Determination of molecular weight distributions of fulvic and humic acids using flow field-flow fractionation

Beckett, Ronald; Zhang, Jue; Giddings, J. Calvin

doi:10.1021/es00157a010

Cited by 356 publications

(243 citation statements)

References 17 publications

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“…The total absorbance at 420 nm of the whole extract was mostly recovered in the acid-insoluble humic fraction, whereas the total fluorescence intensities were in the acid-soluble fulvic fraction. This result is in accordance with those of previous studies showing that fulvic acids are smaller than humic acids by flow field-flow fractionation, 21 and that high-molecular-weight humic acids exhibit low fluorescence intensities. 22 The CLND chromatogram pattern of the acid-insoluble fraction, which contained 70% of the total N in the compost extract, was very similar to the VIS 420 nm chromatogram pattern, suggesting that a molecule in the acid-insoluble fraction has both protein and humic acid-like moieties.…”

Section: Resultssupporting

confidence: 93%

Molecular Characterization of Organic Nitrogen in Cattle Manure Compost by Size-Exclusion HPLC with Chemiluminescent Nitrogen Detection

2013

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Section: Resultssupporting

confidence: 93%

Molecular Characterization of Organic Nitrogen in Cattle Manure Compost by Size-Exclusion HPLC with Chemiluminescent Nitrogen Detection

2013

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“…However, a steric e!ect should be related not only to the amount of humic substance adsorbed but also to its size. It is well-known that humic acids are larger than fulvic acids, although the di!erence may be less than was previously thought (Thurman, Wershaw, Malcolm & Pinckney, 1982;Beckett, Jue & Giddings, 1987). Therefore, if steric hindrance was an important factor in the reduction of Cs a$nity, the e!ects of humic and fulvic acids should di!er.…”

Section: Steric Ewect Of Adsorbed Humic Substancesmentioning

confidence: 98%

Reduced adsorption of caesium on clay minerals caused by various humic substances

Dumat

Staunton

1999

Journal of Environmental Radioactivity

111

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The e!ect of the addition of various humic substances on the adsorption of caesium on two mineral clays has been studied. All measurements were carried out in dilute suspension under controlled conditions of temperature and ionic strength. Only a small proportion of the humic substance was adsorbed on the clays ( (10%). In general, the a$nity of the clay}humic complexes for caesium was less than that of the bare clay. The decrease was greater for illite than for montmorillonite, and greatest at trace concentrations of caesium and increased with increasing concentration of each humic substance. However, no correlation was found between the amount of humic substance adsorbed and the decrease in Cs adsorption when all complexes were considered. Neither size nor the origin of the humic substances could explain the extent of the adsorption decrease. Since neither steric hindrance nor decrease in the number of adsorption sites was the driving force behind this phenomenon, it is hypothesized that the a$nity of the clay surface is modi"ed by the organic macromolecules. The highly selective frayed edge sites of illite are particularly sensitive to the adsorption of polyanions because of their proximity to anion adsorption sites. The observed decrease in Cs adsorption may contribute to the unexpectedly high bioavailability of Cs in organic soils.

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“…The peat filtration was operated for two (2) hours, where the flux measurement and sampling were conducted periodically every 20 minutes. Humic acid content in raw water and permeate solution were analyzed using UV/vis spectrophotometer with 254 wavelength ( =254 m) [26,27] . The PWF and peat water flux were calculated with the following equation:…”

Section: Figure 1 Experimental Setupmentioning

confidence: 99%

The effect of polymer concentration on flux stability of polysulfone membrane

Ariono

Aryanti

Subagjo

et al. 2017

AIP Conference Proceedings

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Abstract. The influence of various polymer concentrations on flux stability of polysulfone membranes was investigated. The polysulfone membrane was prepared by blending polysulfone in DMAc with 25%wt concentration of PEG400 and 4% wt concentration of acetone. It was found that the pure water flux was sharply decreased from 1230 to 7 Lm-2h-1, when the polysulfone concentration was increased from 14% to 24%wt. Furthermore, the increase of polysulfone concentration also affects the fouling behavior of the membranes, in which almost of 90% of FRR was achieved by the addition of 18 %wt of polysulfone concentration. It was suggested that fouling formed on the membrane surface was dominated by reversible fouling, thus it could be easily cleaned by flushing method. In addition, the applied transmembrane pressure (TMP) also plays an important role in fouling behavior of polysulfone membrane. It was observed that irreversible fouling of organic matter was deteriorated by the increase of TMP, which contributed to the reduction of water flux. More stable membrane flux performance was achieved although it was operated at high TMP, when 20% wt concentration of polysulfone was added into membrane solution.

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Determination of molecular weight distributions of fulvic and humic acids using flow field-flow fractionation

Cited by 356 publications

References 17 publications

Molecular Characterization of Organic Nitrogen in Cattle Manure Compost by Size-Exclusion HPLC with Chemiluminescent Nitrogen Detection

Molecular Characterization of Organic Nitrogen in Cattle Manure Compost by Size-Exclusion HPLC with Chemiluminescent Nitrogen Detection

Reduced adsorption of caesium on clay minerals caused by various humic substances

The effect of polymer concentration on flux stability of polysulfone membrane

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