Characterization of the Organic Matter of Humic Acids by Pyrolytic Gas Chromatography–Mass Spectrometry

The results of the pyrolytic analysis of products of the organic matter of Sphagnum fuscum, fuscum peat, and humic acids separated from peat with the use of pyrolysis–chromatography–mass spectrometry in the Rock-Eval version are presented. It was shown that Sphagnum fuscum and peat differed only slightly in the degrees of chemical transformation. Benzene, phenol, and their alkyl-substituted homologues predominated in the thermal desorption products of humic acids upon pyrolysis to 400°C. Acetic acid, monohydric phenols, syringol, and guaiacol, which are the basic compounds in the high-temperature fraction, were formed on the pyrolysis humic acids to 700°C from the carbohydrate, phenylpropionic, and guaiacylpropane structural fragments.     

Degradation of Aqueous Phenol and Chlorinated Phenols by Ozone

The degradation of phenol and its chlorinated derivatives with ozone is studied. The studied compounds are phenol (Ph), 4-chlorophenol (4-CPh) and 2,4-dichlorophenol (2,4-DCPh). The kinetic performances of each phenolic compound and their model mixture are examined. The pH influence on the decomposition dynamics for different phenolic compounds in the range 2–12 is investigated. The increase of the decomposition rate under increasing pH was observed. In the pH range studied, phenol and chlorophenols ozonation proceeds rapidly. The UV absorbency is used for the preliminary control of the degree of decomposition. The HPLC analysis is used to identify intermediates and final products formed during ozonation. It is shown that the basic intermediates are muconic and fumaric acids, malonic and maleic acids, catechol and hydroquinone. The final products are oxalic acid and formic acid. In the case of alkaline media, the principal final product is oxalic acid. Furthermore, intermediates and final decomposition products obtained at different pH are compared. According to the results obtained, the possible mechanism of ozonation by the reaction of hydroxylation and dechloration in the early stage is proposed. The BOD₅/COD ratio is used as a biodegradability measure for the comparison of biodegradability of initial compounds and final products composition.     

Aspects of the chemistry of donor solvent coal dissolution: Promotion of the bond cleavage reactions of diphenylalkanes and the related ethers and amines

The influences of Illinois No. 6 coal, benzyl phenyl sulphide, 9, 10-anthraquinone, tetracene, phenol and benzoic acid on the rates of decomposition of 1,2-diphenylethane, 1,3-diphenylpropane, 1, 4-diphenylbutane, benzyl phenyl ether, dibenzyl ether, N-benzylaniline, and dibenzylamine in tetralin have been investigated. Radical initiators such as benzyl phenyl sulphide enhance the rate of decomposition of the compounds that form benzylic radicals which can decompose via β-scission reactions. Weak organic acids enhance the reaction rates of the compounds, for example, benzyl phenyl ether and N-benzylaniline, that undergo the homolysis reaction via polar transition states. Among the reactive initiators considered in this Paper, benzyl phenyl sulphide is the only compound which, in small quantities, accelerates the conversion of Illinois No. 6 coal to pyridine-soluble products in tetralin at 400 °C. The facile reactions of Illinois No. 6 coal with tetralin and the accelerating effects of benzyl phenyl sulphide, anthraquinone, tetracene and phenols on the decomposition of the diphenylalkanes and the related heteroatom analogues are discussed.     

Aspects of the chemistry of donor solvent coal dissolution. The role of phenol in the reaction

The relative reactivity of phenol in exchange reaction with tetralin-d₁₂ and naphthalene-d₈ indicates that hydrogen exchange occurs by a free radical process rather than by an electrophilic substitution reaction at 427 °C. Substances such as benzyl phenyl ether that initiate free radical reactions increase the rate of the exchange reaction between phenol and tetralin-d₁₂ whereas weak acids have only a modest influence on the exchange. Phenol and 1 -naphthol accelerate the rates of decomposition of some ethers and amines in tetralin. These results suggest that phenolic compounds enhance thermal coal dissolution reactions in donor solvents via their influences on the rates of the homolytic cleavage of carbon-oxygen and carbon-nitrogen bonds.     

