Search Results (143)

In this study, using 70% anhydrous ethanol as the extraction solvent, Moringa oleifera Lam. seed powder was extracted with the microwave-assisted extraction method, followed by purification using macroporous adsorbent resin NKA-9. The purified glucosinolate was subsequently hydrolyzed with myrosinase. The glucosinolate and its enzymatic product were identified as 4-(α-L-rhamnopyranosyloxy) benzyl glucosinolate (4-RBMG) and benzyl isothiocyanate (BITC) by UV–Vis, FT-IR, NMR, and MS. The bioactivities, including anti-oxidation, anti-inflammation, and anti-tumor activities of 4-RBMG and BITC, were systematically evaluated and compared. The results show that at 5–20 mg/mL, the anti-oxidation effects of 4-RBMG on DPPH and ABTS free radicals are superior to those of BITC. However, at the same concentrations, BITC has stronger anti-inflammatory and anti-tumor activities compared to 4-RBMG. Notably, at a concentration of 6.25 μmol/L, BITC significantly inhibited NO production with an inhibitory rate of 96.67% without cytotoxicity. Additionally, at a concentration of 40 μmol/L, BITC exhibited excellent inhibitory effects on five tumor cell lines, with the cell inhibitory rates of leukemia HL-60, lung cancer A549, and hepatocellular carcinoma HepG2 exceeding 90%. This study provides some evidence that the enzymatic product, BITC, shows promise as a therapeutic agent for tumor suppression and inflammation reduction. Full article

Accumulation of ferrous sulfate residue (FSR) not only occupies land but also results in environmental pollution and waste of iron resource; thus, recycling of iron from FSR has attracted widespread concern. To this end, this article shows fabrication and system analysis of hematite (HM) nanoparticles from FSR via microwave-assisted reduction technology. Physicochemical properties of HM nanoparticles were investigated by multiple analytical techniques including X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet visible (UV-Vis) spectrum, vibrating sample magnetometer (VSM), and the Brunauer–Emmett–Teller (BET) method. Analytic results indicated that the special surface area, pore volume, and pore size of HM nanoparticles with the average particle size of 45 nm were evaluated to be ca. 20.999 m²/g, 0.111 cm³/g, and 0.892 nm, respectively. Magnetization curve indicated that saturation magnetization Ms for as-synthesized HM nanoparticles was calculated to be approximately 1.71 emu/g and revealed weakly ferromagnetic features at room temperature. In addition, HM nanoparticles exhibited noticeable light absorption performance for potential applications in many fields such as electronics, optics, and catalysis. Hence, synthesis of HM nanoparticles via microwave-assisted reduction technology provides an effective way for utilizing FSR and easing environmental burden. Full article

A stereoselective and scalable strategy for the synthesis of phosphorus-containing bicyclic and tricyclic compounds from 1-phenylphosphin-2-en-4-one 1-oxide is presented. This activated dienophile, available in both racemic and enantiopure forms, undergoes smooth [4+2] cycloadditions with acyclic and cyclic dienes, affording products with excellent yields and controlled stereochemistry. Notably, the cis/trans-fusion of the cycloadducts (phosphadecalones and phosphahexahydrochrysene) can be selectively controlled by fine-tuning the conditions of microwave-assisted cycloaddition reaction. The influence of temperature, time, and steric effects on cis/trans and endo/exo selectivity was examined in detail. The molecular structure, including the absolute configuration, of eight products has been determined by X-ray crystallography. These analyses further established the endo-selective nature of the cycloaddition, favoring the P=O face of the dienophile. Post-cycloaddition transformations of selected P-stereogenic phosphadecalone, such as isomerization, reduction and deoxygenation, demonstrate the synthetic versatility of the resulting products. Full article

In this study, microwave-assisted extraction (MAE) was performed to recover antioxidant hemp seed oil (HSO) with the purpose of developing polybutylene succinate (PBS)/HSO-based films for active packaging to improve food shelf-life. It was found that MAE achieved comparable yields, structural characteristics, and antioxidant activity to Soxhlet extraction, but in significantly less time (2.5 min vs. 6 h). PBS-based films with 0.5 and 1 wt% HSO were prepared by compression molding. Morphological investigation of the PBS-HSO films highlighted uniform oil droplet dispersion and good compatibility. HSO reduced PBS crystallinity but did not affect the α-form of PBS. Thermal analysis showed reductions in T_m and T_c, whereas T_g remained unchanged at −17 °C. PBS containing 1 wt% HSO exhibited a 42% decrease in Young’s modulus, 47% reduction in elongation at break, and 47% decrease in tensile strength due to the plasticizing effect of the oil and, which reduced the intermolecular forces and facilitated polymer chain disentanglement, in agreement with the FTIR analysis, which showed a distinct broadening of the carbonyl stretching region associated with the amorphous phase (1720–1730 cm⁻¹) in the PBS-HSO films compared to neat PBS. Migration tests showed that the films are unsuitable for fatty foods but safe for aqueous, acidic, and alcoholic foods. Full article

