Green Synthesis Route Research Articles

Photoelectrochemical N2 -to-NH3 Fixation with High Efficiency and Rates via Optimized Si-Based System at Positive Potential versus Li0/.

As a widely used commodity chemical, ammonia is critical for producing nitrogen-containing fertilizers and serving as the promising zero-carbon energy carrier. Photoelectrochemical nitrogen reduction reaction (PEC NRR) can provide a solar-powered green and sustainable route for synthesis of ammonia (NH3 ). Herein, we report an optimum PEC system with a Si-based hierarchically-structured PdCu/TiO2 /Si photocathode and well-thought-out trifluoroethanol as the proton source for lithium-mediated PEC NRR, achieving a record high NH3 yield of 43.09μg cm-2 h-1 and an excellent faradaic efficiency of 46.15% under 0.12-MPa O2 and 3.88-MPa N2 at 0.07V versus lithium(0/+) redox couple (versus Li0/+ ). PEC measurements coupled with operando characterization revealed that the PdCu/TiO2 /Si photocathode under N2 pressures facilitate the reduction of N2 to form lithium nitride (Li3 N), which reacts with active protons to produce NH3 while releasing the Li+ to reinitiate the cycle of the PEC NRR. The Li-mediated PEC NRR process is further enhanced by introducing small amount of O2 or CO2 under pressure by accelerating the decomposition of Li3 N. For the first time, this work provides mechanistic understanding of the lithium-mediated PEC NRR process and opens new avenues for efficient solar-powered green conversion of N2 -to-NH3 . This article is protected by copyright. All rights reserved.

A novel NADH-dependent leucine dehydrogenase for multi-step cascade synthesis of L-phosphinothricin

L-Phosphinothricin (L-PPT) is the effective constituent in racemic PPT (a high-efficiency and broad-spectrum herbicide), and the exploitation of green and sustainable synthesis route for L-PPT has always been the focus in pesticide industry. In recent years, “one-pot, two-step” enzyme-mediated cascade strategy is a mainstream pathway to obtain L-PPT. Herein, RgDAAO and BsLeuDH were applied to expand “one-pot, two-step” process. Notably, a NADH-dependent leucine dehydrogenase from Bacillus subtilis (BsLeuDH) was firstly characterized and attempted to generate L-PPT, achieving an excellent enantioselectivity (99.9% ee). Meanwhile, a formate dehydrogenase from Pichia pastoris (PpFDH) was utilized to implement NADH cofactor regeneration and only CO2 was by-product. Sufficient amount of the corresponding keto acid precursor PPO was obtained by oxidation of D-PPT relying on a D-amino acid oxidase from Rhodotorula gracilis (RgDAAO) with content conversion (46.1%). L-PPT was ultimately prepared from racemized PPT via oxidative deamination catalyzed by RgDAAO and reductive amination catalyzed by BsLeuDH, achieving 80.3% overall yield and > 99.9% ee value.

Influence of starch capping effect on optical absorption and photoluminescence behaviour of ZnS nanoparticles

The green chemical of route synthesis followed and the precursor compounds taken during the synthesis of ZnS nanoparticles (NPs) play an imperative role on their structural and photo physical properties. The green chemical route of synthesis of NPs is proved to be an advantageous method imparting novel properties to the synthesized NPs. Present study involves the synthesis of uncapped and starch capped ZnS NPs by a facile chemical coprecipitation technique. ZnS NPs have been synthesized using zinc acetate and sodium sulfide as precursors. The structural and morphological features of the samples were studied by Xray diffraction (XRD) and field emission electron microscopy (FESEM). Fourier transform infra red spectra (FTIR) was carried out to confirm capping by starch. Compositional analysis was done by electron dispersive spectroscopy (EDS). Optical properties were analyzed using UVabsorption spectra and photoluminescence (PL) measurements. Formation of ZnS NPs with cubic phase was revealed by XRD and quantum confinement effect by the UV absorption. With increase in capping agent (starch) concentration PL intensity decreased. Such heavy metal free, nontoxic ZnS nanoparticles are suitable for optoelectronic applications.

Selective synthesis of dimethyl carbonate via the coupling reaction of CO2 and alcohols by the synergistic catalysis of silver sulfadiazine and superbase

The three-component coupling of methanol, CO2 and propargyl alcohol to manufacture dimethyl carbonate (DMC) provides a new, thermodynamic favorable and green chemical synthesis route. In this work, to overcome the problems of low DMC yield and slow conversion rate of intermediates, the synergistic catalytic strategy of silver sulfadiazine and superbase is developed to improve the reaction efficiency. The effect of various parameters i.e. catalyst and cocatalyst types, catalyst loading, solvent, temperature, proportion of raw materials, pressure and time on the coupling reactions is investigated in detail. Under the optimal conditions, the selectivity of DMC is 89.5% with the yield of 55.6%. And the effect of alkyne derivative α-monosubstituted propargyl alcohol on the efficiency and selectivity of DMC are studied also. The mechanism study shows that propargyl alcohols with different structures apparently affect the reaction process, and the synergistic catalysis of silver sulfadiazine/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is the reason for the high yield and selectivity of DMC.

