•Asphalt binders modified with WTR and APAO were aged in TFOT and PAV process.•WTR/APAO modified asphalt has higher resistance to aging.•WTR/APAO modified asphalt behaves better resistance to ...permanent deformation.•WTR/APAO complex modification helps increase the resistance to fatigue cracking.•APAO strengthened the network in WTR modified asphalt.
Amorphous poly alpha olefin (APAO) was added into the waste tire rubber (WTR) modified asphalt and its effects on aging properties of WTR modified asphalt were investigated. Thin Film Oven Test (TFOT) and Pressure aging vessel (PAV) test were conducted to simulate the short-term and long-term aging respectively. Conventional properties including penetration, softening point, and viscosity were tested; Dynamic Shear Rheometer (DSR) test were conducted both to evaluate the properties of asphalt. The results showed that higher percentage retained penetration, lower softening point increment, and smaller viscosity aging index were gained after adding APAO to WTR modified asphalt. Closer G∗ and δ curves, smaller G∗ ratios due to the introduction of APAO confirmed the improved aging resistance. Higher G∗/sinδ at high temperature and smaller G∗·sinδ at intermediate temperature indicates WTR and APAO are beneficial to improving resistance to permanent deformation and fatigue cracking. Fourier Transform Infrared Spectroscopy (FTIR) measurements revealed that the double bonds in APAO and WTR were consumed for building a strengthened network in WTR modified asphalt and this may explain the better anti-aging properties of WTR + APAO compound modified asphalt.
A spectrally selective TiAlC/TiAlCN/TiAlSiCN/TiAlSiCO/TiAlSiO coating was deposited on stainless steel substrate by unbalanced magnetron sputtering system. Each individual layer of the tandem ...absorber was optimized by varying the reactive gas flow rates (C2H2, N2 and O2) and target power densities (Ti, Al and Si). The optimized tandem absorber shows a solar absorptance of 0.960 and an emittance of 0.15 at 82°C, measured using solar spectrum reflectometer and emissometer, respectively. In order to study the optical properties of the deposited tandem absorber at high operating temperatures the reflectance spectra of the tandem absorber were measured at temperatures ranging from 80°C to 500°C by UV–Vis–NIR spectrophotometer and FTIR spectrometers. The reflectance spectra of the as-deposited sample and after high temperature reflectance measurements did not show any significant changes. The thermal emittance of the tandem absorber at high temperatures (80–500°C) was studied in detail. At the temperature of 200°C, 300°C, 400°C and 500°C the tandem absorber shows the emittance of 0.152–0.157, 0.181–0.19, 0.214–0.246 and 0.251–0.275, respectively with an absorptance of ~0.930. These results show the good selectivity of the tandem absorber even at high operating temperatures (e.g., 500°C) with a photothermal conversion efficiency of 88%, thus demonstrating that the tandem absorber is suitable for solar thermal power generation applications. Reflectance and roughness data of the absorber coating post annealing in air up to 600°C for 2h, carried out independently, corroborated the present results.
•Spectrally selective coatings developed for photothermal conversion.•High temperature emissivity measurements were carried out up to 500°C.•At 500°C, the thermal emissivity was 0.251.
•Mixotrophic condition with glycerol showed the highest biomass.•Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) can be used to analyze algal FTIR data.•The highest lipid content ...was observed in heterotrophic condition using glycerol.•The highest carbohydrate content was obtained in autotrophic condition.•Biodiesel quality increases in heterotrophic condition using glycerol.
The biomass production and changes in biochemical composition of a locally isolated microalga (Chlorella sp.) were investigated in autotrophic, mixotrophic and heterotrophic conditions, using glucose or glycerol as carbon sources and municipal wastewater as the growth medium. Both standard methods and Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) analysis of data acquired by Fourier-transform IR (FTIR) spectrometry showed that autotrophic and mixotrophic conditions promoted carbohydrate accumulation, while heterotrophic conditions with glycerol resulted in the highest lipid content and lowest carbohydrate content. Heterotrophic conditions with glycerol as a carbon source also resulted in high oleic acid (18:1) contents and low linolenic acid (18:3) contents, and thus increasing biodiesel quality. The results also show the utility of MCR-ALS for analyzing changes in microalgal biochemical composition.
