Search Results (10,137)

Moisture-induced damage is one of the primary causes of premature distress in asphalt pavements, leading to reduced service life and increased maintenance costs. Although nanomaterials have shown potential in enhancing asphalt performance, the underlying composite interaction mechanisms among nanomaterials, asphalt binder, and aggregate phases under moisture exposure are still not fully understood. In addition, comparative evaluations under consistent experimental conditions remain limited. This study investigates the influence of five nanomaterials: nano-silica (NS), nano-alumina (NA), nano-titanium dioxide (NT), nano-zinc oxide (NZ), and carbon nanotubes (CNT) on the physical and mechanical properties of asphalt binders and mixtures, with particular emphasis on moisture damage resistance. The nanomaterials were incorporated at dosages of 1.5%, 3.0%, 4.5%, and 6.0% by binder weight. Binder performance was evaluated using conventional and performance grading (PG) tests, while mixture performance was assessed through Marshall properties and moisture susceptibility indicators, including the tensile strength ratio (TSR) and the index of retained strength (IRS). Fluorescence microscopy (FM), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were employed to investigate nanomaterial dispersion characteristics, microstructural morphology, and physicochemical interactions within the asphalt composite system. The results indicate that nanomaterial modification reduced penetration and increased softening point and Marshall stability, reflecting enhanced stiffness and thermal resistance, although ductility decreased at higher dosages. Significant improvements in moisture resistance were observed, particularly under conditioned states. The TSR increased from 81.2% for the control mixture to 92.4% for NS and 91.7% for NA, while the IRS improved from 72.7% to 88.5% for NS. Statistical analysis indicated that both nanomaterial type and dosage significantly affected TSR and IRS performance, with dosage exhibiting comparatively greater influence on moisture resistance improvement. FM and SEM analyses revealed comparatively better dispersion and lower agglomeration tendency for NS and NA, which corresponded to their superior moisture resistance performance. FTIR analysis indicated that the modification process was predominantly physical, with no major formation of new chemical functional groups. Among the investigated nano materials, NS at 6% dosage exhibited the most pronounced improvement, followed by NA at similar dosage levels. Overall, the findings suggest that nanomaterial modification can considerably improve the moisture resistance and mechanical performance of asphalt mixtures under laboratory conditions. However, higher nanomaterial dosages may adversely affect binder workability due to increased viscosity, particularly in CNT-modified binders. Full article

Microplastics (MPs) in wastewater treatment plants are exposed to oxidative conditions during disinfection and advanced oxidation processes (AOPs), which can alter morphology and surface chemistry and influence interactions with coexisting contaminants. Here, accelerated chemical oxidation was simulated using heat-activated potassium persulfate (K₂S₂O₈) and sodium hypochlorite (NaOCl) to examine the oxidative aging of MPs made from polyethylene (PE), polyethylene terephthalate (PET), and polypropylene (PP). Changes in particle morphology and surface chemistry before and after oxidant treatment were characterized using scanning electron microscopy (SEM) for morphological analysis and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy for chemical characterization. Carbonyl formation, an indicator of polymer oxidation, was evaluated using the carbonyl index (CI). Both oxidants induced surface morphological defects and carbonyl functional groups in the MPs, with CI increasing with degradation time. The CI trends suggest that MP oxidation varies with polymer type and oxidant. The effect of oxidative aging on MP sorption capacity was also investigated using copper ions as a model inorganic constituent. Although oxidative aging introduced oxygen-containing functional groups, no statistically significant differences in copper sorption were observed between pristine and oxidized MPs, indicating that MPs can act as vectors for copper regardless of their degree of surface oxidation. Full article

