Search Results (130)

The widespread phase-out of long-chain per- and poly-fluoroalkyl substances (PFASs) has created an urgent need for durable, fluorine-free water-repellent finishes that match the performance of legacy chemistries while minimising environmental impact. Here, the performance of an eco-friendly hybrid organic–inorganic treatment obtained by the in situ hydrolysis–condensation of triethoxy(octyl)silane (OS) in an amino-terminated polydimethylsiloxane (APT-PDMS) aqueous dispersion was investigated. The sol was applied to plain-weave cotton and polyester by a pad-dry-cure process and benchmarked against a commercial fluorinated finish. Morphology and chemistry were characterised by SEM–EDS, ATR-FTIR, and Raman spectroscopy; wettability was assessed by static contact angle, ISO 4920 spray ratings, and AATCC 193 water/alcohol repellence; and durability, handle, and breathability were evaluated through repeated laundering, bending stiffness, and water-vapour transmission rate measurements. The silica/PDMS coating formed a uniform, strongly adherent nanostructured layer conferring static contact angles of 130° on cotton and 145° on polyester. After five ISO 105-C10 wash cycles, the treated fabrics still displayed a spray rating of 5/5 and AATCC 193 grade 7, outperforming or equalling the fluorinated control, while causing ≤5% loss of water-vapour permeability and only a marginal increase in bending stiffness. These results demonstrate that the proposed one-step, water-borne sol–gel process affords a sustainable, industrially scalable route to high-performance, durable, water-repellent finishes for both natural and synthetic textiles, offering a viable alternative to PFAS-based chemistry for outdoor apparel and technical applications. Full article

This study developed iron-oxide-functionalized carbon xerogels for enhanced arsenic adsorption to mitigate global water contamination. The composites were synthesized by integrating magnetite nanoparticles (15–20 nm) into a resorcinol–formaldehyde matrix via sol–gel polycondensation, followed by controlled pyrolysis. Key parameters—magnetite/resorcinol ratios (0.03–0.07), carbonization conditions (temperature, heating rate, duration), and H₂O₂-induced surface modification—were optimized to maximize adsorption performance. Characterization (SEM/EDX, XRD, FTIR, BET, TEM) confirmed uniform magnetite dispersion (~5 wt%) and revealed that pyrolysis at 850 °C enhanced porosity (378.8 m²/g surface area) and refined surface chemistry. Adsorption kinetics followed Elovich (R² = 0.9396) and Power Function (R² = 0.9443) models, indicating chemisorption dominance. Response Surface Methodology optimized desorption parameters using a Central Composite Design with three factors and two center points with repetition. A kinetic study of As(V) desorption from carbon xerogels was conducted, yielding optimal conditions: 1.0 M KOH, 160 rpm agitation, and 90 min contact time. The adsorbent retained >88% regeneration efficiency over four cycles, demonstrating robust reusability. Synergistic effects of magnetite incorporation, tailored pyrolysis, and H₂O₂ modification significantly improved arsenic selectivity and capacity in complex matrices, while enabling magnetic recovery. Full article

Chemical–structural characteristics of three differently synthesized research-benchmark Mn-Na-W-O_x/SiO₂ catalysts for the Oxidative Coupling of Methane (OCM) were systematically studied in this research. XRD, EDX, ICP-OES, and SEM/FIB-SEM techniques, as well as Carrier Gas Hot Extraction (CGHE) and high-temperature XRD analyses, were performed to explain the functional features of the studied catalysts, in particular, the features affecting the quantity and quality of the interactions of oxygen and methane with the catalyst surface and with other molecular and radical species. These enable tracking the potential for the oxygen activation and dynamic transformation of the solid-state chemistry on the surface and sub-surface of these Mn-Na-W-O_x/SiO₂ catalysts. These catalysts were synthesized, respectively, via the sol–gel synthesis method (Cat₁) and the incipient wetness impregnation of the non-structured silica support (Cat₂) and structured SBA-15 silica support (Cat₃), under different sets of temperatures and gas compositions. The catalysts with the homogenous distribution of active components, namely Cat₁ and Cat₃, showed similar trends in terms of their dynamic interaction with oxygen species. They also showed higher levels of crystallinity of the active materials and higher catalytic selectivity towards ethane and ethylene. An explanation is given as to how the structural characteristics of the catalysts on the nanometer–micrometer scale contribute to these. The gained knowledge will be crucial in the selection and treatment of the support and developing a proper synthesis approach for the ultimate goal of designing a selective OCM catalyst. Full article

