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Carbon-based nanodots have garnered recent interest for their simple synthesis and versatile utility, ranging from biomedical to (opto) electronic applications, evolving into a tunable and biocompatible material. Here, for the first time, a biochar (lotus leaf) derived carbon nanodots was synthesized through hydrothermal carbonization. The synthesized hollow spherical biochar was engineered via functionalization by grafting -SO3H active sites. The attained catalyst was broadly analyzed by XRD, FTIR, TGA, BET, SEM-EDX, TEM, and XPS analysis after which it was applied for the acetalization reaction of crude glycerol (a biodiesel by-product) to form solketal, a potential fuel additive to valorize the large waste stream generated from biodiesel industry. Employing the RSM-CCD methodology, the experimental matrix was executed, and subsequent data were scrutinized through multiple regressions to model a quadratic equation. Under specific reaction parameters-a reaction duration of 14 min, a molar ratio of 7.5:1, and a catalyst loading of 5.7 wt.%, maximum solketal yield (95.7%) was attained through the ultrasonication method. Finally, to conclude, life cycle cost analysis (LCCA) for solketal production was studied here which determined the overall cost of solketal production per kilogram to be 0.719 USD ($), indicating high commercial applicability.

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In recent decades, biosynthesis of metal and (or) metal oxide nanoparticles using microbes is accepted as one of the most sustainable, cost-effective, robust, and green processes as it does not encompass the usage of largely hazardous chemicals. Accordingly, numerous simple, inexpensive, and environmentally friendly approaches for the biosynthesis of silver nanoparticles (AgNPs) were reported using microbes avoiding conventional (chemical) methods. This comprehensive review detailed an advance made in recent years in the microbes-mediated biosynthesis of AgNPs and evaluation of their antimicrobial activities covering the literature from 2015-till date. It also aimed at elaborating the possible effect of the different phytochemicals, their concentrations, extraction temperature, extraction solvent, pH, reaction time, reaction temperature, and concentration of precursor on the shape, size, and stability of the synthesized AgNPs. In addition, while trying to understand the antimicrobial activities against targeted pathogenic microbes the probable mechanism of the interaction of produced AgNPs with the cell wall of targeted microbes that led to the cell's reputed and death have also been detailed. Lastly, this review detailed the shape and size-dependent antimicrobial activities of the microbes-mediated AgNPs and their enhanced antimicrobial activities by synergetic interaction with known commercially available antibiotic drugs.

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Green-mediated synthesis of nanoparticles has earned a promising role in the area of nanotechnology due to their biomedical applications. This study describes the synthesis of silver nanoparticles (AgNPs) using Mikania micrantha leaf extract and its functional activities against cancer. The synthesis of AgNPs was confirmed using Ultraviolet-Visible (UV-Vis) spectrum that exhibited an absorption band at 459 nm. The bioactive compounds of M. micrantha leaf extract that functioned as reducing and capping agents were confirmed by a shift in the absorption bands in Fourier Transform Infra-red Spectroscopy (FT-IR). Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) studies validated the spherical shape and size of AgNPs, respectively. Energy Dispersive Spectroscopy (EDS) analysis revealed the presence of elemental silver. The crystalline nature of AgNPs was confirmed by the X-ray Diffraction Analysis (XRD). AgNPs effectively induced cytotoxicity and prevented A549 cell colony formation in a dose-dependent manner. Treatment of A549 cells with AgNPs also increased DNA damage, which was coupled with elevated lipid peroxidation and decreased antioxidant enzymes such as glutathione (GSH), glutathione-s-transferase (GST), and superoxide dismutase (SOD). Following AgNPs treatment, the mRNA expression levels of the pro-apoptotic genes as well as the activities of caspases were significantly elevated in A549 cells while the expression levels of anti-apoptotic genes were downregulated. Our study demonstrates the potential of the synthesised AgNPs for cancer therapy possibly targeting the apoptotic pathway.

