The research is divided into two main parts: the sensing part and the gas delivery part. The reliable chemical information from the chemical sensor requires that the sensitive layer of the sensor exhibits long-term stability. To improve the stability of the sensing layer, camphorsulfonic acid was added to the formic acid. The introduction of photo-irradiation at 254 nm as an additional treatment to the sensing layer was proved to be effective. For gas selectivity of PANI matrix, metal or metal oxide clusters have been incorporated into the matrix. The composite materials of PANI with silver, copper, iron, nickel, palladium and mercury were also prepared and exposed to different gases. The second part of the thesis discusses the gas delivery system to the sensors using the synthetic jet technology. The sniffing functionality was demonstrated using the designed jet cell for operation in the open system. The gas sniffing experiments showed that in the presence of the jet, the response time of the sensor is faster by about two orders of magnitude (20 compared to 1800 seconds). The jet sampling system was applied to continuous monitoring of ammonia gas filter performance using the chemFET array. The jet system collected the gas before and after filtering, and the difference between the two responses was compared to observe the break-through of the filter. It was concluded that the gas sensing system integrated with the gas sampling functionality can be applied to monitor a gas filter performance. The cell was designed so that the impinging jet covers the sensing active area of the array of eight chemFETs. The two-dimensional distribution of the ammonia gas concentrations showed that the jet covers the active sensing area in an effective way so that the sampling volume for sensing is significantly reduced compared with the conventional gas flow cell system. Based on these initial studies shown in this thesis, the proposed gas sniffing system was shown to be effective in realizing fast detections of gases for critical applications of a gas sensor system.

Controlled auto-ignition (CAI) combustion in the gasoline engine has been extensively studied in the last several years due to its potential for simultaneous improvement in fuel consumption and exhaust emissions. At the same time, there has been increasing interest in the use of alternative fuels in order to reduce reliance on conventional fossil fuels. Therefore, this study has been carried out to investigate the effect of alcohol fuels on the combustion characteristics and in-cylinder processes of CAI combustion in a single cylinder gasoline engine. In order to study the effect of alcohol fuels, combustion characteristics were investigated by heat releases analysis in the first part. The combustion process was studied through flame structure and excited molecule by chemiluminescence imaging. Furthermore, in-cylinder gas composition was analysis by GC-MS to identify the auto-ignition reactions involved in the CAI combustion. In addition, the influence of spark-assisted ignition and injection timings were also studied. Alcohol fuels, in particular methanol, resulted in advanced auto-ignition and faster combustion than that of gasoline. In addition, their use could lead to substantially lower HC, NOX and CO exhaust emissions. Spark-assisted ignition assisted gasoline combustion by advancing ignition timing and initiating flame kernel at the centre of combustion chamber but it had marginal effect on alcohol fuels. Auto-ignition always took place at the perimeter of the chamber and occurred earlier with alcohol fuels. Fuel reforming reactions during the NVO period were observed and they had significant effect on alcohol combustion.

Modern societies produce large quantities of municipal solid waste (MSW), which is commonly disposed of by incineration. This has several advantages: it reduces the waste’s volume and sterilizes it while also enabling energy recovery. However, MSW incineration has some notable disadvantages, the most widely debated of which is probably the production and release of persistent organic pollutants (POP) such as polychlorinated dibenzofurans (PCDF), dibenzo-p-dioxins (PCDD), biphenyls (PCB) and naphthalenes (PCN). Of the 210 PCDF and PCDD congeners, 17 are toxic, with hormone-disrupting and carcinogenic properties. Twelve of the 209 PCB congeners and at least 2 of the 75 PCN also exhibit such properties. These POP form in the post-combustion zones of MSW incineration plants and are removed from the flue gas using filtering devices that trap them in the fly ash This thesis concerns the formation and degradation of POP in processes related to MSW incineration. The first paper describes a case study in which PCDD were forming in filters designed to remove them from flue gases, causing emission-related issues in a full-scale MSW incineration