Reflectance Fourier Transform Infrared Spectroscopy Research Articles

Ga-Modification Near-Surface Composition of Pt-Ga/C Catalyst Facilitates High-Efficiency Electrochemical Ethanol Oxidation through a C2 Intermediate.

In electrochemical ethanol oxidation reactions (EOR) catalyzed by Pt metal nanoparticles through a C2 route, the dissociation of the C-C bond in the ethanol molecule can be a limiting factor. Complete EOR processes producing CO2 were always exemplified by the oxidative dehydrogenation of C1 intermediates, a reaction route with less energy utilization efficiency. Here, we report a Pt3Ga/C electrocatalyst with a uniform distribution of Ga over the nanoparticle surface for EOR that produces CO2 at medium potentials (>0.3 V vs SCE) efficiently through direct and sustainable oxidation of C2 intermediate species, i.e., acetaldehyde. We demonstrate the excellent performance of the Pt3Ga-200/C catalyst by using electrochemical in situ Fourier transform infrared reflection spectroscopy (FTIR) and an isotopic labeling method. The atomic interval structure between Pt and Ga makes the surface of nanoparticles nonensembled, avoiding the formation of poisonous *CHx and *CO species via bridge-type adsorption of ethanol molecules. Meanwhile, the electron redistribution from Ga to Pt diminishes the *O/*OH adsorption and CO poisoning on Pt atoms, exposing more available sites for interaction with the C2 intermediates. Furthermore, the dissociation of H2O into *OH is facilitated by the high hydrophilicity of Ga, which is supported by DFT calculations, promoting the deep oxidation of C2 intermediates. Our work represents an extremely rare EOR process that produces CO2 without observing kinetic limitations under medium potential conditions.

Potential biomarkers for southern African hunter-gatherer arrow poisons applied to ethno-historical and archaeological samples

The detection of complex poison recipes applied to ancient hunting weapons has the potential to provide important insights into traditional pharmacological knowledge systems. Yet, recipes comprising many ingredients can be challenging to decipher, especially in older samples that have undergone biodegradation. We present the results of our attempt to analyze samples of poison collected from nineteenth and twentieth century arrowheads from southern Africa, and from a 1000-year-old archaeological bone point. The arrow poison residues and reference samples were analyzed by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR FTIR) and Gas Chromatography Mass Spectrometry (GC–MS). The ATR FTIR analysis is primarily able to separate between different arrow poison binder recipes. The extractives identified by GC–MS analysis consist of a multitude of components from both binders and active substances, confirming and adding to the results from the ATR FTIR analyses. We discuss the results in terms of potential biomarkers for arrow poisons in organic residue analyses of archaeological artefacts; that residues of toxic cardiotonic glycosides can be detected on curated and excavated arrow tips of between about 1000 and 100 years old, serves as proof of concept for working with older materials in the future.

A biocompatible lipid-based bigel for topical applications

The development of biocompatible delivery systems is a necessity for medical and topical applications. Herein, the development of a new bigel for topical application is described. It is composed of 40% colloidal lipid hydrogel and 60% olive oil and beeswax oleogel. Its characterization and the potential of the bigel as a drug carrier through the skin was evaluated in vitro using fluorescence microscopy and two phases of the bigel were labeled with two fluorescent probes: sodium fluorescein (hydrophilic phase) and Nile red (lipophilic phase). The structure of the bigel showed two phases with fluorescence microscopy in which the hydrogel phase was incorporated into a continuous oleogel matrix. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) presented a combination of vibrations characteristic of the different molecules forming the bigel, and Differential Scanning Calorimetry (DSC) showed different transitions attributed to beeswax lipids. Small-angle and wide-angle X-ray scattering (SAXS and WAXS) indicated a predominant lamellar structure with orthorhombic lateral packing that could be related to the arrangement of beeswax crystals. Bigel enables deeper penetration of hydrophilic and lipophilic probes into deeper layers, making it a promising candidate for effective topical carriers in medical and dermatological applications.

