Showing papers on "Humic acid published in 1970"

Humic acid-type phenolic polymers from Aspergillus sydowi culture medium, Stachybotrys spp. cells and autoxidized phenol mixtures.

Abstract: Aspergillus sydowi synthesized orsellinic acid, p-hydroxycinnamic acid, 2,5-dimethylresorcinol, and 6-methylsalicylic acid in a glucose-asparagine medium These phenols were altered by oxidation of C-methyl to carboxyl, β-oxidation of the p-hydroxycinnamic acid, by introduction of additional hydroxyl groups and by decarboxylation to form over 40 different phenols These included orcinol, 3,5-dihydroxybenzoic-, p-hydroxybenzoic-, protocatechuic-, and 2,3,4-trihydroxybenzoic-acids, and 2,3,5-trihydroxy-, 3,4,5-trihydroxy-,2,4,6-trihydroxy-, and 2,6-dihydroxytoluene After the glucose was consumed, amino acids, peptides, and ammonia accumulated in the medium, the pH increased to 7 or 8, and a humic acid-type polymer was formed Appreciable amounts of humic acid-type polymer could be extracted from Stachybotrys atra and S chartarum cells but only very low amounts could be recovered from A sydowi mycelium During the formation of the polymer in S chartarum the hydrolyzable amino acids decreased and were linked with the phenols to form the polymer A mixture of phenols similar to those formed by A sydowi with or without glycine, peptides, or proteins yielded humic acid like polymers when shaken together in buffer solution at pH 7 or 8 The model polymers prepared with peptides in the mixture were similar to the fungus polymers with respect to exchange capacity and release of α-amino nitrogen upon hydrolysis with 6 n HCl Both the fungus and model polymers were highly resistant to decomposition in soil Most of the constituent phenols in both type polymers could be separated following Na-amalgam reduction The decomposition of the nitrogen containing part of the polymers was studied using polymers prepared from phenols and 14C-labeled amino acids or peptides

Photolysis of aqueous solutions of p-benzoquinone: a spectrophotometric investigation

Abstract: The photolysis of aqueous solutions of p-benzoquinone is investigated spectrophotometrically over a wider range of pH, concentration, and the wavelength of irradiation than before. Experimental evidence has been obtained for the formation of benzene-1,2,4-triol as the sole primary photochemical product at all values of pH. Quinol and 2-hydroxy-1,4-benzoquinone are produced in equimolar quantities as secondary products both in acid and alkaline solutions, when the reaction between p-benzoquinone and benzene-1,2,4-triol is very fast. 2-Hydroxy-1,4-benzoquinone at higher concentrations polymerizes to the so-called ‘humic acid’. Between pH 4 and 6 benzene-1,2,4-triol is the chief photoproduct owing to suppression of the secondary reaction.

The effect of inorganic cations on the inhibition and stimulation of protease activity by soil humic acids

Abstract: The extent to which salts relieved the inhibition by humic acids of a given protease was independent of the nature of the inorganic anion added but depended upon the nature and concentration of the inorganic cation; salts of divalent cations were more effective than those of monovalent cations but in all cases the concentrations of cations far exceeded those of the humic acids. Pronase and carboxypeptidase activities were not affected by the order in which each enzyme was preincubated with humic acid and cation (Mg 2 , K + ). However preincubation of trypsin with MgCl 2 or KC1 before addition of humic acid caused a greater decrease of enzyme inhibition than when enzyme was preincubated with humic acid first. In contrast to Pronase and carboxypeptidase, trypsin reacted with humic acid to form an insoluble complex of low activity. The activity was increased by Mg 2+ and Na + ions due to displacement of enzyme from the complex into solution.

The effect of humic and fulvic acids on the growth and efficiency of nitrogen fixation of Azotobacter chroococcum.

Abstract: Humic acid in the form of sodium humate and fulvic acid markedly increased the growth and efficiency of nitrogen fixation ofAzotobacter chroococcum. Fulvic acid proved more effective than the sodium humate. The effectiveness of these substances was more pronounced in increasing the number of cells than affecting the nitrogen fixation. The increases in growth and nitrogen fixation were in direct proportion to the quantities of sodium humate and fulvic acid applied up to 500 and 700 ppm respectively. Thereafter the growth was restricted, although it was not inhibited even at 1,400 ppm.