The rapid increase in use of lithium-ion batteries in energy storage together with limited supply of critical metals used in batteries and environmental concerns have led to the urgent need for sustainable recycling technologies for these batteries. Li-ion battery chemistry, components, various designs, and two main approaches for recycling: pyrolysis and hydrometallurgical techniques are discussed in this review focusing on the novel, sustainable green approach of hydroxy acid leaching followed by a direct regeneration technique. This two-step emerging technique is compared with other conventional recycling methods in this critical review emphasizing simplicity and commercial potential. Current literature reporting rapid developments on this scalable process with pretreatment phases of sorting, discharging, disassembly of batteries, separation of electrode coatings from current collectors, leaching black mass with hydroxy carboxylic acids, separation of graphite, adjustments of Li, Ni, Mn, and Co compositions, and regeneration via co-precipitation or sol–gel formation techniques followed by pyrolysis are discussed in the detailed review. The conclusion section of this direct regeneration focused critical review gives an insight into challenges in hydroxy acid recycling and direct regeneration technology and practical solutions that may help in development into a mainstream technology. Full article

Acidic oxygen evolution reaction (OER) electrocatalysts that provide high activity, lower costs, and long-term stability are needed for the wide-scale adoption of proton-exchange membrane (PEM) water electrolyzers for generating hydrogen through electrochemical water splitting. We report the effects of chromium substitution and temperature treatments on the structure, OER activity, and electrochemical stability of ruthenium oxide (RuO₂) aerogel OER electrocatalysts. RuO₂ and Cr-substituted RuO₂ aerogels (Ru_0.6Cr_0.4O₂) were synthesized using sol–gel chemistry and then thermally treated at different temperatures. Introducing chromium into the synthesis increased the surface area (7–11 times higher) and pore volume (5–6 times higher) relative to RuO₂ aerogels. X-ray diffraction analysis is consistent with s that Cr was substituted into the rutile RuO₂ structure. X-ray photoelectron spectroscopy showed that trivalent Cr substitution altered the surface electronic structure and ratio of surface hydroxides. The specific capacitance values of Cr-substituted RuO₂ aerogels were consistent with charge storage within a hydrous surface. Cr-substituted RuO₂ aerogels exhibited 26 times the OER mass activity and 3.5 times the OER specific activity of RuO₂ aerogels. Electrochemical stability tests show that Cr-substituted RuO₂ aerogels exhibit similar stability to commercial RuO₂. Understanding how metal substituents can be used to alter OER activity and stability furthers our ability to obtain highly active, durable, and lower-cost OER electrocatalysts for PEM electrolyzers. Full article

