Seyitömer bitümlü şist ve linyit örneklerinde ve piroliz kalıntılarındaki PAH'ların belirlenmesi

Abstract

Polisiklik Aromatik Hidrokarbonlar (PAH) bilinen en tehlikeli kanserojen madde gruplarından birini oluş turmaktadır. Tabii bozunma dışında yanma sistemleri ve taşıt eksozundan yayınımları bilhassa nüfusun yoğun yö relerde çevre kirliliğinin en önemli unsurlarından biri sini oluşturmaktadır. PAH'ların insan sağlığına zarar ları ppb veya ppm mertebelerinde dahi etkin olabildikle ri için bu kimyasalların çok düşük derişimlerde izole edilmeleri ve ölçülmeleri gerekmektedir. Bu da hassas alet ve yöntemleri içermektedir. Bu çalışmada Seyitömer bitümlü şist ve linyiti çe şitli atmosfer piroliz kalıntıları ve orjinal bitümlü şist ve linyitinden soxhlet ekstraksiyonu ile alınan bi tümenin aromatik f raksiyonundaki PAH kimyasallarının ka piler kolon kromatograf isi yöntemiyle tanımlanması araş tırması yapılmıştır. Bu 'çalışmanın sonucunda orjinal bitümlü şistin ve bitümlü şistinin normal atmosfer piroliz kalıntısının oldukça önemli miktarda PAH içerdiği bulunmuş ve bunlar arasında kanserojenik etkiye sahip olan bileşiklerde tespit edilmiştir.

Organic matter is present in varying amounts in all types of sediments. Although it is present in high concentrations in coal and peat desopits and accumula tions of petroleum, natural gas and tar sands, much larger quantities occur as finly dispersed discrete organic particles in classic sediments. Such sediments containing high concentration of organic matter are re ferred to as oil shales. Oil shales uiere formed in ancient shallow lakes by the slow deposition of aquatic organisms, spars, pollen grains and vegetable matter such as shreads of shreads of mood, bark and leaves, along with inorganic matter intimately mingled. The inorganic material con sists mainly of clay uilth fire sand, clacite, dolamite and iron compounds. As the lakes dried out, the depo sits became compacted and over geologic time were transformed into impermeable rocks. Oil from ail shale is often referred to as a "synthetic" fuel, but the organic matter in oil shale is a naturally occuring fossil fuel. In fact oil shale's organic matter is the world's largest supply of fossil fuel. Oil shale consists of inorganic material that con tains complex organic polymers which are high molecular wight solids. The organic kerogen is insoluble in con- ve tional organic solvents, and is associeted with small amo'unts of a benzene soluble organic material, bitumen. Vll Oil shale contains a variety of organic materials which can be classified by methods of organic geochemistry and organic petrology into a number of kerogen types. The thermal decomposition of oil shale, pyrolysis or retorting, yields liquid, gaseous and solid products All types of combustion produces traces of arganics especially polycycliç. aromatic hydrocarbons (PAH). Polycyclic aromatic compounds (PAC) can be formed from both natural and anthropogenic sources, although the latter are by far the major contributors of environ mentally hazardous compounds of this class. Natural sources include forest and praire fires, volcanoes and in situ systhesis from degraded biological material, which has led to the formation of these compounds in various sediments, fossils and fossil fuels. Antropagenic sources of PAC include the during of coal refuse banks, coke production, residental fire places, coal-fired residential furnaces, automobiles commercial incinerators, oil fired commercial boilers and rubber tyre wear. A minor source in terms of total PAC production, but of considerable importance with respect to human health, is tobacco smoking. The total emission of PACs world wide from various combustion systems is given in the following table: World-wide emissions of PACs-Tbnnes/year Heating and power generation 260. ODD Industrial processes 105.000 İncireration and open burning 135. ODD Uehicular transport 4.500 Total:. ' 504.500 Vlll Concern over the emission of PACS to the environ ment is centred on the associated health hazard, because PACs comprise the largest group of carcinogens amnung the environmental chemical groups. PACs adsorbed onto airborne particles are believed to be a major contribu tory reason why death iates from lung cancer are higher in urban than in rural areas. Cancers of the lung, stomach, kidneys, scrotum and liver have been associated with exporsurre to PACs. Not all the large number of PACs known to exist are biologically active, however, and many have not been tested either individually or as they occur in complex mixtures. The relative corcinogenic activity of some PACs have been assessed, and many reviews exist on the health hazard associated with PACKs. In addition, PACs have been suggested as precursers in the soot-forming process in combustion systems. Also it has been shown that fuels with increased levels of certain PACs produce higher levels of PACs soot and nitro-containing PACs in the combustion emissions. Since dengerous properties of PAHs can be effective in parts per million (ppm) and parts per billion (ppb) levels, these chemicals should be isolated and measured at low concentrations. Therefore, there is need to use sensitive equipment and methods. In this study, the identification of PAH chemicals is done by capillar column chromatography in products obtained by soxhlet extraction of pyrolysis residue and raw oil shale and lignite of Seyitömer. In order to asress the amount of PAH in the pyroly sis residue and raw oil shale and lighite, bitomens were obtained by soxhlet extraction for 2k hours with 3:1 benzen metanol mixtures. The extraction yields obtained are given in the following table: IX QJ rH XI ca ¦p d» c-.H 3 ? a 0] x: +3 c Q] >.H ai m R id.a ai c.H ID +3 n a CO -a rH a).H.E* C a.H -P U CO M -P X QJ 0J XT U3 1> cn ? tn X3 CM IX) CM ¦J- CM ? CM J- cn VX) QJ -P.H 3 >- N-' 13 O rH S^ QJ -P.H 3 In the latter stages of study, extracts obtained uaa charecterized using chromatographic methods. For this purpose the oils are fractionated into aliphatics, aromatics and polars by eluding them with n-pentane, benzene and methanol using column chromatography. program of ju u v. iu minj to juu l.^3 mm; at a ramp rate of 5 C/min. The carrier gas was helium. Compounds de tected by FID mere identified using the lee linear re tention indices for PAH products. For this purpose naphthalene, phenanthrene, chrysene and picene mere used as internal standarts corresponding tQ the 200,300,^00 anr! ^nfl Innan-n -no-fon + Tnn î nHi nac nd 500 linear retention indices. The chromatograms of the aromatic fractions are shown in the Appendix A. The compounds identified for each chromatagram are given in Apprendix B. Additionaly, The compounds identified in normal atmosphere pyrolysis residue, nitrogen atmosphere pyrolysis residue, steam atmosphere pyrolysis residue oil shale and lignite mixtures pyrolysis residue and raw oil shale and lignite are shown in Appendix C with their carcinogenecities by +,*, D f A > # characters respectively. The majority of the compounds identified were PAH but some nitrogen and sulphur heteropolycyclics were also identified. The greates number of components ob served were 2 ring compounds followed by 3 ring com pounds. The results of this study show that hawever, the pollutionwhich occurs during the fractionation of the bitumens products and by products which have low PAH concentrations may interfer the product distribution in some cases. In addition to this, the separation processes for n-alkanes distribution which is obvious XI in the explanation of the process mechanism which has great use in the literature may be affected and especially components having low molecular weight can be lost. The Lee's retention index which are used for the chromatographic identification fallowing the separation process are limited with only 7D0 compounds. This shows the limitation of the system. In order to establish an objective comparison of the results, it is possible to increase theoretically the number of com pounds from 700 to 40000 using GC/MS system.