Silica dispersion in rubber matrices remains a critical issue due to the polarity mismatch between silica and the rubber phase. This study aimed to synthesize functionalized liquid polyisoprene rubber (F-LIR) and evaluate its role in improving the interfacial interaction between silica and solution styrene–butadiene rubber (SSBR). F-LIR was synthesized by introducing an alkoxysilane-containing functionalizing agent at the termination stage of anionic polymerization. Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (¹H-NMR) were used to confirm the successful introduction of silyl groups at the chain ends of liquid polyisoprene. The optimal loading of F-LIR in SSBR was evaluated through bound rubber content, dynamic mechanical analysis, and mechanical performance testing. The results demonstrated that F-LIR improved the tensile strength, modulus at 300% elongation, and bound rubber content of SSBR composites. These enhancements are attributed to the reaction between the silyl groups of F-LIR and surface hydroxyl groups of silica, together with the co-crosslinking interaction between F-LIR and SSBR. The composites containing 4 phr F-LIR exhibited the best overall balance of properties. This study provides a novel method for synthesizing F-LIR, which bridges silica and the rubber matrix by enhanced filler–rubber interactions at the filler–rubber interface. Full article

For the removal of hexavalent chromium [Cr(VI)] from drinking water, a hybrid biosorbent designated chitosan–natural diatomaceous earth (CNDE) was developed and thoroughly characterized. The material couples the ion-exchange and chelating capacity of chitosan—applied at an 85% degree of deacetylation—with the high-surface-area mineral framework of natural diatomaceous earth, onto which the polymer was deposited as a conformal coating. Surface morphology and internal microstructure were examined by scanning and transmission electron microscopy (SEM/TEM), while elemental composition across the hybrid matrix was resolved by energy-dispersive X-ray spectroscopy (EDX). Fourier transform infrared (FTIR) spectroscopy was employed to identify the surface functional groups responsible for chromate binding, and streaming current measurements established the pH of zero charge (pH_pzc), which governs the electrostatic environment at the sorbent–solution interface. Specific surface area was quantified by the Brunauer–Emmett–Teller (BET) method, and the balance of surface acidic and basic sites was determined through titrimetric analysis of total acidity and alkalinity. Thermogravimetric analysis (TGA) was conducted to assess thermal stability. Batch equilibrium isotherm experiments were performed to evaluate Cr(VI) uptake from model drinking water prepared using dilute potassium dichromate solutions adjusted to target pH levels. The effects of solution pH and competing anions (chloride and sulfate) were also investigated. Kinetic studies were conducted to determine the rate of Cr(VI) adsorption, and residual metal concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). Results indicated that CNDE containing 30% chitosan (CNDE30) achieved effective Cr(VI) removal at pH 5. Adsorption was strongly pH-dependent, decreasing as pH increased from 5 to 8. Equilibrium data were well described by both Langmuir and Freundlich isotherm models, while kinetic data followed a pseudo-second-order model. The presence of chloride ions (15 mg/L) reduced adsorption capacity by approximately one-third, whereas sulfate at the same concentration significantly inhibited Cr(VI) removal. Overall, the isotherm results suggest that CNDE30 is a promising material for Cr(VI) removal from drinking water. Its cost-effectiveness, ease of synthesis, and potential for reuse make it particularly attractive for small-scale and decentralized water treatment applications. Full article

The atmospheric air quality is one of the crucial factors determining people’s health, duration and quality of life. The importance of ammonia (NH₃) and ethylene (C₂H₄) is due to the fact that they are precursors of secondary organic aerosols (SOA) and phytotoxicants, which significantly affect air quality, cause human diseases and damage plants. The Fourier Transform Infrared (FTIR) spectrometry is a powerful tool for long-term monitoring of the atmospheric gas composition, including toxic gases. The paper presents the results of atmospheric FTIR measurements of NH₃ and C₂H₄ at the St. Petersburg State University observational site (59.88° N, 29.83° E, 20 m above sea level) located in a suburb of greater Saint Petersburg. This work demonstrates the applicability of the ground-based atmospheric FTIR spectroscopy to long-term monitoring of air pollution in urbanized areas and in particular to provide information on the NH₃ and C₂H₄ abundance in the atmosphere, including the analysis of their annual cycle, long-term trends, and positive anomalies. It was shown that for NH₃ and C₂H₄, a statistically significant decrease in column-averaged dry-air mole fraction values (X_NH3 and X_C2H4) was observed, amounting to (−2.3 ± 0.2)%/year for the 2009–2025 period and with the rate (−2.2 ± 0.4)%/year for the 2016–2025 period, respectively. Periodically recorded X_NH3 anomalies indicate the presence of intensive emission sources in the region, subjecting ecosystems in adjacent areas to constant exposure to NH₃ concentrations exceeding the critical level. Anomalously high values of X_NH3 and X_C2H4 were recorded simultaneously only once—on 17 October 2017. Using data on HCN total column (as a forest fire indicator) and the results of atmospheric dispersion modeling, it was shown that this pollution event was caused by the influence of biomass burning products emitted from wildfires located approximately 250 km to the north-west from the observational site in the Helsinki area (Finland). Full article