The use of glycerolates of biogenic elements as biocompatible precursors in sol–gel synthesis is an innovative direction and opens up new scientific and practical prospects in chemistry and technology of producing practically important biomedical materials, including hemostatic, antimicrobial, and wound healing materials. Using biocompatible precursors, silicon, zinc, boron, and iron glycerolates, new bioactive nanocomposite hydrogels were obtained by the sol–gel method. The composition and structural features of the hydrogels were studied using a complex of modern analytical techniques, including TEM, XRD, AES, and ESI MS. Hemostatic activity of the hydrogels was studied in the in vivo experiments; using the example of silicon-iron-zinc-boron glycerolates hydrogel, primary toxicological studies were carried out. Antimicrobial properties of hydrogels were studied using the agar diffusion method. The structural features of hydrogels and their relationship to medical and biological properties were revealed. It was shown that glycerolates hydrogels are non-toxic, and exhibit pronounced hemostatic activity, generally comparable to the commercial hemostatic drug Capramine. Antimicrobial activity is more pronounced for silicon-iron-zinc-boron and silicon-iron-boron glycerolates gel. The results obtained indicate that these glycerolates hydrogels are potential hemostatic and antibiotic-independent antimicrobial agents for topical wound healing applications in medical and veterinary practice. Full article

Community drinking water sources are increasingly contaminated by various point and non-point sources, with emerging organic contaminants and microbial strains posing health risks and disrupting ecosystems. This study explores the use of zinc oxide nanoparticles (ZnO-NPs) as a non-specific agent to address groundwater contamination and combat microbial resistance effectively. The ZnO-NPs were synthesized via a green chemistry approach, employing a sol-gel method with lemon peel aqueous extract. The catalyst was characterized using techniques including XRD, ATR-FTIR, SEM-EDAX, UV-DRS, BET, and Raman spectroscopy. ZnO-NPs were then tested for photodegradation of quinoline yellow dye (QY) under sunlight irradiation, as well as for their antibacterial and antioxidant properties. The ZnO-NP photocatalyst showed significant photoactivity, attributed to effective separation of photogenerated charge carriers. The efficiency of sunlight dye photodegradation was influenced by catalyst dosage (0.1–0.6 mg L⁻¹), pH (3–11), and initial QY concentration (10–50 mg L⁻¹). The study developed a first-order kinetic model for ZnO-NPs using the Langmuir–Hinshelwood equation, yielding kinetic constants of equilibrium adsorption and photodegradation of Kc = 6.632 × 10⁻² L mg⁻¹ and kH = 7.104 × 10⁻² mg L⁻¹ min⁻¹, respectively. The results showed that ZnO-NPs were effective against Gram-positive bacterial strains and showed moderate antioxidant activity, suggesting their potential in wastewater disinfection to achieve sustainable development goals. A potential antibacterial mechanism of ZnO-NPs involving interactions with microbial cells is proposed. Additionally, Gaussian Process Regression (GPR) combined with an improved Lévy flight distribution (FDB-LFD) algorithm was used to model QY photodegradation by ZnO-NPs. The ARD-Exponential kernel function provided high accuracy, validated through residue analysis. Finally, an innovative MATLAB-based application was developed to integrate the GPR_FDB-LFD model and FDB-LFD algorithm, streamlining optimization for precise photodegradation rate predictions. The results obtained in this study show that the GPR and FDB-LFD approaches offer efficient and cost-effective methods for predicting dye photodegradation, saving both time and resources. Full article

This article presents the results of the formation of hierarchical micro–nano structures in nanostructured tin dioxide films obtained from the lyophilic film-forming system SnCl₄/EtOH/NH₄OH. The classification of the shape and size of the synthesized structures, in relation to the pH of the solution, is presented. Measurements were carried out on an X-ray diffractometer to study the crystal structure of the samples analyzed. It was found that SnO₂ and NH₄Cl crystallites participate in the formation of the synthesized hierarchical structures. It is shown that the mechanism of the formation of hierarchical structures depends on the amount of ammonium hydroxide added. This makes it possible to control the shape and size of the synthesized structures by changing the ratio of precursors. Full article

