Microwave Assistance Research Articles

A Review on Environment-friendly Protocol for the Synthesis of Pyrazole Derivative

: Pyrazole derivatives are a significant group of heterocyclic compounds that have a diverse variety of biological activities and are used in several fields, such as medicines, agrochemicals, and materials research. Conventional methods for synthesizing pyrazole derivatives typically require severe reaction conditions, hazardous reagents, and environmentally harmful solvents, presenting considerable obstacles to achieving sustainable chemistry. This analysis specifically examines the latest progress made in creating environmentally friendly procedures for producing pyrazole derivatives. The study investigates different strategies in green chemistry, such as reactions without solvents, techniques including microwave and ultrasonic assistance, and using renewable resources and environmentally friendly catalysts. An in-depth analysis is conducted to evaluate the efficiency, selectivity, and environmental impact of these approaches. This review intends to comprehensively explore the potential for sustainable practices in synthesizing pyrazole derivatives by emphasizing advancements in green synthetic methods. It seeks to encourage further research and use of green chemistry concepts in heterocyclic chemistry.

Microwave-assisted Synthesis of Pyrroles, Pyridines, Chromenes, Coumarins, and Betti Bases via Alcohol Dehydrogenation with Chroman-4-one Amino Ligands

: This study outlines the development of a novel approach utilizing microwave assistance for the alcohol dehydrogenative reaction. The process is catalyzed by manganese (II) and cobalt (II) in conjunction with chroman-4-one amino ligands. This research introduces a unique catalytic system capable of synthesizing various heterocyclic compounds, including pyrroles, pyridines, Betti bases, chromenes, and coumarins via alcohol dehydrogenation. The synthesis involved the preparation and characterization of a series of chroman- 4-one amino ligands (C1-C6) using standard analytical techniques. These ligands, in combination with MnCl2‧4H2O and CoCl2, demonstrated remarkable catalytic activity, effectively driving alcohol dehydrogenation. The catalytic cycle was initiated by the in-situ formation of metal complexes with the ligands during the reaction. Characterization using ESI-MS confirmed the presence of metal complexes (Int-1) and other intermediates (Int-II and Int-III) throughout the catalytic cycle. Additionally, the controlled experiment corroborated the efficacy of the catalytic system, evidenced by the evolution of H2 gas.

Optimization of Microwave-Assisted Polyphenol Extraction and Antioxidant Activity from Papaya Peel Using Response Surface Methodology and Artificial Neural Network

The objective of the present study is to determine the optimal conditions of microwave-assisted extraction (MAE) such as microwave power (MWP), irradiation time (I-time), ethanol concentration (EtOH%), and solvent-to-solid ratio (S/S) for maximizing total polyphenol content (TPC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity from papaya peel. Box-Behnken design (BBD) was used considering MWP 300–600 W, I-time 60-120 s, EtOH% 30-70%, and S/S 30-70 mL/g. Additionally, response surface methodology (RSM) and artificial neural networks (ANN) were employed for modelling, with cross-validation to enhance reliability. These models were combined with the desirability function (DF) and/or genetic algorithm (GA) optimization approaches. Maximizing TPC and DPPH activity while maintaining MWP, I-time, EtOH%, and S/S within their respective ranges using hybrid optimization approaches (RSM-DF: TPC = 1058 mgGAE/100g, and DPPH = 83%, RSM-GA: TPC = 1064 mgGAE/100g and DPPH = 79%, and ANN-GA: TPC = 1086 mgGAE/100g, and DPPH = 83%,) yielded consistent optimal results. An additional optimization approach (RSM-DF: TPC = 955 mgGAE/100g, and DPPH = 90%), aimed at minimizing MWP, I-time, EtOH%, and S/S while maximizing TPC and DPPH activity, showed a significant reduction of approximately 3 L in ethanol consumption for each 100 g of dry samples. The maximized TPC and DPPH activity in all four approaches showed a significant (p < 0.05) alignment with their corresponding validation tests, demonstrating the better performance of these modelling and optimization processes. In terms of assessing the effectiveness of microwave assistance, conventional solvent extraction was also performed, maintaining a 70 mL/g S/S ratio of 55% ethanol at 60°C for 2 h. This method resulted in lower values of TPC (857 ± 23 g GAE/100g) yield and DPPH activity (72 ± 5%) compared to the optimized condition of MAE.