Enhancement of Hydrodearomatization Catalyst by Brönsted Acid Site of Al2O3 Support for Clean Diesel Production

Exhaust from diesel engine contributes a main part in both PM10 and PM2.5 problem. Polycyclic aromatic hydrocarbons (PAHs) in diesel fuel should be considered because of their toxicity. Worldwide Fuel Charter recommends the PAHs content less than 2 wt.% in diesel fuel for less toxic of diesel exhaust emission. Nickle Molybdenum Sulfide over Gamma alumina (NiMoS/γ-Al2O3) catalyst is generally used in hydrotreating processes of petroleum refinery. PAHs are saturated by hydrogenation reaction (HYD) to be mono-aromatic or non-aromatic, called Hydrodearomatization (HDA) process. However, NiMoS/γ-Al2O3 catalysts still require improvements of HYD activities. Gamma alumina has been widely used as catalyst support, which generally possesses only Lewis acidity. This work focuses on surface modification of γ-Al2O3 by ammonium fluoride to generate Brönsted acidity, which could improve HYD function of NiMoS catalysts. All γ-Al2O3 supports were characterized by In-situ pyridine adsorption Diffuse Reflectance Infrared Fourier Transform spectroscopy (Pyridine-DRIFT). Increment of fluorine content in the modified γ-Al2O3 leads to increase its Brönsted acidity. The NiMoS over modified γ-Al2O3 exhibits higher HYD activities than that of the γ-Al2O3. Generation of Brönsted acidity on ϒ-Al2O3 support can enhance the HYD function of NiMoS catalyst for HDA process of clean diesel production.

Ohmic-functionalized type I heterojunction: Improved alkaline water splitting and photocatalytic conversion from CO2 to C2H2

A hollow dodecahedron-shaped N-doped carbon (N-C) coated with CoSe2 nanoparticles are fabricated via MOF-derived self-sacrificing strategy based on Kirkendall Effect. By coupling with CdS nanodots, the optimal Ohmic-type functionalized type I heterojunction CdS/N-C/CoSe2 (CCE50) exhibits a significant photocatalytic hydrogen evolution reaction (PHER) rate of 19317.3 μmol h−1 gcat−1 that is 15.7 and 33.7 folds higher than type I CdS/N-C heterojunction (1230.3 μmol h−1 gcat−1) and pure CdS respectively, and successfully transfers the source of photo-corrosion to obtain stable PHER for 5 cycles. Moreover, the CCE50 in alkaline media (pH = 12) achieves a 1.6-fold PHER rate higher than that in the original triethanolamine (TEOA) aqueous solution (pH≈8), where electron paramagnetic resonance (EPR) result shows that it is attributed to the accumulation of O2–. The effective PHER rate can be attributed to the synergistic effect of higher light absorption in hollow CCE50 with multiple scattering and the introduction of Ohmic contact. Besides, the successful conversion from CO2 to C2H2 under 80 kPa CO2 pressure is detected firstly on CdS-based photocatalyst (the conversion rate is 2.8 μmol h−1 gcat−1) without other C1 or C2 gas products. EPR, in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) tests, Kelvin Probe Force Microscopy (KPFM) and density functional theory calculations, etc. have illustrated and verified the photocatalytic mechanism for Ohmic contact-enhancing type I heterojunction, which promotes hydrogen production in alkaline media and C2H2 generation from CO2.

