Reflectance Fourier Transform Infrared Spectroscopy Research Articles

3,4-Dimethoxy phenyl thiosemicarbazone as an effective corrosion inhibitor of copper under acidic solution: comprehensive experimental, characterization and theoretical investigations.

This study investigates the corrosion inhibition potential of 3,4-dimethoxy phenyl thiosemicarbazone (DMPTS) for copper in 1 M hydrochloric acid (HCl) solutions, aiming to disclose the mechanism behind its protective action. Through an integrative methodology encompassing electrochemical analyses-such as weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS)-we quantitatively evaluate the corrosion protection efficacy of DMPTS. It was determined that the optimal concentration of DMPTS markedly boosts the corrosion resistance of copper, achieving an impressive inhibition efficiency of up to 89% at 400 ppm. The formation of a protective layer on the copper surface, a critical aspect of DMPTS's inhibitory action, was characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). These techniques provided empirical evidence of surface morphology modifications and roughness changes, affirming the formation of a protective barrier against corrosion. A significant advancement in our study was the application of Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy, which identified chemical adsorption as the definitive mechanism of corrosion inhibition by DMPTS. The ATR-FTIR results explicitly demonstrated the specific interactions between DMPTS molecules and the copper surface, indicative of a robust protective adsorbed layer formation. This mechanistic insight, crucial to understanding the inhibitory process, aligns with the protective efficacy observed in electrochemical and surface analyses. Theoretical support, provided by the Quantum Theory of Atoms in Molecules (QTAIM) and quantum chemical computations, further validated the strong molecular interaction between DMPTS and copper, corroborating the experimental findings. Collectively, this research not only confirms the superior corrosion inhibition performance of DMPTS in an acidic setting but also elucidates the chemical adsorption mechanism as the foundation of its action, offering valuable insights for the development of effective corrosion inhibitors in industrial applications.

Serum-based ATR-FTIR spectroscopy combined with multivariate analysis for the diagnosis of pre-diabetes and diabetes.

Diabetes mellitus (DM) is a metabolic disease with an increasing prevalence that is causing worldwide concern. The pre-diabetes stage is the only reversible stage in the patho-physiological process towards DM. Due to the limitations of traditional methods, the diagnosis and detection of DM and pre-diabetes are complicated, expensive, and time-consuming. Therefore, it would be of great benefit to develop a simple, rapid and inexpensive diagnostic test. Herein, the infrared (IR) spectra of serum samples from 111 DM patients, 111 pre-diabetes patients and 333 healthy volunteers were collected using attenuated total reflection Fourier-transform IR (ATR-FTIR) spectroscopy and this was combined with the multivariate analysis of principal component analysis linear discriminant analysis (PCA-LDA) to develop a discriminant model to verify the diagnostic potential of this approach. The study found that the accuracy of the test model established by ATR-FTIR spectroscopy combined with PCA-LDA was 97%, and the sensitivity and specificity were 100% and 100% in the control group, 94% and 98% in the pre-diabetes group, and 91% and 98% in the DM group, respectively. This indicates that this method can effectively diagnose DM and pre-diabetes, which has far-reaching clinical significance.

Analysis of protein-protein and protein-membrane interactions by isotope-edited infrared spectroscopy.

The objective of this work is to highlight the power of isotope-edited Fourier transform infrared (FTIR) spectroscopy in resolving important problems encountered in biochemistry, biophysics, and biomedical research, focusing on protein-protein and protein membrane interactions that play key roles in practically all life processes. An overview of the effects of isotope substitutions in (bio)molecules on spectral frequencies and intensities is given. Data are presented demonstrating how isotope-labeled proteins and/or lipids can be used to elucidate enzymatic mechanisms, the mode of membrane binding of peripheral proteins, regulation of membrane protein function, protein aggregation, and local and global structural changes in proteins during functional transitions. The use of polarized attenuated total reflection FTIR spectroscopy to identify the spatial orientation and the secondary structure of a membrane-bound interfacial enzyme and the mode of lipid hydrolysis is described. Methods of production of site-directed, segmental, and domain-specific labeling of proteins by the synthetic, semisynthetic, and recombinant strategies, including advanced protein engineering technologies such as nonsense suppression and frameshift quadruplet codons are overviewed.

