Bituminous coal organic acids

The method should be able to handle the various standards and background samples that are used, such as the modern standard (oxalic acid) and "dead-carbon" (bituminous coal). Organic gases are sometimes submitted for dating, as well as peat, wood, soil, and organic tissue. Carbonates of differing forms make up about half of the samples run. The method should be applicable to these forms of carbon with minimum conversion. The less the sample is handled, the less chance there is of contamination, a major problem in samples of milligram size. 

Adsorption. Adsorption (qv) is an effective means of lowering the concentration of dissolved organics in effluent. Activated carbon is the most widely used and effective adsorbent for dyes (4) and, it has been extensively studied in the waste treatment of the different classes of dyes, ie, acid, direct, basic, reactive, disperse, etc (5—22). Commercial activated carbon can be prepared from lignite and bituminous coal, wood, pulp mill residue, coconut shell, and blood and have a surface area ranging from 500—1400 m /g (23). The feasibiUty of adsorption on carbon for the removal of dissolved organic pollutants has been demonstrated by adsorption isotherms (24) (see Carbon, activated carbon). Several pilot-plant and commercial-scale systems using activated carbon adsorption columns have been developed (25—27). 

F. ferro-oxidants is capable of accelerating the oxidation of pyritic (FeSj) deposits at acid pH values. It is usually found in association with Thio-bacillus and was known as Thiobacillus ferroxidans before the distinction between the two organisms was appreciated. It is responsible for pollution problems arising from acid waters in gold and bituminous coal mines such waters are corrosive to pumping machinery and mining installations (see Fig. 2.20). 

Application of mass spectrometry to the identification of methyl esters of the organic acids obtained by the controlled oxidation of bituminous coal... 

Various bituminous coals were demineralized by an experimental two-step leaching process in which the ball-milled coals were first treated with a hot alkaline solution and then with a dilute mineral acid. Different alkalis and acids were studied to determine their relative effectiveness. In addition, the effects of alkali concentration, treatment temperature, and treatment time were evaluated. Under the best conditions, the process reduced the ash content of the coals by 85-90% and the total sulfur content by 70-90%. As the temperature of the alkaline treatment was raised from 150 to 345 C, the removal of sulfur increased greatly whereas the recovery of organic matter declined. When a 1 M sodium carbonate solution was employed for the treatment, the recovery of organic matter was 91-97% for various coals treated at 250 C and 79-89% for the same coals treated at 300 C. 

It is interesting that a bituminous coal (Sample 4) gave organic acids qualitatively similar to those of lignite coal see Figure Id). Major identified compounds were p-hydroxybenzoic acid and two isomers of hydroxybenzenedicarboxylic acid, benzene di- and tricarboxylic acids. No ortho or meta isomer of hydroxybenzoic acid was detected. We have found that solvent-extractable hydrocarbons obtained from this raw coal consist mainly of n-alkanes (Cjj to 3 ). This is quite different from other results which showed that aromatic hydrocarbons were the major solvent-extractable material of several bituminous and anthracite coals (21). Indeed, petrographic analysis shows that this coal has a high content of sporinite (14.3 wt %) and a low content of vitrinite (30.2 wt %) (33). 

In general terms, lignite and anthracite coals appear to contain much lower proportions of the volatile organic componnds (10) than the bituminous coals, although alkaline extraction of lignite (and bituminous coal) will yield organic acids of various types that can be characterized. On the other hand, the hexane-soluble portion of the pyridine extracts that were obtained at 50°C (120°F) from coal (carbon content 83.6% w/w) have been identified as alkylated chrysenes as well as alkylated picenes in addition to a mixture of C2g, C29, and C30 paraffins. There were also indicates of the presence of an alicyclic or methyl-substituted five-ring (cat-condensed) system as well as l,2,5,6-dibenzanthracene(s) (Table 10.1). 

Application of this technique to the identification of methyl esters of the organic acids obtained by the controlled oxidation of bituminous coal allowed the more volatile benzene carboxylic acid esters to be identified (Studier et al., 1978). These were esters of benzene tetracarboxylic acid, tere-phthalic acid, toluic acid, and benzoic acid. Decarboxylation of the total acid mixture was shown to afford benzene, toluene, Cj-benzenes (i.e., ethylbenzene or xylenes), Cj-benzenes, butylbenzenes, Cj-benzenes, Cybenzenes, naphthalene, methylnaphthalene, C2-naphthalene, biphenyl, methylbi-phenyl, C3-biphenyl, indane, methylindane, Cj-indane, phenanthrene, and fluorene. 

The formation of sulfones, followed by elimination of sulfur as sulfuric acid, has been proposed as a means of removing the organic sulfur from coal prior to combustion. Unfortunately, the formation of a sulfone from sulfur in a thiophene group is rather difficult. However, up to 40% of the organic sulfur in bituminous coal can be removed when the coal is subjected to 1000 psi air at 200°C (390°F) for 1 h, implying that there exists within the coal an appreciable fraction of nonthiophene sulfur from which sulfuric acid is produced ... 

Burow et al. (96) recently explored the utility of liquid SO2 for the removal of organic sulfur from Eastern bituminous coals. Liquid SO2 is supposed to be an excellent solvent for aromatic heterocyclic and alkyl sulfides derived from coal. They have considered the mild Lewis acid characteristics of SO2 and presented the following scheme for reaction... 

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