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The study involves a collection of data from the published article titled "Active sites engineered biomass-carbon as a catalyst for biodiesel production: Process optimization using RSM and life cycle assessment "Energy Conversion Management" journal. Here, the activated biochar was functionalized using 4-diazoniobenzenesulfonate to obtain sulfonic acid functionalized activated biochar. The catalyst was comprehensively characterized using XRD, FTIR, TGA, NH3-TPD, SEM-EDS, TEM, BET, and XPS analysis. Further, the obtained catalyst was applied for the transesterification of Jatropha curcas oil (JCO) to produce biodiesel. An experimental matrix was conducted using the RSM-CCD approach and the resulting data were analyzed using multiple regressions to fit a quadratic equation, where the maximum biodiesel yield achieved was 97.1 ± 0.4%, under specific reaction conditions: a reaction time of 50.3 min, a molar ratio of 22.9:1, a reaction temperature of 96.2 °C, and a catalyst loading of 7.7 wt.%. The obtained product biodiesel was analyzed using NMR and GC-MS analyzed and is reported in the above-mentioned article.

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An active, high surface area, recyclable, magnetic, basic, iron oxide-based nanocatalyst was developed from banana leaves waste and used for microwave-assisted transesterification of soybean oil to biodiesel. According to the Hammett indicator, the catalyst has a high total basicity of 15 < H < 18.4. After optimization through the response surface methodology, the reaction allows 96.5 % biodiesel yield in the presence of 24:1 methanol to soybean oil molar ratio, 6 wt% BLW@Fe3O4, 0.5 h at 65 °C. The magnetic nature of the catalyst improves reusability for up to 6 cycles. Thermodynamic analyses showed that transesterification of soybean oil to biodiesel is an endothermic reaction. Moreover, the catalyst has the potential to reduce biodiesel production costs by utilizing abundant biomass waste materials. The calculated cost for 1 kg of catalyst is $1.14, while the biodiesel's cost per kg produced in this work is merely $1.05, showing high commercial viability.

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The study investigates the potential of utilizing banana trunk-derived porous activated biochar enriched with SO3H- as a catalyst for eco-friendly biodiesel production from the microalga Chlorella vulgaris. An extensive analysis, employing advanced techniques such as XRD, FTIR, TGA, XPS, NH3-TPD, BET, SEM-EDX, and TEM, was conducted to elucidate the physicochemical properties of BT-SO3H catalysts. The synthesized catalyst demonstrated its efficiency in converting the total lipids of Chlorella vulgaris into biodiesel, with varying concentrations of 3%, 5%, and 7%. Notably, using a 5% BT-SO3H concentration resulted in remarkably higher biodiesel production about 58.29%. Additionally, the fatty acid profile of C. vulgaris biodiesel indicated that C16:0 was the predominant fatty acid at 24.31%, followed by C18:1 (19.68%), C18:3 (11.45%), and C16:1 (7.56%). Furthermore, the biodiesel produced via 5% BT-SO3H was estimated to have higher levels of saturated fatty acids (SFAs) at 34.28%, monounsaturated fatty acids (MUFAs) at 30.70%, and polyunsaturated fatty acids (PUFAs) at 24.24%. These findings highlight the promising potential of BT-SO3H catalysts for efficient and environmentally friendly biodiesel production from microalgal species.

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Marine macroalgae have attracted significant interest as a viable resource for biofuel and value-added chemical production due to their abundant availability, low production costs, and high carbohydrate and lipid content. The growing awareness of socio-economic factors worldwide has led to a greater consideration of marine macroalgae as a sustainable source for biofuel production and the generation of valuable products. The integration of biorefinery techniques into biofuel production processes holds immense potential for fostering the development of a circular bioeconomy on a broad scale. Extensive research was focused on the technoeconomic and environmental impact analysis of biofuel production from macroalgal biomass. The integrated biorefinery processes offers valuable pathways for the practical implementation of macroalgae in diverse conversion technologies. These studies provided crucial insights into the large-scale industrial production of biofuels and associated by-products. This review explores the utilization of marine macroalgal biomass for the production of biofuels and biochemicals. It examines the application of assessment tools for evaluating the sustainability of biorefinery processes, including process integration and optimization, life cycle assessment, techno-economic analysis, socio-economic analysis, and multi-criteria decision analysis. The review also discusses the limitations, bottlenecks, challenges, and future perspectives associated with utilizing macroalgal biomass for the production of biofuels and value-added chemicals.