Combined effects of high hydrostatic pressure and chemical pre‐treatment on physico‐chemical properties of beef, using FTIR and diffuse reflectance spectroscopy

AbstractHigh pressure processing (HPP) was combined with a previous short chemical treatment to stabilize the color of beef tissue. Beef samples were treated with a solution containing ascorbic acid, sodium chloride, and a very low concentration of sodium nitrite. The effects of pressure levels (0.1–600 MPa) and preservative solution on: (i) color properties based on diffuse reflectance spectroscopy (DRS), which determines the relative concentrations of muscle pigments, (ii) protein denaturation and changes in the secondary structures by DSC and FTIR‐ATR, were determined.At high pressures, the disappearance of DSC peaks due to protein denaturation, a decrease in the proportion of α‐helix and an increase in the percentage of disordered structures, were evidenced. DRS spectra and Kublelka‐Munk theory equations demonstrated that nitrosilmyoglobin was a more stable chromophore, decreasing discoloration of the tissue. These techniques contribute to the knowledge of the physico‐chemical properties of the tissue submitted to combined preservation processes.Practical ApplicationsThere is an increasing demand from consumers for high‐quality beef products, with significant emphasis placed on color and safety attributes. Extending the shelf life by applying high hydrostatic pressure treatment (HHP) improves food safety and will produce a positive impact on both the industry and consumers. HHP is a non‐thermal preservation technology with generally minimal effects on sensory qualities and nutritional content; however, the direct application of this technology on beef leads to the production of a product with an unacceptable pale coloration. Therefore, it must be remarked that a pre‐treatment stage by immersing the pieces in a preservative solution is essential to improve the color of beef products treated by HHP. In this regard, from a technological point of view, it is very important to know the combined effects of both stages (short chemical treatment and high‐pressure) on the quality of beef products.

Effect of titanium oxide nanoparticles on polymerization reaction of heat and microwave cured polymethylmethacrylate: in vitro study

BackgroundTitanium Oxide Nanoparticles (TiO2NPs) have been introduced to polymethyl methacrylate (PMMA) denture base to enhance its mechanical, physical, and biological performance.ObjectivesThis research aimed to assess the effect of adding TiO2NPs on the degree of polymerization and morphological characterization of heat and microwave cured PMMA.Materials and methodsFabrication of PMMA specimens which were categorized according to the curing technique into heat cured (group I) and microwave cured (group II). Each group was subdivided into two subgroups A and B according to the addition of TiO2NPs. A total number of 24 specimens were fabricated. Each subgroup contains 6 specimens. The specimens were characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDX). The polymerization reaction of specimens was assessed by Attenuated Total Reflection Fourier-Transform Infra-Red Spectroscopy (ATR-FTIR). Results were statistically analyzed using an independent T-test and one-way ANOVA. The significance level was set at p < 0.05.ResultsSEM/EDX revealed that TiO2 NPs appeared as bright areas in the matrix of both groups. The matrix showed organic impurities and minute internal cracks, but group IIB (microwave-cured PMMA with TiO2NPs) showed higher organic impurities than heat-cured PMMA. The FTIR revealed that the addition of 3% by weight TiO2NPs decreased the degree of polymerization of both heat and microwave-cured PMMA but the decrease was insignificant (p > 0.05).ConclusionsIncorporation of 3% by weight TiO2NPs does not significantly affect the degree of polymerization of both heat and microwave-cured PMMA. Hence, denture materials can benefit from the advantages of the TiO2NPs without any alterations to their structures.Graphical abstract

INFRA-ART: An Open Access Spectral Library of Art-related Materials as a Digital Support Tool for Cultural Heritage Science

Easily accessible characterization techniques such as X-ray fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), or Raman spectroscopy, are at this moment the most commonly used analytical tools in heritage and conservation science. Materials identification in works of art is a fundamental step for understanding an object's history or an artist's technique. Comprehensive characterization and diagnosis of the various constituent materials in artworks can provide valuable information on the artist's working methods, as well as significant evidence for dating, provenance attribution, or forgery detection. The development of databases with high-quality data on the pure substances used as artists’ materials is of utmost importance for the identification and characterization of unknown samples. However, there are relatively few open access spectra libraries dedicated exclusively to the cultural heritage field. To address this need, within the frame of the postdoctoral project INFRA-ART, an open access spectral library of art-related materials has been developed. The database is an ongoing compilation of spectra that contains at this moment over 1,000 high-quality attenuated total reflection–FTIR, Raman, and XRF spectra associated with over 500 known reference materials. In this article, a summary of the database structure and design, functionality, and use is presented, in view of the dissemination of this new open access spectral library to the scientific community.