Infrared Spectroscopy Study of Edge Water Penetration at Hydrophilic Bonding Interface

Hydrophilic wafer bonding is a process used to bond two wafers without adding material between the two surfaces. Water has a definite impact both during the bonding (bonding wave propagation, adhesion) (1) and after annealing (mechanical strength of the bonding interface, adherence) (2) during such a process. To have a better understanding of mechanisms ruling direct hydrophilic wafer bonding, it is thus important to quantify the amount of water present at the bonding interface.It is known that water is able to penetrate at the bonding interface at room temperature and 40% relative humidity. This has been demonstrated by analyzing defects with scanning acoustic microscopy (SAM) and from X-Ray Reflectivity (XRR) measurements (3,4). Kinetics observed by Tedjini et al. were consistent with a Lucas-Washburn flow through a one nm gap driven by the capillary forces of the hydrophilic surfaces.Nevertheless, no investigation of this phenomenon was performed using Fourier Transform Infra-Red Multiple Internal Reflection (FTIR-MIR) spectroscopy (5). Infrared spectroscopy of silanols, hydrogen bonded water and free water is well documented (6–8) and provides knowledge about water content and organization at the bonding interface. Here FTIR-MIR spectroscopy yields a direct measurement of the relative amount of water and its structure at the interface.More precisely this study will enable us to compare Si-Si, Si-SiO2 and SiO2-SiO2 water penetration kinetics at a fixed distance from the edge of the bonded substrates. A schematic view of the FTIR-MIR setup is shown in Figure 1 to explain the measurement principle.We report the study of water kinetics penetration at bonding interface by FTIR-MIR characterization. A Gaussian decomposition of the OH stretching absorption band signal allows identifying the contributions of silanols, surface bonded water and free liquid water as shown on Figure 2. The integral of each Gaussian peak is otherwise proportional to the relative amount of water. Surface preparation will be discussed and results compared to other characterizations techniques.REFERENCES Larrey V, Mauguen G, Fournel F, Radisson D, Rieutord F, Morales C, et al. Adhesion Energy and Bonding Wave Velocity Measurements. ECS Transactions. 23 sept 2016;75(9):145-52.Fournel F, Tedjini M, Larrey V, Rieutord F, Morales C, Bridoux C, et al. Impact of Water Edge Absorption on Silicon Oxide Direct Bonding Energy. ECS Transactions. 23 sept 2016;75(9):129-34.Tedjini M, Fournel F, Moriceau H, Larrey V, Landru D, Kononchuk O, et al. Interface water diffusion in silicon direct bonding. Appl Phys Lett. 12 sept 2016;109(11):111603.Rieutord F, Tardif S, Landru D, Kononchuk O, Larrey V, Moriceau H, et al. Edge Water Penetration in Direct Bonding Interface. ECS Trans. 24 août 2016;75(9):163-7.Rochat N, Olivier M, Chabli A, Conne F, Lefeuvre G, Boll-Burdet C. Multiple internal reflection infrared spectroscopy using two-prism coupling geometry: A convenient way for quantitative study of organic contamination on silicon wafers. Appl Phys Lett. 2 oct 2000;77(14):2249-51.Baum M, Rébiscoul D, Juranyi F, Rieutord F. Structural and Dynamical Properties of Water Confined in Highly Ordered Mesoporous Silica in the Presence of Electrolytes. J Phys Chem C. 30 août 2018;122(34):19857-68.Caër SL, Pin S, Esnouf S, Raffy Q, Ph. Renault J, Brubach JB, et al. A trapped water network in nanoporous material: the role of interfaces. Physical Chemistry Chemical Physics. 2011;13(39):17658-66.Davis KM, Tomozawa M. An infrared spectroscopic study of water-related species in silica glasses. Journal of Non-Crystalline Solids. 2 juin 1996;201(3):177-98. Figure 1