Fast Dissolution of Chitin in Amino Acids Based Deep Eutectic Solvents Under the Assistance of Microwave.

Due to the abundant hydrogen bond networks, high crystallinity, and high molecular weight of chitin, it is difficult to dissolve chitin in most solvents. Meanwhile, most of the existing solvent systems have the disadvantages of high toxicity, low solubility, and high cost. Therefore, the efficient and rapid dissolution of chitin using green solvents is urgently needed. In this work, ternary DES with amino acids, urea, and 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) is prepared at first. Then chitin can be dissolved fastly with the assistance of a microwave. Compared with the conventional heating process (110°C, 6-8h), the microwave process can be shortened to only 3-10min. The successful dissolution of chitin is verified by means of fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), rheology studies, and optical light microscope, and the dissolution mechanism contributed to the synergistic destroying of the hydrogen bond networks of chitin by amino acids and DBU. The DES solvent can be well recovered with the remaining of its dissolving ability to chitin.

Influence of Annealing Temperature on the OER Activity of NiO(111) Nanosheets Prepared via Microwave and Solvothermal Synthesis Approaches.

Earth-abundant transition metal oxides are promising alternatives to precious metal oxides as electrocatalysts for the oxygen evolution reaction (OER) and are intensively investigated for alkaline water electrolysis. OER electrocatalysis, like most other catalytic reactions, is surface-initiated, and the catalyst performance is fundamentally determined by the surface properties. Most transition metal oxide catalysts show OER activities that depend on the predominantly exposed crystal facets/surface structure. Therefore, the design of synthetic strategies to obtain the most active crystal facets is of significant research interest. In this work, rock salt NiO OER catalysts with (111) predominantly exposed facets were synthesized by a solvothermal (ST) method either heated under supercritical or microwave-assisted (MW) conditions. Particular emphasis was placed on the influence of the post annealing temperature on the structural configuration and OER activity to compare their catalytic performances. The as-prepared electrocatalysts are pure α-Ni hydroxides which were converted to rock salt NiO (111) nanosheets with hexagonal pores after heat treatment at different temperatures. The OER activity of the electrodes has been evaluated in 0.1 M KOH using geometric and intrinsic current densities via normalization by the disk area and BET area, respectively. The lowest overpotential at a geometric current density of 10 mA/cm2 is found for samples pretreated by heating between 400 and 500 °C with a catalyst loading of 115 μg/cm2. Despite the very similar nature of the catalysts obtained from the two methods, the ST electrodes show a higher geometric and intrinsic current density for 500 °C pretreatment. The MW electrodes, however, achieve an optimal geometric current density for 400 °C pretreatment, while their intrinsic current density requires pretreatment over 600 °C. Interestingly, pretreated electrodes show consistently higher OER activity as compared to the poorly crystalline/less ordered hydroxide as-prepared electrocatalysts. Thus, our study highlights the importance of the synthesis method and pretreatment at an optimal temperature.

Development of inorganic–organic CdSe(en)0.5via microwave-assisted method and topotactic transformation into porous CdSe nanosheet photoanode for photoelectrochemical hydrogen production

In this study, inorganic–organic hybrid CdSe(en)0.5 nanosheet (NS) was developed on Cd foil via the microwave-assisted (MW) method with different MW irradiation cycles. Furthermore, the photoelectrochemical (PEC) performance of the mother material was improved through a second hydrothermal method with different time variations (3, 6, and 12 h at 160 °C). After the second hydrothermal, organic moieties were removed, and a porous photoanode was obtained. The optimized CdSe-6H photoanode showed a photocurrent density of 7.4 mA cm−2 (0 V vs Ag/AgCl) with 272 μmol cm−2/3h hydrogen gas evolution under one sun illumination. The enhanced PEC performance was attributed to the topotactic transformation, improved light absorbance, enhanced charge separation, and improved surface area. This work offers a rational approach for building inorganic–organic electrodes through the MW method and porous photoanode for PEC hydrogen production.

