Gas-phase ion chemistry of silyl cations obtained from hexamethyldisilazane

The gas-phase ion-molecule reactions of the Me3SiN(H)SiMe2+ ion, obtained by electron ionization from Me3SiN(H)SiMe3, have been studied in a Fourier transform ion cyclotron resonance spectrometer in order to understand the mechanistic details of an important chemical system presently used in film formation. This silyl cation has been observed to undergo addition reactions at electron rich centers to form stable adducts that may undergo further methane elimination in the case of alcohols and amines. The most important feature of these reactions is the fact that a metathesis type reaction can be observed in the presence of H2O, and other hydrogen labile substrates like alcohols, leading to the formation of the corresponding oxygen-containing ion, i.e. Me3SiOSiMe2+. For alcohols (ROH), facile formation of a tertiary product ion, presumably corresponding to an Me3Si-O-Si(Me)=O+-R structure with elimination of an amine reveals the strong tendency of these nitrogen-containing ions to undergo metathesis type reactions with oxygen containing substrates.

Cleaning of ceramic filter plates

In this thesis, cleaning of ceramic filter plates clogged by iron oxides was studied. Oxalic acid is considered as the most effective cleaning agent for the plates fouled by iron oxides, but when using oxalic acid, sparingly soluble calcium oxalate may be formed and it can blind the filter media. Suitability of another chemical for cleaning the plates clogged by iron oxides was studied in this thesis. The literature part was mostly about the properties of the chemical, about its reactions, industrial uses, safety issues etc. In the experimental part, the efficiency of the chemical for cleaning of the ceramic plates clogged by iron oxides was studied. Two kinds of plates were used in the experiments; the others were clogged by hematite and the others by magnetite. Both soaking and flow-through experiments were done. A suitable concentration, pH and temperature were tried to find in the experiments. Also the effect of ultrasound was studied. The efficiency of the cleaning was examined by measuring the permeability of the plates during the experiments. ICP-OES analysis was performed for determining the amount of dissolved iron in the washing solution. Some experiments were also done with oxalic acid. The results from the oxalic acid experiments were compared to the results from the experiments with the other chemical. In the experiments with the other chemical, the permeability increased more and the amounts of dissolved iron were larger. According to the results from the experiments, the method of application of the washing solutions had an impact on the washing results.

The evaluation of hazardous gas components caused by the thermal degradation of plant oils and animal fats

Neste Oil has introduced plant oils and animal fats for the production of NExBTL renewable diesel, and these raw materials differ from the conventional mineral based oils. One subject of new raw materials study is thermal degradation, or in another name pyrolysis, of these organic oils and fats. The aim of this master’s thesis is to increase knowledge on thermal degradation of these new raw materials, and to identify possible gaseous harmful thermal degradation compounds. Another aim is to de-termine the health and environmental hazards of identified compounds. One objective is also to examine the formation possibilities of hazardous compounds in the produc-tion of NExBTL-diesel. Plant oils and animal fats consist mostly of triglycerides. Pyrolysis of triglycerides is a complex phenomenon, and many degradation products can be formed. Based on the literature studies, 13 hazardous degradation products were identified, one of which was acrolein. This compound is very toxic and dangerous to the environment. Own pyrolysis experiments were carried out with rapeseed and palm oils, and with a mix-ture of palm oil and animal fat. At least 12 hazardous compounds, including acrolein, were analysed from the gas phase. According to the experiments, the factors which influence on acrolein formation are the time of the experiment, the sphere (air/hydrogen) in which the experiment is carried out, and the characteristics of the used oil. The production of NExBTL-diesel is not based on pyrolysis. This is why thermal degradation is possible only when abnormal process conditions prevail.

Vaahdonestokemikaalin syöttötapahtuman tehostamisen vaikutus märkäosan toimintaan