Mussel-inspired modification of 2D MoS2 to construct a hybrid nanocomposite membrane with enhanced pervaporation dehydration of isopropanol

In this work, a thin-film nanocomposite (TFN) membrane was constructed using a hybrid polydopamine (PD)-MoS2 (MoS2@PD) filler for pervaporation dehydration of isopropanol. The exfoliated MoS2 was first modified through bio-inspired coating of PD. The resulting MoS2@PD with different weight ratio with respect to PEI was then deposited into the hydrolyzed polyacrylonitrile support through pressure-assisted filtration, followed by crosslinking with trimesoyl chloride. Characterization experiments were performed with the membranes using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy, X-Ray Photoelectron Spectroscopy, Energy-Dispersive X-ray Spectroscopy, Field Emission Scanning Electron Microscopy, Atomic Force Microscopy, and water contact angle analyses. The PD serves as a bridging agent between MoS2 and the crosslinked PEI, enhancing the membrane’s physicochemical properties, including surface morphology and hydrophilicity. For membrane performance on pervaporation dehydration of 70/30 wt% isopropanol/water mixture at 25 °C, the addition of MoS2@PD led to a simultaneous increase in permeation total flux and water content in the permeate. Notably, MoS2@PD0.3-TFN membrane demonstrated a permeation flux of 2870.10 g∙m−2∙h−1 and 0.86/99.14 wt% isopropanol/water permeate mixture. The membrane also maintained stable performance under varying feed concentration, feed temperature, and long-term operations. This study contributes valuable insights into the development of MoS2-based membrane with enhanced pervaporation separation performance.

Influence mechanism of K on cellulose pyrolysis by stepwise isothermal method in-situ DRIFTS method

The influence mechanism of alkali metal potassium (K) on cellulose pyrolysis is a vague and fundamental key topic in the field of biomass thermal conversion. In this study, the pyrolysis of cellulose and K-impregnated cellulose was compared by in-situ DRIFTS (Diffused Reflectance Infrared Fourier Transform Spectroscopy) and TG (Thermal Gravimetric)–MS (Mass Spectrum) experiment, and quantum chemical calculations were used to verify the peak position and pyrolysis mechanism of infrared (IR) spectroscopy. Stepwise isothermal in-situ DRIFTS was designed to study the reaction path at high temperatures. It was found that in the early stage of pyrolysis, K accelerated the activation of cellulose by attacking the hydrogen bond (H-bond) in the crystal structure of cellulose, increased the dehydration rate between molecules, and promoted the decomposition of cellulose. Simultaneously, it weakened the epoxy–ether bond, inhibited the formation of dehydrated sugar, and promoted the formation of furan. Subsequently, K combined with carbonyl groups to form C–O–K structures, which improved the thermal stability of certain oxygen-containing functional groups such as carbonyls/aldehydes, so that these structures were retained until higher temperature. K promoted the conversion of dehydrated sugars to straight-chain ketones/aldehydes, which led to an increase in carbon conversion. During the coke generation stage, K promoted the formation of disordered carbon and residues, thereby inhibiting coke aromatization. The isothermal in-situ DRIFTS method proposed in this study was demonstrated to better inhibit the high temperature drift of IR spectrum during pyrolysis. It clarified the conversion between functional groups at high temperatures, which is expected to promote the development of other high-temperature pyrolysis mechanism.