Waterborne epoxy resin emulsified asphalt (WEA) is often used as a preventive maintenance material for asphalt pavement due to its excellent mechanical properties and high-temperature stability. However, its relatively poor toughness and low-temperature crack resistance limit its broader application. To address this issue, a PPG-IPDI-based waterborne polyurethane/epoxy resin (WER/PU) emulsion was synthesized via the prepolymer dispersion method using polypropylene glycol (PPG), isophorone diisocyanate (IPDI), 2,2-bis(hydroxymethyl)propionic acid (DMPA), and epoxy resin (E-44) as the main raw materials. Fourier transform infrared (FT-IR) spectroscopy confirmed that flexible polyurethane segments were successfully grafted onto the epoxy resin. This WER/PU emulsion was then incorporated as a modifier into emulsified asphalt to prepare waterborne polyurethane/epoxy resin composite-modified emulsified asphalt (WER/PU-CMEA). A series of laboratory tests were conducted to compare the compatibility, conventional properties, mechanical performance, high temperature rheological properties, low-temperature crack resistance and aging resistance of ordinary emulsified asphalt (OEA), WEA, and WER/PU-CMEA. Scanning electron microscopy (SEM) was employed to analyze the modification mechanism of WEA by WPU. The results show that WER/PU exhibits good compatibility with emulsified asphalt, and the synergistic effect of WER/PU significantly enhances the overall performance of the emulsified asphalt. Compared with WEA, WER/PU-CMEA shows a slight decrease in tensile strength and high-temperature stability, but it notably improves material compatibility, flexibility, bond strength, elongation at break, high-temperature creep-recovery performance, and low-temperature crack resistance. This study provides a promising approach for developing high-performance emulsified asphalt materials, which have strong application potential in pavement maintenance, waterproof coatings, and tack coats. Full article

Flavonoids from Pinus koraiensis needle (PN) litterfall were efficiently recovered using an enzyme-assisted ultrasonic extraction (EAU) method optimized via response surface methodology (RSM). The optimal conditions (enzyme dosage 1.7%, ethanol concentration 70%, ultrasonic time 21 min, cellulase–pectinase ratio 1:3, liquid–solid ratio 40:1, enzymatic hydrolysis at 42.5 °C for 1 h, ultrasonic extraction at 50 °C and 150 W) yielded a total flavonoid content (TFC) of 17.08 mg rutin/g, which was significantly higher than that obtained via conventional extraction (CE). Scanning electron microscopy (SEM) confirmed that the treatment disrupted the cell wall, promoting flavonoid release. Ultra-performance liquid chromatography coupled with triple-quadrupole time-of-flight mass spectrometry (UPLC-Triple-TOF/MS) identified 60 flavonoids in the purified extract obtained under the optimal EAU conditions (OT group), including quercitrin, tiliroside, taxifolin, and procyanidin B2. Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) showed higher crystallinity but slightly reduced thermal stability for OT flavonoids. Notably, compared with the purified flavonoids obtained by CE (CK1 group), the OT group achieved a higher TFC and exhibited significantly better in vitro antioxidant activity (DPPH IC₅₀ = 71.82 μg/mL; ABTS IC₅₀ = 28.93 μg/mL) and in vitro carbohydrate-digesting-enzyme-inhibitory activity (α-glucosidase (α-GLU) IC₅₀ = 79.52 μg/mL; α-amylase (α-AMY) IC₅₀ = 793.9 μg/mL), with α-AMY inhibition being approximately 8.2-fold higher. These findings suggest that enzyme-assisted ultrasonic extraction is an efficient and reliable method for recovering flavonoids from PN and may provide a theoretical reference for the development and utilization of these flavonoids. Full article