The present research aimed to extract antioxidants from the fumitory aerial part in the flowering stage (containing leaves, stems, and flowers) by performing traditional and novel extraction procedures (maceration, ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE)). The fumitory macerate showed significantly lower ABTS radical scavenging activity, expressed as a higher IC₅₀ value (the concentration of extract required to neutralize 50% of radicals, 11.4 ± 0.1 mg/mL), in comparison to the other two extracts, whose IC₅₀ values varied in a narrow range (8.6–9.5 mg/mL). In the DPPH assay, the trend was different: MAE (11.4 ± 0.3 mg/mL) ≥ UAE (12.0 ± 0.8 mg/mL) ≥ macerate (12.8 ± 0.1 mg/mL). In the CUPRAC assay, the UAE and MAE extracts (17.84 ± 0.85 and 18.05 ± 0.71 µmol Trolox equivalents (TE)/g, respectively) showed significantly higher antioxidant activity compared to the macerate (16.43 ± 0.45 µmol TE/g). Regarding the results of the FRAP method, there was no statistically significant difference in ferric ion reduction between the macerate, UAE, and MAE extracts (3.00–3.27 µmol Fe²⁺/g). However, the extract prepared using MAE provided the highest antioxidant potential, as shown in all four tests used. Due to demonstrated extracts’ antioxidant properties, additional research could address additional biological effects or the creation of delivery systems or encapsulates for the controlled delivery of fumitory bioactives. Full article

The growing production of polyurethane foam (PUF) and increasing global PUF waste generation urges the development of a circular economy strategy to promote the recovery of its raw materials, namely polyether polyols, in a sustainable and economically feasible way. This work assesses the promising microwave-assisted PUF aminolysis technology from three different perspectives: (a) evaluating the experimental feasibility and characteristics of the recycled products; (b) modeling an industrially relevant holistic process based on experimental findings to assess energy requirements and c) comparing the environmental impacts ascribed to the production of virgin vs. recycled polyols. The most relevant findings are as follows: (1) the recycled polyols out of MW-aminolysis are indistinguishable from virgin polyols; (2) the potential energy consumption of the overall process (including post-processing steps) for a continuous PUF depolymerization process with a 14.8 kg/h RP production capacity is as low as 1.9 kWh/kg RP and (3) recycled polyols have a substantially lower environmental footprint than virgin polyols in all selected impact categories, ranging from a reduction in CO₂ emissions (38% decrease) to water consumption (74% decrease). These results and analyses pave the way for enhancing material circularity in the PU sector. Full article

We report a method for synthesizing different phases of samarium–cobalt particles through microwave-assisted combustion combined with high-temperature reduction and diffusion, and identify the optimal temperature for forming the 1:5 phase using this approach. Initially, the samarium-to-cobalt ratio in a nitrate solution was determined. Using urea as both a reductant and fuel, samarium–cobalt oxides were synthesized via microwave-assisted combustion. The main components of the oxides were confirmed to be SmCoO₃ and Co₃O₄. Subsequently, samarium–cobalt particles were synthesized at various diffusion temperatures. The results indicate that at 700 °C, the oxides were reduced to elemental Sm and Co. As the reduction temperature increased, the alloying of samarium and cobalt occurred, and the particle size gradually increased. At 900 °C, a pure 1:5 phase was formed, with particle sizes of approximately 800 nm, a coercivity of 35 kOe, and a maximum energy product of 14 MGOe. Based on the microwave-assisted combustion method, this study clarifies the transition temperatures of samarium–cobalt phases during the reduction and diffusion process, and further establishes the synthesis temperature for the 1:5 phase, providing new insights into the preparation and development of samarium–cobalt materials and potentially other rare earth materials. Full article

A solvent-free, microwave-assisted approach for the ring-opening reactions of phenyl glycidyl ether with a series of commercially available imidazoles and pyrazoles is described. Microwave irradiation allows reactions to proceed rapidly. This straightforward approach efficiently generated adducts with competitive yields compared to traditional methods that use conventional heating or organic solvents. This technique is particularly suited for high-throughput screening in drug discovery, offering a significant reduction in time and resource consumption. Full article