Enhancing forensic investigations: Identifying bloodstains on various substrates through ATR-FTIR spectroscopy combined with machine learning algorithms

The forensic analysis of bloodstains on various substrates plays a crucial role in criminal investigations. This study presents a novel approach for analyzing bloodstains using Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR) in combination with machine learning. ATR-FTIR offers non-destructive and non-invasive advantages, requiring minimal sample preparation. By detecting specific chemical bonds in blood components, it enables the differentiation of various body fluids. However, the subjective interpretation of the spectra poses challenges in distinguishing different fluids. To address this, we employ machine learning techniques. Machine learning is extensively used in chemometrics to analyze chemical data, build models, and extract useful information. This includes both unsupervised learning and supervised learning methods, which provide objective characterization and differentiation. The focus of this study was to identify human and porcine blood on substrates using ATR-FTIR spectroscopy. The substrates included paper, plastic, cloth, and wood. Data preprocessing was performed using Principal Component Analysis (PCA) to reduce dimensionality and analyze latent variables. Subsequently, six machine learning algorithms were used to build classification models and compare their performance. These algorithms comprise Partial Least Squares Discriminant Analysis (PLS-DA), Decision Trees (DT), Logistic Regression (LR), Naive Bayes Classifier (NBC), Support Vector Machine (SVM), and Neural Network (NN). The results indicate that the PCA-NN model provides the optimal solution on most substrates. Although ATR-FTIR spectroscopy combined with machine learning effectively identifies bloodstains on substrates, the performance of different identification models still varies based on the type of substrate. The integration of these disciplines enables researchers to harness the power of data-driven approaches for solving complex forensic problems. The objective differentiation of bloodstains using machine learning holds significant implications for criminal investigations. This technique offers a non-destructive, simple, selective, and rapid approach for forensic analysis, thereby assisting forensic scientists and investigators in determining crucial evidence related to bloodstains.

Differentiation and prediction of the in vitro antifungal activity of Brazilian propolis against Fonsecaea pedrosoi using chemometrics and diffuse reflectance infrared Fourier Transform spectroscopy

The in vitro antifungal activity of ethanolic extracts of propolis was evaluated at five different concentrations in twelve Fonsecaea pedrosoi strains using agar dilution. Eight propolis extracts were collected from towns located in the central region of the state of Rio Grande do Sul, Brazil. Diffuse reflectance infrared Fourier Transform spectroscopy (DRIFTS) was employed to analyze the spectra of lyophilized propolis extracts. The use of chemometric tools allowed for the development of models with more relevant factors and with fewer variables. Partial least squares (PLS) regression was applied, allowing for the development of PLS-DRIFTS models to predict antifungal activity of all fungal strains with root mean square error of cross validation (RMSECV) lower to 5.00 mm2 and coefficient correlation of cross-validation (R2) upper to 0.99 with five to eight latent variables at 4000-2400 and 2200-600 cm-1. Concluding, DRIFTS models associated with chemometrics are powerful screening tools of propolis samples with fungistatic properties against Fonsecaea pedrosoi.

Plasma-Induced Interfacial Processes in Metal Halides FTIR Gas Cell Windows

Fourier transform infrared spectroscopy (FTIR) is one of the most widely used vibrational diagnostic techniques to investigate gas-phase reactive oxygen and nitrogen species (RONS). However, the technique carries intrinsic challenges, particularly in relation to interfering peaks in the spectral data. This study explores the interfacial processes that occur when reactive oxygen and nitrogen species generated by a non-equilibrium air plasma interact with the metal halide windows of an FTIR gas cell, leading to the appearance and evolution of spurious absorption peaks which complicate spectral interpretation. Raman spectroscopy, X-ray photoelectron spectroscopy, time of flight secondary ion mass spectrometry and attenuated total reflectance-FTIR spectroscopy were used to elucidate the origin of spurious absorption peaks spanning the 1400–1300 cm−1 spectral range as a result of KBr exposure to plasma generated species. It was found that plasma exposed KBr contained a lower atomic fraction of Br which was replaced by the NO3 nitrate group, the main absorbance peak of which progressively evolved with plasma exposure and affected the window transparency over the corresponding FTIR region. A correlation was revealed between KNO3 formation, plasma power and exposure time to a growth and change in molecular vibrational energies corresponding to asymmetric NO3 stretching vibrations in the KNO3 structure.

