Search Results (11,294)

The rising volume of sludge production poses significant environmental threats. Sludge has a high moisture content (MC), which increases its disposal and transport expenses. On the other hand, sludge has low dewaterability due to its high concentration of soluble organic compounds. To reduce sludge production, understanding and improving preconditioning and mechanical dewatering are crucial for breakthroughs in advanced sludge dewatering. The sludge samples used in this analysis were obtained from the Sarabium municipal wastewater treatment plant, with a moisture content of 97% and a specific filtration resistance (SRF) of 9.15463 × 10¹⁵ m/kg. Sludge dewatering was enhanced by treating the samples chemically with ferric chloride, aluminum sulfate, Moringa olifera, and cationic polyacrylamide CPAM and physically with wood chips, slag, rice husk, and wheat straw. The experiments examined the sludge’s initial characterization (specific resistance to filtration (SRF) and time to filtrate (TTF)). To verify the structural characteristics (density), elemental composition, and the presence of various functional groups, a characterization investigation was conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS). The results showed that chemical conditioning with ferric chloride is better than aluminum sulfate and Moringa. Wood chips also provide better results for physical conditioning than rice husk, wheat straw, and slag. The reaction occurred at the carbonyl group, where FTIR showed more activated sites during SEM analysis, as evidenced by the FTIR results. Still, when CPAM was added to conditioned sludge, there was no difference in sludge dewatering performance, and the activated sites remained unchanged. Hence, this research found that mechanical sludge dewatering was improved by conditioning with ferric chloride (pH of 6 and dose of 0.12 g/g of dry solid) and wood chips (dose of 1.5 g/g of dry solid), which reduced sludge volume after dewatering by 82.5% under low pressure, which in turn minimizes transportation, energy, and handling costs. This study supports SDG 3 and SDG 6 by improving sludge dewatering efficiency and promoting sustainable wastewater management using natural wood chips. Full article

The influence of potassium oxide (K₂O) doping on the hydrodeoxygenation (HDO) performance of trimetallic CoMo–Ni/Al₂O₃ catalysts was systematically investigated using guaiacol as a lignin-derived model compound. Catalysts containing 0, 1, 3, and 5 wt% K₂O were synthesized and characterized by SEM-EDS, N₂ physisorption, XRD, FTIR, and HRTEM. SEM micrographs showed homogeneous morphologies with no significant agglomeration, while EDS analysis confirmed elemental compositions close to nominal values, with K₂O contents increasing proportionally and maintaining uniform surface distribution. Adsorption–desorption isotherms confirmed mesoporous structures with specific surface areas ranging from 258 to 184 m² g⁻¹, decreasing with increasing K₂O loading. XRD revealed γ-Al₂O₃, NiO, (NH₄)₃[CoMo₆O₂₄H₆]·7H₂O, and K₂O phases, with slight peak shifts indicating surface modification rather than lattice incorporation of K⁺. FTIR spectra evidenced characteristic polyoxomolybdate vibrations and metal–oxygen interactions with alumina. HRTEM revealed MoS₂ slab lengths between 1.85 and 2.51 nm, stacking numbers from 2.08 to 3.17, and Mo edge-to-corner ratios (f_e/fc) between 1.39 and 2.43, corresponding to dispersions of 0.45–0.57. Guaiacol conversion remained high (≥95%) for all catalysts, while HDO selectivity strongly depended on K₂O content. At 5 wt% K₂O, cyclohexane selectivity reached 81.3% with an HDO degree of 65%, compared to 52.0% and 31% for the undoped catalyst. Pseudo-first-order kinetic analysis revealed that potassium promotes demethylation and demethoxylation steps while suppressing rearrangement pathways, steering the reaction network toward direct deoxygenation. These results demonstrate that K₂O acts as an efficient structural and electronic promoter, enabling precise control of HDO selectivity without compromising catalytic activity. Full article

Quito, recognized as the first UNESCO World Cultural Heritage Site, holds a vast documentary legacy at constant risk of deterioration due to environmental, biological, and aging factors. Preserving these historical documents demands sustainable and non-invasive approaches. This study presents the first documented investigation in Ecuador on the use of ionizing radiation for the conservation of historical paper materials. Fifteen fragments, naturally detached from deteriorated documents housed in two major heritage repositories, the Biblioteca Nacional Eugenio Espejo and the Biblioteca Fray Ignacio de Quezada, were selected for analysis. Samples were irradiated with a Co-60 gamma source at doses of 4, 6, and 8 kGy at the “Francisco Salgado T.” Irradiation Center. To evaluate potential alterations, pre- and post-irradiation analyses were conducted using surface pH measurements, colorimetry (ΔE from CIELAB coordinates), and FTIR-ATR spectroscopy. The results showed no statistically significant changes in the analyzed parameters, suggesting that gamma irradiation at these doses does not compromise the structural or visual integrity of the paper. This work represents a pioneering step in Ecuador toward integrating scientific methods into cultural heritage preservation, supporting the safe application of ionizing radiation in the conservation of historical documents. Full article

