Dioxine – Eine Aufgabe für die Umwelttechnik

Dioxins – Task for Environmental Engineering Two decades of the environmental history of dioxins, i.e. of PCCDs and PCDFs, are examined, with the main emphasis being placed on developments in Germany. After a brief consideration of the important, environmentally relevant properties of dioxins, interest is focussed on the course of the Seveso incident of 1976. The environmental effects of dioxins observed in Seveso received global publicity. In the following years our knowledge of the analysis and toxicology of this group of substances greatly improved and the production of dioxins in the aromatics sector of the chemical industry was drastically reduced. In the 1980s, discussions concentrated on the formation of dioxins in waste incineration. The results obtained during this period led to the present situation in which waste incineration is no longer a significant source of dioxin emission in Germany. The greatest known source of dioxins in Germany is in the metallurgical industry. By the year 2000 this dioxin source will also have been largely eliminated.     

Bestimmung von Pentan als Indikator für die oxidative Ranzigkeit von Ölen

Determination of Pentane as an Indicator of Oil Rancidity Pentane, determined by a headspace gas chromatographic method, is an excellent indicator of oil rancidity. The methodology applied is very simple and could be performed in an oil laboratory without purchasing additional equipment. The amount of pentane correlated well with the iodometrically determined peroxide value (R²-value of 0.976). Heating the oil sample in air followed by an estimation of pentane is an alternative means to assess oil stability against oxidative deterioration.     

Gekoppelte LC-GC für die Analyse von Olivenölen

Coupled LC-GC for the Analysis of Olive Oils The analysis of the so-called sterol fraction of fats and oils can be strongly improved by the application of on-line coupled LC-GC. LC replaces saponification, the (difficult) extraction of the non-saponifiable and the clean-up by preparative thin layer chromatography. The proposed method eliminates most of the manual sample preparation work, is more accurate, and provides more information at the same time, since the free and esterified components are analyzed separately. Analyzing olive oils, mostly small admixtures of other oils can be detected. For the determination of solvent extracted oil in “extra virgin” or “pure” olive oils, the method is more suitable than the conventional determination of the triterpenedialcohols erythrodiol and uvaol. Finally pressed oil of first quality (“extra virgin”) can be distinguished from that of second quality (“pure” olive oil). Oils of second quality are usually the result of pression with an excessive delay after harvesting the olives.     

“Einfache Triacylglycerine” in Fetten und Ölen aus den Samen von Wildpflanzen: Wertvolle Rohstoffe für die chemische Industrie

“Simple Triacylglycerols” in Fats and Oils from the seeds of Wild Plants Industry requires fairly pure compounds as starting material for chemical syntheses. The common edible fats and oils as well as fatty acid mixtures derived therefrom do not meet this requirement. Yet, the tropical and subtropical flora includes plants whose seed oils are by far not as complex as edible oils. Some tropical oils contain up to 90% of a simple triacylglycerol corresponding to as much as 95% of their constituent fatty acids. Simple triacylglycerols and almost pure fatty acids are ideal starting material for the semi-synthesis of valuable compounds. Moreover, seeds of industrial plants growing wild can serve as sources of genes that are of use in breeding domesticated plants for the earth's various climatic zones. It appears advisable to process the oils produced by these plants not according to traditional technology, but to separate triacylglycerols from phospholipids, sterols and vitamins by adsorption chromatography. Each of these classes of compounds is of commercial interest. Partial lipolysis of triacylglycerols leads to diacylglycerols, monoacylglycerols and fatty acids; complete lipolysis as well as alkaline hydrolysis yield fatty acids. Hydrogenolysis of triacylglycerols affords long-chain alcohols. Triacylglycerols, diacylglycerols monoacylglycerols, fatty acids and alcohols can all serve as starting material for the semi-synthesis of valuable compounds.     

Expertensysteme für die Prozeßführung,–Erfahrungen aus dem Verbundprojekt TEX-I

Expert systems for process control – experience with the TEX-I project. The paper gives a brief overview of some topics concerned with expert systems technologies in a real-time environment. After a four-year-project the perspectives of the technology are much more realistic, and the promises more or less reduced. What we see is a software-technology that is hard to use but well suited for complex applications. Unsolved is the problem of knowledge elicitation, the bottelneck of knowledge engineering.     