An Optical‐Transmission Study of the Interaction Between Montmorillonite and Humic Acids

Abstract: The interaction between montmorillonite and kaolinite clay minerals and humic acid (HA) was studied in suspensions by absorbance measurements. Changes in absorbance as a result of the interaction were interpreted as an indication of changes in the size of clay tactoids. Na-humate caused dissociation of montmorillonite tactoids in suspension. Drying-wetting cycles increased the effect of Na-humate and resulted in tactoids similar in their size to those of the Li-saturated montmorillonite. Na-humate had no effect on the absorbance of kaolinite suspensions.

Alkaline nitrobenzene oxidation of plant lignins and soil humic colloids.

Abstract: Plant lignins and soil humic colloids were isolated using H2SO4, NaOH and 1,4-dioxane and their elemental composition, methoxyl contents and cation exchange capacities were determined. The isolated lignin and humic colloid samples were oxidized by the alkaline nitrobenzene technique and the degradation products characterized by the types and amounts of phenolic aldehydes produced.

Studies on tile composition of aromatic nuclei of humus

Abstract: X-ray diffraction analysis of humic acid (1) revealed that. among four types of humic acid. A. D. Rp and P type according to the classification system proposed by Kumada (2), only A type had the distinct diffraction band corresponding to (002) spacing of amorphous carbon. It was also reported that several artificial humic acids prepared from anthraquinone, hydroxyanthraquinone. charcoal. anthracite etc. showed high similarity to A type humic acid in their spectrophotometric properties and stability toward oxidizing reagent (3).

The infrared identification of a humo‐polysaccharide ester in soil humic acid1/

Abstract: Studies involving methylation, dissolution, infrared spectroscopy and gas‐liquid chromatography were conducted with humic compounds extracted from a Greenville loam and a Cecil sandy loam. The results indicated that methylated humic acid and non‐methylated hymatomelanic acid have similar infrared characteristics, with intense C‐H absorption at 2980 ‐ 2920 cm‐1, and strong C=0 stretching but with very weak C00‐ stretching at 1720 and 1650 cm‐1 respectively. Gas‐liquid chromatography yielded chromatograms, having the same number of components, appearing at similar retention times. Dissolution separated hymatomelanic acid into fraction A, with humic acid characteristics; and fraction B, a polysaccharide. This separation released the infrared carboxyl peak at 1650 cm‐1 in fraction A. It was concluded that hymatomelanic acid was a naturally occurring ester compound, composed of humic material in ester linkages with polysaccharide.

A semi-micro-method for the determination of quinoid groups in humic acids

Abstract: A method for determining quinoid groups in humic acids based on their reduction with Fe(II) in a triethanolamine alkaline solution followed by amperometric titration of the excess reductant is described. The reduction reaction proceeds in a homogeneous medium under mild conditions, one equivalent of the reducing agent being consumed per each quinoid carbonyl. Highly conjugated aromatic ketones were also reduced by the reagent used. However, in the majority of the humic acid samples studied, they were present in insignificant quantities.

Sweetening petroleum distillates with humic acid salts

Abstract: CATALYZED AQUEOUS ALKALINE SOLUTIONS ARE UTILIZED IN AN OXIDATIVE TREATMENT OF SOUR PETROLEUM DISTILLATES. THE CATALYST IN SOLUTION IS A HEAVY METAL SALT OF HUMIC ACID WITH A PREFERRED SPECIE BEING COBALT HUMATE. MERCAPTANS CONTAINED IN AQUEOUS CAUSTIC SOLUTIONS ARE OXIDIZED IN THE PRESENCE OF SAID HUMIC ACID SALT TO FORM DISULFIDES WHICH ARE THEN EASILY SEPARATED FROM CASUTIC SOLUTIONS, THEREBY ALLOWING FOR REUSE OF THE CAUSTIC SOLUTIONS IN TREATING ADDITIONAL PETROLEUM DISTILLATES. THE HUMIC ACID USED IN FORMING SAID SALTS MAY BE DERIVED FROM LEONARDITE.