Interaction between the bituminous and humic components of peat

It was established that an increase in the bituminosity of peat with the degree of decomposition can be explained by an exchange interaction between the π electrons of the molecular polyconjugation systems of humic acids and the quasi-polyconjugation systems of bitumens (the presence of the latter is caused by a synergistic effect of the interaction of separated aromatic rings and the hydrogen bonds of functional groups). This interaction leads to the formation of unique associates, and this fact explains an increase in the concentration of humic substances in a composition with bitumens with increasing the degree of decomposition. The concept of associates is confirmed by a considerable increase in the EPR signal observed upon the removal of a low bitumen content, which was accompanied by changes in its parameters in a number of cases. The formation of these associates occurs under different geoclimatic conditions of peat deposit formation. The lower bituminosity of lowland peats is caused by steric hindrances created by the Ca²⁺ ions bound to the functional groups of humic substances for the access of hydrocarbon molecules.     

Composition of long-chain fatty compounds and sterols of four milled peat samples from Finnish peatlands

Four milled peat samples from three Finnish peatlands were studied in terms of their extract content and composition of fatty compounds and sterols using capillary g.c.-m.s. The extract yields obtained by CH₂Cl₂-acetone (9:1 v/v) ranged from 49 to 180 mg g⁻¹ of dry peat. The wax content of peat extracts varied between 43 and 55 wt %. The acidic part of extracts contained mainly long-chain fatty acids and ω-hydroxy acids with some α,ω-alkanedioic acids. The neutral extractives included predominantly primary alkanols with smaller amounts of n-alkanes and sterols. The extracts of all four peat samples were qualitatively similar but the milled peat Al with high heat value (27.1 MJ kg⁻¹) differed from the other peats in extract content and composition. The peat B with enhanced self-heating ability resembled the ordinary milled peats A2 and C in peat technological characteristics and extractive composition. Accordingly, the self-heating ability of milled peat in stockpiles does not correlate directly to the distribution pattern of long-chain fatty compounds and sterols.     

Yeast α-Glucosidase Inhibitory Phenolic Compounds Isolated from Gynura medica Leaf

Gynura medica leaf extract contains significant amounts of flavonols and phenolic acids and exhibits powerful hypoglycemic activity against diabetic rats in vivo. However, the hypoglycemic active constituents that exist in the plant have not been fully elaborated. The purpose of this study is to isolate and elaborate the hypoglycemic activity compounds against inhibition the yeast α-glucosidase in vitro. Seven phenolic compounds including five flavonols and two phenolic acids were isolated from the leaf of G. medica. Their structures were identified by the extensive NMR and mass spectral analyses as: kaempferol (1), quercetin (2), kaempferol-3-O-β-D-glucopyranoside (3), kaempferol-3-O-rutinoside (4), rutin (5), chlorogenic acid (6) and 3,5-dicaffeoylquinic acid methyl ester (7). All of the compounds except 1 and 3 were isolated for the first time from G. medica. Compounds 1–7 were also assayed for their hypoglycemic activity against yeast α-glucosidase in vitro. All of the compounds except 1 and 6 showed good yeast α-glucosidase inhibitory activity with the IC₅₀ values of 1.67 mg/mL, 1.46 mg/mL, 0.38 mg/mL, 0.10 mg/mL and 0.53 mg/mL, respectively.     

Phytoconstituents and Bioactivity of Plants of the Genus Spiraea L. (Rosaceae): A Review

The genus Spiraea L. belongs to the Rosaceae Juss. family and includes more than 100 species distributed in the temperate zone and subtropical zone of the Northern Hemisphere at the center of species diversity in East Asia. Representatives of the genus are known as ornamental plants with many forms and varieties, are widely used in conventional medicine, and have a high resource potential. This review provides information on the diversity of phenolic compounds (flavonoids, phenolcarboxylic acids, and lignans), terpenoids, alkaloids, steroids, and other classes of secondary metabolites in the species of Spiraea worldwide. The article also presents little-known and hard-to-find data published in Russian concerning Spiraea phytochemistry. The biological activities of extracts and their fractions and of individual compounds having different types of biological activity (e.g., antioxidant, antibacterial, anti-inflammatory, and antifungal) are discussed. Data about biotechnological research on representatives of the genus Spiraea are presented too. The analysis of the literature showed that further chemical and pharmacological studies on Spiraea plants are quite promising.     