Interaction mechanisms of typical collectors with zircon surfaces and their influence on surface morphology and hydrophobicity for selective flotation

Zircon is the primary mineral that contains the critical metals zirconium and hafnium. However, the extraction of pure zircon from its natural ore is challenging. The inadequate understanding of the interaction mechanisms between traditional flotation collectors, namely n-octyl phosphonic acid (nOPA), octyl-hydroxamic acids (OHA), and oleic acid (OL), with zircon, has hindered the development of highly selective flotation reagents. Therefore, a combination of atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), Zeta potential tests, contact angle measurements, and flotation tests was employed to elucidate the mechanism of collector adsorption on surface morphology and the chemical bonding interactions at the interface. The AFM, XPS, and DRIFTS results consistently demonstrate that all three reagents can chemically bond with zircon surfaces. nOPA exhibits stronger interactions with zircon compared to OL and OHA, as it coordinates with two zirconium sites to form a monolayer. Zeta potential and contact angle measurements reveal that the surface morphology and weak adsorption, which is driven by weak interactions, contribute to an improvement in hydrophobicity. Flotation results further validate that the three reagents can selectively float zircon in specific pH ranges. The interfacial bonding interactions, which are influenced by weak interactions, play significant roles in the flotation of zircon.

Determination of the pKa Value of Protonated Mono and Polyamine in Solution Using Fourier Transform Infrared Titration.

The pKa values of propanolamine hydrochloride (PAMH) and poly(allylamine hydrochloride) (PAAMH) in concentrated solutions were determined by both Fourier transform infrared spectroscopy (FT-IR) titration and classical potentiometric (POT) titration and compared. Starting with the respective fully protonated forms PAMH and PAAMH and increasing the pH value by sodium hydroxide addition in situ attenuated total reflection FT-IR (ATR FT-IR) spectra on PAMH and PAAMH solutions show the variation of diagnostic infrared (IR) bands. From the decrease of the most intense δ(NH3+) band the dissociation process of the NH3+ groups could be followed. Thereby, from the respective normalized band area A the dissociation degree αIR of the ammonium groups could be determined. Plotting pH versus αIR and fitting this curve by a modified Henderson-Hasselbalch function pH = pKa + B log (αIR/1 - αIR) the parameters pKa and cooperativity factor B were obtained. pKa values from FT-IR titration were qualitatively in line with respective pKa values from POT titration. Quantitative systematic pKa deviations between polyelectrolyte (PEL) and respective monoelectrolyte and the tentative effects of PEL molecular weight, ambient ionic strength, and titration concept (FT-IR and POT) are discussed based on classical models of weak PEL.

Enhancement of Fe-Nb interaction by acid modification over SO42--FeOx-Nb2O5 catalyst for NH3 selective catalytic reduction of NOx

A series of iron-based composite oxide catalysts, modified with acid and niobium, were produced for the purpose of selective catalytic reduction of NOx with NH3 (NH3-SCR) via co-precipitation. The obtained SO42--FeOx-Nb2O5 (S-FeNbOx) catalyst exhibited significantly better SCR performance than the unmodified FeOx catalyst, with a NOx conversion above 90% and N2 selectivity higher than 95% in the temperature range of 275–450 °C. The characterization results suggest that the addition of Nb not only modifies the electronic structure and alleviates the reducibility but also enhances the surface acidity of the catalysts. The sulfuric acid modification of FeOx-Nb2O5 catalyst promotes the formation of redox-acid sites. The in situ Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFTs) results revealed that the combining sulfuric acid and niobium modifications resulted in a significant increase in the amount of Brønsted acid sites, and also led to a blue shift of the band related to the Lewis acid sites, implying the existence of a synergistic effect of the two modification methods. The creation of redox-acid sites significantly enhances the adsorption and activation capacity of NH3 on the catalyst surface. These results suggest that the NH3-SCR reaction to primarily follow the Eley-Rideal (E-R) mechanism on the catalyst.

UV Light Causes Structural Changes in Microplastics Exposed in Bio-Solids.