In various industries, particularly the chemical and pharmaceutical fields, Fourier transform infrared spectroscopy (FTIR) spectroscopy provides a unique capacity to detect and characterise complex ...chemicals while minimising environmental damage by minimal waste generation and reducing the need for extensive sample preparation or use of harmful reagents. This review showcases the versatility of ex situ and in situ FTIR applications for substance identification, analysis, and dynamic monitoring. Ex situ FTIR spectroscopy’s accuracy in identifying impurities, monitoring crystallisation processes, and regulating medication release patterns improves product quality, safety, and efficacy. Furthermore, its quantification capabilities enable more effective drug development, dosage procedures, and quality control practices, all of which are consistent with green analytical principles. On the other hand, in situ FTIR spectroscopy appears to be a novel tool for the real-time investigation of molecular changes during reactions and processes, allowing for the monitoring of drug release kinetics, crystallisation dynamics, and surface contacts, as well as providing vital insights into material behaviour. The combination of ex situ FTIR precision and in situ FTIR dynamic capabilities gives a comprehensive analytical framework for developing green practices, quality control, and innovation in the chemical and pharmaceutical industries. This review presents the wide range of ex situ and in situ FTIR spectroscopy applications in chemical, pharmaceutical and medical fields as an analytical green chemistry tool. However, further study is required to fully realise FTIR’s potential and develop new applications that improve sustainability in these areas.
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•FTIR is valuable for identification, quality and stability assessment.•FTIR supports sustainability, aligning with green chemistry principles.•In situ FTIR enables vital insights into material behaviour and reaction mechanisms.•FTIR could be used in the analysis of diseases and biological material.
•Petroleum ether extracted residue of coal tar was stepwise separated using four solvents by CC.•A same set of fractions and residue were analyzed by GPC, TG-FTIR, PY-GC/MS and FTIR.•The order of the ...final thermal weight loss rates is: TS > PCT > EAS > THFS > MAS.•Pyrolysis products of TS, EAS, MAS and IS all contain more oxygen compounds.•The pyrolysis volatiles of THFS mainly contain aliphatic and their average content is 82.39 wt%.
The petroleum ether extracted residue (PCT) of the low temperature coal tar were separated and analyzed in this study. PCT was stepwise separated into toluene eluent (TS), ethanol eluent (EAS), methanol eluent (MAS), tetrahydrofuran eluent (THFS) and residue (IS) by chromatography column (CC) with Al2O3. Their composition and structure feature were confirmed by gel permeation chromatography (GPC), Uv-fluorescence, thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR), pyrolysis gas chromatography-mass spectrometer (PY-GC/MS) and Fourier transformed infrared (FTIR). The results show that the yields of TS, EAS, MAS, THFS are 1.70 wt%, 33.22 wt%, 18.97 wt% and 1.41 wt%, respectively. The order of their molecular weights from small to large is as follows: MAS < PCT < TS < EAS < THFS. The compound types of pyrolysis volatiles from TS, EAS, MAS and IS change completely with the temperature rising. TS pyrolysis volatiles mainly contain oxygen compounds and nitrogen compounds. EAS pyrolysis volatiles mainly contain aromatic hydrocarbons and oxygen compounds·THFS pyrolysis volatiles mainly contain aliphatic hydrocarbons (C33-C43 alkanes), and their average content is 82.39 wt%. The pyrolysis temperature from 500 °C to 600 °C is the cut-off point, at which light aromatic hydrocarbons and low boiling phenols are detected, and they may connected by bridge bonds.
Cellulase activity on insoluble cellulose substrates declines as the substrate is modified. The role of structural changes that result in substrate recalcitrance, such as changes to cellulose ...crystallinity, requires further investigation. Crystallinity of cellulose samples with varying extents of digestion can only be compared meaningfully using a high throughput - Fourier transform infrared spectroscopy (HTS-FTIR) technique when the many variables involved are carefully controlled. Hence, changes to the HTS-FTIR sample preparation methods previously described in literature were necessary in order to obtain clean raw spectra and reliable measures of cellulose crystallinity. The sample preparation methods of residual cellulose after digestion by individual cellulases and a complex cellulase mixture from
T. fusca
were improved to remove extraneous overlapping signals, provide accurate extent of digestion, and correct errors caused by varying concentrations. These improved preparation methods enabled measurement of crystallinity index values of residual cellulose which did not show a correlation between cellulose crystallinity and the decline in cellulase activity.
•The thermo-oxidation of cotton and cotton treated with DNA was investigated.•At low heating rates, DNA favours cotton dehydration instead of depolymerisation.•At high heating rates, DNA favours ...cotton dehydration instead of depolymerisation.