An improved defoamer dosage procedure and a more efficient dosing point to the approach system were studied in this thesis. Their influence on paper machine wet end operations was investigated. The improved defoamer dosing procedure was examined at UMP-Kymmene Tervasaari PM8. Air content and its controlling methods at the paper machine were studied in the literature survey. Also the influence of dissolved gases and entrained air in the papermaking furnish were introduced. Feeding methods – a TrumpJet chemical mixer and traditional feeding devices – were reviewed. The defoamer’s functioning methods were studied. The influence of the use of defoamers was estimated based on the main selected wet end operations. In the experimental part, defoamer mixing with a traditional feeding method and two improved mixing stages were compared based on the air content profiles in PM8’s approach system. The reference dosage procedure was PM8’s old dosing system. The first dosage procedure in the comparison involved two TrumpJet chemical mixers installed on the bottom wire trays. The second element of comparison involved the improvement brought by a third TrumpJet chemical mixer installed on the top wire tray. This second comparison of the efficient defoamer feeding concept was made at a higher production speed of PM8. The air content control situation was also studied at the higher production speed. In addition the connection between the defoamer and air content was observed and a mill-scale system was studied. The economical benefits of the new dosing procedure were also reviewed. Air content profiles of short circulation were measured in the reference situation and the two comparison points of the study. These air content measurements proved the main gas load is introduced to PM8's paper furnish from the white water tray. Thick stock air content was not essential when the air volume flow was considered. The improved defoamer dosing procedure made lower dosage amounts possible. Compared with the traditional feeding system, the new defoamer feeding concept made only few direct improvements to the wet end operations and the produced paper itself. The lower defoamer need was noticed to have a positive influence on hydrophobic sizing and paper defects. The surfaces of the white water tanks and the operation of pumps were assessed based on the density variations of the suspension. The temperature in the white water silo was stated to have a significant influence on the air content measured in the first centrifugal cleaning stage.

Explosion-proof requirements for Electrical Machines in Chemical, Oil and Gas Industry in Russia and CIS Countries

One of the main industries which form the basis of Russian Economical structure is oil and gas. This industry is also playing a significant role for CIS countries. Oil and gas industry is developing intensively attracting foreign investments. This situation is providing sustainable development of machinery production for hazardous areas. Operating in oil and gas areas is always related with occurrence of explosion gas atmospheres. Machines for hazardous areas must be furnished with additional protection of different types. Explosion protection is regulated with standards according to which equipment must be manufactured. In Russia and CIS countries explosion-proof equipment must be constructed in compliance with GOST standards. To confirm that equipment is manufactured according to standards’ requirements and is safe and reliable it must undergo the approval procedure. Certification in Russia is governed by Federal Laws and legislation. Each CIS country has its own approval certificates and permissions for operating in hazardous areas.

Balancing effluent quality, economic cost and greenhouse gas emissions during the evaluation of (plant-wide) control/operational strategies in WWTPs

The objective of this paper was to show the potential additional insight that result from adding greenhouse gas (GHG) emissions to plant performance evaluation criteria, such as effluent quality (EQI) and operational cost (OCI) indices, when evaluating (plant-wide) control/operational strategies in wastewater treatment plants (WWTPs). The proposed GHG evaluation is based on a set of comprehensive dynamic models that estimate the most significant potential on-site and off-site sources of CO2, CH4 and N2O. The study calculates and discusses the changes in EQI, OCI and the emission of GHGs as a consequence of varying the following four process variables: (i) the set point of aeration control in the activated sludge section; (ii) the removal efficiency of total suspended solids (TSS) in the primary clarifier; (iii) the temperature in the anaerobic digester; and (iv) the control of the flow of anaerobic digester supernatants coming from sludge treatment. Based upon the assumptions built into the model structures, simulation results highlight the potential undesirable effects of increased GHG production when carrying out local energy optimization of the aeration system in the activated sludge section and energy recovery from the AD. Although off-site CO2 emissions may decrease, the effect is counterbalanced by increased N2O emissions, especially since N2O has a 300-fold stronger greenhouse effect than CO2. The reported results emphasize the importance and usefulness of using multiple evaluation criteria to compare and evaluate (plant-wide) control strategies in a WWTP for more informed operational decision making

Gas collisions and pressure quenching of the photoluminescence of silicon nanopowder grown by plasma-enhanced chemical vapor deposition

The quenching of the photoluminescence of Si nanopowder grown by plasma-enhanced chemical vapor deposition due to pressure was measured for various gases ( H2, O2, N2, He, Ne, Ar, and Kr) and at different temperatures. The characteristic pressure, P0, of the general dependence I(P)=I0exp(-P/P0) is gas and temperature dependent. However, when the number of gas collisions is taken as the variable instead of pressure, then the quenching is the same within a gas family (mono- or diatomic) and it is temperature independent. So it is concluded that the effect depends on the number of gas collisions irrespective of the nature of the gas or its temperature

A simple and rapid method for urinary acetone analysis by headspace/gas chromatography

Urinalysis of acetone is important to monitor workers occupationally exposed to acetone and/or isopropanol, as well as in diagnosis of some diseases related to lipid metabolism impairment. This work shows a sensitive, simple and rapid static headspace-gas chromatographic procedure for quantitative determination of acetone in urine. The method was applied to measure acetone in 207 samples from general population volunteers, resulting in a mean level of 1.12 mg/L (± 0.47) and a range of 0.20 - 1.95 mg/L. The method is reproducible and reliable, making it suitable for routine analysis of acetone in urine.