Microplastics have emerged as a major environmental health concern due to their environmental persistence, fragmentation, and widespread distribution. Conventional adsorption strategies often have limited efficiency, reuse, and scalability, and may generate secondary pollutants. This work explores the use of ferrotitaniferous sand milled for 4, 8, 12, 16, 32, and 52 h and subsequently functionalized with polyethylene glycol (PEG) for the removal of Polyethylene Terephthalate(PET) microplastics. The samples were characterized using Fourier-Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The average particle size of the samples decreases with the milling time from $60\pm 35$ μm to $3\pm 1$ μm. The magnetic properties enable rapid separation of sand–microplastic aggregates from water using magnets. Ferrotitaniferous sand exhibits soft ferrimagnetic behavior, with a maximum saturation of 50.09 emu/g. The remanence and coercivity increase as the average particle size decreases. Ultraviolet–visible (UV-Vis) spectroscopy was used to quantify the hydrothermally fragmented PET microparticles in water. The maximum microplastic adsorption removal was 95% within 30 s for the 12 h milled sample coated with PEG. The results show that PEG increases the samples’ adsorption capacity from 20.48 to 32.36 mg/g. The novelty of this work lies in the use of magnetic Ferrotitaniferous sands as a promising, sustainable resource for magnetic separation technologies. Full article

Infrastructure maintenance and emergency repairs require rapidly setting cementitious materials, yet conventional cement presents issues of high energy consumption and substantial CO₂ emissions. Addressing this challenge, this research has developed a ternary alkali-activated cementitious material (CGFM) composed of calcium carbide residue (CCR), granulated blast furnace slag and fly ash. This study separately investigates the effects of CCR content (0–10%), alkali content (6–12%) and activator modulus (1.0–1.5) on workability and early mechanical strength. The hydration mechanism was examined through X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Thermogravimetry-Derivative Thermogravimetry (TG-DTG) and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) analysis, whilst life cycle assessment was employed to quantify the ecological impacts. Results indicated that a 3% CCR dosage significantly improved the gel structure, achieving a 7-day compressive strength of 69.8 MPa and a 37% increase in flexural strength. At a CCR dosage of 3%, alkali content of 8%, and modulus of 1.4, CGFM achieved a peak compressive strength of 80.2 MPa by the seventh day. This performance is attributable to its substantial gel content and high degree of polymerisation, which results in a dense structure. Life cycle assessment confirmed that compared to sulphoaluminate cement mortar, CGFM mortar reduced CO₂ emissions by 64.6% and energy consumption by 48.6%. Full article

This systematic research was conducted as the first comprehensive scientific analysis of ancient lime plaster samples from Anuradhapura, a World Heritage Site in Sri Lanka. Five ancient heritage sites from 1st to 10th Century AD, covering two stupa domes: Abhayagiri (AP01) and Jethavana (AP02), Monk residence building near Ruwanweliseya Stupa (AP03), Deeghapashan Rock Shelter Building of Abhayagiri Monastery Complex (AP04), and Vessagiriya Rock Shelter wall lime Plaster (AP05) were examined by employing Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetric analysis (TGA), optical microscopy (OM), scanning electron microscopy (SEM) and gas chromatography-mass spectrometry (GC-MS). The current work investigated the composition, mineralogical and microstructural properties, binding media, and organic additives. Our findings indicate that calcareous lime from seashells and river sand are the main raw materials, with ratios of 1:2.7, 1:2.0, 1:2.4, 1:4.4, and 1:3.7 for the AP01, AP02, AP03, AP04, and AP05 samples, respectively. Data also suggest that plant-based materials, mainly wood apple wax, along with nanoscale fibrous materials, were used as the main additives to enhance the properties of lime plasters. This study provides insights into the raw materials, their mixing ratios, and the techniques employed in the lime plastering of ancient Anuradhapura City, and serves as a scientific reference for the conservation and restoration of ancient buildings resilient to climate change. Full article