Electric arc furnace dust (EAFD) is a zinc-containing solid waste generated during steelmaking, and advanced recycling strategies are needed to facilitate the recovery of valuable zinc. This study investigated the microwave-assisted carbothermic reduction in EAFD using coke as a reductant, with a focus on temperature (900–1100 °C), holding time (0–60 min), and the C/Zn molar ratio (3–5). The results demonstrated that the zinc removal rate exhibited positive correlations with both temperature and time. Under optimized conditions (1100 °C, 60 min), a zinc removal rate of 95.45% was achieved, accompanied by a complete decomposition of the ZnO phases. Furthermore, increasing the C/Zn molar ratio enhanced the zinc recovery efficiency and product purity. Isothermal kinetic analyses indicated that the reaction proceeds in two stages: during the initial stage (0–30 min), the process was governed by three-dimensional diffusion control with an activation energy of 146.50 kJ/mol, while the final stage (30–60 min) transitioned to chemical reaction control with an activation energy of 267.32 kJ/mol. Comparative assessments indicated that microwave processing significantly reduced the activation energy compared to conventional heating methods. These findings suggest that microwave-assisted reduction is capable of attaining a high-grade recovery of Zn from EAFD, thus opening up new avenues for the resource-oriented utilization of EAFD. Full article

This study presents the development and evaluation of a microwave-assisted prototype for scalable red palm oil production. The prototype, equipped with industrial magnetrons delivering a combined power of 2 kW, is designed to process up to 6 kg of oil palm fruit per batch. The design, optimized using COMSOL Multiphysics simulations, focused on waveguide configurations and cavity dimensions to ensure uniform energy distribution and minimize hotspots. Performance testing validated the system’s capability to deliver consistent heating across six trays and produce high-quality red palm oil. Results demonstrated a significant reduction in free fatty acid (FFA) content from 20.4% to 2.1% while retaining carotene content within the industrial standard range (558.2 ppm). The Deterioration of Bleachability Index (DOBI) showed a slight reduction but remained within acceptable limits, underscoring the prototype’s ability to maintain oil clarity and processability. Microwave heating effectively inactivated lipase enzymes, reducing FFA and enhancing oil stability, as confirmed by previous studies. The chemical-free process preserved essential nutrients, aligning with sustainability goals. This innovative system provides a scalable, energy-efficient solution for community and industrial applications, offering improved product quality with minimal environmental impact. Future work will focus on optimizing the system further and exploring its applications in broader agricultural processing contexts. Full article

This study investigates the valorization of tomato by-products—peels, seeds, and juice—through innovative extraction and bioprocessing techniques. Lycopene recovery from tomato peels was optimized using ultrasound- and microwave-assisted extraction (UAE-MAE) with ethyl lactate as the solvent. The optimal conditions (0.03 g/mL, 500 W microwave power, 600 W ultrasound power) yielded a lycopene content of 37.08 mg/100 g of peels and an extraction yield (EY) of 91.20%. For tomato seeds, oil extraction methods, including conventional stirring, UAE-MAE, Soxhlet extraction, and pressurized liquid extraction (PLE), were evaluated. Conventional stirring achieved the highest oil yield (19.66%), followed closely by UAE-MAE (19.53%). However, PLE produced the highest lycopene content (44.0 mg/100 g oil) and significant levels of linoleic acid (544.7 mg/g oil), though Soxhlet extraction yielded slightly more (608.9 mg/g oil). Tomato juice was processed into high-nutritional value vinegar via a two-stage fermentation process. The final product had 5.42% acidity, a pH of 2.85, and retained a high lycopene content (9.19 mg/100 g). This study underscores the potential of innovative extraction and bioprocessing strategies for the valorization of tomato by-products, promoting waste reduction and the development of high-value functional products in alignment with principles of the circular bioeconomy. Full article