Microwave-assisted synthesis of solketal from glycerol and acetone in the presence of SAPO-34 and SAPO-5

Solketal is one of the most promising additives improving the properties of motor fuels. Investigations related to process intensification of synthesis of solketal from glycerol and acetone is gaining importance. The present work illustrates the use of the microwave mode for intensification of this process in the presence of silicoaluminophosphates (SAPO) as catalysts. The main focus of the study was placed on tuning the textural, acidic, and catalytic properties of SAPO-34 and SAPO-5 via variation of the synthesis parameters, such as the nature of Al and Si sources and the structure-directing agent. The catalytic properties of SAPO materials were investigated in the synthesis of solketal from glycerol and acetone under microwave assistance at the acetone/glycerol molar ratio of 2.4 in a methanol solution (glycerol/methanol: 1 g/1 mL) and 56 °C. It was demonstrated that the selectivity towards solketal was 91.1–98.6 % in the presence of the studied materials. The activities of mesoporous SAPO-34 and SAPO-5 prepared in the presence of triethylamine were higher as compared with microporous SAPO-34 prepared in the presence of tetraethylammonium hydroxide due to the high mesoporosity and a larger content of acid sites. The 90.4 % conversion of glycerol and 98.6 % selectivity towards solketal were observed in the presence of mesoporous 7.6%SAPO-34 for 90 min. The advantage of using microwave technology is shown. The solketal yield in the reaction under microwave irradiation was 3 times higher than that in the process performed under thermal heating conditions.

WITHDRAWN: rGO@CaO/NiO as a bifunctional heterogeneous nanocatalyst for high-quality biodiesel production from degraded waste oil by microwave-assisted: Diesel engine parameters assessment

In this research, a highly effective rGO@CaO/NiO bifunctional nanocatalyst was synthesized and utilized for the generation of biodiesel from degraded waste oil (DWO) through microwave assistance. A comprehensive analysis was conducted to assess the catalyst structure, revealing a notable specific surface area with significant surface characteristics for the rGO@CaO/NiO bifunctional nanocatalyst. The maximum biodiesel yield was achieved 97.46% under optimum conditions including methanol to oil ratio of 11.1 mol/mol, catalyst content of 3 wt.%, microwave time of 7.5 min, and stirring speed of 700 rpm. The catalyst's reusability was demonstrated through multiple cycles, maintaining high stability and consistent biodiesel yield over seven iterations. The activation energy and exponential factor for the conversion of DWO to biodiesel were determined as 30.91 kJ/mol and 2.3×104 min-1, respectively. The physical attributes of DWO-derived biodiesel revealed that they fall within the ASTM D6751 standard range. The impact of adding biodiesel to petrodiesel/biodiesel blends at various torques on the emission of key pollutants (CO, NOx, CO2, and UHC) and engine performance (BP, EGT, BTE, and BSFC) was investigated, yielding promising results. The rGO@CaO/NiO appears as a superior choice for biodiesel production, offering exceptional reusability, and significant biodiesel efficiency achieved within a short reaction time.