plant. It was shown that the PCDD formation was probably due to chlorophenol condensation on the filters’ surfaces. The second paper describes the validation of a cooling probe designed to prevent POP formation during high temperature (>450 °C) flue gas sampling. The results obtained also confirmed that PCDF and PCDD formation takes place at temperatures below 600 °C. In the third paper, three different fly ashes were subjected to thermal treatment under an inert atmosphere in a rotary kiln and in sealed ampoules at 400 °C. The concentrations, degrees of chlorination and congener profiles of the POP in the treated ashes and emitted gases were compared to those for the untreated ashes. The trends observed for PCDF mirrored those for PCN, while the trends for PCDD closely resembled those for PCB. The PCDF congener profiles of the kiln ash were similar regardless of the initial ash composition, suggesting that the mechanisms of PCDF formation were similar in all cases. The fourth paper describes the surface characterization of the three fly ashes studied in paper three by SEM, EDX, XPS and XRD. In addition, the thermal desorption and subsequent degradation of POP from the ashes was studied at temperatures of 300-900 °C. The composition of the gases released as the temperature increased differed between the ashes and depended on their composition. Doping experiments using isotopically labelled PCDF and PCDD suggests that PCDD desorbed at lower temperatures than PCDF. This thesis examines several problems relating to POP formation during MSW incineration, from sampling to the ultimate fate of incineration residues. The results obtained illustrate the wide range of processes that contribute to thermal POP formation and degradation during and after MSW incineration. / Förbränning av hushållssopor är en vanlig metod för att hantera ett växande avfallsproblem. Metoden har flera fördelar, såsom minskning av volym och vikt, sterilisering och energiåtervinning. Sopförbränning har dock vissa nackdelar och det mest debatterade är sannolikt utsläpp av persistenta organiska föroreningar (POPs) som polyklorerad dibensofuran (PCDF), dibenso-p-dioxin (PCDD), bifenyl (PCB) och naftalen (PCN). Det finns totalt 210 PCDF- och PCDD- kongener, med mellan ett till åtta klor på kolskelettet, varav 17 är giftiga med hormonstörande och cancerframkallande egenskaper. Även tolv av totalt 209 PCB-kongener samt minst två av totalt 75 PCN-kongener uppvisar liknande egenskaper. Dessa klorerade organiska föroreningar bildas då rökgaserna kyls ner i sopförbränningsanläggningarna och avlägsnas från rökgaserna med hjälp av filter och hamnar i flygaskan. Denna avhandling handlar om bildning och nedbrytning av POPs i sopförbränningsrelaterade processer.   Den första artikeln är en fallstudie där PCDD bildas i filtren i en fullskalig sopförbränningsanläggning. Bildningen ledde till förhöjda halter organiska föroreningar i rökgaserna, vilket ledde till ökade utsläpp. Den funna bildningsvägen för PCDD i filtren befanns sannolikt bero på kondensation av klorfenoler på filterytorna. Den andra artikeln är en valideringsstudie av en kylprob avsedd att användas vid rökgasprovtagning vid hög temperatur (> 450 °C) för att undvika bildning av POPs under provtagningen. Studien bekräftade att majoriteten av PCDF- och PCDD- bildning i rökgaser från sopförbränning sker vid temperaturer under 600 °C. I den tredje artikeln berättas om behandling av tre olika flygaskor från olika sopförbränningsanläggningar. Askorna behandlades vid 400 °C i inert atmosfär i både en roterugn och i förseglade ampuller. De resulterande koncentrationerna, kloreringsgraderna och kongenprofilerna av de organiska föroreningarna jämfördes. Likheter hittades mellan PCDF och PCN, medan PCDD och PCB betedde sig på ett annat sätt. Studien fann också att PCDF kongenprofiler i aska som behandlats i roterugnen liknade varandra, oberoende av askornas sammansättning, vilket tyder på en liknande bildningsväg. För den fjärde artikeln, genomfördes ytkarakterisering (SEM, EDX, XPS och XRD) på de tre flygaskorna från artikel tre som sedan hettades upp från 30 °C till 900 °C i vacuum. Det som frigjordes på grund av uppvärmningen samt nedbrytningsprodukter från askorna studerades med hjälp av masspektrometri och infraröd spektroskopi. Studien fann att de gaser som frigjordes när temperaturen ökade skilde mellan askorna, beroende på deras sammansättning. Studien fann också att när aska dopad med isotopmärkt PCDF och PCDD utsattes för samma behandling, frigjordes PCDD vid lägre temperatur än PCDF. Denna avhandling berör flera aspekter av problematiken kring klorerade organiska föroreningar som bildas vid sopförbränning, från provtagning till hur man ska hantera flygaskan. Avhandlingen belyser även olika typer av bildning och nedbrytning av POPs i varma processer kopplade till sopförbränning.

