Adsorption of butanol and water vapors in silicalite-1 films with a low defect density

Pure silica zeolites are potentially hydrophobic and have therefore been considered to be interesting candidates for separating alcohols, e.g., 1-butanol, from water. Zeolites are traditionally synthesized at high pH, leading to the formation of intracrystalline defects in the form of silanol defects in the framework. These silanol groups introduce polar adsorption sites into the framework, potentially reducing the adsorption selectivity toward alcohols in alcohol/water mixtures. In contrast, zeolites prepared at neutral pH using the fluoride route contain significantly fewer defects. Such crystals should show a much higher butanol/water selectivity than crystals prepared in traditional hydroxide (OH–) media. Moreover, silanol groups are present at the external surface of the zeolite crystals; therefore, minimizing the external surface of the studied adsorbent is important. In this work, we determine adsorption isotherms of 1-butanol and water in silicalite-1 films prepared in a fluoride (F–) medium using in situ attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy. This film was composed of well intergrown, plate-shaped b-oriented crystals, resulting in a low external area. Single-component adsorption isotherms of 1-butanol and water were determined in the temperature range of 35–80 °C. The 1-butanol isotherms were typical for an adsorbate showing a high affinity for a microporous material and a large increase in the amount adsorbed at low partial pressures of 1-butanol. The Langmuir–Freundlich model was successfully fitted to the 1-butanol isotherms, and the heat of adsorption was determined. Water showed a very low affinity for the adsorbent, and the amounts adsorbed were very similar to previous reports for large silicalite-1 crystals prepared in a fluoride medium. The sample also adsorbed much less water than did a reference silicalite-1(OH–) film containing a high density of internal defects.The results show that silicalite-1 films prepared in a F– medium with a low density of defects and external area are very promising for the selective recovery of 1-butanol from aqueous solutions

Infravörös és Raman spektroszkópia és mikroszkópia alkalmazási lehetőségeinek kutatása az emberi szervezet fiziológiai állapotának jellemzésére = Study of application possibilities of infrared and Raman spectroscopy and microscopy in characterisation of physiological condition of the human body

A pályázatban szereplő kutatók jelentős szakmai tapasztalattal rendelkeznek az infravörös és Raman spektroszkópia területén. Ezt a felhalmozott szaktudást igyekeztünk kamatoztatni az orvosi diagnosztikával kapcsolatos kutatásokban. Infravörös spektroszkópiai mérésekkel sikerült elsőként igazolni, hogy az emberi bőr és haj színképe összefügg az emberi szervezet egészségi állapotával. A haj biológiai reakciója lassú (egy hónap) ezzel szemben a bőr igen gyorsan reagál a szervezetben lejátszódó folyamtokra. Mintegy 2200 páciens alkarján lévő bőr in vivo vizsgálatából, mintegy 85% biztonsággal szűrtük ki a beteg egyéneket. Az emberi haj színképéből speciális kemometriai módszerekkel az emlőrákos pácienseket szelektálni lehetett az egészségesektől. Meggyőződésünk, hogy a módszerünk a jelenlegi állapotában is alkalmas tömeges szűrővizsgálatokra, megbízhatósága, gyorsasága, egyszerűsége és olcsósága ezt mindenképpen indokolja. Sikerült diagnosztizálnunk kiváló biztonsággal a bőrmérésekből a diabétesz jelenlétét, valamint a haj színképekből a prosztata rákra utaló spektrális jeleket sikerült felismernünk. Ezen a területen további kutatásokra van szükség. Ezeken kívül szuvas fogak okozta elváltozásokat detektáltunk a fogzománcban, valamint tanulmányoztuk a tengeri kagylók és korallok szerkezetét. Foglalkoztunk biológiailag fontos vegyületek és fémkomplexek spektroszkópiai és elméleti szerkezetkutatásával is. | The participants of the present project have had considerable experience in the infrared and Raman spectroscopy. The knowledge accumulated is being directed toward research connected with medical diagnosis. From infrared spectroscopic measurements, we have demonstrated for the first time that the infrared spectra of human skin and hair exhibit clear correlation with the health condition of the human body. The biological changes in hair are rather slow (about one month), but human skin reflects very quickly various biological changes in human body. In vivo measurement of forearm skin spectra on about 2200 patients were used to select ill patients the reliability was about 85%. We have demonstrated for the first time that special chemometric methods can be used to sort the hair samples of suspected breast cancer patients. We are completely sure that our methods at present stage of developments are suitable for mass screening application, its reliability, speed, simplicity and low cost fully refer to this request. Illness specific spectroscopic signals have been obtained for diagnosis of diabetes using FTIR spectra of human skin and characteristic spectral features were observed in hair spectra of breast cancer patients. We have also studied spectroscopic effects of teeth cavity, and structural studies of sea shells and corals. Spectroscopic and theoretical studies of molecules and metal complexes of biological interests have been performed as well