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The consumption of energy levels has increased in association with economic growth and concurrently increased the energy demand from renewable sources. The need under Sustainable Development Goals (SDG) intends to explore various technological advancements for the utilization of waste to energy. Municipal Solid Waste (MSW) has been reported as constructive feedstock to produce biofuels, biofuel carriers and biochemicals using energy-efficient technologies in risk freeways. The present review contemplates risk assessment and challenges in sorting and transportation of MSW and different aspects of conversion of MSW into energy are critically analysed. The circular bioeconomy of energy production strategies and management of waste are also analysed. The current scenario on MSW and its impacts on the environment are elucidated in conjunction with various policies and amendments equipped for the competent management of MSW in order to fabricate a sustained environment.

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Providing sufficient energy supply and reducing the effects of global warming are serious challenges in the present decades. In recent years, biodiesel has been viewed as an alternative to exhaustible fossil fuels and can potentially reduce global warming. Here we report for the first time the production of biodiesel from oleic acid (OA) as a test substrate using porous sulfonic acid functionalized banana peel waste as a heterogeneous catalyst under microwave irradiation. The morphology and chemical composition of the catalyst was investigated using Powder X-ray diffraction (PXRD) analysis, Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric analysis (TGA), Transmission electron microscopy (TEM), and Scanning electron microscopy- Energy dispersive X-ray spectroscopy (SEM-EDX). The SEM-EDX analysis of the catalyst revealed the presence of sulfur in 4.62 wt% amounting to 1.4437 mmol g-1 sulfonic acids, which is accorded to the high acidity of the reported catalyst. Using response surface methodology (RSM), through a central composite design (CCD) approach, 97.9 ± 0.7% biodiesel yield was observed under the optimized reaction conditions (methanol to OA molar ratio of 20:1, the temperature of 80 °C, catalyst loading of 8 wt% for 55 min). The catalyst showed excellent stability on repeated reuse and can be recycled at least 5 times without much activity loss.

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Green synthesis of metal nanoparticles is a rapidly growing research area in the field of nanotechnology because of their biomedical applications. This study describes the synthesis of silver nanoparticles (AgNPs) using Spilanthes acmella leaf extract and its ameliorative effects against doxorubicin-induced toxicity. The formation of AgNPs was confirmed by a ultraviolet-visible (UV-vis) spectrum that revealed an absorption band at 430 nm. A shift in the absorption bands in Fourier-transform infrared spectroscopy (FT-IR) confirmed the bioactive molecules of S. acmella leaf extract that acted as a reducing and capping agent. The spherical shape of AgNPs was confirmed by scanning electron microscope (SEM) analysis, and the presence of elemental silver was indicated by energy dispersive X-ray spectroscopy (EDS) analysis. X-ray diffraction (XRD) analysis revealed that the crystalline size of the synthesized AgNPs was 6.702 nm. Treatment of Dalton's lymphoma ascites (DLA) mice with 20 mg/kg of doxorubicin (DOX) significantly increased the activities of serum toxicity markers including aspartate amino-transferase (AST), alanine amino-transferase (ALT), and lactate dehydrogenase (LDH). However, compared to DOX alone treatment, the coadministration of DOX and AgNPs reduced AST, ALT, and LDH activities. DOX alone treatment reduced glutathione (GSH) contents and decreased the activities of glutathione-s-transferase (GST) and superoxide dismutase (SOD) in DLA mice. However, the administration of AgNPs to DOX-treated DLA mice increased GSH content and the activities of GST and SOD. Consistently, biosynthesized AgNPs were found to possess significantly higher free-radical scavenging activities when compared to the S. acmella leaf extract, as measured by ABTS, DPPH, and O2 •- assays. The biosynthesized AgNPs also showed significant inhibitory activities against erythrocyte hemolysis and lipid peroxidation in the liver homogenate.