Gels, specifically hydrogels and aerogels, have emerged as versatile materials with profound implications in pharmaceutical sciences. This comprehensive review looks into detail at hydrogels and aerogels, providing a general introduction to gels as a foundation. The paper is then divided into distinct sections for hydrogels and aerogels, each delving into their unique formulations, advantages, disadvantages, and applications. In the realm of hydrogels, we scrutinize the intricacies of formulation, highlighting the versatile advantages they offer. Conversely, potential limitations are explored, paving the way for a detailed discussion on their applications, with a specific focus on their role in antimicrobial applications. Shifting focus to aerogels, a thorough overview is presented, followed by a detailed explanation of the complex formulation process involving sol–gel chemistry; aging; solvent exchange; and drying techniques, including freeze drying, supercritical drying, and ambient-pressure drying (APD). The intricacies of drug loading and release from aerogels are addressed, providing insights into their pharmaceutical potential. The advantages and disadvantages of aerogels are examined, accompanied by an exploration of their applications, with a specific emphasis on antimicrobial uses. The review culminates in a comparative analysis, juxtaposing the advantages and disadvantages of hydrogels and aerogels. Furthermore, the current research and development trends in the applications of these gels in pharmaceutical sciences are discussed, providing a holistic view of their potential and impact. This review serves as a comprehensive guide for researchers, practitioners, and enthusiasts, seeking a deeper understanding of the distinctive attributes and applications of hydrogels and aerogels in the ever-evolving research concerning pharmaceutical sciences. Full article

The use of heterogeneous catalysts to increase the development of green chemistry is a rapidly growing area of research to save industry money. In this paper, mesoporous SiO₂-Al₂O₃ mixed oxide supports with various Si/Al ratios were prepared using two different sol–gel routes: hydrolytic sol–gel (HSG) and non-hydrolytic sol–gel (NHSG). The HSG route was investigated in both acidic and basic media, while the NHSG was explored in the presence of ethanol and diisopropyl ether as oxygen donors. The resulting SiO₂-Al₂O₃ mixed oxide supports were characterized using EDX, N₂ physisorption, powder XRD, ²⁹Si, ²⁷Al MAS-NMR and NH₃-TPD. The mesoporous SiO₂-Al₂O₃ supports prepared by NHSG seemed to be more regularly distributed and also more acidic. Consequently, a simple one-step NHSG (ether and alcohol routes) was selected to prepare mesoporous and acidic SiO₂-Al₂O₃-NiO mixed oxide catalysts, which were then evaluated in ethylene oligomerization. The samples prepared by the NHSG ether route showed better activity than those prepared by the NHSG alcohol route in the oligomerization of ethylene at 150 °C. Full article

In this work, bismuth sulfide (Bi₂S₃) thin films were deposited by a chemical bath deposition (CBD) technique (called soft chemistry), while titanium dioxide (TiO₂) nanoparticles were synthesized by sol–gel and zinc oxide (ZnO) nanoparticles were extracted from alkaline batteries. The resulting nanoparticles were then deposited on the Bi₂S₃ thin films by spin coating at 1000 rpm for 60 s each layer to create heterojunctions of Bi₂S₃/ZnO and Bi₂S₃/TiO₂. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The optical and contact angle analyses were undertaken by UV–Vis spectroscopy and a contact microscopy angle meter, respectively. The calculated band gap values were found to be between 1.9 eV and 2.45 eV. The Bi₂S₃ presented an orthorhombic structure, the TiO₂ nanoparticles presented an anatase structure, and the ZnO nanoparticles presented a wurtzite hexagonal crystal structure. Furthermore, heterogeneous solar photocatalysis was performed using the Bi₂S₃, Bi₂S₃/ZnO, and Bi₂S₃/TiO₂ thin film combinations, which resulted in the degradation of Congo red increasing from 8.89% to 30.80% after a 30 min exposure to sunlight. Full article

