Antioxidant properties of hymatomelanic acids from brown coal

The antioxidant activity of a low-temperature fraction of hymatomelanic acids from brown coal in a model process of the radical chain oxidation of cumene was determined using a gas-volumetric method. Their antiradical activity was evaluated by spectrophotometry using a reaction with 2,2-diphenyl-1-picrylhydrazyl (DPPH). The pronounced ability of hymatomelanic acids to cause antioxidant and antiradical effects in model systems was demonstrated. It was found that the antioxidant and antiradical activities increased with the concentration of hymatomelanic acids. The determined properties of hymatomelanic acids from brown coal can be useful for technical and biomedical applications.     

Preparation of waxes and humic acids from brown coal from the Sergeevskoe deposit

The comparative extraction of coal with organic solvents was performed. Humic acids were separated from solid residues. The yields, particle-size distributions, and chemical compositions of the resulting products were analyzed. It was demonstrated that brown-coal wax and humic fertilizers can potentially be obtained using coal from the Sergeevskoe deposit.     

Ozonization of humic acids in brown coal oxidized in situ

The effect of the ozonization of humic acids in chloroform and glacial acetic acid media on the yield and component composition of the resulting products was studied. The high efficiency of ozonization in acetic acid was found. Water-soluble low-molecular-weight substances were predominant among the ozonization products.     

Characterization of brown coal humic and fulvic acids by IR spectroscopy

The reactivity of functional and polymer derivatives of brown coal humic and fulvic acids was studied. It was found that the resulting products contained active functional groups, and they can be used in the subsequent organic syntheses.     

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.     

Physicochemical properties of the humic substances of peat and brown coal

A comparison characteristic of the spectroscopic, viscous, and electrokinetic properties of the humic substances of peat and brown coal is given. Quantitative relationships between absorbance and the concentration of humic acids (HAs) were obtained. Methods for the determination of the amounts of humic substances in peat- and coal-alkaline reagents were proposed. The average molecular weights of the humic substances of peat and coal were determined by viscometry. A method was proposed for studying the electro-kinetic properties of humic substances of different nature. The dependence of electrophoretic mobility and kinetic potentials on the concentration and nature of HAs was determined. The electrophoretic mobility method can be used for rapid analysis to determine the concentrations of the functional groups of HAs.     

Composition of humic substances in oxidized brown coal from Mongolia

The composition and properties of humic substances and residual coals separated from naturally or artificially oxidized (with 20% nitric acid, 30% hydrogen peroxide, and 4.8% potassium permanganate) brown coal samples with various initial degrees of humification from the Ulaan Ovoo deposit were studied using elemental, structural, and spectroscopic analysis (IR, UV, ¹³C NMR, and EPR spectroscopy).     

Removal of humic substances from water by brown coal sorbents

Brown coal sorption materials with high activity toward humic substances were prepared using a larger scale laboratory unit with a spouted-bed system. The effect of thermal treatment conditions on the sorption properties of these materials was studied. It was found that the sorption activity of the resulting samples toward humates was closely related to the limiting sorption volume of the materials with respect to benzene.     

Capillary structure and reactivity of chars from brown coal humic acids containing Ca,Fe, Mn and Na

Salts of Ca, Fe, Mn and Na were added to humic acids extracted from brown coal. The influence of the added inorganic substances on the course of carbonization and gasification with H₂O, CO₂ and 10% O₂ was studied.     

褐煤和柴煤中腐植酸的测定

本国际标准介绍了褐煤和柴煤中腐植酸的测定方法。第二版（ISO5073：1999）是在对第一版（ISO5073：1985）进行技术修改后形成的。本版鹰植酸的测定咀相对比较简单酌容量法取代了重量法（ISO5073：1985）同时附录A还介绍了预先测定腐植酸含碳比的方法。     

Amino-acids in humic,nitrohumic and nitrofuvic acids from coal

The humic acids, HA, extracted from a Spanish lignite and the nitrohumic acids, NHA, and nitrofulvic acids, NFA, extracted from the same lignite after its nitration, are hydrolysed with 6N HCI under reflux. The α-amino acids present in the hydrolysates are determined and thirteen α-amino acids are identified. The amounts of nitrogen in the amino-acids released by the hydrolysis increase according to the sequence: NFA > NHA > HA.     

