thus important in calculating M.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…The determination of 112 is important in the calculation of molecular. masses (M) from ultracentrifugation measurements by use of the equation (Jones et al, 1995).…”

Section: Theoretical Backgroundmentioning

confidence: 99%

See 2 more Smart Citations

Computer modelling of partial specific volumes of humic substances

Birkett

Jones

Bryan

et al. 1997

European J Soil Science

View full text Add to dashboard Cite

The determination of the structure of humic substances from peat soils and natural waters is a major problem in soil science. Humic substances are chemically heterogeneous and consist of molecules covering a wide distribution of molecular size. A quantity related to both molecular size and structure in the hydrated state is the volume of the humic molecules per unit mass or partial specific volume (V2). The partial specific volumes of humic substances have been estimated from atom and chemical group volume contributions for 17 proposed structures of fulvic and humic acids taken from the literature. The results show that the partial specific volume reflects the composition of humic substances, decreasing with increase in the carbon: hydrogen (C : H) molar ratio. The more oxidized the humic material the smaller is its partial specific volume. These trends agree with our experimental measurements of partial specific volumes for a range of humic materials (aquatic fulvics, aquatic and peat humics). The predicted values of partial specific volumes for the proposed structures, however, are overestimated by approximately 15% compared to the experimental values. There is little difference between values of V2 calculated from the detailed humic structures and those calculated from their empirical formulae; calculations of partial specific volumes using a random modelling approach leads to overestimation by approximately 37%. It seems that the estimates based on additivity of atom and chemical group volumes do not take into account an overall contraction of the structures because of hydrophobic interactions. In general terms the values of the partial specific volumes of humic substances suggest they are more compact molecules than globular proteins, and intrinsic viscometry studies suggest that aqueous salt solutions approach 0-solvent conditions for humic substances.

show abstract

Calculation of the interaction between dissolved organic carbon and organic micropollutants by three dimensional force field methods

Govers

Roon

Parsons

2003

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

Abstract-A 3D optimized potential for liquid simulation (OPLS) force field method with 6-31G* atomic charges and a geometrical optimization approach was studied for the calculation of enthalpies of transfer at 300 K of partitioning processes. A 3D fulvic acid model of dissolved organic carbon was built. Limonene, ␣-pinene, fluoranthene, p,pЈ-DDT, and 2,4-D were inserted into a general site of preference, and interaction energies were calculated. Energies of hydration were calculated and subtracted from fulvic acidcontaminant interactions. The resulting values for the enthalpies of transfer from water to dissolved organic carbon were Ϫ2.2, ϩ0.9, Ϫ6.4, Ϫ4.0, and Ϫ4.3 kcal/mol for limonene, ␣-pinene, fluoranthene, p,pЈ-DDT, and 2,4-D, respectively. This led to a change of the partition constant by a factor of 0.17 to 1.27 at a temperature increase from 5 to 55ЊC. The values of fluoranthene and p,pЈ-DDT compared favorably with their experimental values of Ϫ4.4 and Ϫ5.0 kcal/mol. Prior to this, a general scaling factor for electrostatic interactions in both the pure liquid (s liq ϭ 2.89) and the hydrated solute (s hyd ϭ 3.70) was derived from the experimental values of enthalpies of vaporization and aqueous solution. Resulting predicted enthalpies of vaporization deviated by Ϫ3.1 (water), 0.4 (limonene), 0.2 (␣-pinene), 3.9 (fluoranthene), Ϫ3.0 (p,pЈ-DDT), and 0.9 (2,4-D) kcal/mol from experimental data, whereas enthalpies of aqueous solution deviated by Ϫ1.3 (limonene), Ϫ5.7 (␣-pinene), 4.2 (fluoranthene), and 0.3 (p,pЈ-DDT) kcal/mol. Results are discussed in terms of molecular structures and their interactions.

show abstract

Experimental determination of partial specific volumes of humic substances in aqueous solutions

Cited by 22 publications

References 17 publications

The density of humic acids and humic like substances (HULIS) from fresh and aged wood burning and pollution aerosol particles

The density of humic acids and humic like substances (HULIS) from fresh and aged wood burning and pollution aerosol particles

Computer modelling of partial specific volumes of humic substances

Calculation of the interaction between dissolved organic carbon and organic micropollutants by three dimensional force field methods

Contact Info

Product

Resources

About