Bio-solids (biological sludge) from wastewater treatment plants are a significant source of the emission of microplastics (MPs) into the environment. Weakening the structure of MPs before they enter the environment may accelerate their degradation and reduce the environmental exposure time. Therefore, we studied the effect of UV-A and UV-C, applied at 70 °C, on three types of MPs, polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), that are commonly found in sewage sludge, using three shapes (fibers, lines, granules). The MPs were exposed to UV radiation in bio-solid suspensions, and to air and water as control. The structural changes in and degradation of the MPs were investigated using Attenuated Total Reflectance-Fourier Transform Infrared Spectrometry (ATR-FTIR) and surface morphology was performed with SEM analysis. UV exposure led to the emergence of carbonyl and hydroxyl groups in all of the PP samples. In PE and PET, these groups were formed only in the bio-solid suspensions. The presence of carbonyl and hydroxyl groups increased with an increasing exposure time. Overall, UV radiation had the greatest impact on the MPs in the bio-solids suspension. Due to the surface-to-volume ratio of the tested samples, which influences the degradation rate, the fibers were more degraded than the other two plastic shapes. UV-A was slightly more effective at degrading the MPs than UV-C. These findings show that ultraviolet radiation in combination with an elevated temperature affects the structure of polymers in wastewater bio-solids, which can accelerate their degradation.

Utilizing Drug Amorphous Solid Dispersions for the Preparation of Dronedarone per os Formulations

Dronedarone (DRN), an antiarrhythmic drug, exhibits potent pharmacological effects in the management of cardiac arrhythmias. Despite its therapeutic potential, DRN faces formulation challenges due to its low aqueous solubility. Hence, the present study is dedicated to the examination of amorphous solid dispersions (ASDs) as a strategic approach for enhancing the solubility of DRN. Initially, the glass forming ability (GFA) of API was assessed alongside its thermal degradation profile, and it was revealed that DRN is a stable glass former (GFA III compound) that remains thermally stable up to approximately 200 °C. Subsequently, five commonly used ASD matrix/carriers, i.e., hydroxypropyl methylcellulose (HPMC), povidone (PVP), copovidone (PVP/VA), Soluplus® (SOL), and Eudragit® E PO (EPO), were screened for the formation of a DRN-based ASD using film casting and solvent shift methods, along with miscibility evaluation measurements. SOL proved to be the most promising matrix/carrier among the others, and, hence, was used to prepare DRN ASDs via the melt-quench method. The physicochemical characterization of the prepared systems (via pXRD) revealed the complete amorphization of the API within the matrix/carrier, while the system was physically stable for at least three months after its preparation. In vitro release studies for the ASDs, conducted under non-sink conditions, revealed the sustained supersaturation of the drug for at least 8 h. Finally, the use of attenuated total reflectance (ATR) FTIR spectroscopy showed the formation of a strong molecular interaction between the drug molecules and SOL.

Lattice-Strained Metallic Aerogels as Efficient and Anti-Poisoning Electrocatalysts for Oxygen Reduction Reaction.

Lattice strain engineering optimizes the interaction between the catalytic surface and adsorbed molecules. This is done by adjusting the electron and geometric structure of the metal site to achieve high electrochemical performance, but, to date, it has been rarely reported on anti-poisoned oxygen reduction reaction (ORR). Herein, lattice-strained Pd@PdBiCo quasi core-shell metallic aerogels (MAs) were designed by "one-pot and two-step" method for anti-poisoned ORR. Pd@PdBiCo MAs/C maintain their original activity (1.034 A mgPd -1 ) in electrolytes with CH3 OH and CO at 0.85 V vs. reversible hydrogen electrode (RHE), outperforming the commercial Pd/C (0.156 A mgPd -1 ), Pd MAs/C (0.351 A mgPd -1 ), and PdBiCo MAs/C (0.227 A mgPd -1 ). Moreover, Pd@PdBiCo MAs/C also show high stability and anti-poisoning with negligible activity decay after 8000 cycles in 0.1 m KOH+0.3 m CH3 OH. These results of X-ray photoelectron spectroscopy, CO stripping, and diffuses reflectance FTIR spectroscopy reveal that the tensile strain and strong interaction between different elements of Pd@PdBiCo MAs/C effectively optimize the electronic structure to promote O2 adsorption and activation, while suppressing CH3 OH oxidation and CO adsorption, leading to high ORR activity and anti-poisoning property. This work inspires the rational design of MAs in fuel cells and beyond.