The efficient recovery of highly concentrated cadmium (44.55 g/L) from zinc smelting dust leachate is recognized as a significant metallurgical challenge. In this study, we focused on the selective separation of Cd from coexisting arsenic and zinc using trioctylamine (N235) as the extractant. Accordingly, key operational parameters including initial pH, extractant concentration, phase ratio, and temperature were optimized in a systematic manner. Under the optimized conditions of 30% N235, 15% TBP, and 55% sulfonated kerosene by volume, together with an initial pH of 0.5, an organic to aqueous phase ratio of 1 to 1, and a temperature of 20 °C, a three-stage countercurrent extraction process was found to dramatically enhance the Cd extraction efficiency to 99.80% while successfully rejecting As. Subsequently, stripping with 0.7 mol/L aqueous ammonia achieved an 81.4% stripping efficiency in a single stage, and washing with 1.0 mol/L HCl ensured complete regeneration of the organic solvent. Furthermore, Fourier transform infrared spectroscopy (FT-IR) and electrospray ionization mass spectrometry (ESI-MS) analyses corroborate that the extraction proceeds via an anion exchange mechanism. Specifically, within the chloride rich acidic environment, protonated N235 was shown to preferentially coordinate with the tetrachlorocadmate anion CdCl₄²⁻ to form the highly stable and lipophilic complex (R₃NH)₂CdCl₄. Overall, this work provides a scalable technological framework and a robust theoretical foundation for the extraction of highly concentrated heavy metals from complex secondary metallurgical resources. Full article

Food adulteration with melamine represents a serious threat to food safety due to its toxic effects and its ability to falsely elevate protein values measured by nitrogen-based methods. Visual inspection and visible reflectance spectroscopy are unsuitable for identifying low-level adulteration. This study evaluates Fourier Transform Infrared (FTIR) spectroscopy combined with chemometric tools for the identification of melamine in brown rice flour adulterated at 0–2.00% (w/w). Under the tested conditions, no clear FTIR-detectable interactions between melamine and starch or proteins were observed, suggesting that melamine primarily acts as a physical admixture. Characteristic melamine absorption bands were identified at 3466, 3415, 1431, and 810 cm⁻¹. Spectral normalization and second-order derivative processing improved sensitivity and enabled quantitative calibration models. The method achieved a limit of detection of 1408 mg/kg. Although this value is above the regulatory threshold of 2.5 mg/kg, the approach provides a rapid, non-destructive screening tool for identifying highly adulterated samples and prioritizing them for confirmatory chromatographic or mass spectrometric analysis. Overall, FTIR spectroscopy combined with chemometric analysis offers an efficient first-line approach for identification of melamine adulteration in brown rice flour. Full article

The release kinetics of functional compounds from active packaging systems plays a crucial role in determining their efficiency, as it directly affects the availability of the incorporated agents and the extension of the product’s shelf life. Therefore, controlled release behaviour is essential for optimizing the functionality of such materials. In the present study, corona treatment was used as a surface modification technique to tailor the release behaviour of polyphenols—curcumin, quercetin, and rutin—from polylactic acid (PLA) films. Polyphenol release was performed in a model medium (3% acetic acid), and the experimental data were fitted using commonly applied kinetic models to elucidate the release mechanism. The results indicate that corona-treated films exhibit significantly accelerated release kinetics and higher cumulative release compared to untreated samples. To interpret the observed behaviour, different surface characterization techniques were applied. Scanning electron microscopy (SEM) revealed only minor changes in the morphology of the uncharged and charged samples, which are unlikely to account for the observed differences in the release behaviour. Fourier transform infrared spectroscopy (FT-IR) confirmed that corona treatment has led to formation of new peaks in PLA spectrum and change in the shape and intensity in PLA–polyphenol loaded films. Contact angle measurements demonstrated increased surface wettability after treatment. These changes are associated with enhanced polymer–medium interactions and improved mobility of the incorporated polyphenols, leading to accelerated release. These findings demonstrate that corona treatment is an effective strategy for tuning the release kinetics of PLA-based systems. The developed materials show strong potential for use in active packaging applications, where controlled release of antioxidant compounds is essential for extending product shelf life. Full article