Hard and transparent films formed by nanocellulose-TiO2 nanoparticle hybrids

T he formation of hybrids of nanofibrillated cellulose and titania nanoparticles in aqueous media has been studied. Their transparency and mechanical behavior have been assessed by spectrophotometry and nanoindentation. The results show that limiting the titania nanoparticle concentration below 16 vol% yields homogeneous hybrids with a very high Young's modulus and hardness, of up to 44 GPa and 3.4 GPa, respectively, and an optical transmittance above 80%. Electron microscopy shows that higher nanoparticle contents result in agglomeration and an inhomogeneous hybrid nanostructure with a concomitant reduction of hardness and optical transmittance. Infrared spectroscopy suggests that the nanostructure of the hybrids is controlled by electrostatic adsorption of the titania nanoparticles on the negatively charged nanocellulose surfaces

Photolysis-assisted, long-path FT-IR detection of air pollutants in the presence of water and carbon dioxide

Seven important air pollutants have been investigated by photolysis-assisted FT-IR spectroscopy. This technique renders invisible the spectra of water and carbon dioxide. which are two of the main concerns in long-path infrared spectroscopy. A cell, equipped with a UV lamp, was used to oxidise the analyte in the air sample and the spectrum recorded was used as a new background for the original sample spectrum. The optimum UV irradiation time and correctness of the concentrations were determined for this technique and compared with those from traditional methods. The signal-to-noise (S/N) ratios of the so-called "shadow spectra" were better than, or at least comparable to, the S/N ratios in the absorbance spectra obtained by using as background an air or an evacuated cell reference and subtraction of the spectra of water and carbon dioxide from a spectral library. The detection limits for the volatile organic compounds investigated have been improved by using this new method in which an appropriate back-round spectrum can be obtained quickly. The limitations of the method are that it cannot be applied to non-UV reactive compounds, such as methane. and the detection limits can be appreciably degraded when bands due to ozone in the shadow spectra overlap with those of the compounds under investigation

FTIR spectroscopy of the atmosphere. I. Principles and methods

In recent years Fourier transform infrared (FTIR) spectroscopy has been the dominant technique used for measuring the infrared (IR) absorption and emission spectra of most materials, with substantial advantages in signal-to-noise ratio, resolution, speed, and detection limits. The major advantage of the FIFIR technique over other spectroscopic methods is that practically all compounds show characteristic absorption/emission in the IR spectral region and based on this property they can thus be analyzed both quantitatively and qualitatively. The quest for highly sensitive detection methods for atmospheric trace gas samples, either in laboratory setup or in outdoor remote sensing, has been on agenda for several decades. The fast and intensive development of FTIR spectroscopic techniques has propelled the progress of trace gas analysis of the atmosphere. Since the early 1970s the number and scope of FTIR atmospheric measurements has increased steadily. In this review article we are making an attempt to summarize the results of the most significant contributions to the field of FTIR spectroscopy to trace gas analysis of the atmosphere. Beside the basic description of the extractive and open-path measurement methods, the difficulties connected with collection of appropriate background reference spectra, the ways of qualitative analysis and quantitative evaluation of measured spectra, the problems of calibration, and the effects of spectral resolution on detection sensitivity are discussed. The techniques reviewed include in situ IR absorption measurements over open paths in the field, such as remote sensing using the sun, the sky, or natural hot objects as IR sources of radiation, and also IR emission measurements of hot trace gas sources e.g., stack emissions, exhaust gases of combustion sources, and other industrial effluents

FTIR analysis of gaseous compounds in the mainstream smoke of regular and light cigarettes

Fourier-transform infrared (FTIR) spectroscopy has been applied to the study of mainstream cigarette smoke from cigarettes of different stated strengths (regular and various light cigarettes with different reported nicotine, tar and CO contents). This technique has allowed for the measurement of a variety of gaseous components including hydrocarbons and both nitrogen and carbon oxides. The results demonstrate that the strength of the cigarette does not have a significant bearing on the quantity of the observed components produced. Additionally, open-path FTIR studies of diluted sidestream and exhaled smoke have been conducted. These measurements revealed that the majority of gaseous pollutants originated from the sidestream smoke, while the primary smoke was 'purified' or diluted upon exhalation by the smoker