Heterogeneous reactivity of soybean/palm biodiesel soot with NO2 and CF3COOH in a Knudsen reactor and DRIFTS/TGA/SEM characterization of the soot

The characteristics and atmospheric reactivity of soot generated from an alternative fuel (soybean/palm biodiesel) have been investigated for the first time using a Knudsen flow reactor with a mass spectrometer as detector for gaseous species. The heterogeneous reactions with nitrogen dioxide (NO2) and trifluoroacetic acid (CF3COOH, TFA) have been investigated. Uptake coefficients calculated for the reaction of NO2 (γ0= (3.85 ± 0.70) ∙10–3) are one order of magnitude higher than the corresponding TFA reactions (γ 0= (6.06 ± 0.24) ∙10–4). NO is the only product observed in the gas phase. Knudsen cell reactor has also been used in the characterization of chemical functions on the surface since NO2 can be used to identify reducing groups, while TFA is used to evaluate basic sites. Compared to other soot samples, biodiesel soot shows higher reactivity with NO2 which has implications in the regeneration process of the diesel particulate filter (DPF). IR bands attributable to polycyclic aromatic compounds have been observed by Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFTs). Bands of carbonyl compounds are also clearly observed. Thermogravimetric analysis/ differential scanning calorimetry-mass spectrometry (TGA/DSC-MS) is used to obtain more information about the volatile organic compounds present on the soot surface. Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) analysis indicates a particle size in the range 14–40 nm and carbon as the major element (92 %). According to the obtained results, a mechanism of processes occurring at the surface has been proposed.

Insights into the Sensing Mechanism of a Metal-Oxide Solid Solution via Operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy.

Recently, the influence of Nb addition in the oxide solid solution of Sn and Ti was investigated with regard to the morphological, structural and electrical properties for the production of chemoresistive gas sensors. (Sn,Ti,Nb)xO2-based sensors showed promising features for ethanol monitoring in commercial or industrial settings characterized by frequent variation in relative humidity. Indeed, the three-metal solid solution highlighted a higher response level vs. ethanol than the most widely used SnO2 and a remarkably low effect of relative humidity on the film resistance. Nevertheless, lack of knowledge still persists on the mechanisms of gas reaction occurring at the surface of these nanostructures. In this work, operando Diffuse Reflectance Infrared Fourier Transform spectroscopy was used on SnO2- and on (Sn,Ti,Nb)xO2-based sensors to combine the investigations on the transduction function, i.e., the read-out of the device activity, with the investigations on the receptor function, i.e., compositional characterization of the active sensing element in real time and under operating conditions. The sensors performance was explained by probing the interaction of H2O and ethanol molecules with the material surface sites. This information is fundamental for fine-tuning of material characteristics for any specific gas sensing applications.

Infrared Spectroscopy Study of Edge Water Penetration at Hydrophilic Bonding Interface

In this article, we report on the use of a new characterization technique to measure the water penetration at the bonding interfaces and to quantify it. This complements previous studies done using X-ray reflectometry and surface acoustic microscopy: Fourier Transform Infra-Red Multiple Internal Reflection (FTIR-MIR) spectroscopy is used here to characterize the evolutions of contributions of silanols, surface bonded water and free liquid water groups.