Gewinnung leichter Kohlenwasserstoffe aus schweren Ölen — Verfahren und Entwicklungen

Manufacture of light hydrocarbons from heavy oils – processes and developments . High quality crude oils are running short and their price continues to increase. At the same time there is a trend towards light petroleum products for use as transportation fuels or petrochemical raw materials. Consequently, the conversion of heavy oils, i.e., particularly distillation residues but also heavy oils from tar sands, is gaining increasing commercial importance. The cracking processes currently used in the refining industry are reviewed. Emphasis is placed on their application to metal-and asphaltene-containing heavy oils. Feed pretreatment by solvent deasphalting is discussed and the manufacture of syncrude from tar sands is considered. New developments for conversion of heavy oils are outlined. The future production of shale oil and of transportation fuels from oil shale is briefly treated.     

Verfahrensingenieure für das 21. Jahrhundert – Herausforderungen für die Hochschulausbildung

Chemical Engineers for the 21st Century – A Challenge to University Education The education of chemical engineers at the dawn of the 21st Century faces enormous challenges. The number of new students has dropped significantly since early 1990s. Globalisation is having an effect on the working environment of the engineering profession and changing the job market for process engineers whose activities now extend far beyond the chemical industry. As a result, universities and engineering schools now face increasing competition for students and scientific staff and for retention of degree programs and departments. This article throws light on the current situation of the universities, changes in working environment and conditions, and the demands placed on future chemical engineers and their education. Whatever changes may occur, e.g. through the introduction of Bachelor and Master degrees, the characteristic and proven profiles of engineering school and university training must be maintained while enhancing the conditions for good graduates.     

Biosensoren –- Sensoren für die Biotechnik?

Biosensors – Sensors for biotechnology? Increasing analytical requirements are to be expected in biotechnology, diagnostics, and environmental protection as a result of increasing product purity demands and the need to satisfy legal requirements. Biosensors are suitable for some of these purposes. The present review discusses the principal types and properties of such sensors in order to compare them with other sensors for the same purpose. It is seen that biosensors in combination with equipment having automated sample preparation and calibration can serve to overcome shortfalls in managing the increased analytical requirements for a number of substances.     

Über die Zerlegung von Kohlenwasserstoff-Gemischen mit Hilfe selektiver Extraktionsmethoden × — Zerlegung von Gatschen aus einem paraffinbasischen Rohöl

The Analysis of Hydrocarbon Mixtures with the Help of Selective Extraction Methods × — Analysis of Crude Waxes from a Paraffin Based Crude Oil The analysis of three crude waxes from different fractions of paraffin based crude oil, with the help of solid-liquid extraction and finally by urea-adduct formation, is reported. On the basis of selected physical data and suitable diagrams, the structural composition of the hydrocarbon components of these three crude waxes is discussed.     

Ölpflanzenanbau und Verwertung der Produkte aus agrarpolitischer Sicht

Oil-Bearing Plant Cultivation and Utilization from the Viewpoint of Agricultural Policy Cultivation of oil-bearing plants has a greater importance than generally thought. Hardly any other agricultural commodity is more dependent on supply by the world market than oilseeds. The European Economic Community meets only 30% of its requirement of plant oils and less than 10% of its requirement of plant proteins by its own production. From this aspect the marketing instruments are fully justified. Rapeseed is undoubtedly the most important oilseed of the temperate zone. It has a great future in entire Europe. More than twothirds of the German rapeseed production was harvested in the northernmost federal state. Without exaggeration, one might designate Schleswig-Holstein as the most intensive winter rape region of the world. This would not have been possible without successful breeding work carried out at research institutes and plant breeding firms. In this context one might recall the impressive quality improvement of rapeseed by switching over to low-erucic varieties. The next step must be the improvement of protein content. The author anticipates intensive research that would provide useful results within a short time. The same holds for the stability of the oil by reducing the linolenic acid content, which is genetically not an easy task. In view of the importance of meeting the energy requirement the utilization of biomass in future will become an important part of agricultural considerations. Although the utilization of plant oils as fuel might not be very successful, the fat market must be considered from a global viewpoint. For the time being and in the near future plant oil will remain a food item. A good quality and informing the public will ensure their sale.     

Eine neue Vernetzungsmethode für geformte Gebilde aus Vinylchlorid-Polymerisaten

Shaped articles, like fibers and films, from copolymerizates of vinylchloride and vinyl-trialkoxysilanes are crosslinkable after shaping in a simple manner by treating the shaped articles with aqueous baths of hydrochloride acid. The network formation can be determined by IR-spectroscopy. The crosslinked copolymerizates show in contrary to the uncrosslinked copolymerizates an increase in the tensile strength at higher temperatures. There is no lost of weight in boiling the crosslinked films in trichloroethylene. Normal uncrosslinked PVC-films loose about 30 wt.-% under these conditions.