Determination of cocaine in brazilian paper currency by capillary gas chromatography/mass spectrometry

The presence of illicit drugs such as cocaine and marijuana in US paper currency is very well demonstrated. However, there is no published study describing the presence of cocaine and/or other illicit drugs in Brazilian paper currency. In this study, Brazilian banknotes were collected from nine cities, extracted and analyzed by capillary gas chromatography/mass spectrometry, in order to investigate the presence of cocaine. Bills were extracted with deionized water followed by ethyl acetate. Results showed that 93% of the bills presented cocaine in a concentration range of 2.38-275.10 µg/bill.

Sustainable Waste-to-Energy Production: Performance Evaluation of Distributed Generation fuelled by Landfill Gas

The environmental impact of landfill is a growing concern in waste management practices. Thus, assessing the effectiveness of the solutions implemented to alter the issue is of importance. The objectives of the study were to provide an insight of landfill advantages, and to consolidate landfill gas importance among others alternative fuels. Finally, a case study examining the performances of energy production from a land disposal at Ylivieska was carried out to ascertain the viability of waste to energy project. Both qualitative and quantitative methods were applied. The study was conducted in two parts; the first was the review of literatures focused on landfill gas developments. Specific considerations were the conception of mechanism governing the variability of gas production and the investigation of mathematical models often used in landfill gas modeling. Furthermore, the analysis of two main distributed generation technologies used to generate energy from landfill was carried out. The review of literature revealed a high influence of waste segregation and high level of moisture content for waste stabilization process. It was found that the enhancement in accuracy for forecasting gas rate generation can be done with both mathematical modeling and field test measurements. The result of the case study mainly indicated the close dependence of the power output with the landfill gas quality and the fuel inlet pressure.

Flow analysis-hydride generation-gas phase derivative molecular absorption spectrophotometric determination of antimony in antileishmanial drugs

In the present work, the development of a method based on the coupling of flow analysis (FA), hydride generation (HG), and derivative molecular absorption spectrophotometry (D-EAM) in gas phase (GP), is described in order to determine total antimony in antileishmanial products. Second derivative order (D²224nm) of the absorption spectrum (190 - 300 nm) is utilized as measurement criterion. Each one of the parameters involved in the development of the proposed method was examined and optimized. The utilization of the EAM in GP as detection system in a continuous mode instead of atomic absorption spectrometry represents the great potential of the analytic proposal.

Comparison of gas chromatographic and gravimetric methods for quantization of total fat and fatty acids in foodstuffs

Different methods to determine total fat (TF) and fatty acids (FA), including trans fatty acids (TFA), in diverse foodstuffs were evaluated, incorporating gravimetric methods and gas chromatography with flame ionization detector (GC/FID), in accordance with a modified AOAC 996.06 method. Concentrations of TF and FA obtained through these different procedures diverged (p< 0.05) and TFA concentrations varied beyond 20 % of the reference values. The modified AOAC 996.06 method satisfied both accuracy and precision, was fast and employed small amounts of low toxicity solvents. Therefore, the results showed that this methodology is viable to be adopted in Brazil for nutritional labeling purposes.

Gas-phase solvolysis type reactions of SiCl3+ cations

Gas-phase SiCl3+ ions undergo sequential solvolysis type reactions with water, methanol, ammonia, methylamine and propylene. Studies carried out in a Fourier Transform mass spectrometer reveal that these reactions are facile at 10-8 Torr and give rise to substituted chlorosilyl cations. Ab initio and DFT calculations reveal that these reactions proceed by addition of the silyl cation to the oxygen or nitrogen lone pair followed by a 1,3-H migration in the transition state. These transition states are calculated to lie below the energy of the reactants. By comparison, hydrolysis of gaseous CCl3+ is calculated to involve a substantial positive energy barrier.

Measuring air pressure with a polymeric gas sensor

In this communication we describe the application of a conductive polymer gas sensor as an air pressure sensor. The device consists of a thin doped poly(4'-hexyloxy-2,5-biphenylene ethylene) (PHBPE) film deposited on an interdigitated metallic electrode. The sensor is cheap, easy to fabricate, lasts for several months, and is suitable for measuring air pressures in the range between 100 and 700 mmHg.

Evaluation of pesticide adsorption in gas chromatographic injector and column

Components in complex matrices can cause variations in chromatographic response during analysis of pesticides by gas chromatography. These variations are related to the competition between analytes and matrix components for adsorption sites in the chromatographic system. The capacity of the pesticides chlorpyrifos and deltamethrin to be adsorbed in the injector and chromatographic column was evaluated by constructing three isotherms and changing the column heating rate to 10 and 30 ºC min-1. By using ANCOVA to compare the slope of calibration graphs, results showed that the higher the injector temperature (310 ºC) the lower the pesticide adsorption. Also, deltamethrin influenced the adsorption of chlorpyrifos on the column chromatographic.