Showing papers on "Humic acid published in 1981"

Activated carbon adsorption of humic substances

Abstract: Activated carbon pore-size distribution is an important parameter relative to the carbon's capacity for adsorbing humic substances. The effect of coagulation on adsorption should also be examined wherever granular activated carbon is to be used following coagulation. Experimental investigations using a commercial humic acid and a fulvic acid extracted from peat, and a number of commercial activated carbons, several of which were coal-based, are reported.

Redox behavior, complexing, and adsorption of hexavalent actinides by humic acid and selected clays

Abstract: The sediments smectite and illite clay strongly adsorb Np(VI) from deoxygenated artificial seawater solution In addition the former reduces the Np(VI) to Np(V) Humic acid strongly adsorbs U(VI), Np(VI), and Pu(VI) from aqueous bicarbonate-carbonate media The humic acid reduces Np(VI) to Np(V), and Pu(VI) to Pu(IV), but does not reduce U(VI) Detailed spectrophotometric evidence for the complex-forming reactions is presented

Metal Transfer Between Solid and Aqueous Phases

Abstract: The greater part of the dissolved heavy metals transported by natural water systems is, under normal physicochemical conditions, rapidly adsorbed onto particulate material. However, heavy metals immobilized in bottom sediments do not necessarily stay in that condition, but may be released as a result of chemical changes in the aquatic milieu. The following sections will pay special attention to the interaction between water and sediment, and the possibilities of immobilization and remobilization of metals in unpolluted as well as in polluted systems.

Sulfur transformations in relation to carbon and nitrogen in incubated soils

Abstract: Changes in biomass-S in relationship to biomass-C and N were evaluated, and the transformation of 35S-labelled SO42− among organic matter fractions were followed during incubation of a Black Chernozemic (Udic Haploboroll) and Orthic Gray Luvisol (Typic Cryoboralf) soils There was a net immobilization of S with and without the addition of cellulose or sulfate after 64 days In contrast, a net mineralization of N occurred Cellulose decomposition rates responded to supplies of S available for new microbial cell synthesis Fluctuations in the amounts of biomass-S during incubation of both soils followed biomass-C and biomass-N changes and C/S and C/N ratios of the biomass ranged between 47–121 and 49–77, respectively Microbially-incorporated S was found concentrated within the biomass or partially transformed into soil organic matter Fractionation of soils after incubation, by a 01 m NaOH-01 m Na4P2o7 extraction-separation technique showed significant increases in the C and N contents of the conventional humic acid (HA-A) and fulvic acid (FA-A), and humin (

Composition analysis of humus and characterization of humic acid obtained from city refuse compost

Abstract: The humus composition was analyzed and the humic acid characterized by UV and visible absorption spectroscopy in order to investigate the rotting and maturing process of city refuse compost according to the method of Kumada et al. During the composting process, the following findings were obtained: (1) the HT value was almost constant, but the HE/HT ratio varied somewhat, (2) HA increased with decrease in FA, and the PQ value so increased clearly, (3) the shoulder-like absorption at a wavelength near 270 nm weakened, and (4) the RF value of humic acid increased, whereas the Δ log K value seldom varied. The IR spectrum of humic acid gradually changed as follows: (1) the absorption band in the 1700-1600 cm-1 region and in the 1550-1500 cm-1 region increased slightly, (2) the band in the 1100-1000 cm-1 region decreased, and (3) the bands at 835 and 710 cm-1 com pletely disappeared. On the whole, the shape of the IR spectrum of the city refuse compost became featureless. These changes were probably d...