The paper focuses on the synthesis and characterization of the spectroscopic and electrochemical properties of novel oxime esters. Six benzothiazole-based compounds were synthesized using a simple three-step procedure. The chemical structure of novel oxime esters was confirmed by Nuclear Magnetic Resonance spectroscopy (¹H and ¹³C NMR), as well as FT-IR spectroscopy and elemental analysis. The melting point of these compounds was also determined. The spectroscopic properties were studied in 10 solvents with different polarity. The fluorescence quantum yield was determined using Coumarin I as a reference. Additionally, the E_0→0 transition energy was determined. The electrochemical properties were determined using cyclic voltammetry. To justify their use as potential photoinitiators, preliminary studies were conducted to assess their utility in initiating light-induced polymerization. Based on the results, the proposed oxime esters are potential Type I photoinitiators for free radical polymerization. Full article

Background/Objectives: Pyrazole carboxamides are widely used as adaptable medicinal-chemistry scaffolds and have been explored as cholinesterase (ChE) inhibitor chemotypes. In this work, we prepared a new series of 4-arylazo-3,5-diamino-N-tosyl-1H-pyrazole-1-carboxamides 5(a–m) and evaluated their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), supported by structure-based computational analyses. Methods: Thirteen derivatives 5(a–m) were synthesized, fully characterized with analytical techniques (FT-IR, H NMR, and C NMR), and tested in vitro against AChE and BChE, with tacrine (THA) used as the reference inhibitor. Docking calculations were used to examine plausible binding modes. The top-ranked complexes (7XN1–5e and 4BDS–5i) were further examined by 100 ns explicit-solvent molecular dynamics (MD) simulations in Cresset Flare, followed by RMSD/RMSF analysis and contact-persistence profiling. Predicted ADME/Tox. properties were also assessed to identify potential developability issues. Results: The series showed strong ChE inhibition, and several compounds were more potent than THA. Compound 5e (4-nitro) was the most active AChE inhibitor (K_I = 20.86 ± 1.61 nM) compared with THA (K_I = 164.40 ± 20.84 nM). For BChE, the K_I values ranged from 31.21 to 87.07 nM and exceeded the reference compound’s activity. MD trajectories supported stable binding in both systems (10–100 ns mean backbone RMSD: 2.21 ± 0.17 Å for 7XN1–5e; 1.89 ± 0.11 Å for 4BDS–5i). Most fluctuations were confined to flexible regions, while key contacts remained in place, consistent with the docking models. ADME/Tox. predictions suggested moderate lipophilicity but generally low aqueous solubility; all compounds were predicted as non-BBB permeant, and selected liabilities were flagged (e.g., carcinogenicity for 5e/5g/5h/5i; nephrotoxicity for 5f/5g). Conclusions: The 4-arylazo-3,5-diamino-N-tosyl-1H-pyrazole-1-carboxamide scaffold delivers low-nanomolar ChE inhibition, with docking and MD supporting stable binding modes. Future optimization should prioritize solubility improvement and mitigation of predicted toxicities and metabolic liabilities, especially given the predicted lack of BBB permeability for CNS-directed applications. Full article

Polylactide (PLA) composites were prepared and doped with starch (10% by weight), and mineral salts used as mineral fertilisers (MgSO₄, KNO₃, Ca(NO₃)₂ and Ca₃(PO₄)₂) were prepared. The content of the added fertilisers was 2% by mass in the composites. The tensile strength properties of the obtained composites were tested. The effect of the addition of fertilisers on the structure of polylactide was analysed using spectroscopic methods (FTIR and FTRaman). The thermal properties of the obtained composites were tested using thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC). PLA composites with fertilisers were tested for biodegradability in two types of soil—field soil and horticultural soil—and in compost. Biodegradability was assessed based on the mass loss of biodegraded composites, spectroscopic tests and visual assessment of changes occurring in the composites. Tests were performed on the respiratory activity of microorganisms in the compost extract in which the tested composites were placed. The addition of mineral salts used in the tested composites significantly influenced the biodegradation rate of the composites. Mineral compounds (MgSO₄, KNO₃ and Ca(NO₃)₂) added to the PLA–starch composite improve its mechanical properties. It should also be noted that the addition of mineral salts to the prepared composites did not affect the chemical structure of polylactide. The addition of mineral salts to PLA also did not significantly affect its thermal properties, as demonstrated by DSC and TG thermal analysis. Full article

