Search Results (14)

Novel AB-Polybenzimidazole (AB-PBI)/TiO₂ nanocomposite membranes have been prepared using a synthetic green chemistry approach. Modified Eaton’s reagent (methansulfonic acid/P₂O₅) was used as both reaction media for microwave-assisted synthesis of AB-PBI and as an efficient dispersant of partially agglomerated titanium dioxide powders. Composite membranes of 80 µm thickness have been prepared by a film casting approach involving subsequent anti-solvent inversion in order to obtain porous composite membranes possessing high sorption capacity. The maximal TiO₂ filler content achieved was 20 wt.% TiO₂ nanoparticles (NPs). Titania particles were green synthesized (using a different content of Mentha Spicata (MS) aqueous extract) by hydrothermal activation (150 °C), followed by thermal treatment at 400 °C. The various methods such as powder X-ray diffraction and Thermogravimetric analyses, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Energy-dispersive X-ray spectroscopy, Electronic paramagnetic resonance, Scanning Electron Microscopy and Transmission Electron Microscopy have been used to study the phase and surface composition, structure, morphology, and thermal behavior of the synthesized nanocomposite membranes. The photocatalytic ability of the so-prepared AB-Polybenzimidazole/bio-TiO₂ membranes was studied for decolorization of Reactive Black 5 (RB5) as a model azo dye pollutant under UV light illumination. The polymer membrane in basic form, containing TiO₂ particles, was obtained with a 40 mL quantity of the MS extract, exhibiting the highest decolorization rate (96%) after 180 min of UV irradiation. The so-prepared AB-Polybenzimidazole/TiO₂ samples have a powerful antibacterial effect on E. coli when irradiated by UV light. Full article

This study investigated the valorization of Ilex guayusa leaves by producing a low-caffeine, antioxidant-rich product through the supercritical antisolvent extraction (SAE) process. The objective was to concentrate the antioxidants while selectively reducing the caffeine. The SAE treatments were conducted using an ethanolic extract of guayusa leaves under varying pressure (80 bar–150 bar) and temperature (35–45 °C) conditions to improve the recovery of chlorogenic acid (CGA) and caffeine fractionation. The co-precipitation of antioxidants with polyvinylpyrrolidone (PVP) (ratio 1:1–1:2 mass/mass) as an encapsulant was also studied. The SAE precipitates were analyzed for their recovery yield, CGA and caffeine contents, antioxidant activity, and total phenols. Based on the statistical analysis, the optimal conditions for the SAE were 120 bar and 45 °C. Under these conditions, the CGA concentration increased from 43.02 mg/g extract to 237 mg/g precipitate, while the caffeine was reduced to less than 1% mass. Co-precipitation with PVP improved the recovery yield by more than two times than the SAE alone while maintaining the caffeine content below 1% mass. Additionally, the co-precipitation with PVP facilitated the formation of spherical microparticles, indicating successful encapsulation of the bioactive compounds, with an IC₅₀ of 0.51 ± 0.01 mg/mL for DPPH and 0.18 ± 0.01 mg/mL for ABTS. These results highlight the effectiveness of the SAE co-precipitation process in developing low-caffeine functional ingredients with potential food and pharmaceutical applications. Full article

In recent years, concerns about the harmful effects of synthetic UV filters on the environment have highlighted the need for natural sun blockers. Lignin, the most abundant aromatic renewable biopolymer on Earth, is a promising candidate for next-generation sunscreen due to its inherent UV absorbance and its green, biodegradable, and biocompatible properties. Lignin’s limitations, such as its dark color and poor dispersity, can be overcome by reducing particle size to the nanoscale, enhancing UV protection and formulation. In this study, 100–200 nm lignin nanoparticles (LNPs) were prepared from various biomass by-products (hardwood, softwood, and herbaceous material) using an eco-friendly anti-solvent precipitation method. Pure lignin macroparticles (LMPs) were extracted from beech, spruce, and wheat straw using an ethanol–organosolv treatment and compared with sulfur-rich kraft lignin (KL). Sunscreen lotions made from these LMPs and LNPs at various concentrations demonstrated novel UV-shielding properties based on biomass source and particle size. The results showed that transitioning from the macro- to nanoscale increased the sun protection factor (SPF) by at least 2.5 times, with the best results improving the SPF from 7.5 to 42 for wheat straw LMPs and LNPs at 5 wt%. This study underscores lignin’s potential in developing high-quality green sunscreens, aligning with green chemistry principles. Full article