Catalytic upgrading of bio-oil model mixtures in the presence of microporous HZSM-5 and γ-Al2O3 based Ni, Ta and Zr catalysts

Bio-fuel production from bio-oil was investigated in the presence of microporous HZSM-5 and Al2O3 (MA) based catalysts. This study focused on the catalytic upgrading of a model bio-oil compound with ethanol for bio-fuel production. The model compound containing hydroxypropanol/furfural/formic acid: 4/6.5/5 by volume was used as a bio-oil mixture. Activity tests were performed under atmospheric pressure with a volumetric feed ratio of 30/70 bio-oil mixture/ethanol using a 0.5 g catalyst. In the reaction studies performed on the commercial microporous HZSM-5 catalyst, the optimum co-cracking temperature was determined as 400 °C. Mesoporous γ-Al2O3 support was synthesized by the evaporation-induced self-assembly (EISA) synthesis method, and Ni, Ta, and Zr metals were incorporated into the structure of the catalyst by the impregnation method to improve the surface acidity. The synthesized catalysts were characterized by X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), N2 adsorption–desorption, scanning electron microscopy energy dispersive spectroscopy (SEM/EDS), X-ray fluorescence (XRF), Fourier-transformed infrared spectroscopy (FTIR), pyridine adsorbed diffuse reflectance FTIR spectroscopy (DRIFTS), and thermogravimetric/differential thermal analysis (TGA-DTA). Monometallic and pure alumina catalysts indicated an ordered mesoporous structure with surface area values 106–389 m2/g. Lewis and Brønsted acid sites associated with mild acidity were observed in the DRIFTS results of the 10 wt% Zr-containing alumina catalyst (10Zr@MA). The highest oil phase selectivity and isoparaffin selectivity in oil phase values were obtained in the presence of 10Zr@MA as 17.22% and 80.96%, respectively. 10Zr@MA catalyst showed the best catalytic activity compared to other catalysts, with 9.54% coke formation.

Carotenoids contribution in rapid diagnosis of multiple sclerosis by Raman spectroscopy

Rapid and accurate diagnosis of any illness determines the success of treatment. The same applies to multiple sclerosis (MS), chronic, inflammatory, and neurodegenerative diseases (ND) of the central nervous system (CNS). Unfortunately, the definitive diagnosis of MS is prolonged and involves mainly clinical symptoms observation and magnetic resonance imaging (MRI) of the CNS. However, as we previously reported, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy shed new light on the minimally invasive, label-free, and rapid diagnosis of this illness through blood fraction. Herein we introduce Raman spectroscopy coupled with chemometric analysis to provide more detailed information about the biochemical changes behind MS. This pilot study demonstrates that mentioned combination may provide a new diagnostic biomarker and bring closer to rapid MS diagnosis. It has been shown that Raman spectroscopy provides lipid and carotenoid molecules as useful biomarkers which may be applied for both diagnosis and treatment monitoring.

Application of Acid Protease for Eco-friendly Pre-treatment of Goat Skin to Improve Antimicrobial Finish Using Herbal Natural Extracts