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trans-Anethole (trans-AN) is widely applied in food, daily necessities, and pharmaceuticals and is typically available from inefficient natural oil extraction or complex organic transformations over mineral acid or noble metals. Here, a green and sustainable route was developed to stereoselectively produce trans-AN (ca. 90% selectivity) over an organic polymeric phosphonate-hafnium catalyst (PAS-Hf) through the cascade transfer hydrogenation and dehydration of biomass-based 4'-methoxypropiophenone (4-MOPP), with an environmental impact factor (E-factor) of 47.73. The porous structure and the enhanced hydrophobicity of the spherical catalyst PAS-Hf ensured the formation of more accessible and stable Lewis (Hf4+) and Brønsted (SO3H) acid active sites, which could be used for rapid conversion of biomass-based 4-MOPP to AN (100% conversion, 97.2% yield) in 0.5-2 h (TOF: 9.3 h-1). Density functional theory (DFT) calculations elucidated that the addition of PAS-Hf could remarkably facilitate the overall conversion process by decreasing the reaction energy barrier (151.33 to 48.27 kJ mol-1) of the rate-determining step. The good thermal stability and heterogeneity of the bifunctional catalyst were responsible for its constant activity during at least five consecutive cycles. The synergistic/relay catalysis of Lewis acid-base and Brønsted acid species could be extended to more than ten kinds of aldehydes and ketones. This acid-base multi-catalytic protocol has considerable potential in cascade biomass conversion via heterogeneous catalysis without any base additive.

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[This corrects the article DOI: 10.1039/D0RA09941D.].

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A sustainable method was used to produce aromatic ketones by the solvent-free benzylic oxidation of aromatics over mesoporous Cu(II)-containing propylsalicylaldimine anchored on the surface of Santa Barbara Amorphous type material-15 (CPSA-SBA-15) catalysts. For comparison, mesoporous Cu(II)-containing propylsalicylaldimine anchored with Mobil Composition of Matter-41 (CPSA-MCM-41) was assessed for these reactions under similar reaction conditions. The washed CPSA-SBA-15(0.2) (W-CPSA-SBA-15(0.2)) catalyst was prepared using an easy chemical method for the complete removal of non-framework CuO nanoparticle species on the surface of pristine CPSA-SBA-15(0.2) (p-CPSA-SBA-15(0.2) prepared with 0.2 wt% of Cu, and its catalytic activity was evaluated with different reaction parameters, oxidants and solvents. In order to confirm the catalytic stability, the recyclability was assessed, and the performance of hot-filtration experiments was also evaluated. All the catalysts used for these catalytic reactions were characterized using many instrumental techniques to pinpoint the mesoporous nature and active sites of the catalysts. The proposed reaction mechanism has been well documented on the basis of catalytic results obtained for solvent-free oxidation of aromatics. Based on the catalytic results, we found that W-CPSA-SBA-15(0.2) is a very ecofriendly catalyst with exceptional catalytic activity.

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Synthesis of metal nanoparticles using plant extracts is one of the most simple, convenient, economical, and environmentally friendly methods that mitigate the involvement of toxic chemicals. Hence, in recent years, several eco-friendly processes for the rapid synthesis of silver nanoparticles have been reported using aqueous extracts of plant parts such as the leaf, bark, roots, etc. This review summarizes and elaborates the new findings in this research domain of the green synthesis of silver nanoparticles (AgNPs) using different plant extracts and their potential applications as antimicrobial agents covering the literature since 2015. While highlighting the recently used different plants for the synthesis of highly efficient antimicrobial green AgNPs, we aim to provide a systematic in-depth discussion on the possible influence of the phytochemicals and their concentrations in the plants extracts, extraction solvent, and extraction temperature, as well as reaction temperature, pH, reaction time, and concentration of precursor on the size, shape and stability of the produced AgNPs. Exhaustive details of the plausible mechanism of the interaction of AgNPs with the cell wall of microbes, leading to cell death, and high antimicrobial activities have also been elaborated. The shape and size-dependent antimicrobial activities of the biogenic AgNPs and the enhanced antimicrobial activities by synergetic interaction of AgNPs with known commercial antibiotic drugs have also been comprehensively detailed.