This study investigated the use of Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) as a cost-effective analytical approach for screening the bioactivity of green algal extracts. Samples of five Caulerpa species—C. ashmeadii, C. paspaloides, C. cupressoides, C. verticillata, and C. prolifera—were collected from Dzilam, Yucatán, Mexico, across seven seasonal campaigns. Sequential extraction was performed using solvents of increasing polarity: hexane, dichloromethane, acetone, and methanol. After solvent evaporation, extracts were analyzed via ATR-FTIR, and Total Phenolic Content (TPC) and Trolox Equivalent Antioxidant Capacity (TEAC) were quantified. Statistical analysis (PERMANOVA) revealed that the type of solvent accounted for most of the variance (61.6%), while species and collection date contributed minimally. Infrared (IR) band assignments highlighted functional groups associated with lipids, such as terpenes, and carbohydrates. K-means clustering enabled the subdivision of less polar extracts, notably grouping numerous samples from C. verticillata. Classification models comparing full-spectrum and IR band datasets showed that Partial Least Squares Discriminant Analysis (PLS-DA) with full-spectrum data achieved the best performance. TPC showed a positive correlation with absorption at 1730.8 cm⁻¹, which is associated with ester-containing metabolites. Although ATR-FTIR effectively distinguished extraction solvents, it was less sensitive to subtle biological variation among Caulerpa. However, the method remains a practical tool for rapid screening, with spectral data supporting solvent-based classification. Reduction of salt content prior to extraction may minimize interference in both FTIR measurements and biological assays. Full article

Cancer and multidrug-resistant microbial infections remain major global health challenges, underscoring the need for multifunctional, biocompatible, and environmentally sustainable therapeutic platforms. Herein, selenium–hyaluronic acid nanoconjugates (Se/HA NPs) were synthesized through an eco-friendly ascorbic acid-mediated reduction approach to improve the bio-functional stability and therapeutic performance of selenium-based nanomaterials. The formation of Se/HA NPs was confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR). FTIR analysis supported the involvement of ascorbic acid- and hyaluronic acid-associated functional groups in nanoparticle formation and stabilization. TEM revealed well-dispersed, predominantly spherical nanoparticles with diameters ranging from 29.72 to 80.38 nm, while XRD confirmed their crystalline nature with an average crystallite size of 31.2 nm. Biologically, Se/HA NPs exhibited strong antibacterial activity against Enterococcus faecalis (21 mm), Staphylococcus aureus (24 mm), Escherichia coli (25 mm), and Klebsiella pneumoniae (27 mm), outperforming hyaluronic acid alone and showing activity comparable to standard antibiotics, with a minimum inhibitory concentration (MIC) of 15.62 µg/mL. Notably, Se/HA NPs showed pronounced antifungal activity against Candida albicans, with an inhibition zone of 34 mm and an MIC of 7.8 µg/mL. In MG-63 osteosarcoma cells, Se/HA NPs demonstrated potent cytotoxicity, with a half-maximal inhibitory concentration (IC₅₀) of 8.36 µg/mL compared with 746.37 µg/mL for hyaluronic acid. Moreover, Se/HA NPs enhanced wound closure to 73.41% and showed strong anti-inflammatory activity, with an IC₅₀ of 5.37 µg/mL, demonstrating multifunctional bioactivity. Full article