Due to its moisture retention capacity and huge surface area, leather is highly prone to microbial proliferation and biodeterioration; hence, leather products desired have an antimicrobial finish. In this study, acid protease enzyme pre-treatment of goat skin was utilized as an eco-friendly substitute for conventional wet-chemical processing. The treatment can impart the desired surface properties to improve the antimicrobial finish with natural extracts obtained from leaves of Azadirachta indica (Neem Tree), Ocimum sanctum (Holy Basil, Tulsi), and Camellia sinensis (Green Tea). The procedure was optimized for different process parameters, including enzyme concentration, pH, material to liquor ratio (MLR), treatment time, and temperature. The effect of the treatment on bulk and surface properties of the skin was characterized by weight loss analysis, X-Ray Diffraction (XRD), Thermal Gravimetric Analysis (TGA), and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Photoelectron Spectroscopy (XPS), Water contact angle measurement, Scanning Electron Microscopy (SEM) respectively. The effect of the enzymatic treatment on organoleptic properties and the mechanical strength of the skin was also studied. The enzymatic treatment resulted in weight loss, and removal of non-collagen components, thus opening the fibrous collagen matrix of the skin. Hence, the skin treated with acid protease enzyme provides better affinity and accessibility for phytoactive compounds from the natural extracts and better attachment by electrostatic attachment due to an increase in surface functional groups after the enzymatic treatment compared to untreated skin. The effectiveness of the antimicrobial finish was measured as a zone of inhibition and with a modified Hohenstein test against test microorganisms E. coli and S. aureus.Azadirachta indica (Neem Tree) extract showed the highest inhibitory activity (97%) against E. coli, while the Ocimum sanctum (Holy Basil, Tulsi) extract exhibited the highest inhibitory activity (95%) against S. aureus.

Kinetic studies on photo-degradation of thermally-treated spruce wood during natural weathering: Surface performance, lignin and cellulose crystallinity

The hygroscopic behavior of wood-based materials is undoubtedly influential on the material surfaces exposed to climatic conditions. The paper aims to kinetically investigate the photo-degradation and surface characteristics of thermally-treated spruce wood at 185 °C and un-treated (reference) sample through 2 years of natural weathering. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and X-ray diffraction (XRD) were employed to investigate the chemical changes occurred in lignin and crystalline structure of cellulose as a function of outdoor exposure. Detailed measurements of morphological and surface changes were evaluated during exposing periods. Surface wettability and roughness as well as cracks were increased for all samples due to weathering as the exposure time extended. Prominently, the color changes (ΔE) and photo-chemical reactions were found to be negligible in short-time weathering thanks to thermal modification. In the long–term exposing, more OH-bonds caused by lignin leaching out resulted in presence of cracks and the affinity for water on reference sample. Degree of crystallinity significantly decreased by 12.7% in thermally treated wood and 18.3% in reference sample after long-term weathering while, the crystallinity index of thermally-treated wood increased to 4.7% in 6-month weathering. Hence, the amorphous structures and chromophores groups appeared on the reference wood at a faster and more intense rate during exposing time. Thermal treatment delayed photo-yellowing as well as color change of wood due to up-graded lignin and cellulose crystallinity through a photo-stable structure. Accordingly, kinetic studies ascertained the service-time of wood products in exterior uses.

HCHO Sensing Mechanism of In4Sn3O12 Revealed by DRIFTS and DFT

The combination of operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy measurement and Density Functional Theory calculation reveals the counterintuitive HCHO sensing mechanism of In4Sn3O12. It is merely partial oxidation of HCHO into formate (or HCOOH) with medium activation energy (0.43–0.68 eV) and sufficient electron donation effect that is responsible for the sensor signal at the optimum temperature of 200 °C. The Sn (3a)-connected O is the active site and plays key roles in both HCHO adsorption and partial oxidation.

Sensing mechanisms of CO and H2 with NiO material – DRIFTS investigations

The response of nickel oxide gas sensors towards CO and H2 and the underlying gas sensing mechanisms were investigated with special focus on the influence of ambient humidity interference. Surface reactions were tracked by using diffuse reflectance infrared Fourier transformation spectroscopy with simultaneous resistance measurements. The sensor response to both gases is barely influenced by the background humidity. Spectroscopic results reveal that the underlying processes at the surface are almost identical for CO and H2 reception and similar to the effect of the removal of oxygen. Accordingly, the detection of the analytes is based purely on the reduction and oxidation of the oxide material instead of the formation of analyte specific surface species.