Microwave-assisted synthesis of carbon nanodots from Bombax ceiba leaves for enhanced Tribo-corrosion resistance: An experimental and computational analysis

This study presents a novel method for synthesizing carbon nanodots (BC-CNDs) from Bombax ceiba leaf extract via microwave assistance, yielding cost-effective, biodegradable, and water-soluble nanomaterials. Spectroscopic analysis, including FT-IR, UV–Vis, and fluorescence emission spectrophotometry, revealed the distinctive characteristics of BC-CNDs. Additionally, an anti-corrosive coating (BC-CNDs-C) was formulated by blending BC-CNDs with a plasticizer and binder. Quantitative evaluation of BC-CNDs-C showed an impressive inhibitory rate of 92.55% against corrosion. Electrochemical measurements indicated a notable increase in polarization resistance (Rp values: 1782.2 Ω cm2 for P1 to 4778.3 Ω cm2 for P4) and a decrease in corrosion current density (Icorr values: 0.065 μA/cm2 for P1 to 0.010 μA/cm2 for P4) with the incorporation of BC-CNDs, highlighting their effectiveness in enhancing corrosion resistance. Additionally, structural analyses via scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirmed the reliability of BC-CNDs-C as a corrosion barrier. This research contributes to the development of sustainable materials for corrosion protection, addressing corrosion-related challenges in various industrial applications.

Microwave-assisted Synthesis of Benzimidazole Derivatives: A Green and Effective Approach

Benzimidazole derivatives are pivotal in medicinal chemistry due to their diverse therapeutic applications. Traditional synthesis methods often require catalysts and long reaction times, which can be inefficient and environmentally unfriendly. Hence, there is a growing need for more efficient and eco-friendly synthetic methodologies. A newly devised and efficacious synthetic methodology has been established for the synthesis of benzimidazole derivatives, employing microwave assistance without the requirement for a catalyst. This method facilitated the synthesis of fifteen derivatives with notable efficiency, characterized by significantly reduced reaction times ranging from 5 to 10 minutes and impressive yields ranging from 94% to 98%. The identity and purity of the synthesized benzimidazole derivatives were meticulously verified through a comprehensive analysis, encompassing a comparison of their physicochemical properties and spectral characteristics with authenticated reference data. This method represents a significant advancement in the synthesis of benzimidazole derivatives, offering a rapid and high-yielding alternative to traditional synthetic routes.

Chemical-Functional Analysis of Extracts Obtained from Zuccagnia punctata Powder Using Green Solvents (NaDESs) in Conjunction with Traditional and Non-Traditional Techniques.

Zuccagnia punctata Cav. (Family Fabaceae. Subfamily Caesalpinioideae) is a native plant species with a long history of use in Argentine traditional medicine. The purpose of the present study was to extract bioactive compounds with antioxidant and antifungal activity from Z. punctata aerial parts using conventional solvents (water, ethanol 60°, vegetal oil) and unconventional solvents (natural deep eutectic solvents or NaDESs) such as green solvents with and without the assistance of ultrasound (UAE) and microwaves (MAE). NaDESs such as glucose: lactic acid (LGH), sucrose: citric acid (CAS), choline chloride: urea (CU) and glucose: fructose: sucrose (FGS) were used. LGH and CU were effective in the extraction of phenolic compounds (6710 ± 10.12 µg GAE/mL and 7140 ± 15.00 µg GAE/mL, respectively) as well as ethanol (6270 µg ± 12.00 µg GAE/mL) using conventional methods. Two chemical markers of Z. punctata (2',4'-dihydroxychalcone and 2',4'-dihydroxy -3-methoxychalcone) were extracted in a high proportion in ethanol, oil, LGH and CU with UAE. The ABTS antioxidant capacity was higher in the extracts obtained with LGH and CU (SC50: 0.90 ± 0.10 µg GAE/mL and 1.08 ± 0.16 µg GAE/mL, respectively). The extract obtained with vegetal oil was the most potent as antifungal, followed by the extracts in ethanol, LGH and CU. These findings highlight the importance of using environmentally friendly solvents such as NaDESs to obtain bioactive metabolites from Z. punctata, an endemic plant of Argentina with a potential application in the food, cosmetic and pharmaceutical industries.