Our recent work has demonstrated that deoxyribose nucleic acid (DNA) can act as an effective flame retardant when applied to cotton fabrics as a thin coating. DNA acts as a Lewis acid and promotes the dehydration of cotton cellulose to form char, limiting the production of volatile species. Here, the effect of heating rates on thermal degradation behaviour has been studied in order to understand the thermo-oxidation behaviour under slow heating and fast (flash) pyrolysis. The low heating rate effect has been studied using thermogravimetry coupled with infrared spectroscopy and pyrolysis-combustion flow calorimetry, whereas high heating rate effect was obtained by performing thermogravimetry at 200–500°C/min and flash-pyrolysis tests coupled with infrared spectroscopy. The information obtained by the latter has been successfully employed in order to (i) better explain the results collected from combustion tests and (ii) demonstrate that the type of the gaseous species and their evolution, as well as the char formation, as a consequence of the fabric thermo-oxidation, are independent of the adopted heating rate.
•Slow pyrolysis of bamboo was conducted by TG-FTIR-GCMS.•FTIR indicated functional group emission such as H2O, CH4, CO2, CO, and CO.•CO2 and acids are main composition of evolved gas during bamboo ...pyrolysis.•Slow pyrolysis mechanism at different temperature stages was established.
Slow pyrolysis of bamboo is an important conversion pathway to produce biofuels and chemicals such as biomass-derived fertilizer precursor (biochar). In this study, evolved gas analysis during pyrolysis of bamboo was conducted by a combination of TG, FTIR and GC–MS to establish a detailed pyrolysis mechanism of bamboo biomass. The main decomposition temperature zones were 300–400 °C and it reached the maximum mass loss intensity at 350 °C based on DTG curves. The main functional groups escaped from biomass during pyrolysis were –OH, –CH2, –CH3, CO, C–O, and –COOH. The main compounds during pyrolysis of bamboo were acetic acid and 2-propenoic acid, ethenyl ester at 300 °C, 2-oxo-propanoic acid and 1-hydroxy-2-propanone at 350 °C and acetic acid and acetic acid ethenyl ester at 400 °C. Evolved gas analysis indicated that components in bamboo occurred in different temperatures and pyrolysis mechanisms and resulted in distinguishing pyrolysis product emission characteristics.
Chemical stabilization of clays is commonly used to improve unfavorable engineering properties. Though the effects of non-traditional additives on soil improvement have been investigated in recent ...years, documented research studies on the macro- and micro-level characteristics of problematic clays stabilized by non-traditional additives are fairly limited. The current study examines the time-dependent changes induced in the strength, mineralogy, morphology, molecular and micro-fabric characteristics of montmorillonitic and kaolinitic clays stabilized with a non-traditional calcium-based additive, which is commercially available under the product name SH-85. The physico-chemical bonding mechanisms induced by the stabilization process were studied at a micro-level using various spectroscopic and microscopic techniques, such as X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometry (EDAX), Fourier transform infrared spectroscopy (FTIR), Brunauer, Emmett and Teller (BET) surface area analysis and particle size analysis (PSA) using a laser diffraction approach. Unconfined compressive strength (UCS) tests were also performed on stabilized specimens at various curing times to examine macro-level characteristics. The UCS test results showed that the 6% and 9% additive content were optimal for montmorillonitic and kaolinitic clays, respectively, with the UCS of both stabilized clays improving significantly after 7days of curing. This relatively rapid curing reaction process is very advantageous and cost-effective for geotechnical engineering applications. The micro-level study revealed that the calcium-based additive modified the porous network of the stabilized clays. The pores were filled and particles were bonded by cementitious products, including calcium silicate hydrate (C-S-H) and calcium aluminate hydrate (C-A-H) for the stabilized montmorillonitic and kaolinitic clays, respectively.
•Calcium-based additive significantly improved the strength of clayey soils.•Microstructural testing proved beneficial for identifying stabilizing mechanisms.•Reactions between additive, water, and soil formed cementing products.•Porous network of stabilized clay changed at the micro-level, increasing strength.•Rapid change in strength and soil microstructure occurred at early stage of curing.
The current measurement techniques described in the literature for the determination of the carbonyl index (CI) for polyolefins such as polyethylene and polypropylene were compared and contrasted. ...These were all found to be inconsistent or inaccurate and were not capable of differentiating significant changes in carbonyl peak evolution throughout accelerated ageing. As a consequence of these findings, a methodology, specified area under band (SAUB) is presented here to more accurately represent the CI as a general means of reporting. The increased precision in the methodology is explained and compared to other methodologies for determining CI. The SAUB method is also shown to be capable of elucidating the differences in relative extent and rates of CI for different polyolefins, exposed to the same conditions over the same time period.