Rheological properties of humic acids

It has been found that humic acids in aqueous solution, as previously found with their sodium salts, behave as linear polyelectrolytes. A possible explanation in terms of intermolecular associative forces is suggested.     

Modified humic acids from lignite

Native and modified humic acids obtained from Tisul lignite (from the Kansko-Achinsk Basin) are investigated by IR Fourier, ESR, and solid-state ¹³C NMR analysis. Treatment with hydrogen peroxide changes the functional-group composition of the humic acids and increases the sorptional capacity.     

年青褐煤H_2O_2降解生产黄腐酸工艺及产物性质

对云南金所年青褐煤进行H2O2降解制备黄腐酸的试验研究,通过透析将黄腐酸分为相对分子质量不同的7个级分,对其进行元素分析、红外光谱等研究。结果表明:对黄腐酸产率影响最大的因素是煤与氧化剂质量比,其次是氧化降解时间,氧化剂质量分数影响最小。优化工艺:煤与H2O2质量比1∶0.38,氧化降解温度30℃,氧化降解时间180 min,H2O2质量分数为15%,在此条件下黄腐酸产率达19%。理化分析结果表明:降解产物黄腐酸中总酸性基团、羧基质量摩尔浓度显著提高;随着相对分子质量的增加,氧元素和含氧官能团减少。     

风化煤腐植酸多种改性的机理探讨

腐植酸（HA）的改性有许多方法,主要是硝酸氧解、磺甲基化。其它的还有与金属络合以及与高聚物接枝共聚,但接枝共聚对设备要求较高、工艺复杂,而且价格高,不适合于做钻井泥浆助剂。     

Changes of chemical properties of humic acids from crude and fungal transformed lignite

The development of biological processes for fossil energy utilization has received increasing attention in recent years. There are abundance of lignite resources in China and the lignite, a low-grade coal, can be transformed by a Penicillium sp. After fungal transformation, the contents of humic acid and water-soluble humic material increased from 38.6% to 55.1%, and from less than 4.0% to 28.2%, respectively. The differences in chemical properties of crude lignite humic acid (aHA), fungal transformed lignite humic acid (bHA) and water-soluble humic material from fungal transformed lignite (WS) were studied. Elemental analysis and size exclusion chromatography showed that the N content of bHA increased by 47.36% compared with aHA, and the molecular mass of bHA was smaller than aHA. And the WS with the smallest molecular mass contained most content of N. The ¹³C NMR and FT-IR spectra of aHA and bHA showed that aHA contained more aromatic structure than bHA.     

Extraction of humic acids from Kansko-Achinsk lignite

A method has been developed for practically complete alkaline extraction of humic acids from Kansko-Achinsk lignite. The maximum yield of humic acids may be ensured by correct selection of the extractant and the extraction temperature and time. The content of functional groups in the humic acids is determined, and their NMR spectra are analyzed. Their ability to bind heavy metals is assessed. Their stimulation of plant growth is studied, and the biological activity of the humic acids is assessed.     

Variation of the metal complexing ability of humic acids with coal rank

The variation of the metal complexing ability of humic acids with the rank of the parent coal was investigated by determining the conditional stability constants of complexes formed between cupric ions and humic acids from several coals. Humic acids were extracted from four Spanish coals varying in rank from peat to subbituminous coal. The stability constants were determined at pH 5.0 and μ = 0.1 by a modified version of Schubert's ion exchange method. The stability of the metal-humic acid bonds decreases with the rank of parent coal. The stoichiometry of the complexes tends to 1:1 with increasing coalification of humic acids. The influence of oxidative conditions of extraction on the conditional stability constants of complexes was also examined and it was found that they do not affect significantly the elemental composition or the metal complexing ability of regenerated humic acids.     

Sorbent production from low-ash brown coal

The process for the production of a sorbent upon the carbonization of low-ash brown coal in a fluidized bed in a temperature range of 700–850°C was studied. The dependences of the main characteristics of the sorbent on temperature and the fraction of processed coal were found. The characteristics of the lignite sorbent obtained by the TERMOKOKS-KS technology are presented.     

Characteristic properties of brown coal lithotypes from the Tevshiin Govi deposit in Mongolia

The organic and mineral compositions and the technological properties of brown coals of the clarain and fusain types from the Tevshiin Govi coal deposit in Mongolia are characterized. The reactivity of petrographical lithotypes toward the process of ozonolysis was evaluated, and the composition of their ozonolysis products was studied.