3D printed solid phase microextraction scaffolds as novel tool for sample preparation; application in antifungal drugs analysis

3D printed solid phase microextraction scaffolds as a novel sorbent were introduced for the extraction of antifungal drugs in wastewater and human plasma prior to their determination by HPLC-UV. The designed adsorbent was prepared as cubic scaffolds using fused deposition modeling (FDM) 3D printer and Polylactic acid (PLA) filament. Scaffold surface was chemically modified using alkaline ammonia solution (Alkali treatment). The application of this new design in the extraction of three antifungal drugs ketoconazole, clotrimazole and miconazole was investigated. Alkali surface modification time was optimized (0.5-5hr) and 4hr selected as the best-modification time. Morphology of the modified surface and its chemical changes were studied using Field Emission Scanning Electron Microscope (FE-SEM) and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), respectively. Surface wettability of scaffolds was measured by Water Contact Angel (WCA) and the porosity created in the scaffolds was studied by N2 adsorption/desorption studies analysis. Analytical performance of the method, under optimum conditions (extraction time: 25 min, desorption solvent: methanol, volume of desorption solvent: 2 mL, desorption time: 10 min, solution pH: 8, solution temperature: 40 °C, salt concentration: 3 mol L−1) were obtained as 3.10 and 10.0 µg L−1 for LOD and LOQ, respectively. The calibration graphs were linear in the range of 10–150 µg L−1 and 10-100 µg L−1 for wastewater and plasma, respectively.

Study of metal and organic contaminants transported by microplastics in the Lebanese coastal environment using ICP MS, GC-MS, and LC-MS

An untargeted study of multiclass contaminants associated with microplastics (MPs) in the East Mediterranean was carried out. Samples were collected in 2020–2021 from the shoreline at 14 different locations, along the Lebanese coast. Attenuated Total Reflectance (ATR) FTIR spectroscopy showed the predominant presence of polyethylene and polypropylene among plastic debris. The non-polar and polar organic compounds sorbed on the MPs were identified and quantified by GC - TOF MS and LC – electrospray MS/MS, respectively. Deconvolution of accurate GC–MS scan data allowed the identification of >130 organic pollutants, 64 of which could be confirmed by matching with the authentic standards, among which a number of previously unreported in targeted GC–MS(MS) methods. In addition to highly toxic, legacy chlorinated pollutants, high levels (average values from 0.8 to 4.0 μg g−1) of some musks, UV filters and UV absorbers were detected. Untargeted LC-MS demonstrated the persistence of several pesticides (i.e., chlorpyrifos) and pharmaceuticals, such as phenacetin and minoxidil, which were quantified. In addition, a study of metals associated with microplastics using ICP-MS confirmed the high potential of microplastics to act as a vector of, among others, toxic metals, such as Cd, Pb, Bi or Hg.

Effective Malachite Green Degradation over the Noble Metal-Doped and MOF-Coupled CsSnBr3 Nanocomposite Catalyst

Environmental protection laws require effective and green solutions to tackle water and air pollution issues. For this purpose, perovskite photocatalytic materials have proven to be a promising solution. In this study, CsSnBr3 perovskite, coupled with ZIF-67 and decorated with noble metal Au, was shown to effectively enhance the charge separation and increase the light-absorbing capacity, and thus make the photocatalytic reaction more efficient by surface plasmon resonance. Characterization results from XRD, FTIR, and UV-visible diffuse reflectance spectroscopy indicated that a mixture of cubic and tetragonal crystalline phases was found in the prepared catalyst material. XPS also revealed that in the presence of two oxidation states for tin (Sn), the Au 4f XPS peaks of Au NPs coincided with those retained in colloidal Au particles. Using malachite green as a model compound, organic pollutant photocatalytic degradation tests proved that CsSnBr3 generated good photocatalytic activity for aromatic pollutant degradation. In this research, the synthesized 4Au-7ZIF-CsSnBr3 catalyst yielded an MG degradation rate twice as high as the unpromoted CsPbBr3.