A facile and low-cost strategy to fabricate CsPbBr₃ single crystals is essential for developing perovskite optoelectronic devices. Herein, we have presented a room temperature anti-solvent precipitate method for growing sub-centimeter-sized CsPbBr₃ single crystals. The as-prepared CsPbBr₃ single crystal has an orthorhombic structure, and phase transition occurs as the measured temperature increases. The as-grown CsPbBr₃ single crystal also shows abundant surface morphologies including footsteps, precipitated crystals, cracks, and pits. Subsequently, a metal–semiconductor–metal (MSM)-structured photodetector was fabricated based on the CsPbBr₃ single crystal. Under 525 nm green light illumination, the photodetector exhibits an obvious response and the photocurrent linearly increases with the increase in the light intensity. The rise time of the photodetector increases from 0.82 s to 2.19 s as the light intensity is enhanced from 15 mW/cm² to 160 mW/cm², indicating that more time is required to reach to a stable photocurrent. However, the decay time is as fast as ~0.82 ms, irrelevant of the light intensity. The photocurrent, under continuous light illumination, was further studied and this indicates that a stronger light intensity can accelerate the attenuation of the device. Full article

Lignin, a main byproduct from paper manufacturing and biorefineries, is now emerging as a new low-cost, renewable starting material for new product development. Its biocompatibility and safety make it valuable for creating novel and value-added products. Lignin, a polymer with many hydrophilic and active groups, confers many useful properties. However, there are several challenges to overcome due to its complex chemical structure and heterogeneous self-assembly behavior. Nanostructured systems using lignin could address these challenges, finding applications in food science, cosmetics, and healthcare. This study explores two main green synthesis approaches for lignin nanoparticles: bottom-up based on the self-assembly in a solvent–antisolvent system and top-down based on the ultrasonication. These nanoparticles are evaluated for morphology, estimation of phenolic content and antioxidant effects. Specifically, the antisolvent nanostructures show a spherical conformation with a higher antioxidant activity due to a better organization of phenolic hydroxyl groups. Obtained result have been exploited to draw an efficient and cheap technological route for lignin valorization. Full article

The excessive use of synthetic pesticides has detrimental impacts on humans, non-target organisms, and the environment. Insect pest management strategies are shifting toward biopesticides, which can provide a feasible and environmentally friendly green solution to the pest problem. The key objective of the present research work was the preparation of Mentha piperita-based nanobiopesticides with enhanced stability, solubility, and pesticidal potential. Nanobiopesticides based on the Mentha piperita extract were prepared using the antisolvent precipitation method. The central composite design of response surface methodology (RSM) was utilized to optimize different process parameters, e.g., the amounts of the stabilizer and plant extract. The nanosuspension of Mentha piperita prepared with the stabilizer SLS showed a particle size of 259 nm and a polydispersity index of 0.61. The formulated biopesticides in the form of nanosuspensions showed good antibacterial activities as compared to the Mentha piperita extract against two phytopathogenic bacterial strains, Clavibacter michiganensis and Pseudomonas syringae. The M. piperita nanosuspension had higher antifungal efficacy against A. niger and F. oxysporum than the Mentha piperita extract. The M. piperita extract and its nanosuspensions were tested for pesticidal activity against the stored-grain insects Tribolium castaneum and Sitophilus oryzae. Mentha piperita-based nanobiopesticides demonstrated significantly high (p  <  0.05) average mortality of 84.4% and 77.7% against Tribolium castaneum and Sitophilus oryzae, respectively. Mentha piperita-based nanobiopesticides showed enhanced pesticidal potential and could be used as a good alternative to synthetic chemical pesticides. Full article