Due to a wide band gap and large exciton binding energy, zinc oxide (ZnO) is currently receiving much attention in various areas, and can be prepared in various forms including nanorods, nanowires, nanoflowers, and so on. The reliability of ZnO produced by a single dopant is unstable, which in turn promotes the development of co-doping techniques. Co-doping is a very promising technique to effectively modulate the optical, electrical, magnetic, and photocatalytic properties of ZnO, as well as the ability to form various structures. In this paper, the important advances in co-doped ZnO nanomaterials are summarized, as well as the preparation of co-doped ZnO nanomaterials by using different methods, including hydrothermal, solvothermal, sol-gel, and acoustic chemistry. In addition, the wide range of applications of co-doped ZnO nanomaterials in photocatalysis, solar cells, gas sensors, and biomedicine are discussed. Finally, the challenges and future prospects in the field of co-doped ZnO nanomaterials are also elucidated. Full article

Results obtained in physics, chemistry and materials science on nanoparticles have drawn significant interest in the use of nanostructures on dental implants. The main focus concerns nanoscale surface modifications of titanium-based dental implants in order to increase the surface roughness and provide a better bone–implant interfacial area. Surface coatings via the sol–gel process ensure the deposition of a homogeneous layer of nanoparticles or mixtures of nanoparticles on the titanium substrate. Nanotubular structures created on the titanium surface by anodic oxidation yield an interesting nanotopography for drug release. Carbon-based nanomaterials hold great promise in the field of dentistry on account of their outstanding mechanical properties and their structural characteristics. Carbon nanomaterials that include carbon nanotubes, graphene and its derivatives (graphene oxide and graphene quantum dots) can be used as coatings of the implant surface. Their antibacterial properties as well as their ability to be functionalized with adequate chemical groups make them particularly useful for improving biocompatibility and promoting osseointegration. Nevertheless, an evaluation of their possible toxicity is required before being exploited in clinical trials. Full article

Carbon aerogels represent a distinctive category of high surface area materials derived from sol-gel chemistry. Functionalizing these aerogels has led to the development of composite aerogels with the potential for a wider range of applications. In this study, the technique of lyophilization was employed to fabricate aerogel composites consisting of inorganic salts and cellulosic fibers. Cellulose carbonization can occur through chemical dehydration by heat treatment in an inert atmosphere. X-ray diffraction analysis spectra and scanning electron microscopy images indicate that the formed polymeric composites contain partially carbonized cellulose fibers, amorphous carbon, and calcium carbonates. CaCO₃ primarily forms through the reaction of CaCl₂, which moistens cellulose or amorphous carbon fibers with CO₂ in ammonia fumes. The water loss in 3D structures was analyzed using thermogravimetric analysis, Fourier Transform Infrared Spectroscopy, and ultraviolet-visible-near-infrared spectroscopy. Depending on the synthesis method, 3D structures can be created from partially or completely dehydrated cellulose fibers. The aerogels were examined for their ability to support the growth of bacterial biofilm and then adorned with metal silver and AgCl to produce bactericidal products. Due to their open pores and CaCO₃ content, these aerogels can serve as durable and environmentally friendly thermal insulators with bactericidal properties, as well as a medium for absorbing acidic gases. Full article

The sol–gel chemistry of silica has long been used for manipulating the size, shape, and microstructure of mesoporous silica particles. This manipulation is performed in mild conditions through controlling the hydrolysis and condensation of silicon alkoxide. Compared to amorphous silica particles, the preparation of mesoporous silica, such as MCM-41, using the sol–gel approach offers several unique advantages in the fields of catalysis, medicament, and environment, due to its ordered mesoporous structure, high specific surface area, large pore volume, and easily functionalized surface. In this review, our primary focus is on the latest research related to the manipulation of mesoporous silica architectures using the sol–gel approach. We summarize various structures, including hollow, yolk-shell, multi-shelled hollow, Janus, nanotubular, and 2D membrane structures. Additionally, we survey sol–gel strategies involving the introduction of various functional elements onto the surface of mesoporous silica to enhance its performance. Furthermore, we outline the prospects and challenges associated with mesoporous silica featuring different structures and functions in promising applications, such as high-performance catalysis, biomedicine, wastewater treatment, and CO₂ capture. Full article