Geochemistry of artificially heated humic and sapropelic sediments. I. Protokerogen

Abstract: Experiments designed to simulate burial maturation have provided information on the geochemistry of classes of organic constituents in Holocene sediments of different origin. Humic acids and kerogens isolated from laboratory-heated Laguna Mormona, Baja California, algal mat (sapropelic facies) and Staten Island, California, peaty deltaic soil (humic facies) were characterized by a variety of techniques including elemental analysis, electron spin resonance, programmed temperature pyrolysis, vitrinite reflectance, and stable isotope ratios. The study shows that the generation of kerogen during burial is the net result of temperature/time dependent synthetic and destructive reactions involving protokerogen and associated solvent-extractable organic matter. For the Staten Island sediment, where the initial content of humic substances is high, conversion of humic acid to gas-prone kerogen is quantitatively the most significant maturation process. For the Laguna Mormona algal mat, where lipid content is high, evidence suggests that some formation of oil-prone kerogen may occur by cross-linkage and binding of free lipids during diagenesis. Kerogen formation from humic acid in this sediment is minor.

The Persulfate Oxidation Of A Soil Humic Acid

Abstract: We extracted humic acid (HA) from an Encinillas soil, Xeroumbrepts, Inceptisols, and oxidized it with potassium persulfate for 2 hours at 140°C. The oxidation products, after methylation, were analyzed by direct injection into a gas chromatographic-mass spectrometric computer system. The most abundant compounds isolated from the HA oxidation products were n-C16 and n-C18 fatty acids, followed by several benzenecarboxylic and phenolic acids. Dicarboxylic acids and dialkyl phthalates constituted only a relatively small proportion of the isolated compounds. No n-alkanes were detected. Persulfate degrades only 40 percent of total weight HA, leaving a residue that can easily be recovered for further structural investigations. Persulfate, therefore, may be used as first oxidant in a sequential HA degradation.

Inhibition of malate dehydrogenase by humic acids

Abstract: Malate dehydrogenase (from pig heart mitochondria) is markedly inhibited by a number of humic acids extracted from different types of soil or prepared synthetically. The inhibitors were found to be competitive for both substrates of the forward reaction, whereas inhibition is of the mixed type with NADH in the reverse reaction. In both directions, inhibition is strictly dependent on the number of phenolic hydroxyl groups on the humic acids. The affinity of the inhibitors for the enzyme is increased in such a way that it is readily reversible in the forward reaction but becomes more irreversible in the opposite direction. Studies on complex formation between humic acids and NAD+ led to the conclusion that different effects on both reactions are due to the formation of such a complex. Enzyme activity could be recovered in the presence of calcium ions. This is assumed to be due to changes in the electron structure of the humic acid particles.

Hydrolysis of aluminium on weakly acidic organic exchangers: Implications for phosphate adsorption

Abstract: In contrast to its behaviour on soil clays and in aqueous solution, aluminium is more extensively hydrolysed between pH3 and 4.5 on organic exchangers because the weakly acidic carboxyl groups appear to act as sinks for the protons released by hydrolysis and polymerization of the Al(H2O)63+ ions. In consequence, the basicity (measured by the OH/Al mole ratio) of Al adsorbed on samples of acid peat, humic acid and Amberlite IRC-50 resin was closely correlated with the apparent pKa of the acid groups. The amount of phosphate adsorbed depended not only on the amount of Al adsorbed but also on the basicity of the adsorbed Al. Phosphate and OH− ions competed for Al on the exchange sites with the result that the P/Al mole ratio on the exchanger was inversely related to the basicity of the adsorbed Al. Once adsorbed, the Al was quite stable and P adsorption on the Al-exchanger was unaffected by a rise in pH from 4.5 to 6.4.

Electron intensity, the role of humic acids in extracellular electron transport and chemical determination of pE in natural waters

Abstract: Experimental systems demonstrate that humic acids are capable of accepting electrons from a wide spectrum of donors and transferring those electrons to a wide spectrum of acceptors, linking normally thermodynamically discrete redox couples. By functioning as a wide redox potential ‘flavoprotein’, humics encompass all the redox potentials pertinent to aquatic systems and hence determine relative electron activity, the negative log of which is pE. A chemically determined, system oxidation-reduction potential allows pE to be used along with pH in developing a biochemical framework for thermodynamically derived predictions of aquatic system behavior.