White light emission from chiral carbonized polymer dots

A series of novel carbonized polymer dots have been synthesized and characterized via the condensation reaction between curcumin and various amino acids with the assistance of microwave. More strikingly, both CPDs prepared from curcumin and L/D-aspartic acid can emit strong white light in aqueous solution and in doped polyvinylpyrrolidone. The white light emitting diodes based on L-Asp-CPD/PVP and D-Asp-CPD/PVP exhibit the CIE coordinates of (0.36, 0.34) and (0.38, 0.32) at the drive current of 0.12 A, CRI of 84.9 and 89.7, and CCT of 4385 K and 3410 K, respectively. The stability of LED derived from D-Asp-CPD was better than that from L-Asp-CPD at operational time of 5 h and the driven current of 0.02 A.

Biosintesis Nanopartikel ZnO dengan Ekstrak Temu Kunci (Boesenbergia rotunda) Dibantu Gelombang Mikro, Serta Pengujian Aktivitasnya Terhadap Bakteri

Numerous ZnO nanoparticles have been successfully synthesized using diverse plant extracts, yet research utilizing B. rotunda extract as a capping agent with microwave assistance has been lacking. Hence, this study aimed to employ microwave-assisted B. rotunda extract to produce ZnO nanoparticles and test their antibacterial activity. By utilizing 10 mL of 1% (m/v) B. rotunda extract at pH 12.5 and calcinating for 3.8 hours at 200°C, coupled with 20 minutes of microwave treatment, ZnO nanoparticles averaging 78.78 nm in diameter were synthesized. Particle size was determined using the ImageJ software to analyze TEM images. UV-Vis absorption spectroscopy indicated a peak wavelength at 360 nm, while FTIR analysis identified compounds from B. rotunda extract crucial in nanoparticle formation. Antibacterial testing revealed the nanoparticles' ability to create an inhibition zone against E. coli growth.

A matter of extraction – Extraction yields and ratios of faecal lipid biomarker from archaeological soils using Soxhlet, microwave-assisted and accelerated-solvent extraction

The performance of Soxhlet (SOX), microwave-assisted (MAE) and accelerated-solvent extraction (ASE) in the analysis of faecal lipid biomarkers (FLB, Δ5-sterols, stanols, stanones) from archaeological soils was investigated to assess effectiveness and reproducibility of the extraction methods. Results from two Anthrosols that were analysed in six replicates show that SOX achieves significantly higher extraction yields for individual substances and steroid sums than MAE, while ASE produces the lowest lipid yields. Regarding the FLB ratios, which are used for sourcing of faeces, the three extraction methods show comparable values with three out of five ratios differing significantly between different soil samples. The reproducibility of extraction yields decreases with SOX > ASE > MAE, as well as for concentrations <100 ngg−1 sediment. Analyses of six different soils indicate a weak influence of soil properties (pH, texture, total organic carbon and cation exchange capacity) on the effectiveness of extraction methods. From our study we conclude that the classical SOX is still the preferred extraction approach when reliably higher FLB yields are of foremost interest or low concentrations are expected, as it is most effective and reproducible. However, considering the drawbacks of SOX (high extraction times and high solvent consumption), MAE and ASE appear to be comparably attractive for extracting FLBs in archaeological contexts. In addition to comparable FLB ratios, MAE and ASE are economically more efficient, as they reach a higher sample throughput and waste lower amounts of extractant.

Rapid Synthesis and Evaluation of Resveratrol-Piperazine Cocrystals by Ultrasound and Microwave Methods.

