FTIR Signal Research Articles

Investigation of the interference between organic and mineral matter in coal and carbonaceous shale using FTIR spectroscopy

ABSTRACT Thirty-two coal (lignite-bituminous in rank) and carbonaceous shale samples, ranging from immature to overmature, were collected from the various coal-bearing basins (Saurashtra Basin, Bikaner Nagaur Basin, Damodar Basin, Mahanadi Basin, and Foreland Basin) in India and characterized petrographically (vitrinite reflectance and maceral composition), geochemically (total organic carbon and total sulfur) and chemically (Fourier Transform Infrared spectroscopy, FTIR). This paper explores utilization of FTIR study on bulk non-demineralized carbonaceous shale and coal to examine the interference between mineral and organic matter visible on FTIR spectra and application of such techniques to assess organic matter chemistry based on FTIR signal. Mineral matter is considerably affecting the organic matter FTIR signal in the region between 1700–1350 and 900–700 cm−1, while the 3100–2800 cm−1 region is unaffected. The general trends of organic matter evolution with thermal maturity, i.e. a decrease of aliphatic and oxygen-bearing groups and increase in aromatic signal, are visible in bulk non-demineralized samples; however, the interpretation of the signal is problematic due to the dilution-related signal weakening and region-specific overlapping. The quality of the FTIR signal is lower than the signal from demineralized kerogens or targeted specific maceral grains via combination of FTIR with microscopy. The spectra can still be useful for more qualitative aspects of FTIR, like assessment of organic functional groups, study of coal impurities, or as a complementary method in conjunction with other analytical techniques such as X-ray for mineral matter characterization.

Synthesis of novel carbon dots based combustion catalysts and their effects on thermolysis and laser ignition of 1,1′-dihydroxy-5,5′-ditetrazolium dihydroxyammonium salt (TKX-50)

The carbon dots (CDs) were prepared by the oxidation etching method. On this basis, the composite materials of CDs and Cu (CDs/Cu) were synthesized by the hydrothermal method. The elemental composition, morphology and structure were analyzed by TEM, SEM, EDS, XRD and XPS. The effects of CDs and CDs/Cu for thermal decomposition of TKX-50 pyrolysis were studied by DSC-FTIR-MS and in-situ solid FTIR. The CDs and CDs/Cu reduced the low-temperature decomposition peak temperature of TKX-50 by 10.1 ℃ and 16.1 ℃ respectively (10 ℃·min−1), and the second decomposition peak almost disappeared. This is because CDs and CDs/Cu can effectively facilitate the thermal decomposition of TKX-50 into NH2OH and 1,1′-ditetrazole diol (BTO). The CDs can promote the direct decomposition of BTO into small molecule gases and stable polymers at the initial pyrolysis stage. And they inhibit the combination of BTO and NH3 into 5,5′-bistetrazole-1,1′-didiolate (ABTOX), which is more difficult to decompose. So, the HCN and N2/CO were increased obviously during pyrolysis while NH3 and H2O content were decreased. On the other hand, the CDs/Cu promotes the decomposition of NH2OH in the first reaction. It manifested as the increase of NH3 and H2O. At the same time, the CDs/Cu facilitates the transition of difficult to decompose ABTOX losing NH3 to BOX to accelerate thermal decomposition reaction, playing a synergistic catalytic effect. Thus, in-situ solid FTIR signal of ABTOX was significantly weakened and the total content of NH3 was raised, especially the significant expansion of NH3 in the second stage. Finally, the influence of the catalysts in ignition characteristics was contrasted and discussed. Under the lower-power density region, the CDs and CDs/Cu decreased the ignition delay time of TKX-50. The CDs/Cu caused the flame propagation velocity of TKX-50 faster. Therefore, the CDs and their composites, as another new lightweight carbon material, are expected to be applied in the catalytic combustion of energetic materials.

Pilot study CCQM-P172 – spectroscopic methods for HNO3 value assignment

Pilot study CCQM-P172 – spectroscopic methods for HNO3 value assignment

Algae-bacterial aquaculture can enhance heavy metals (Pb2+ and Cd2+) remediation and water re-use efficiency of synthetic streams