This study systematically compared spray drying (SD) and freeze drying (FD) for microencapsulating Idesia polycarpa oil using a soy protein isolate/maltodextrin (SPI/MD) wall system. SD produced predominantly spherical and compact microcapsules with higher solubility (51.33%), encapsulation efficiency (81.9%), and superior oxidative stability (oxidation induction period, 6.05 h), together with improved thermal resistance, indicating its suitability for applications requiring enhanced stability and aroma retention. In contrast, FD yielded irregular and porous microcapsules with significantly higher emulsifying activity (29.12 m² g⁻¹, p < 0.05) but lower solubility and encapsulation efficiency. Integrated physicochemical characterization-including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), particle size and polydispersity index (PDI), ζ-potential, differential scanning calorimetry (DSC), oxidative stability index (OSI) measurements, and volatile profiling via odor activity value (OAV) analysis—revealed clear process-dependent structure–function relationships. The denser SPI/MD matrix formed during SD restricted lipid molecular mobility and oxygen diffusion, thereby suppressing lipid oxidation and promoting the retention of key lipid-derived odorants. Conversely, the porous structure generated by FD facilitated interfacial functionality but increased molecular diffusion pathways. Overall, this work demonstrates that SPI/MD-based microencapsulation functions as a molecular stabilization platform for highly unsaturated plant oils and provides mechanistic guidance for selecting drying strategies to tailor Idesia polycarpa oil microcapsules for specific food applications. Full article

Verbascum sinaiticum (V. sinaiticum), locally known as “Qetetina” in Ethiopia, is a rich source of phenolic compounds, but its stability and sensory limitations restrict its application. This study evaluated the physicochemical, functional, morphological, structural, storage stability, and in vitro digestibility characteristics of V. sinaiticum extract encapsulated with 100% Gum Arabic (GA), 100% maltodextrin (MD), and a mixed coating material (MD:GA = 8:2 ratio) using freeze-drying. MD-based microcapsules demonstrated superior functional properties, including high water solubility (98.48%), low moisture content (1.36%), low hygroscopicity (14.61%), and high encapsulation efficiency (81.31%). During 32 days of storage, MD microcapsules retained 71.84% of total phenolic content and showed minimal release under gastric and thermal conditions, while GA encapsulates were less stable. Structural analysis using XRD, FTIR, and SEM confirmed successful encapsulation, with compact morphology, consistent phenolic preservation, and structural integrity. Furthermore, encapsulation masked the undesirable sensory attributes of the extract, enhancing its potential use in nutraceuticals. Overall, freeze-drying with MD provided the most effective encapsulation system, significantly improving the stability and storage potential of V. sinaiticum extract. Full article

This study investigated the influence of acrylonitrile-butadiene rubber (NBR) at 5 and 15 phr on the properties of silica-filled styrene-butadiene /polyisoprene (SBR/NR) rubber blends intended for boot tread production. Fourier Transform Infrared Spectroscopy evaluated the performance of the resulting SBR/NR/NBR composites with Attenuated Total Reflectance (FTIR-ATR), which confirmed interactions between the rubber matrix and the silica filler. In addition, changes in thermal and mechanical properties, as well as cross-linking parameters, were systematically examined. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) are used to provide a comprehensive understanding of the structural, thermal, and mechanical behavior of silica-reinforced SBR/NR/NBR composites. The rheological characteristics of the tested composites were examined as a function of the mixture ratio. Atomic force microscopy (AFM) revealed variations in the sample’s surface roughness and morphology with varying rubber blend ratios. The findings confirmed that incorporating NBR improves filler dispersion, increases cross-link density, and enhances mechanical properties, including hardness and tensile strength, while also influencing thermal stability and curing behavior. The results suggest the potential of these composites for reliable, efficient sole manufacturing in the footwear industry, where durability, strength, and processability are critical requirements. Full article