A dissertação se situa no campo de pesquisa de métodos não invasivos de análise clínica, mais especificamente, de prognóstico da gravidade de insuficiência cardíaca, IC, com base em bioindicador presente no ar exalado por pacientes, em estudo no IncorHCFMUSP. O bioindicador mais relevante encontrado por GC-MS foi a acetona (propanona). Para a coleta do ar exalado desenvolveu-se dispositivo que compreende frasco borbulhador (impinger) com difusor, contendo 5 mL de água, imerso em banho de gelo e acoplado a saco plástico para definição de volume amostrado (7,6 L). A preservação de amostras deu-se por congelamento a -80ºC. Para a determinação do analito, escolheu-se método espectrofotométrico (474 nm) baseado na reação da acetona com salicilaldeído em meio básico, apresentando limite de detecção de 0,3 mg/L em fase líquida e 0,3 µg/L em ar exalado. Foram realizados estudos de eficiência de coleta por geração de atmosfera controlada. Resultados iniciais obtidos com amostras coletadas de pacientes portadores de IC pelos colaboradores do Incor indicam a potencialidade do bioindicador e dos equipamentos e métodos desenvolvidos para acetona nesta dissertação. / The dissertation fits in the research field of noninvasive clinical analysis, more specifically, the prognosis of the severity of heart failure, HF, based on a biomarker found in the air exhaled by patients, in a study at InCor-HCFMUSP. The most relevant biomarker found by GC-MS was acetone (propanone). For the breath collection a device was developed which comprises a scrubber flask (impinger) with diffuser, containing 5 mL of water, immersed in an ice bath and attached to a plastic bag for delimitation of the sample volume (7,6 L). For the determination of acetone a spectrometric method (474 nm) was chosen based on a reaction of acetone with salicylaldehyde in alkaline medium, with detection limits of 0,3 mg/L in liquid phase and 0,3 µg/L in breath. Preliminary studies made with samples collected from HF patients by the co-workers from InCor indicate the potential of the identified biomarker and the suitability of the equipment and methods developed in this dissertation for its analysis.

A dissertação se situa no campo de pesquisa de métodos não invasivos de análise clínica, mais especificamente, de prognóstico da gravidade de insuficiência cardíaca, IC, com base em bioindicador presente no ar exalado por pacientes, em estudo no IncorHCFMUSP. O bioindicador mais relevante encontrado por GC-MS foi a acetona (propanona). Para a coleta do ar exalado desenvolveu-se dispositivo que compreende frasco borbulhador (impinger) com difusor, contendo 5 mL de água, imerso em banho de gelo e acoplado a saco plástico para definição de volume amostrado (7,6 L). A preservação de amostras deu-se por congelamento a -80ºC. Para a determinação do analito, escolheu-se método espectrofotométrico (474 nm) baseado na reação da acetona com salicilaldeído em meio básico, apresentando limite de detecção de 0,3 mg/L em fase líquida e 0,3 µg/L em ar exalado. Foram realizados estudos de eficiência de coleta por geração de atmosfera controlada. Resultados iniciais obtidos com amostras coletadas de pacientes portadores de IC pelos colaboradores do Incor indicam a potencialidade do bioindicador e dos equipamentos e métodos desenvolvidos para acetona nesta dissertação. / The dissertation fits in the research field of noninvasive clinical analysis, more specifically, the prognosis of the severity of heart failure, HF, based on a biomarker found in the air exhaled by patients, in a study at InCor-HCFMUSP. The most relevant biomarker found by GC-MS was acetone (propanone). For the breath collection a device was developed which comprises a scrubber flask (impinger) with diffuser, containing 5 mL of water, immersed in an ice bath and attached to a plastic bag for delimitation of the sample volume (7,6 L). For the determination of acetone a spectrometric method (474 nm) was chosen based on a reaction of acetone with salicylaldehyde in alkaline medium, with detection limits of 0,3 mg/L in liquid phase and 0,3 µg/L in breath. Preliminary studies made with samples collected from HF patients by the co-workers from InCor indicate the potential of the identified biomarker and the suitability of the equipment and methods developed in this dissertation for its analysis.