Resveratrol-piperazine cocrystals have been obtained by ultrasound (US) and microwave-assisted (MW) techniques, using the solution and slurry-based methods, to study the influence of the synthesis method on the resulting cocrystal properties, and scalability of the processes. The potential of these cocrystals is represented by the unique properties of their components, resveratrol, and piperazine, which could be also used in veterinary practice. Resveratrol has antimicrobial, antiviral and anticarcinogenic properties, while piperazine can be used in the treatment of parasitic infections. The influence of ultrasound and microwave-assisted treatment was studied by varying synthesis parameters such as reaction time, temperature, and US or MW power. The main advantage of using these methods is represented by shorter synthesis time compared to conventional methods, resulting in the direct formation of the cocrystals. All samples were obtained in high purity, above 97%. Cocrystal yield correlated positively with ultrasound reaction time, while temperature was not found to influence the microwave synthesis yield up to 50°C, in the case of solution-based methods. MW and US-assisted solution-based methods lead to yields between 52.9 and 68.1%. In the case of the slurry-based method, a minimum reaction time of 5 min leads to the formation of cocrystals with high purity. The resveratrol-piperazine cocrystal's solubility and in vitro antibacterial activity were also evaluated, showing promising results. Ultrasound and microwave-assisted techniques offer a viable alternative for synthesizing resveratrol-piperazine cocrystals with short reaction times, high yield, and purity, suitable for scalable resveratrol-piperazine cocrystals.

Green Approaches for the Extraction of Banana Peel Phenolics Using Deep Eutectic Solvents.

Banana peels, comprising about 35% of the fruit's weight, are often discarded, posing environmental and economic issues. This research focuses on recycling banana peel waste by optimizing advanced extraction techniques, specifically microwave-assisted (MAE) and ultrasound-assisted extraction (UAE), for the isolation of phenolic compounds. A choline chloride-based deep eutectic solvent (DES) with glycerol in a 1:3 ratio with a water content of 30% (w/w) was compared to 30% ethanol. Parameters, including sample-to-solvent ratio (SSR), extraction time, and temperature for MAE or amplitude for UAE, were varied. Extracts were analyzed for hydroxycinnamic acid (HCA) and flavonoid content, and antioxidant activity using FRAP and ABTS assays. DES outperformed ethanol, with HCA content ranging from 180.80 to 765.92 mg/100 g and flavonoid content from 96.70 to 531.08 mg/100 g, accompanied by higher antioxidant activity. Optimal MAE conditions with DES were an SSR of 1:50, a temperature of 60 °C, and a time of 10 min, whereas an SSR of 1:60, time of 5 min, and 75% amplitude were optimal for UAE. The polyphenolic profile of optimized extracts comprised 19 individual compounds belonging to the class of flavonols, flavan-3-ols, and phenolic acids. This study concluded that DESs, with their superior extraction efficiency and environmental benefits, are promising solvents for the extraction of high-value bioactive compounds from banana peels and offer significant potential for the food and pharmaceutical industries.

An environmentally friendly production method: The pectin and essential oil from the waste peel of juvenile pomelo (Citrus maxima ‘Shatian Yu’) were extracted simultaneously in one step with an acid-based deep eutectic solvent

In agricultural production, the juvenile pomelo (Citrus maxima ‘shatian Yu’) is sometimes disregarded, yet its peel is rich in pectin and essential oils. The following parameters were found to be ideal for the extraction of pectin and essential oil: pH of 5.75, a liquid-solid ratio of 4 mL/g, a microwave power of 560 W, and a 30-min irradiation period. The maximum production of pectin was 26.70% ± 1.35% and the greatest output of essential oil was 2.09% ± 0.11% under these circumstances, both exceeding the yields of traditional steam distillation. Utilizing gas chromatography-mass spectrometry, the constituents of the essential oil were identified. There were 62 chemicals were found in the oil that was prepared by combining eutectic solvent extraction with microwave assistance, which better conserved the biological activity of juvenile pomelo peel essential oil. Overall, this technique shows how effective and eco-friendly acid-based deep eutectic solvent microwave-assisted extraction can be as a solution for treating agricultural waste.