The synergistic interaction between algae and bacteria can be exploited to develop the next-generation wastewater treatment systems as the traditional activated sludge process are expensive, time-consuming, and release several greenhouse gasses. Thus, the protocooperation of algae bacterial consortia was studied during bioremediation of Pb2++Cd2+, followed by a bioassay study with bioremediated stream using Sorghum bicolor. Bacterial [Bacillus sp., (NCBI Acc. No. MK999907), Bacillus sp. (NCBI Acc. No. MN005950) and Micrococcus sp. (NCBI Acc. No. MN005949)]-algal [Scenedesmus acutus (NCIM 5584) and Chlorella pyrenoidosa (NCIM 2738)] consortium was constructed in such as way, which can tolerate and efficiently remove 200 ppm Pb2+ +1.5 ppm Cd2+. The individual consortia showed higher bioremediation attributes when they were mixed in equal quantities. However, the algae-bacterial consortia in the protocooperation study showed ∼30–33% higher bioremediation than individual consortia of algae/bacteria. Due to positive protocooperation 30% higher algal AFDW, 13% higher bacterial CFU mL−1, 82% lower dissolved oxygen, and 62% higher bicarbonates were reported as compared to individual consortia systems. For reuse of water, Sorghum plants were treated with bioremediated mixed metal stream (amino acid rich) reported higher total chlorophyll, Fv/Fm, and dry weight. The FTIR signal patterns and SEM-EDX images of Sorghum roots treated with bioremediated mixed metal stream were found negative for presence of any metals, whereas the seedlings treated with mixed metal showed deposition of Pb2+and Cd2+. Therefore, algal bacterial consortia-based bioremoval approaches can be adopted as an efficient tool for metal bioremediation and reuse of wastewater.

FT-IR saliva analysis for the diagnosis of psoriasis: A pilot study

Psoriasis is a chronic, autoimmune disease with multiple interplaying risk factors. Saliva has gained growing interest as an excellent biological fluid exhibiting a strong diagnostic potential in dermopathies. Saliva profiling through Fourier Transform Infrared Spectroscopy in attenuated Total Reflection (FT-IR ATR) was investigated for the diagnosis of psoriasis. Particularly, multivariate analysis was carried out after a suitable pre-processing, applying unsupervised principal component analysis (PCA) for feature extraction in the Amide I/II, Thiocyanate and within Thiocyanate and bio fingerprint bands. Further, linear discriminant analysis (LDA) and support vector machine (SVM) were trained to establish discrimination models between psoriatic subjects and healthy controls. PCA-LDA evidenced a classification performance in the bio fingerprint region (2150–900 cm−1) of 93.75% accuracy, and a sensitivity and specificity of 87.5% if compared to SVM (87.5% accuracy, with a sensitivity and specificity of 75%). Saliva profiling and multivariate analysis provide a powerful approach in diagnosis and follow-up of inflammatory dermatopathies. FT-IR saliva profiling, signal processing and machine learning algorithms evidenced the possibility of automatic classification of psoriatic patients, with a potentially interesting insight in mass screening and preliminary diagnosis.

FTIR signal assignment in Chitin using density functional theory calculations – A monomer approximation

Density functional theory (DFT) calculations are performed on Chitin to investigate the geometry and vibrational properties under monomer approximation. Vibrational spectra of chitin have been analysed using the DFT monomer approach, and complete assignments of experimental FTIR signals are being reported in the present work. DFT calculations with the 6-311G basis set produces results for vibrational modes that reasonably agree with the experimental FTIR results.

Nanocomposite PLA/C20A Nanoclay by Ultrasound-Assisted Melt Extrusion for Adsorption of Uremic Toxins and Methylene Blue Dye.

Design of functional materials it is of great importance to address important problems in the areas of health and environment. In the present work, the synthesis and application of poly-meric nanocomposite materials with poly (lactic acid) (PLA) and modified nanoclay (cloisite 20A) with 1,4-diaminobutane dihydrochloride at different reaction times were studied. The concentra-tions of the nanoclays in the PLA matrix were 0.5, 1 and, 5% by weight (wt%). TGA showed that sample C20AM 120 (120 min of treatment) obtained the highest degree of modification considering the weight losses of the analyzed samples. An FT-IR signal at 1443 cm−1 suggests that the organic modifier is intercalated between the galleries of the clay. XRD, SEM and XPS suggest good disper-sion at low concentrations of the nanoclay. Adsorption tests revealed that the highest percentage of removal of uremic toxins and methylene blue was the sample with 5% wt/wt chemically modified nanoclay, suggesting good affinity between the modified nanoclays in the PLA matrix with the nitrogenous compounds.

