Papers by Keyword: FTIR Spectroscopy

Abstract: Graphene oxide (GO) and reduced graphene oxide (rGO) were obtained from graphite foil wastes (GFWs) by oxidation with KMnO₄ in the presence of concentrated sulfuric acid at 25–50°C. The resulting GOs were compared with that obtained from flake graphite under the same conditions. The samples were investigated by UV–Vis, FTIR, and Raman spectroscopy methods. Spectroscopic data, as well as EDS and XRD analyses, have shown that the GO samples obtained in both cases are almost identical. The hydrodynamic diameter and ζ-potential of both sample suspensions were also determined. The average particles size of GO(graflex) is 321.5 nm, while the particles size of GO(graphite) reaches 252 nm. The measured ζ-potential values for GO(graflex) and GO(graphite) are –31.58 and –50.04 mV, respectively. Therefore, GFWs can serve as precursor for the production of GOs.

Abstract: In this study, Dynamic Shear Rheometer (DSR) and Fourier Transform Infrared (FTIR) spectroscopy tests were performed on 35-50 and 70-100 penetration-graded asphalts. Both tests were performed on specimens at three different ageing states: unaged, short-term aged using the standard rolling thin film oven (RTFO) device, and long term aged by placing RTFO residue in the pressure aging vessel (PAV) apparatus. The tests were accomplished to quantify how ageing affects the results of both tests, namely the complex shear modulus for the DSR test and the carbonyl, sulfoxide, and ageing indices for the FTIR spectroscopy test. Both sets of measurements confirm that the harder asphalt stays harder than the softer asphalt after undergoing ageing, but the rate of hardness is higher for the softer asphalt. For instance, on average, PAV ageing was found to increase the amplitude of the shear complex modulus, from the unaged state, by 4.3 times and by 6.2 times for the 35-50 and 70-100 asphalts, respectively. It was also found that ageing decreases the phase angle for asphalt and the decrease is more pronounced for the softer asphalt (70-100) than the harder one (35-50). This was attributed to more maltenes content in the softer asphalt that transform into asphaltenes during ageing. Correlation coefficient between FTIR signals from the same samples revealed that FTIR spectroscopy as used in this research has an excellent repeatability. The repeatability was also confirmed using measures of dispersion such as the coefficient of variation, which was found not to exceed the 1.2%. The 35-50 asphalt was found to have more C=O and S=O links than the 70-100 asphalt since it showed more absorbance in the carbonyl and sulfoxide bands. These links are thought to make the asphalt physically harder. An analysis of variance study revealed that ageing is a statistically significant factor as measured using ageing indices calculated from FTIR spectroscopy data with the index AI_FTIR being the most sensitive to ageing among all considered indices. Empirical power equations with high coefficient of determination values were established to predict DSR results from FTIR index values, which was possible since both types of measurements show the same trend with ageing.

Abstract: A major function of resin is to provide defense against external attacks by releasing the resin flow on the attacked or damaged area. Nonetheless, the leakage of the resin on the surface can have a negative aesthetic and economic impact on wood material. The aim of this study is to investigate which treatments affect the chemo-physical properties of the resin in order to hinder the exudation on wood surface during service. To achieve a thickening of the resin, it is necessary to remove the volatile turpentine, and several studies have been carried out in this direction, providing useful information about this process. The heat treatment at different temperatures, 60°C, 100°C and 150°C, respectively, gives different mass losses, thus confirming that the turpentine can remain for long time in the resin, and the changes in structural, morphological, and chemical properties are affected by the temperature. FTIR spectroscopy, before and after thermal treatment, does not show major changes in chemical structures. However, from the samples analyzed with UHPLC-DAD-MS significant differences of the ratios of 20 compounds were observed, which characterize possible chemical reactions, such as decomposition, dehydrogenation, oxidation and isomerization. After heat treatment, the glass transition temperature of resin increased. Color changes are evident: resin becomes darker with increasing the temperature of treatment, apart from the resin heated at 100°C. The chemical changes in the composition of the resin caused by heat treatment need further investigation.

Abstract: M-type hexagonal ferrites have wide range of applications in magnetic recording media, microwave devices, micro electrochemical systems, high frequency devices, magneto-optical devices and many more. In present research, M-type strontium hexagonal ferrites doped with ‘magnesium’ having chemical composition (SrMg_xFe_12-xO₁₉) for x= 0.00, 0.05, 00.10, 0.15, 0.20, were synthesized to investigate the influence of rare earth metal doping on the structure and dielectric properties via sol-gel auto combustion technique. Molecular absorption/transmission, structural properties and dielectric response were investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and Dielectric measurements of ‘Mg’ doped strontium hexaferrites. X-ray diffraction analysis verified the magneto-plumbite structure. Crystal sizes were found in varying order for different concentrations of ‘Mg’ ranging from 12.357 to 15.375 nm. The FT-IR spectra exhibited higher frequency band (500–515.84 cm^-1) indicating tetrahedral site’s vibrations of metallic cations and lower frequency band (385.35–375.16 cm^-1) exhibiting octahedral sites due to metallic oxygen bond that confirmed the hexagonal structure. The resonance peaks were observed in dielectric constant, loss, tangent loss, AC conductivity, electric modulus and quality factor versus frequency graphs. The dielectric properties were found to be enhanced gradually by increasing concentration of magnesium. The best Q-factor was found for magnesium concentration (x=0.20). The dielectric parameters specify that these ferrite nanoparticles are good applicants for the higher frequency implementations.