The feasibility of replacing toxic chlorobenzene antisolvents with environmentally friendly anisole in the fabrication of planar triple-cation perovskite solar cells was explored here. The successful integration of anisole not only ensures comparable device performance but also contributes to the development of more sustainable and green fabrication processes for next-generation photovoltaic technologies. Nevertheless, to ensure the possibility of achieving well-functioning unencapsulated devices whose working operation depends on outdoor atmospheric conditions, we found that adjusting the cesium concentrations in the perovskite layers enabled the electrical characterization of efficient devices even under high relative humidity conditions (more than 40%). We found that 10% of CsI in the precursor solution will make devices with low hysteresis indexes and sustained performance stability over a 90-day period both with cholorobenzene and anisole antisolvent. These results further confirm that green anisole can replace chlorobenzene as an antisolvent. Full article

Phenolic compounds from propolis extract (PE) have antioxidant and antimicrobial properties; however, extracts from this raw material are not water soluble. This study aimed to stabilize the phenolic compounds from green propolis extract in cassava and potato starch nanoparticles produced by the anti-solvent precipitation method. The obtained materials displayed a crystalline structure related to starch nanomaterials with a V_6h-type crystalline structure. The starch nanoparticles interacted with the phenolic compounds by means of hydrogen bonds and increased the hydrophobicity in the nanomaterials. The developed starch nanomaterials loaded with the phenolic compounds from PE could be potentially used as a novel ingredient in food packaging. Full article

In recent years, all-inorganic cesium lead bromide (CsPbBr₃) perovskites have garnered considerable attention for their prospective applications in green photonics and optoelectronic devices. However, the development of efficient and economical methods to obtain high-quality micron-sized single-crystalline CsPbBr₃ microplatelets (MPs) has become a challenge. Here, we report the synthesis of CsPbBr₃ MPs on Si/SiO₂ substrate by optimizing the ultrafast antisolvent method (FAS). This technique is able to produce well-dispersed, uniformly sized, and morphologically regular tetragonal phase single crystals, which can give strong green emission at room temperature, with excellent stability and excitonic character. Moreover, the crystals demonstrated lasing with a whispering gallery mode with a low threshold. These results suggest that the single-crystalline CsPbBr₃ MPs synthesized by this method are of high optical quality, holding vast potential for future applications in photonic devices. Full article

Mixed Ni-Al oxide catalytic precursors with different elemental ratios (20, 50, and 80 wt.% Ni⁰) were synthesized using green supercritical antisolvent co-precipitation (SAS). The obtained oxide precursors and metal catalysts were characterized in detail by X-ray diffraction (XRD) analysis, atomic pair distribution function (PDF) analysis, CO adsorption, and high-resolution transmission electron microscopy (HRTEM). It was found that the composition and structure of the Ni-Al precursors are related to the Ni content. The mixed Ni_1−xAl_xO oxide with NiO-based crystal structure was formed in the Ni-enriched sample, whereas the highly dispersed NiAl₂O₄ spinel was observed in the Al-enriched sample. The obtained metal catalysts were tested in the process of anisole H₂-free hydrogenation. 2-PrOH was used as a hydrogen donor. The catalyst with 50 wt.% Ni⁰ demonstrated the highest activity in the hydrogenation process. Full article

Lignin nanoparticles (LNP) with various morphologies could be prepared with solvent–antisolvent methods. However, the employed toxic chemicals limited its large-scale application. In this study, an extremely green method using only ethanol and water as solvent and antisolvent was reported. Besides, with the syringaldehyde (SA) addition and its anchoring action on the lignin particles, a forming process of the tailed structure was observed and resulted. Moreover, the improved electronegativity originating from the phenolic hydroxyl groups enhanced the size distribution uniformity, and the new absorption peaks at 1190 cm⁻¹ demonstrated the involvement of SA in the LNP formation. Lastly, the tailed lignin nanoparticles (T-LNP) composited with, respectively, polyvinyl alcohol, chitosan, cellulose nanofibers, cationic etherified starch, and sodium alginate were successfully prepared. The outstanding UV-shielding and free radical scavenging properties in the above composites showed their great potential in wide applications in packaging materials. Full article