Enhancing bioactive phenolic extraction from unfermented Cabernet Sauvignon pomace through tailored synergies of pH, proteolysis, and microwave processing

The impact of enzyme-assisted (EAE), microwave-assisted (MAE), and microwave enzyme-assisted (MEAE) extractions using water were evaluated and compared to aqueous (AEP), conventional ethanolic (CSE), and microwave ethanolic (MSE) controls for the release of phenolics from Cabernet Sauvignon grape pomace. Optimization of extract total phenolic content (TPC) involved stepwise screening of time, temperature, slurry pH, solids-to-liquid ratio, and enzyme conditions. The use of 0.1 % alkaline protease in MEAE (1:10 g pomace/mL water, pH 11.5, 70 °C, 30 min) reduced extraction time by 50 % compared to AEP, EAE, and CSE methods, doubling the TPC of the extracts to 100.9 mg GAE/g dry weight pomace compared to ethanolic extractions. MAE and MEAE extracts exhibited in vitro antioxidant activities (ABTS and ORAC) similar to ethanolic extracts and had greater antioxidant activities than AEP/EAE extracts while boosting relative contents of catechins, procyanidins, trans-piceid, and malvidin-3,5-diglucoside as detected by untargeted metabolomics. Quantitation by HPLC showed increased levels of gallic acid, protocatechuic acid, syringic acid, p-coumaric acid, polymeric phenols, and polymeric pigments in MEAE compared to hydroethanolic methods. Scanning electron microscopy further supported the synergistic role of microwave processing and proteolysis in disrupting the grape cell structure to aid in releasing valuable bioactive phenolic compounds.

Immobilization of 137Cs in NaY type zeolite matrices using various heat treatment methods

The accumulation of liquid radioactive waste presents a significant global challenge, necessitating effective strategies for safe management. This study investigates the immobilization of 137Cs radionuclides, a prominent component of liquid radioactive waste, in ceramic matrices based on 137Cs-saturated NaY Faujasite zeolite. Various thermal methods were employed, including cold pressing and sintering, cold pressing and sintering with microwave assistance, hot pressing, and spark plasma sintering, to enhance immobilization capabilities. Zeolite powder was saturated with 137Cs radionuclides using an adsorption technique with low-activity model liquid radioactive waste. In-situ XRD and dilatometry methods were used to study the thermal behavior during NaY Faujasite annealing. The influence of calcination temperature on lattice parameters and crystallite size was assessed. Immobilization effectiveness was evaluated through relative density, Vickers microhardness, compressive strength, and metal ion leaching kinetics. Mechanistic evaluation was performed using XRD and SEM-EDX studies. Results showed that spark plasma sintering exhibited the highest efficiency for immobilizing 137Cs radionuclides in NaY Faujasite matrices. This research contributes to liquid radioactive waste management by providing insights into the thermal behavior and enhanced immobilization capabilities of ceramic matrices.

A new fabricated hetero-atom doped carbon quantum dots as a fluorescent probe for metronidazole determination using garlic and red lentils with microwave assistance.

Biocompatible and highly fluorescent phosphorus, nitrogen and sulfur carbon quantum dots (P,N,S-CQDs) were synthesized using a quick and ecologically friendly process inspired from plant sources. Garlic and red lentils were utilized as natural and inexpensive sources for efficient synthesis of the carbon-based quantum dots using green microwave-irradiation, which provides an ultrafast route for carbonization of the organic biomass and subsequent fabrication of P,N,S-CQDs within only 3 min. The formed P,N,S-CQDs showed excellent blue fluorescence at λem= 412 nm when excited at 325 nm with a quantum yield up to 26.4%. These fluorescent dots were used as a nano-sensor for the determination of the commonly used antibacterial and antiprotozoal drug, metronidazole (MTR). As MTR lacked native fluorescence and prior published techniques had several limitations, the proposed methodology became increasingly relevant. This approach affords sensitive detection with a wide linear range of 0.5-100.0μM and LOD and LOQ values of 0.14 μM and 0.42 μM, respectively. As well as, it is cost-effective and ecologically benign. The MTT test was used to evaluate the in-vitro cytotoxicity of the fabricated P,N,S-CQDs. The findings supported a minimally cytotoxic impact and good biocompatibility, which provide a future perspective for the applicability of these CQDs in biomedical applications.