Physicochemical properties of thermally treated poplar wood in silicone and rapeseed oils: A comparative study

The use of poplar as a nondurable wood in exterior applications exposed to harsh environments is limited and can impose a high maintenance cost. The heat treatment in silicone oil (SOHT) and rapeseed oil (ROHT) at 190 °C for 4 h was carried out on the poplar wood to impart long-lasting protection to the wood. The water-related properties of treated wood before and after the leaching test were determined. The chemical composition and thermal behavior of samples were also studied by FTIR and DSC analyses. The SOHT resulted in a darker color wood showing its higher effectiveness compared with the ROHT in terms of modifying wood properties. The SOHT changed the chemical composition of wood more drastically than ROHT. The SOHT samples showed good hydrophobic stability even after the leaching. Strong relations between surface wettability and FTIR signal, related to the changes of wood biopolymers, were also determined. The smallest spreading area of water drop was observed in SOHT samples. The SOHT resulted in the lower water absorption and the volumetric swelling of wood samples which were less affected by the time of soaking in water. The DSC analysis confirmed the lower capacity of moisture uptake and the higher thermal stability of SOHT samples. This study suggests that SOHT has a higher potential for improving the water-related properties of poplar wood than ROHT.

Comprehensive porosity determination of combustion-deposited SiOx thin films and correlation with FTIR signal

Porous silicon oxide thin films were deposited by combustion chemical vapour deposition (CCVD). Depending on the process parameters applied, the layer thickness ranged from 18 to 165 nm, as obtained by profilometry and spectral ellipsometry (SE). The layer morphology was investigated by scanning electron microscopy (STEM) and atomic force microscopy (AFM) revealing roughnesses of the respective films between 0.1 and 42.4 nm. The porosity of the films was determined using weighing, SE, and Rutherford backscattering spectrometry (RBS) with all methods giving similar values. The porosity varied between 21 and 93%. These high porosities can be an effect of voids resulting from pores and roughness. The investigations revealed an open porosity. The received porosities were correlated with FTIR signal. The FTIR signal strength per unit volume Ψ correlates linearly with the porosity. This result can be used as a calibration curve. Thus, the porosity of an unknown silicon oxide layer can be deduced from the measured FTIR signal and the layer thickness. All methods applied here yield a consistent description of the layer properties.

Substituent effect on redox potential of terephthalate-based electrode materials for lithium batteries

The substituent effect on the redox potential of lithium terephthalate was studied using symmetrical dilithium disubstituted-terephthalates incorporating bromo, methoxy and amino groups. All the terephthalate derivatives have been synthesized and evaluated as anode material for lithium-ion batteries. The electrochemical results revealed an increase in the reduction potential in the case of bromo and methoxy groups and almost the same in the case of amino group compared to unmodified dilithium terephthalate. In addition, a very first tendency between the 13C chemical shifts and FTIR signal of the carbonyl and the reduction potential of the studied disubstituted-terephthalates was formulated.

Surface lignin removal on coir fibers by plasma treatment for improved adhesion in thermoplastic starch composites

The high lignin to cellulose ratio of coir fibers results in low compatibility between these fibers and natural polymers like starch, leading to poor mechanical properties in the composites. Plasma treatment using either air or oxygen proved to be an effective in removing the lignin rich amorphous layer on coir fibers, as it was clearly observed by SEM. The ratio of the FTIR signal related to lignin (1508cm−1) and cellulose (1317cm−1) decreases 10 times for air plasma treated fibers and 20 times for oxygen plasma treated samples. Composites of plasma treated short coir fibers and thermoplastic starch presented considerable increase in mechanical properties in comparison to composites made with untreated fibers. Tensile strength increased by up to 300% and elastic modulus improved by a factor of nearly 20 times, which was associated with enhanced fiber-matrix adhesion after plasma treatment with oxygen for 7.2min at 80W power.

Effect of Al concentration on photoluminescence properties of sol-gel derived hydrogen annealed ZnO

The effect of the Al/Zn atomic ratio on the photoluminescence properties of hydrogen annealed undoped and Al rich ZnO (AZO) films was studied. The Al/Zn atomic ratios in the AZO films were varied from 0 to 40%. All the AZO films exhibited three peaks in the UV, green and red regions, whereas the undoped ZnO films had two peaks in the UV and green regions. The PL intensity in the UV and red regions increased with an increase in Al concentrations. The highest PL intensity in the UV region was observed in the 20% Al/Zn atomic ratio due to improvement in crystal quality which was also confirmed by XRD measurements. The PL emission in the red region was due to complex luminescent centers like (Vzn-Alzn)−. A blue shift was seen in the red region with the introduction of Al. The 20% AZO films obtained the strongest signal at −420 cm−1, whereas no FTIR signal was observed at 420 cm−1 in undoped ZnO. The bond signature at −420 cm−1 might be responsible for the highest PL intensity in NBE and red regions.