Humic acid as a colloidal surfactant

Abstract: The Na+-humate sol is studied as a surface active substance (surfactant) capable of lowering the surface tension of water, and of spreading on the water surface with observable velocity to form a thin film. Based on these properties, it is concluded that sol should contain molecules of intermediate molecular weight as well as their associates (micelles) whose weight depends on the number of molecules in the micelles.

Interlayer formation of humin in smectites

Abstract: The stability of humin, the alkali-resistant part of humic matter in soil1–4, is usually accounted for by its intimate association with inorganic soil colloids, especially swelling clays and iron compounds. Although the stability of these organo-clay complexes has been explained by interlamellar intercalation, there is evidence2–4 that large-sized humic acid nuclei are unlikely to penetrate layer silicates in normal soil conditions. The ability of clay minerals to promote polymerization of organic monomers has long been recognized5, and has been confirmed recently6–8; however, the conditions in which these catalytic properties were exhibited were unlike those existing in natural soils. We now report the results of preliminary investigations suggesting that humin-like substances may form between layers of silicate clays from smaller aromatic molecules in conditions that resemble those occurring naturally.

Characterization of humic and fulvic acids isolated from marine sediments of Sagami and Suruga Bays with C-13 and proton nuclear magnetic resonance

Abstract: The C-13 and proton NMR spectra of marine humic and fulvic acids isolated from sediments of Sagami and Suruga Bays and Aldrich humic acid were obtained using pulse Fourier transform mode. The C-13 and proton NMR spectra, which clarified the differences in chemical characteristics among the various humic substances, showed that the marine humic acids had more aliphatic and less aromatic character than the Aldrich humic acid, and the marine fulvic acids had polysaccharide-like character. The C-13 NMR spectra of the marine humic substances, in particular, had many relatively well-resolved peaks with significant intensities, indicating the presence of variously bonded carbon atoms in them.

Surface characteristics of kaolinitic clays and clay-humic acid complexes by potentiometric and conductometric titrations

Abstract: Acid and non-acid forms of kaolinite clays were found by potentiometric and conductometric titrations to possess a weak acid species, the concentration of which was increased by acidic preparation conditions and by the presence of soil organic matter bound to the clay. A stronger acid species was also found in untreated and in organic-free, HCl-treated samples (washed free of excess acid). The end points for organic-free and/or ion-exchanged samples were used to predict the end points for untreated samples. A surface-chemical model involving MOH2 +, MOH, and MO- species (where M = Al and/or Fe) was fitted to the titration data and to the cation-exchange capacities. MOH2 + is the stronger acid and MOH the weaker acid; exchange of Na + counterions by H + converts MO-Na + sites to MOH sites. Humic acid was probably complexed or chelated to some hydroxylated Al/Fe sites through COOH and phenolic OH groups. The COOH groups contributed supplementary stronger acid species which were not exchangeable, whereas the OH groups contributed supplementary weaker acid species and also increased the CEC relative to that for organic-free samples.

Mixed phosphatic fertilizer and process for producing the same

Abstract: In producing a mixed phosphatic fertilizer, humic acid is mixed with fused phosphate to cause the humic acid to react on alkaline ingredients of the fused phosphate for turning these alkaline ingredients into chelate compounds, so that water-soluble phosphoric acid contents of succeedingly added phosphatic fertilizers such as calcium superphosphate and calcium triple-superphosphate are not reduced or insolubilized by being reacted with such alkaline ingredients. Thus, unlike the prior art, a stabilized predetermined level of water-soluble phosphoric acid contents can be secured in the resultant mixed phosphatic fertilizer along with a predetermined level of citric acid-soluble phosphoric acid contents.

Properties of poultry litter humic acid fractions and their metal-complexes

Abstract: Molecularly homogenous fractions of humic acid extracted from poultry litter were characterized by elemental and functional group analysis, molecular weight determination, U.V. and infrared spectroscopy. The divalent and trivalent metal complexes prepared from different fractions of humic acid were characterized by infrared spectroscopy. The molecular weight of molecularly homogenous fractions of poultry litter humic acid ranged from 2545 to 40219.