Analysis of Phenolic Compounds and Antioxidant Activity in Wild Blackberry Fruits

Twenty three different wild blackberry fruit samples were assessed regarding their phenolic profiles and contents (by LC/MS quadrupole time-of-flight (QTOF) and antioxidant activity (ferric reducing ability of plasma (FRAP) and 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS)) by two different extraction methods. Thirty four phenolic compounds were detected (8 anthocyanins, 15 flavonols, 3 hydroxycinnamic acids, 6 ellagic acid derivatives and 2 flavones). In samples, where pressurized liquid extraction (PLE) was used for extraction, a greater increase in yields of phenolic compounds was observed, especially in ellagic acid derivatives (max. 59%), flavonols (max. 44%) and anthocyanins (max. 29%), than after extraction by the ultrasonic technique extraction (UAE) method. The content of phenolic compounds was significantly correlated with the antioxidant activity of the analyzed samples. Principal component analysis (PCA) revealed that the PLE method was more suitable for the quantitative extraction of flavonols, while the UAE method was for hydroxycinnamic acids.     

Oxygen-containing organic compounds of the bituminous components of high-moor peat from the south of Western Siberia

The composition of the bituminous components of high-moor peats from the south of West Siberia (Tomsk oblast, Temnoe bog) was analyzed. The similarity of the compositions of fatty acids, n-alkan-2-ones, n-aldehydes, tetra- and pentacyclic ketones, esters, and aromatic alcohols in all of the test peat samples was found. At the same time, the total concentration of alkanones, which prevailed among the oxygen-containing organic compounds in raised bog peats, was small in floating bog peats. The peats of the floating bog section were differed from the raised bog peats in the composition of pentacyclic alcohols, which included compounds from the lupene group in addition to oleanene derivatives. Tetracyclic alcohols in floating bog peats mainly consisted of saturated structures, whereas raised bog peats contained exclusively unsaturated stenols. The differences in the concentrations and composition of fatty acids, acyclic ketones, aldehydes, esters, steroids, and terpenoids observed in peats from two sections of the Temnoe bog mainly depend on the conditions of peat buildup and burial.     

The effect of hydrothermal dewatering of Pontianak tropical peat on organics in wastewater and gaseous products

This paper describes a study of the effects of hydrothermal dewatering of raw tropical peat from Pontianak, West Kalimantan-Indonesia, on the amounts of organic compounds released into wastewater and gaseous products. Hydrothermal upgrading and dewatering of the peat was carried out in a batch-type autoclave reactor at temperatures between 150 and 380 °C at a maximum pressure of 25.1 MPa for 30 min. It was found that the extent of decomposition of organics during hydrothermal dewatering depended on temperature increase.Wastewater from hydrothermal dewatering was found to contain organic carbon (TOC) ranging from 800 ppm at low temperatures, to 7504 ppm at high temperatures. A number of sugars and furans were detected in the wastewater at 250 °C, and organic acids and alcohols at all temperatures. Phenol and phenolic derivatives were observed at 250 °C, and significant amounts of CO₂, CO and H₂ were detected at all temperatures studied; CH₄ was detected only at 380 °C, but at this temperature CO₂ was no longer detected.A simplified schematic diagram of the decomposition behavior of tropical peat in the hydrothermal dewatering process is discussed with respect to the change in the concentration of organics in wastewater and gaseous products as determined by TOC, GC, GC–MS and ¹³C NMR analyses of the solids produced.     

Effect of the alkylation of brown coal and peat on the composition and properties of humic acids isolated from them

The effect of alkylation with alcohols in the presence of a mineral acid on the yield of humic acids from brown coal and peat was studied. A change in the ratio between the phenol and carboxyl groups of humic acids depending on the conditions of brown coal and peat alkylation was shown. An increased biological activity of humates obtained from the alkylated materials was noted.     