The depth profiling of TiO2 pigmented coil coatings using step scan phase modulation photoacoustic FTIR

The depth distribution of a TiO2 pigment within the polyurethane (PU) coil coatings is investigated using step scan phase modulation photoacoustic (SS-PM-PA) FTIR. Coil coatings with different pigment contents were prepared and the modulation frequency (MF) of the SS-PM-PA FTIR varied to record the depth distribution of the pigment within the coating. The TiO2 pigment was shown to contribute significantly to the SS-PM-PA FTIR signal. A TiO2 aggregated region within the topcoat is found close to the topcoat-primer interface and further away from the topcoat surface. A deeper TiO2 aggregated region can be identified when pigment content is relatively low. The SS-PM-PA FTIR signal shows a considerable contribution from the primer originated signal, provided the TiO2 pigment content is sufficiently high and the modulation frequency applied is relatively low. SEM cross-section imaging results show a strong correlation of the TiO2 depth distribution with SS-PM-PA FTIR results, which confirms the applicability of the SS-PM-PA FTIR technique to the depth profiling study of TiO2 pigmented coil coatings.

Comparative fingerprint and extraction yield of Diospyrus ferrea (willd.) Bakh. root with phenol compounds (gallic acid), as determined by uv–vis and ft–ir spectroscopy

ObjectiveTo analyze the comparative finger print and extraction yield of D.ferrea root with phenol compound (Gallic acid), as determined by UV–Vis spectroscopy and FTIR spectroscopy. MethodThe UV Vis spectroscopy and FTIR spectroscopy are adequate techniques to fingerprint comparatively and to evaluate the extraction yield of D.ferrea root extract. The higher extraction yield was recorded in ethanol comparatively superior and richer in phenol (gallic acid). Gallic acid has therapeutic application for inflammatory allergic diseases due to its ability to inhibit histamine. Finger print region was recorded between 500-3500 cm-1 for each extract and functional groups were identified and compared with the standard. ResultThe extraction factor was superior in ethanol (270 nm) rich in polar molecules. The FTIR signal at 900, 1500, 1714, 3000, 3100cm-1 considered as a good indicator of phenol (gallic acid). The functional groups of each extract were identified. ConclusionThe UV and FTIR method was validated as a good tool to investigate the finger print and to predict the composition of different root extract of D.ferrea.

Thin polymer film based rapid surface acoustic wave humidity sensors

Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of glass slides, were studied using transmission FTIR spectroscopy upon varying relative humidity (RH) from 2 to 70%. The obtained data revealed fast dynamics of water vapor adsorption–desorption with responses on the order of several seconds. Based on the fast FTIR signal intensity changes versus RH, it was proposed that a similar rapid response can be achieved for PVA and PVP coated SAW devices due to changes in mass-loading and film viscoelastic properties upon absorption of water vapor in the films. Sub-micron thickness films were spin-coated onto the surface of LiNbO 3 SAW substrates. Both PVA and PVP based humidity sensors revealed prompt reversible response to variations in humidity, although PVP-based device demonstrated better sensor parameters with total insertion loss variation of about 50 dB over the studied RH range and response time 1.5 s for the humidity step 5–95% (recovery time – 2.5 s), representing one of the fastest SAW-based humidity sensors reported to date.

FTIR sensitivity enhancement on Pt/SiO 2/Au layered structures: A novel method for CO adsorption studies on Pt surfaces

Specular reflectance FTIR study of carbon monoxide adsorbed on platinum is performed on Pt/SiO 2/Au layered structures prepared by deposition of thin films on silicon (1 0 0) wafers. The layered structures consist of 5 nm thick platinum films over SiO 2 films of varying thicknesses with 50 nm thick reflecting gold films underneath. Due to optical interference effects, the reflectance of each of these structures varies with the incident infrared wavelength and goes through a minimum at a wavelength that depends on the thickness of the SiO 2 layer. The decrease in the reflectance R causes an effective increase in the Δ R / R value resulting in a large increase in the infrared absorption band intensity of linearly-adsorbed CO. The peak height changes with changing the SiO 2 thickness in the structures and is greatest for the sample which has lowest reflectance near the absorption wavelength of CO (∼2100 cm −1). This improvement in the ratio of FTIR signal to background reflectance can be very useful for probing low surface area model catalytic surfaces at atmospheric pressures and under reaction conditions. A spectrum of CO adsorbed on nanofabricated Pt nanowire catalysts on TiO 2 support is also shown as an example of the sensitivity enhancement on layered structures.

