Humic substances are complex, organic substances occurring in natural media such as water, soils and sediments. Humic substances represent the highest pool of recent carbon on earth, and they influence climate, soil fertility and depollution. In spite of such importance, the structure and properties of humic substances are largely unknown. We studied the surfactant activity of humic acids from peat of increasing degrees of humification and sapropel, sampled in the Upa River of the Tula region. We measured critical micelle concentration (CMC) of humic acids of different ages. Our results show that CMC decreases from 1.5 g/100 ml for the less transformed sapropel, to 1.0 g/100 ml for the medium-transformed mesotrophic sphagnum peat, to 0.25 g/100 ml for the most transformed eutrophic alder peat. We also found that the limiting adsorption of humic acids from the younger sapropel, of 7.1 9 10 -6 mol/m 2 , and from sphagnum peat, of 7.6 9 10 -6 mol/m 2 , are higher than the limiting adsorption of humic acids from the older eutrophic alder peat, of 3.3 9 10 -6 mol/m 2 .
The review is devoted to the methods of introducing aryl functional groups to the CNT surface. Arylated nanotubes are characterized by extended solubility, and are widely used in photoelectronics, semiconductor technology, and bioelectrocatalysis. The main emphasis is on arylation methods according to the radical mechanism, such as the Gomberg–Bachmann and Billups reactions, and the decomposition of peroxides. At the same time, less common approaches are also considered. For each of the described reactions, a mechanism is presented in the context of the effect on the properties of functionalized nanotubes and their application. As a result, this will allow us to choose the optimal modification method for specific practical tasks.
Humic substances were isolated from different origin peats of the Tula region: reed fen peat (RFP), sphagnum high-moor peat (SHP), black alder fen peat (BFP), sphagnum transition peat (STP) by water-alkaline extraction. The yield of humic substances from reed fen peat is maximal and comes in at 11,1±0,2%; The minimum yield is from sphagnum transition peat 7,4±0,2%, which is explained by the degree of transformation of the initial biomaterial and the conditions of occurrence of peats. Analyzed peats are in a row according to the content of humic substances: RFP>SHP>BFP>STP. The yields of hymatomelanic acids come in at 23,3–25,3%. Polydispersity of humic substances and monodispersity of hymatomelanic acids have been proved by gel-penetrating chromatography. Four fractions differing in their molecular masses and relative content were obtained from humic substances of peats regardless of their origin. Values of the molecular masses of the fractions of HS of BFP are dominant and 25% higher than of the fractions of HS of RFP. Sphagnum peats have a similar qualitative composition and, as a consequence, have similar molecular masses of isolated humic substances correlating with the degree of peat decomposition and with the yields of humic substances. Hymatomelanic acids are one fraction: the molecular weight of GMAs of BFP is 42 kDa, which is 44% higher than of GMAs STP. The correlation between the degree of humification and peat's genesis was revealed. It was shown that the amount of hymatomelanic acids in humic substances of peats can be marker of phases of humification of peats.
By the method of biotesting, it has been established that the addition of oil-degrading microorganisms of the genus Rhodococcus to the soil contaminated with hydrocarbonshas a positive effect on morphogenesis and sowing qualities of the cockweed test culture, which is associated with the microbiological oxidation of oil by bacteria of the studied strains. It was revealed that a positive effect was observed in 5 of 8 variants of the experiment on the medium with hexadecane with the joint introduction of humic acids and microorganisms. Under the conditions of oil pollution, the introduction of Rh. erythropolis X5 and Rh. erythropolis S67 microorganisms into the substrate with the addition of humic acids as a whole has a stimulating effect on the morphogenesis and sowing qualities of cockweed. It should be noted that it was in the “oil + humic acids + microorganism” variant that the indicators were obtained that maximally exceeded the values of the contaminated control. Reducing the toxicity of oil and hexadecane, and in some cases, the complete removal of the negative effects of toxicants in the relation to the test culture are apparently connected with the intensification of the process of oil biodegradation due to the stimulating effect of humic acids on the microorganisms. It is proved that the introduced humic acids act as adaptogens in the relation to the microorganisms Rh. erythropolis X5 and Rh. erythropolis S67, increasing their resistance to stress loads under conditions of oil stress. Thus, the results show that the introduction of humic acids can contribute to more effective biodegradation of oil pollution of soils. At the same time, in order to increase the efficiency of humic acids, the use of humic acids of sphagnum transitional peat + Rh.erythropolis X5, humic acids of sphagnum high-moor peat + Rh. erythropolis X5, humic acids of reed fen peat + Rh. erythropolis S67 in the conditions of oil pollution seems more promising. On a substrate with hexadecane, it is advisable to consider the use of humic acids of sphagnum high-moor peat, because in this variant, the parameters that maximally exceed the contaminated control were noted.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.