Chemical composition and distribution of the components of valley peat from Amur oblast

The chemical composition of sedge peat from the Egor’evskoe deposit as lowland peat from Amur oblast was characterized. The elemental composition of organic matter and mineral macro- and microcomponents was studied, and the distribution of bitumens, their fractions, and humic acids in the depth of occurrence was revealed. It was found that peat genesis processes occur over the entire vertical profile, and the most converted organic matter is formed at a depth of to 90 cm. The individual composition of alkane fractions consists of C₁₃–C₃₆ normal structure homologues with a carbon preference index somewhat higher than unity; the presence of pristane, phytane, and farnezane was detected. In the fractions of fatty acids, predominantly even compounds from C₁₀ to C₃₀ were identified with special distribution features at the separate stages of peat formation. The analysis of the individual composition of n-alkanes and fatty acids made it possible to supplement botanical characteristics with information on the contribution of macrophytes, algal material, and microorganisms to the formation of the organic matter of peat.     

Decomposition of a Lignin Model Compound under Hydrothermal Conditions

Lignin, which is the second most abundant polymeric aromatic organic substance in wood biomass after cellulose, and contains many oxygen‐based functional groups, has been proposed as an alternative source of chemical compounds. Guaiacol, a model compound for lignin, was reacted in supercritical water using a batch‐type reactor at temperatures of 653–673 K and various pressures under an argon atmosphere. The effects of temperature and reaction time at the same pressure were combined into a single severity parameter that was used to monitor the decomposition of guaiacol to its derived compounds. The main products in aqueous solution were catechol, phenol, and o‐cresol. The amounts present approached 40.73 wt %, 14.18 wt %, and 4.45 wt %, respectively. With an increase in the reaction time at the same conditions, the amount of guaiacol decreased and the quantity of derived compounds of guaiacol increased. Based on the experimental results, a reaction mechanism for the decomposition of guaiacol was proposed. The process investigated in this study may form the basis for an efficient method of wood biomass decomposition.     

Ozonation of Non-Biodegradable Mixtures of Phenol and Naphthalene Derivatives in Tanning Wastewaters

The decomposition of non-biodegradable mixtures of phenol and naphthalene derivatives in aqueous solution by ozonation is investigated. The toxic water pollutants are the intermediate synthesis products obtained via the sulfonation reaction of naphthalene and phenol. These organic compounds are phenol (PH), p-phenol sulfonic acid (p-PSA), and 2-naphthalene sulfonic acid (2-NSA). The kinetic study of ozonation is realized by the pH variation in the range of 2–12. The pH-dependence of the ozone reactivity for different organics is observed. The intermediates and final products determination is measured by UV absorbency and HPLC technique. It is shown that the main sub-products are muconic, fumaric, maleic and malonic acids and catechol. The final products are basically oxalic acid and formic acids as well as formaldehyde. In the initial stage of ozonation, hydroxylation and desulfuration of p-PSA and 2-NSA is detected. The effect of the preliminary ozonation on the biodegradability of the contaminants is estimated by BOD₅/COD-ratio variation, which significantly increases from 0.15 to 0.88.     

雨养沼泽泥炭腐植酸的性质和结构

腐植酸类物质是土壤、泥炭和自然水体中有机物的主要成分,其来源不同,结构和性质也不同。本研究阐述了雨养沼泽泥炭腐植酸的性质,评估了泥炭剖面内腐植酸的均质性,并研究了泥炭腐殖化程度对腐植酸性能的影响。结果表明,以不同来源的苔藓为主的雨养沼泽植物对泥炭腐植酸结构的影响较大。泥炭腐植酸的成岩作用程度介于活有机体和煤炭之间,当碳水化合物、氨基酸等被破坏后,耐分解的芳烃和多环芳烃结构出现,泥炭腐植酸的结构趋于形成。然而,与土壤、水体和其他腐植酸相比,泥炭腐植酸的芳香性较低。相对而言,雨养沼泽泥炭腐植酸处于活有机体向成岩转化过程的初始阶段。羧基和酚羟基含量的变化取决于提取腐植酸的泥炭年龄和分解程度,羧酸酸度随泥炭深度和腐殖化程度增加而增大。     

