Oil Degradation Products Research Articles

Chemical effects of a polyglycol on brass surfaces as determined by XPS/depth profiling

Polyglycol compounds are compatible with alternative refrigerants which are replacing CFC-12 and thus are likely to be used for lubrication of automotive air-conditioning (A/C) compressors. A/C compressors may contain brass components which could be adversely affected by the polyglycol compounds. In this work, X-ray photoelectron spectroscopy (XPS) coupled with depth profiling with Ar + was used to investigate the effects of a polyglycol lubricant on brass. Oxidation of the lubricant at 150°C produces degradation products which preferentially remove Zn from the brass surface leaving behind a layer of soft, porous Cu, a corrosion phenomenon best known as brass dezincification. The soft Cu layer can wear off excessively in loaded sliding contacts thus producing early compressor failures. High-molecular-weight acids are the most likely candidates among the oil degradation products responsible for the attack on brass surfaces.

Rapid gas chromatographic determination of volatile degradation products of glucosinolates in rapeseed oil

Volatile degradation products of glucosinolates are usualy determined by gas chromatography with flame ionization detection. Compared with the content in seeds and extraction meals, the content of glucosinolate degradation products in oils is one (in crude oils) or several (in refined or hydrogenated oils) orders of magnitude lower so that an isolation and concentration step is necessary if FID is being used. More selective and more sensitive detectors for this determination were applied

DSC‐cell ‐ A versatile tool to study thermo‐oxidation of aviation lubricants

AbstractThe versatility of a differential scanning calorimetry (DSC) cell in studying thermal and/or thermal‐oxidative degradation of lubricants is shown using ester‐based aviation turbine oils as an example.The following applications are discussed: 1. quality control of fresh and used oils by pressure differential scanning calorimetry; 2. influence of metal catalysis on oil degradation; 3. identification of volatile degradation products by PDSC gas chromatography‐mass spectrometry via a TENAX trap; 4. determination of spontaneous ignition temperatures; 5. influence of metall metal oxides, wear debris and oil degradation products on ignition behaviour; 6. inhibition of spontaneous ignition by antioxidants.

Spontaneous ignition temperatures of aviation turbine oils

The usefulness of pressure differential scanning calorimetry (PDSC) in studying spontaneous ignition of aviation turbine oils is shown. The following applications are discussed: (1) determination of spontaneous ignition temperatures (SITs) of commercial aviation turbine oils; (2) catalysis of spontaneous ignition by metal/metal oxides; (3) influence of oil degradation products, like carbonaceous deposits, volatiles and wear debris; (4) inhibition by antioxidants.

Sequential growth of bacteria on crude oil.

By modification of the enrichment culture procedure three bacterial strains capable of degrading crude oil in sea water were isolated in pure culture, UP-2, UP-3, and UP-4. Strain UP-2 appears to be highly specialized for growth on crude oil in sea water since it showed strong preference for oil or oil degradation products as substrates for growth, converted 66% of the oil into a form no longer extractable by organic solvents, quantitatively degraded the paraffinic fraction (gas chromatographic analysis), emulsified the oil during exponential growth, and produced 1.6 x 10-8 cells per mg of oil. After exhaustive growth of UP-2 on crude oil the residual oil supported the growth of UP-3 and UP-4, but not a previously isolated oil-degrading bacterium, RAG-1. Strains UP-2, UP-3, and UP-4 grew on RAG-1-degraded oil (specifically depleted of n-alkanes). The growth of UP-3 and UP-4 on UP-2 and RAG-1-degraded oil resulted in the production of new paraffinic compounds as revealed by gas chromatography. When the four strains were grown either together in a mixed culture or sequentially, there was over 75% oil conversion. By plating on selective media, growth of the individual strains was measured kinetically in the reconstituted mixed culture, revealing competition for common growth substances (UP-2 and RAG-1), emhanced die-off (UP-2), and stabilization (UP-4) during the stationary phase.

Sequential Growth of Bacteria on Crude Oil

By modification of the enrichment culture procedure three bacterial strains capable of degrading crude oil in sea water were isolated in pure culture, UP-2, UP-3, and UP-4. Strain UP-2 appears to be highly specialized for growth on crude oil in sea water since it showed strong preference for oil or oil degradation products as substrates for growth, converted 66% of the oil into a form no longer extractable by organic solvents, quantitatively degraded the paraffinic fraction (gas chromatographic analysis), emulsified the oil during exponential growth, and produced 1.6 x 10-8 cells per mg of oil. After exhaustive growth of UP-2 on crude oil the residual oil supported the growth of UP-3 and UP-4, but not a previously isolated oil-degrading bacterium, RAG-1. Strains UP-2, UP-3, and UP-4 grew on RAG-1-degraded oil (specifically depleted of n-alkanes). The growth of UP-3 and UP-4 on UP-2 and RAG-1-degraded oil resulted in the production of new paraffinic compounds as revealed by gas chromatography. When the four strains were grown either together in a mixed culture or sequentially, there was over 75% oil conversion. By plating on selective media, growth of the individual strains was measured kinetically in the reconstituted mixed culture, revealing competition for common growth substances (UP-2 and RAG-1), emhanced die-off (UP-2), and stabilization (UP-4) during the stationary phase.