Evaluation of enzymatic stamp removal strategies on handmade (cellulose-based) and machine-made (lignin-containing) papers

Two different biocleaning techniques for stamp removal from different paper samples (handmade and machine-made) were investigated. Cellulose is the main component of handmade paper, while higher concentration of lignin is present in machine-made paper. Biocleaning methods included the direct application on paper surfaces of the extracellular enzymatic mixture (EEM) extracted from the yeast Sporidiobolus metaroseus and the recombinant protein CthediskatG of Chaetomium thermophilum var. dissitum. The produced microbial enzymes (EEM or CthediskatG) were also combined with agarose hydrogels. The effectiveness of the cleaning ability of the individual methods was determined using different spectrophotometer measurements based on colorimetric analysis and by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR). Some tested samples were also subjected to microstructural and chemical analysis using Scanning Electron Microscope-Energy-Dispersive X-ray spectroscopy (SEM-EDX). The analysis showed that the EEM-based approaches were the most suitable, mainly they are less time-consuming and easy to produce, and moreover slight differences were displayed between EEM and CthediskatG during the removal of the stamp by hydrogel-enzyme approaches. Both EEM applications (direct and hydrogel) speed up the stamp removal process from real paper samples. However, for the complete elimination of the stamp smears a quick N,N-dimethylformamide post-treatment is advised too.

Low-temperature catalytic performance of toluene oxidation over Cu-Mn oxide catalysts derived from LDH precursor

A series of CuMn mixed oxides catalysts (CMO-T) were prepared by calcination of CuMn layered double hydroxides (CuMn-LDH) for catalytic oxidation of toluene. The obtained CMO-400 catalyst exhibited a high catalytic activity with T50 and T90 of 210 and 231 °C (WHSV = 30000 mL·g−1·h−1). Meanwhile, the CMO-400 exhibited high stability and durability even at 20 vol% water vapor. The effects of calcination temperature on the texture and structural properties were investigated systematically, which proved the formation of copper-manganese solid solution with abundant multiple-phase interfaces. In addition, the strong interaction between Cu and Mn could lead to more surface adsorbed oxygen due to oxidation reduction cycle of Mn3++Cu2+=Mn4++Cu+. Accordingly, for CMO-500 catalyst, the formation of spinel Cu1.5Mn1.5O4 phase prevented good dispersion of the manganese-oxide phases and weakened the reducibility and oxygen mobility. In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) revealed that the intermediates accumulated continuously were difficult to be oxidized rapidly without the replenishment gaseous oxygen. Moreover, the complete transformation of the intermediate benzoate may be the key rate-controlling step in the reaction. The Facile method of preparing mixed-metal solid solution from LDH precursor system could be widely developed for the design of transition metals in catalytic oxidation of toluene.

Reaction mechanism of NO and SO2 Co-removal by calcium hydroxide

Flue Gas simultaneous Desulfurization and Denitrification (FGDD) is expected to become a new generation of low-cost technology to achieve ultra-low emissions especially in smelting kilns and industrial boilers. The fixed bed system and in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) were used to clarify the reaction mechanism of NO and SO2 co-removal by calcium hydroxide absorbent. The hydroxyl radical on the surface of calcium hydroxide was identified by Protium Nuclear Magnetic Resonance (1H NMR) and radical scavenger 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO). With synergistic effect of hydroxyl radical and oxygen, NO and SO2 are oxidized to NO2 and SO3 respectively, and then absorbed as nitrate and sulfate, according to the three-step chain reactions: SO2 +HO* →HOSO2 *, HOSO2 * +O2→SO3 +HO2 * and HO2 * +NO→HO* +NO2. The key point is the recycling of hydroxyl radical.