Changes in the composition of the bituminous components of valley peat under stimulated microbial action

The stimulated microbial oxidation of valley peat by aboriginal microflora was experimentally studied for evaluating the participation of microflora in the conversion of organic matter in present-day swamp deposits. The esters of n-carboxylic acids, triphenyl phosphates, C₁₄–C₃₁ n-alkanes, squalene, methyldehydroabietate, steroids, and pentacyclic terpenoids with the predominance of unsaturated structures mainly with the alcohol groups were identified in the composition of the bituminous components of microflora. It was found that the absolute concentrations of all of the identified groups of organic compounds in peat considerably decreased as a result of biodegradation. The relative concentrations of high-molecularweight (C₂₇–C₃₄) homologues and C₁₆–C₂₀ homologues predominant in bacteria in the composition of peat n-alkanes increased. Steroids and pentacyclic triterpenoids were enriched in unsaturated structures and compounds with the alcohol groups. Aldehydes disappeared from the composition of acyclic compounds. The fractions of palmitic acid derivatives in methyl ethers and isoprenoid structures in alkanones sharply increased.     

Structural changes in humic acids during the coalification process

Humic acids from four coals, varying in rank from peat to subbituminous coal, have been characterized by elemental analysis, acidic groups, molecular weight, electrophoresis and visible, FT-i.r. and CP/MAS ¹³C n.m.r. spectroscopy. The humic acids increase in carbon content, molecular weight, condensation degree and aromaticity (f_a) with increasing maturation of the parent coals, while the oxygen content decreases with a loss of oxygen functional groups. The presence of lignin-like polymers, poly-saccharides and peptidic materials in humic acids from peat was established using i.r. and ¹³C n.m.r. spectroscopy. The structural changes observed in humic acids are in agreement with the recognized coalification theory and tend to support the hypothesis of condensation of humic acids into insoluble humin of coal.     

Kinetics analysis of phenol and benzene decomposition in supercritical water

Decomposition of phenol and benzene was studied in supercritical water (SCW) at 370–450 °C and 25 MPa over very short residence times (0.5–100 s). The study of simple model compounds such as phenol and benzene is an essential preliminary step to elucidate the primary mechanism of char and gas formation from lignin compounds. A quantitative detailed chemical kinetics model for the primary pathways of phenol and benzene decomposition in SCW was determined using the reaction pathways for its decomposition under supercritical conditions. The activation energy of benzene decomposition (91.16 kJ mol⁻¹) in SCW is much higher than that of phenol (54.17 kJ mol⁻¹) under similar experimental conditions. This emphasized the importance of the substituent group (hydroxyl group) in the benzene ring to enhance its decomposition rate. In addition, the reaction rate parameters, which are deduced for the overall reaction network of its decomposition under similar conditions, show good agreement with each another. Hence, the reaction rates of these reaction pathways are successfully described in this study.     

高有效氮可降低泥炭藓泥炭中的多酚含量

泥炭藓是雨养泥炭沼泽中的优势植物和主要造炭植物。多酚类化合物通常被视为是一种植物防御性化合物的次生代谢产物。泥炭藓含有独特的多酚,可抑制微生物活性,减缓泥炭残体分解。在自然生态系统中生物活性氮不断增加的背景下,泥炭藓残体成为检测大气氮沉降对泥炭残体多酚含量潜在影响的理想基质。本研究选择长期大气氮沉降梯度上的11处欧洲雨养泥炭地,测试了泥炭藓泥炭样本的总氮含量和可溶性多酚浓度。试验结果表明,由于外源性有效氮的增加,导致泥炭藓残体中氮浓度持续增长,残体中多酚含量降低。这种负相关关系与有关泥炭藓中多酚与蛋白质生物合成争夺相同前体的报道相一致。由于有效氮的抑制分解作用,导致多酚含量下降,加快泥炭残体的分解,因此长期氮富集所导致的泥炭藓残体化学特征变化将对全球碳平衡产生重要影响。