Abstract: In the present work we pay an attention to the molecular structural changes between raw coal and its enriched, dense productions. Bituminous Ukhaa-Khudag coal in the form of an enriched, dense coal product is currently used as an energy source by Mongolian consumers for everyday need. There are three types of samples from one source: it is a raw coal (sample 1) and two of industrial prod- ucts as an enriched, dopant (organic based) added coal (sample 2) and simply enriched coal (sample 3). The raw coal general characterization is given through the elemental analysis, thermogravimetry analysis, moreover functional groups were identified by Fourier Transform infrared spectroscopy. The differences in the FTIR spectra of the samples were done.Some details are as follows: hydroxyl group vibrations are existing, rather weak in agreement of TG result; vibrations of aliphatic group were rarely in the long wave near region, carbonate minerals in the region of 1300-900 cm−1 are visible but overlapped, and an isolated out-of-plane deformational vibration (around 800 cm−1) or two-adjacent (800-750 cm−1) or three-adjacent (around 700 cm−1) of sp2-hybrid bonded aromatic CHx-groups were still presenting.After the processing hydroxyl group bands were affected in enriched coals, sample 2 and 3. In the spectrum of the sample 2 the long wave bands were intensively blurred.Industry processing retains an amount of water in the productions. Water excess influenced absorbance bands were able to be removed via the drying processing, however, the affection to the spectral struc- ture in sample 2 was unrecoverable.

Abstract: When using binders in coatings, whose film formation process relays on the oxygen uptake to start the cross-linking reaction, the use of special metal salts, so called driers, can catalyze the process, accelerating the curing of the film and reducing the waiting time between the applications of the next layers of paint. In this work, three primary driers, based on cobalt, iron and manganese are compared, to determine which one is more efficient in drying of alkyd and boiled linseed oil based coating. The study has been done using FTIR spectroscopy to investigate the rate of drying for each drier. The obtained results confirm that using the cobalt drier, the film formation is faster than with the other two alternative driers.

Abstract: In this paper, results of feasibility study on microplastics (MPs) assessment in leachates from the Latvian solid municipal landfill Getliņi are discussed. The application of leachates for the treatment of cigarette butts (CGB) was evaluated. Methods of fluorescent microscopy, Fourier transform infrared (FTIR) spectroscopy and FTIR-microscopy were used for the identification and characterization of MPs in the leachates and analysis of CGB. Presence of the secondary MPs (e.g., degraded polyolefin mixtures) was determined in the tested landfill leachates, while cellulose acetate (CA) was not determined in these products. The leachates were tested as potential media for the thermophilic (55°C) fermentation of CGB without air supply. Degradation of CGB was determined after one-week fermentation that was confirmed comparing the changes in FTIR spectra of CA prior and after the treatment. This study provoked a path for further experimental studies of controlled degradation of cigarette butts under natural conditions in landfill environments.

Abstract: Candlenut Shells is one of the many commodities growing in Indonesia and experiencing rapid progress production development. The shell of candlenut has good characteristic that allow it to be used as carbon. activated carbon is one of material that can be applied for various application. In this paper, we reported the synthesis of activated carbon from candlenut shell in order to get high quality of carbon by controlling the heating temperature in synthesis. Variation of heating temperature in to produce carbon were 300, 400, 500, 600 and 700 °C . FTIR Spectroscopy was carried out to determine the functional groups on the carbon from candlenut shells. FTIR analysis during the carbonization process was indicated the change in functional group of chemical structure from the candlenut shell, which is shown by decreasing the absorption spectrum of some functional groups of the candlenut shell after the carbonization process. The carbonization process has formed aromatic C = C and reduction functional group OH (aromatic compounds), C-H (aromatic ring), C-O (vibration ether structure) dan C=O (Ester compounds). And results of carbonization of candlenut shells at various temperatures have an electrical conductivity value that increases with increasing carbonization temperature. The carbonization temperature that is raised to 700 °C causes carbon to be more conductive with an increased electrical conductivity value. XRF characterization results also showed that in addition to carbon elements in the cundlenut shells, other elements were also found such as calcium, magnesium, aluminum, potassium, strontium, manganese, iron and zinc. Ca and Mg are the largest content besides carbon.

Abstract: Direct femtosecond laser printing was used to fabricate circular-and coaxial-shaped hole arrays at ultrafast printing rate up to 10⁶ elements per second. To achieve such fast printing rate, we implemented a spatial multiplexing of either a single Gaussian or cylindrical vector beams into linear array of identical laser spots. Being compared to ordinary microholes, the coaxial openings arranged at the same periodicity demonstrate enhanced transmission in the mid-IR spectral range resulted from coupling between localized electromagnetic mode supported by coaxial unit cell and the lattice-type surface plasmon resonance. At optimized geometry of the coaxial openings and their arrangement we demonstrated resonant transmission as high as 92% at wavelengths ranging from 7.5 to 9 μm. This makes the coaxial microhole arrays with tailored spectral properties produced with ultrafast and inexpensive direct laser printing promising for sensing applications based on surface enhanced infrared absorption.

Abstract: We demonstrated efficient crystallization of amorphous Si films induced by their direct irradiation with near-IR femtosecond laser pulses coming at sub-MHz repetition rate. Comprehensive analysis of morphology and composition of the laser-annealed film by atomic-force microscopy, Fourier-transform IR, Raman and energy dispersive X-ray spectroscopy as well as numerical modeling of optical spectra confirmed efficient crystallization of amorphous Si and high-quality of the obtained films opening pathway for applications in thin-film solar cells, transistors and displays.