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An ever-increasing energy demand and environmental problems associated with exhaustible fossil fuels have led to the search for an alternative renewable source of energy. In this context, biodiesel has attracted attention worldwide as an eco-friendly alternative to fossil fuel for being renewable, non-toxic, biodegradable, and carbon-neutral. Although the homogeneous catalyst has its own merits, much attention is currently paid toward the chemical synthesis of heterogeneous catalysts for biodiesel production as it can be tuned as per specific requirement and easily recovered, thus enhancing reusability. Recently, biomass-derived heterogeneous catalysts have risen to the forefront of biodiesel productions because of their sustainable, economical and eco-friendly nature. Furthermore, nano and bifunctional catalysts have emerged as a powerful catalyst largely due to their high surface area, and potential to convert free fatty acids and triglycerides to biodiesel, respectively. This review highlights the latest synthesis routes of various types of catalysts (including acidic, basic, bifunctional and nanocatalysts) derived from different chemicals, as well as biomass. In addition, the impacts of different methods of preparation of catalysts on the yield of biodiesel are also discussed in details.

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Biosynthesis of nanoparticles by exploiting different plant materials has become a matter of great interest in recent years and is considered as a green technology as it does not involve any harmful and toxic chemicals in the synthetic procedure. In this paper, we report a novel one-pot M. acuminata peel ash extract mediated bio-synthesis of basic iron oxide nanoparticles (MAPAE@Fe3O4). The nanoparticles were fully characterized by different analytical techniques such as XRF, IR, XRD, XPS, SEM, TEM, VSM and TGA. The synthesized nanoparticles exhibited high basicity due to the presence of metal oxides, primarily basic K2O in the outer layer of Fe3O4 surfaces, and showed good catalytic activity for the synthesis of ß-nitroalcohol via the Henry reaction at room temperature under solvent-free conditions. The catalyst was separated from the reaction medium by simply applying an external bar magnet making the process economical and less labor intensive. Furthermore, the catalyst can be reused up to the 4th cycle without much loss of its activity.

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A waste snail shell (Pila spp.) derived catalyst was used to produce biodiesel from soybean oil at room temperature for the first time. The snail shell was calcined at different temperatures of 400-1000 °C. The synthesized catalysts underwent XRD, SEM, TEM, EDS, FTIR, XRF, TG/DTA and N2 adsorption-desorption isotherm (BET) analysis. The major component CaO was determined at a calcination temperature of 900 °C as depicted in the XRD results. 100% conversion of soybean oil to methyl ester biodiesel was obtained, as confirmed by 1H NMR. A biodiesel yield of 98% was achieved under optimized reaction conditions such as a calcination temperature of 900 °C, a catalyst loading of 3 wt%, a reaction time of 7 h and a methanol to oil ratio of 6 : 1, and biodiesel conversion was confirmed by FT-NMR and IR spectroscopies. A total of 9 fatty acid methyl esters (FAMEs) were identified in the synthesized biodiesel by the retention time and fragmentation pattern data of GC-MS analysis. The catalyst was recycled 8 times without appreciable loss in its catalytic activity. A high biodiesel yield of 98% was obtained under these optimised conditions. The catalyst has the advantage of being a waste material, therefore it is easily prepared, cost free, highly efficient, biogenic, labor effective and environmentally friendly, making it a potential candidate as a green catalyst for low cost production of biodiesel at an industrial scale.

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Coupling reactions to make esters and amides are among the most widely used organic transformations. We report efficient procedures for amide bond formation and for the monoesterification of symmetrical diols in excellent yields without any requirement for high dilution or slow addition using resin-bound triarylphosphonium iodide. Easy purification, low moisture sensitivity, and good to excellent yields of the products are the major advantages of this protocol.

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