Integrating catalytic function with oxygen-carrying capability into bi-functional materials represents a promising strategy for reverse chemical looping pyrolysis (RCLPy), which utilizes a reduced metal oxide to improve the bio-oil quality through in situ hydrogen donation and deoxygenation. In this study, a systematic evaluation of two typical catalysts (CaO and ZSM-5) was conducted for the pyrolysis of microalgae Nannochloropsis sp. under RCLPy conditions. First, the effect of each catalyst on the pyrolysis behavior of microalgae was analyzed by Gaussian fitting of derivative thermogravimetric (DTG) curves. Second, gases evolved during thermogravimetric analysis (TGA) were monitored in real time using Fourier-transform infrared spectroscopy (FTIR) for detecting CO, CO₂, H₂O, and functional groups (e.g., C–C, C=C, C=O), and mass spectrometry (MS) for tracking nitrogen-containing compounds. Third, the composition of bio-oils produced under RCLPy conditions was examined by Gas Chromatography–Mass Spectrometer (GC–MS) analysis. The results demonstrate that the catalyst enhances the bio-oil quality by elevating the content of aromatics up to 41.9 area% and that of aliphatic hydrocarbons to 19.1 area%, respectively, while reducing the content of nitrogen-containing compounds to 3.8 area%. However, the elimination pathway of oxygen and nitrogen elements involves different mechanisms. These findings provide valuable guidance for the design of bifunctional oxygen carriers aimed at enhancing the quality of bio-oil derived from microalgae pyrolysis. Full article

Polyurethane-based implantable devices (PUIDs) delivered via catheter are increasingly used in structural heart interventions; however, limited in vivo data exist regarding their long-term biostability and biological safety. This study evaluated a balloon-shaped implant made of Pellethane^®, a polyether-based polyurethane, designed as a three-dimensional intracardiac spacer and deployed via percutaneous femoral vein access. The device was chronically positioned adjacent to the tricuspid valve annulus in seven pigs for 24 weeks. Explanted devices and surrounding tissues were evaluated through material characterization (SEM, GPC, FT-IR, and ¹H-NMR) and histological analysis. SEM and FT-IR confirmed preserved surface morphology and chemical bonds, GPC showed stable molecular weight, and ¹H-NMR revealed intact urethane and ether linkages. Materials characterization revealed no evidence of hydrolytic or oxidative degradation, indicating structural stability of the devices. Histological analysis showed stable device positioning with minimal thrombosis or inflammatory response. Biocompatibility was confirmed via ISO 10993-1:2018 Standard (International Organization for Standardization (ISO): Geneva, Switzerland, 2018), and extractable substances were evaluated under exhaustive extraction conditions specified by ISO 10993-18:2020 (International Organization for Standardization (ISO): Geneva, Switzerland, 2020), with no toxicologically significant findings. These findings support the long-term biostability and biological safety of the PUIDs in dynamic cardiac environments, informing future design criteria for catheter-delivered cardiovascular devices. Full article

Cemented tailings backfill (CTB) is widely used in mining operations due to its operational simplicity, reliable performance, and environmental benefits. However, the poor consolidation of fine tailings with ordinary Portland cement (OPC) remains a critical challenge, leading to excessive backfill costs. This study addresses the utilization of modified manganese slag (MMS) as a supplementary cementitious material (SCM) for fine tailings from an iron mine in Anhui, China. Sodium silicate (Na₂SiO₃) modification coupled with melt-water quenching was implemented to activate the pozzolanic reactivity of manganese slag (MS) through glassy structure alteration. The MMS underwent comprehensive characterization via physicochemical analysis, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) to elucidate its physicochemical attributes, mineralogical composition, and glassy phase architecture. The unconfined compressive strength (UCS) of the CTB samples prepared with MMS, OPC, tailings, and water (T-MMS) was systematically evaluated at curing ages of 7, 28, and 60 days. The results demonstrate that MMS predominantly consists of SiO₂, Al₂O₃, CaO, and MnO, exhibiting a high specific surface area and extensive vitrification. Na₂SiO₃ modification induced depolymerization of the highly polymerized Q⁴ network into less-polymerized Q² chain structures, thereby enhancing the pozzolanic reactivity of MMS. This structural depolymerization facilitated formation of stable gel products with low calcium–silicon ratios, conferring upon the T-MMS10 sample a 60-day strength of 3.85 MPa, representing a 94.4% enhancement over the T-OPC. Scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS) analysis revealed that Na₂SiO₃ modification precipitated extensive calcium silicate hydrate (C-S-H) gel formation and pore refinement, forming a dense networked framework that superseded the porous microstructure of the control sample. Additionally, the elevated zeta potential for T-MMS10 engendered electrostatic repulsion, while the aluminosilicate gel provided imparted lubrication, collectively improving the flowability of the composite slurry exhibiting a 26.40 cm slump, which satisfies the requirements for pipeline transportation in backfill operations. Full article