All-inorganic metal halide perovskite nanocrystals (IPeNCs) have become one of the most promising luminescent materials for next-generation display and lighting technology owing to their excellent color expression ability. However, research on IPeNCs with stable blue emission is limited. In this paper, we report stable blue emissive all-bromide IPeNCs obtained through a modified ligand-assisted reprecipitation method using an ultraviolet (UV)-curable prepolymer as the anti-solvent at a low temperature. We found that the blue emission originates from quantum-confined CsPbBr₃ nanoparticles formed together with the colorless wide-bandgap Cs₄PbBr₆ nanocrystals. When the temperature of the prepolymer was increased from 0 to 50 °C, CsPbBr₃ nanoparticles became larger and more crystalline, thereby altering their emission color from blue to green. The synthesized all-bromide blue-emitting IPeNC solution remained stable for over 1 h. It also remained stable when it was mixed with the green-emitting IPeNC solution. By simply exposing the as-synthesized IPeNC–prepolymer solutions to UV light, we formed water-stable composite films that emitted red, green, blue, and white colors. We believe that this synthetic method can be used to develop color-emitting composite materials that are highly suitable for application as the color conversion films of full-color liquid crystal display backlight systems and lighting applications. Full article

Lavandula stoechas subsp. luisieri is a Spanish subspecies from the Lamiaceae family. Its essential oil has been traditionally used for several medical applications though little is known about other extracts. Similar to many other studies aiming to obtain traditional plant extracts to be used in different applications, this work evaluated the antioxidant and antimicrobial activities of Lavandula luisieri extracts and the correlation with their composition. Traditional hydrodistillation and ethanolic maceration were used to obtain the essential oil and the maceration extract, respectively. A green and sustainable methodology was applied to the maceration extract that was under a Supercritical Antisolvent Fractionation process to obtain a fine solid enriched in rosmarinic acid and the terpenes oleanolic and ursolic acids. Antimicrobial activities of all extracts and pure identified compounds (rosmarinic and ursolic acids) were evaluated against five bacterial strains; Listeria monocytogenes, Enterococcus faecium, Staphylococcus aureus, Salmonella Typhimurium and Escherichia coli and were compared with the pure compounds identified, rosmarinic and ursolic acids. All strains were sensitive against L. luisieri essential oil. The solid product obtained from the supercritical process was concentrated in the identified actives compared to the maceration extract, which resulted in higher antimicrobial and DPPH scavenging activities. The supercritical sustainable process provided L. luisieri compounds, with retention of their antimicrobial and antioxidant activities, in a powder exemptof organic solvents with potential application in the clinical, food or cosmetic fields. Full article

In the present work, four green processes have been compared to evaluate their potential to obtain rosemary extracts with in vitro anti-proliferative activity against two colon cancer cell lines (HT-29 and HCT116). The processes, carried out under optimal conditions, were: (1) pressurized liquid extraction (PLE, using an hydroalcoholic mixture as solvent) at lab-scale; (2) Single-step supercritical fluid extraction (SFE) at pilot scale; (3) Intensified two-step sequential SFE at pilot scale; (4) Integrated PLE plus supercritical antisolvent fractionation (SAF) at pilot scale. Although higher extraction yields were achieved by using PLE (38.46% dry weight), this extract provided the lowest anti-proliferative activity with no observed cytotoxic effects at the assayed concentrations. On the other hand, extracts obtained using the PLE + SAF process provided the most active rosemary extracts against both colon cancer cell lines, with LC₅₀ ranging from 11.2 to 12.4 µg/mL and from 21.8 to 31.9 µg/mL for HCT116 and HT-29, respectively. In general, active rosemary extracts were characterized by containing carnosic acid (CA) and carnosol (CS) at concentrations above 263.7 and 33.9 mg/g extract, respectively. Some distinct compounds have been identified in the SAF extracts (rosmaridiphenol and safficinolide), suggesting their possible role as additional contributors to the observed strong anti-proliferative activity of CA and CS in SAF extracts. Full article