The rapid detoxification and mineralization of Cr(VI) in aqueous environments hold critical importance for emergency response and resource recovery yet remain technically challenging. Herein, we report the synthesis of FeS₂/ZVI composites through ethanol-assisted wet ball-milling and their application in Cr(VI) removal under microwave (MW) irradiation. This study systematically investigates the effects of MW irradiation on the removal efficiency of Cr(VI) using FeS₂/ZVI composites, with particular focus on key parameters including composite dosage, initial pH, MW temperature, and Cr(VI) concentration. Notably, 1 g/L FeS₂/ZVI composites achieved near-complete removal (>99%) of 50 mg/L Cr(VI) within 7 min at a MW irradiation temperature of 333 K, which exhibited 5.9-fold and 13.1-fold superior performance compared to pure pyrite and ZVI, respectively. Additionally, there is a 96.1% reduction in reaction time in comparison to non-MW irradiation system. In real electroplating wastewater samples, Cr(VI) concentration was reduced from 38.93 to 0.42 mg L⁻¹ by MW irradiation-assisted treatment, validating its potential for practical applications in industrial Cr(VI) pollution control. The activation energy determined by fitting the Arrhenius equation showed a 39.7% reduction for the MW-assisted FeS₂/ZVI system (16.0 kJ mol⁻¹) compared to conventional thermal heating (from 25.6 kJ mol⁻¹), indicating that MW irradiation induced catalytic enhancement of FeS₂/ZVI, thereby lowering the energy barrier for Cr(VI) reduction. Moreover, MW irradiation-assisted processes facilitated the mineralization of reduced Cr(III) to stable spinel FeCr₂O₄. These findings collectively establish a synergistic mechanism between MW activation and FeS₂/ZVI composites, offering innovative pathways for efficient Cr(VI) detoxification and resource recovery from high-strength industrial wastewaters. Full article

The banana weevil (Cosmopolites sordidus) is a significant pest that reduces banana yields and can result in plant mortality. (2R,5S)-theaspirane, a kairomone from senesced banana leaves, is one of the natural banana volatiles, aiding weevil attraction. A rapid and cost-effective synthesis of (2R,5S)-theaspirane was developed utilizing microwave-assisted conditions and the principles of green chemistry. The process comprised five steps, beginning with the reduction of dihydro-β-ionone, followed by lipase-mediated kinetic resolution to attain high enantiomeric excess. Microwave-assisted heating significantly reduced reaction times. Optimized cyclization with the minimum quantities of selenium dioxide oxidation was employed. The final diastereomers were separated by chromatography, yielding compounds which exceeded 99% enantiomeric purity. Full article

Blackberries (Rubus fructicosus L.) are categorized as functional foods, as they are rich in bioactive compounds. Due to limited shelf life and susceptibility to postharvest quality deterioration, it is imperative to investigate postharvest interventions that can prolong the fruit’s quality. This research aimed to develop sonicated and microwave-assisted pasteurized (SMAP) edible gels with citrus peel essential oil (CPEO). Additionally, we aimed to evaluate the effects of different temperatures (4, 20 and 30 °C) on the postharvest quality of the following blackberry treatments:control (C), blanched (B), coated (SMAP) and blanched + coated (B+SMAP). The synergistic effect of B+SMAP coating gels was more effective at maintaining the quality of blackberries after 21 days in storage by inhibiting fruit weight loss by 18% and fruit decay by 65% compared to the control group at 4 °C. The SMAP-coated fruits limited total flavonoid reduction by 23% and total flavanols by 24% when stored at 4 °C after 21 days. The B+SMAP treatment hindered the loss of total phenolic content by 16%, total antioxidant activity by 27% and DPPH radical scavenging activity by 19% under storage at 4 °C for 21 days. We concluded that the SMAP coating gel is an innovative and health-friendly approach for extending the postharvest quality of blackberries during storage. Full article

Metal nanoparticles supported in carbon materials are the traditional electrocatalyst currently used in many applications. However, these composite materials have many problems associated with the optimization of both components for the specific application, besides the stability of the mixture. Self-supported metallic materials may be an interesting strategy in order to avoid the traditional carbon supports; however, these metallic materials should present highly active surface area. Iron aerogels are presented in this work as effective and affordable unsupported electrocatalysts. The combination of their metallic structure with high porosity (i.e., 85 m² g⁻¹ and 0.45 cm³ g⁻¹ of mesopore volume), due to their interconnected tridimensional structure, leads to a great activity versus the oxygen reduction reaction. A method for producing iron aerogels based on microwave-assisted sol–gel methodology is presented. The incorporation of carbon functionalities to the iron aerogels seems to clearly influence the mechanism of the reaction, favoring the direct mechanism of the oxygen reduction reaction and thus notably improving the performance of the electrocatalysts. Chemical vapor deposition seems to be an adequate methodology for incorporating carbon functionalities to the transition metal structure without affecting the tridimensional network and leading to current densities over 4 mA cm⁻² and great stability even after 10,000 s. Full article