Airborne microplastics (AMPs) undergo ultraviolet (UV)-driven physicochemical aging during atmospheric transport, influencing cloud processes, greenhouse-gas release, and potential respiratory health impacts. Quantifying this transformation is particularly challenging for particles smaller than 10 µm and for polymers such as polyethylene terephthalate (PET), whose intrinsic ester carbonyl band obscures newly formed acid carbonyls in conventional infrared analyses. Here, we develop a µFTIR attenuated total reflection (µFTIR-ATR) imaging method combined with a fourth-derivative oxidation index (carbonyl ratio at 1701/1716 cm⁻¹) that resolves these overlapping bands and enables sensitive, quantitative evaluation of PET surface oxidation. The approach automates detection, identification, and oxidation analysis of particles down to ~2 µm. Laboratory UV irradiation experiments show a systematic increase in this derivative-based oxidation index with exposure dose. Application to ambient PET collected from Mt. Fuji, Tokyo, Osaka (Japan), and Siem Reap (Cambodia) reveals clear regional differences corresponding to local UV-A environments: PET from Siem Reap exhibited the highest oxidation, whereas particles from the Japanese sites showed moderate but variable aging. These results demonstrate that derivative-based µFTIR-ATR imaging provides a practical and highly sensitive tool for quantifying photo-oxidative degradation in fine AMPs and highlight the value of chemical-aging metrics for interpreting atmospheric processing and transport pathways. Full article

Wellbore instability in shale formations represents a worldwide challenge in drilling engineering. The development of high-performance shale stabilizers is crucial for enhancing wellbore stability. A core–shell structured shale stabilizer, designated AAD-CaCO₃, was synthesized via inverse emulsion polymerization using acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and dimethyl diallyl ammonium chloride (DMDAAC) as monomers. Nano-CaCO₃ was generated in situ by reacting calcium chloride and sodium carbonate. Sodium bisulfite and ammonium persulfate were used as initiators. The product was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Its effects on the rheological properties and filtration performance of a bentonite-based mud were evaluated. The stabilizer’s efficacy in inhibiting shale hydration swelling and dispersion was evaluated through linear swelling tests and shale rolling dispersion experiments, while its plugging performance was examined via a filtration loss test with a nanoporous membrane and spontaneous imbibition tests. The results indicated that AAD-CaCO₃ possesses a core–shell structure with the nano-CaCO₃ encapsulated by the polymer. It moderately improved the rheology of the bentonite-based mud and significantly reduced both the low-temperature and low-pressure (LTLP) filtration loss and the high-temperature and high-pressure (HTHP) filtration loss. AAD-CaCO₃ could be adsorbed onto shale surfaces through electrostatic attraction, resulting in substantially reduced clay hydration swelling and an increased shale cutting recovery rate. Effective plugging of micro-nanopores in shale was achieved, demonstrating a dual mechanism of chemical inhibition and physical plugging. Full article

The growing demand for sustainable materials and the valorization of waste streams have intensified research on wastewater biorefineries and bioplastics. Within this framework, this study aims to develop and characterize poly (lactic acid) (PLA)-based films partially substituted with microalgae biomass derived from wastewater treatment at different concentrations (PLA-MA: 0, 10, 20, 30, 40, and 50%). The films were produced and systematically characterized in terms of their morphological (SEM), structural (FTIR), physical (thickness, weight, swelling, and solubility), thermal (TGA), mechanical (tensile strength, elongation at break, and Young’s modulus), optical (colorimetry and UV–Vis), barrier (water vapor permeability), and biodegradability properties. FTIR analysis confirmed the successful incorporation of microalgae biomass into the polymeric matrix and indicated good compatibility at low biomass loadings, whereas higher concentrations (>20%) introduced hydrophilic functional groups associated with increasing structural incompatibility. Partial substitution of PLA with microalgae biomass significantly modulated the physical, mechanical, and optical properties of the resulting composites. Notably, biodegradability assays revealed that the PLA-MA 50% composite achieved 89% degradation within 120 days, demonstrating that microalgal biomass markedly accelerates material decomposition. Furthermore, antimicrobial tests conducted for PLA-MA 0%, 20%, and 50% confirmed the safety of wastewater-derived microalgae for incorporation into the polymer matrix. Overall, these results highlight the potential of wastewater-derived microalgae biomass as a promising and sustainable component for short-life-cycle bioplastic applications, particularly in the agricultural sector. Full article