TG-FTIR study of pyrolysis products evolving from dyestuff production waste

Solid waste from dyestuff production is classified as ‘hazardous waste’. The thermal degradation of a dyestuff residue was studied in an inert atmosphere using Thermogravimetric Analysis coupled with Fourier Transform Infrared Analysis (TG-FTIR). A heating rate of 30 °C/min was applied, with final temperature of 950 °C. A total weight loss of 35.1 wt% was observed, and the temperature trend of evolving gaseous products, such as CO 2, CO, H 2O, HCN and SO 2, was investigated. When heated in an inert atmosphere, the dyestuff residue starts decomposing below 200 °C, while reaching a peak rate in volatiles’ evolution around 257 °C. Sulphur and nitrogen evolve as SO 2 and HCN, respectively. Also other gases and vapours, such as CO 2, CH 3OH and H 2O are detected. At higher temperatures several compounds can still be monitored (temperature of maximum FTIR signal): methane (500 °C), carbon dioxide (650–950 °C) and carbon monoxide (900 °C). Hydrogen chloride was not detected in this experiment.

Characterization of self-cleaning glasses using Langmuir–Blodgett technique to control thickness of stearic acid multilayers: Importance of spectral emission to define standard test

The photocatalytic properties of commercialized self-cleaning glasses have been evaluated by the degradation of stearic acid C 17H 35COOH (SA), selected as a model molecule representative of fatty dirt. The relative amount of SA has been determined by measuring the FTIR peak area in the range 2752 and 2992 cm −1 corresponding to the C–H stretching bands. In order to estimate the thickness of one layer, the deposit of SA has been performed using the Langmuir–Blodgett (LB) method, which allows obtaining organized monomolecular layers of amphiphilic organics on a substrate. The thickness of one SA layer, obtained by Langmuir–Blodgett deposition, has been correlated to the FTIR signal. The photocatalytic degradation of a SA layer of a controlled thickness was carried out in a double jacket Pyrex reactor equipped with a UV Philips HPK 125 lamp. The photocatalytic degradation rate of the SA layer with different thicknesses was determined. The SA degradation rate was investigated under UV-A and UV-B irradiations to determine the influence of the photon wavelength range on efficiency.

Do Parallel β-Helix Proteins Have a Unique Fourier Transform Infrared Spectrum?

Several polypeptides have been found to adopt an unusual domain structure known as the parallel β-helix. These domains are characterized by parallel β-strands, three of which form a single parallel β-helix coil, and lead to long, extended β-sheets. We have used ATR-FTIR (attenuated total reflectance-fourier transform infrared spectroscopy) to analyze the secondary structure of representative examples of this class of protein. Because the three-dimensional structures of parallel β-helix proteins are unique, we initiated this study to determine if there was a corresponding unique FTIR signal associated with the parallel β-helix conformation. Analysis of the amide I region, emanating from the carbonyl stretch vibration, reveals a strong absorbance band at 1638 cm −1 in each of the parallel β-helix proteins. This band is assigned to the parallel β-sheet structure. However, components at this frequency are also commonly observed for β-sheets in many classes of globular proteins. Thus we conclude that there is no unique infrared signature for parallel β-helix structure. Additional contributions in the 1638 cm −1 region, and at lower frequencies, were ascribed to hydrogen bonding between the coils in the loop/turn regions and amide side-chain interactions, respectively. A 13-residue peptide that forms fibrils and has been proposed to form β-helical structure was also examined, and its FTIR spectrum was compared to that of the parallel β-helix proteins.

Surface structure of cadmium selenide nanocrystallites

Extended x-ray-absorption fine structure ~EXAFS!, Fourier-transform infrared absorption ~FTIR!, and elemental analysis were used on a variety of CdSe nanocrystallites ~NC’s ! to study surface structure. All CdSe NC’s were grown by standard inverse micelle techniques. Two sets of NC’s samples were made. One set was made so that only the size of the NC’s was varied, while the surface treatment was kept the same. The other set was made so that only the surface treatment was varied, while the size distribution was kept the same. For the EXAFS experiments, reference compounds similar in structure were measured. FTIR found surface Cd atoms to be passivated by pyridines and water groups. Fourier-filtered first-shell Cd EXAFS also supports the existence of water groups attached to the surface Cd atoms. The lack of any SeO and Si(CH3) 3 in the FTIR signal indicates that most surface Se atoms have unterminated bonds. Fourier-filtered first-shell Se EXAFS spectra indicate that Se has only Cd as its first-nearest neighbor, and that the coordination number is reduced from the bulk value, suggesting surface Se atoms are unpassivated. Our data support the existence of surface Se lone-pair orbitals that can trap an optically excited hole. @S0163-1829~97!00908-9# Nanocrystallites ~NC’s ! represent a domain of condensed matter that is not well understood. The evolution of physical