Novel porous ambient temperature cured fly ash geopolymer for lead adsorption from wastewaters

ABSTRACT This paper discusses the ability of the fly ash (FA) and abmbient cured Alkali activated Fly ash geopolymer (FAAG) for sequestering Pb (II) ions from aqueous solution. Various physiochemical properties such as the influence of pH and contact time were investigated for achieving the conditions for maximum removal via batch mode using powdered samples. The adsorbents were characterized by employing powder X-Ray diffraction, Attenuated Total Reflection Fourier Transform Infra-Red spectroscopy, and Scanning Electron Microscopy/EDAX before and after the treatment. The adsorption capacity of Pb2+ ions by raw FA and FAAG were examined by the Inductively coupled plasma mass spectrometry (ICP-MS). The results represented that the maximum adsorption capacity of Pb2+ ions by FAAG is 75 mg/g with attained equilibrium time of 120 min whereas raw fly ash at 150 min at 21.5 mg/g capacity. The pozzolanic reactivity of fly ash in water glass hardening resulted mainly N-A-S-H gel and traces of lead silicate due to the immobilization of lead in the network. This was conformed from the binding energy lines at 139.7 eV in XPS survey lines and lead silicate at 25 and 34° 2θ as identified in XRD phase assemblages. ICP-MS test results of leachate of lead immobilized geopolymer sample are devoid of lead ions and thus sorption sites of fly ash geopolymer lead to potential safety disposal of lead. Thus, recycling of fly ash into geopolymer by less energy intensive process and subsequent use in heavy metal disposal could achieve the concept of disposal waste and recycling, which could contribute to achieve the sustainable goals.

Calcium oxide nanoparticles: Biosynthesis, characterization and photocatalytic activity for application in yellow tartrazine dye removal

Dyes are substances that have a high polluting potential, due to their low biodegradability and chemical stability, causing serious environmental damage when disposed of incorrectly. Yellow tartrazine (YT) dye as an environmental liability requires attention, since it causes toxic effects in fish (Danio rerio) with a potential allergic effect in humans. In this context, the present study aims to synthesize and characterize calcium oxide nanoparticles (CaO-NPs) to evaluate the photocatalytic activity for the YT photodegradation under visible irradiation. CaO-NPs were synthesized by the biosynthesis method from golden linseed (Linum usitatissimum L.) extract. Central Composite Rotational Design (CCRD 23) was used to determine the ideal condition for the photocatalytic tests. X-ray diffraction (XRD), zeta potential (ZP), physical adsorption of N2, zero charge point (pHzcp), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy by Energy Dispersive Spectroscopy (SEM-EDS), Diffuse Reflectance Spectroscopy (DRS) and Field Emission Gun – Scanning Electron Microscope (FEG-SEM) were used to the CaO-NPs characterization. Thus, CaO-NPs presented SBET = 14±0.02 m2g−1, Dp = 20.9±0.02 nm and Vp = 0.054±0.004 cm3g−1, characteristic of a mesoporous material. ATR-FTIR spectrum showed characteristic stretches of specific functional groups (–CH, –CO, C = C, Ca-O, –OH) from plant extract and metallic precursor. CaO-NPs showed pHZCP equal to 7.74, positive surface charge (+12.7 mV) and bang gap energy of 2.61 eV. FEG-SEM micrographs showed that has a small agglomeration with defined morphology, but with irregular particle size (around 48 nm), and SEM-EDS micrographs showed an elemental composition (in weight) of the 50.24% oxygen, 3.32% magnesium, 2.29% iron, 10.44% calcium, 14.07% silicon, 3.33% aluminum and 0.63% potassium. Regarding CCRD 23, the ideal condition was the pH = 7.0, [CaO-NPs] = 1.2 g/L and [YT] = 20 mg/L, with 76.2% of photodegradation and a pseudo first-order reaction specific reaction rate k = 0.089 min−1. After V cycles of CaO-NPs recycling, there was a decrease of around 22.83%, indicating a saturation of the active sites available in the nanocatalyst Therefore, CaO-NPs showed potential application for TY photodegradation to be used in wastewater treatment being an alternative nanocatalyst, meeting nanotechnology and sustainable development.