A facile green synthesis route to silver nanoparticles using cyanobacterium Nostoc carneum and its photocatalytic, antibacterial and anticoagulative activity

A facile green synthesis route to silver nanoparticles using cyanobacterium Nostoc carneum and its photocatalytic, antibacterial and anticoagulative activity

A Green Route to Methyl Formate from CO2-Derived Formamides over Solid Base Catalysts

The transformation of CO2 and CO2-derived chemicals into high value-added chemicals is an important method for reducing CO2 emissions and achieving carbon neutrality. Methyl formate (MF) is a critical C1 building block in synthesizing a wide range of important chemicals, such as formic acid, ethylene glycol, and formamide methyl propionate. Here, we report a green route for the sustainable synthesis of MF from CO2-derived formamides via the alcoholysis reaction catalyzed by supported CaO solid bases. The CaO/MgO catalyst with 13.5 wt.% CaO exhibited higher alcoholysis reaction efficiency and achieved 94.5% conversion of N-formylmorpholine and 100% selectivity of MF in methanol at 120 °C. Based on the kinetic studies, characterization results of structural and basic properties (XRD, and TEM, CO2-TPD, etc.), we found that the density of strong basic sites is linearly related to the activity of alcoholysis reaction, and the higher the base density on these catalysts, the greater the reaction rate. This study presents a sustainable route for the synthesis of MF by using CO2-derived formamides and green methanol, and a promising strategy for producing more efficient solid alcoholysis catalysts of amides.

Batch and Continuous Flow Treatment Studies of Trichloroethylene Contaminated in Water by Silver and Cerium Doped Zinc Oxide Adsorption and Photocatalysis

The development of photocatalytic treatment in continuous flow systems to be more practical is challenging. This research aimed to study batch and continuous flow treatment of trichloroethylene (TCE) contaminated in water by silver and cerium doped zinc oxide (0.005Ag-0.005Ce-ZnO) visible light driven photocatalyst. This catalyst was selected to represent the green route synthesis with simplicity and ease of upscaling. The 0.005Ag-0.005Ce-ZnO powder was synthesized using sticky rice flour as a template. Mechanical coating of the 0.005Ag-0.005Ce-ZnO powder on activated alumina (Al2O3) beads was done to improve the appropriate packing in the fixed bed columns. Characterization of 0.005Ag-0.005Ce-ZnO showed a higher response to visible light and smaller crystallite size compared to zinc oxide synthesized with the same method. Using sticky rice starch as a template increased the uniform distribution of the elements. The photocatalytic batch test over 0.005Ag-0.005Ce-ZnO powder, 0.30 g/100 mL, could remove TCE up to 80% in 180 min. The decrease of TCE via photocatalysis compared to volatilization, adsorption, and photolysis presented the predominance of photocatalysis. Langmuir-Hinshelwood kinetics described that the decrease of TCE more depended on the reaction than adsorption. In addition, the TCE degradation steadily remained at 80-90% along the run of 0.005Ag-0.005Ce-ZnO@Al2O3 photocatalysis under visible light from both warm white lamps and sunlight in the continuous flow system. Besides photocatalysis, TCE adsorption on 0.005Ag-0.005Ce-ZnO@Al2O3 packed in the columns showed significant results. Our findings presented the possibility of applying the photocatalytic continuous flow system to remove TCE in industrial wastewater.

A Sustainable Solution to Skin Diseases: Ecofriendly Transdermal Patches.

Skin is the largest epithelial surface of the human body, with a surface area of 2 m2 for the average adult human. Being an external organ, it is susceptible to more than 3000 potential skin diseases, including injury, inflammation, microbial and viral infections, and skin cancer. Due to its nature, it offers a large accessible site for administrating several medications against these diseases. The dermal and transdermal delivery of such medications are often ensured by utilizing dermal/transdermal patches or microneedles made of biocompatible and biodegradable materials. These tools provide controlled delivery of drugs to the site of action in a rapid and therapeutically effective manner with enhanced diffusivity and minimal side effects. Regrettably, they are usually fabricated using synthetic materials with possible harmful environmental effects. Manufacturing such tools using green synthesis routes and raw materials is hence essential for both ecological and economic sustainability. In this review, natural materials including chitosan/chitin, alginate, keratin, gelatin, cellulose, hyaluronic acid, pectin, and collagen utilized in designing ecofriendly patches will be explored. Their implementation in wound healing, skin cancer, inflammations, and infections will be discussed, and the significance of these studies will be evaluated with future perspectives.

Ag and Zn doped TiO2 nano-catalyst synthesis via a facile green route and their catalytic activity for the remediation of dyes

A facile green synthesis route was employed for the fabrication of Ag–Zn doped TiO2 nano-catalyst and utilized for the remediation of dyes. Nicotiana tabacum leaves extract was used to prepare the Ag–Zn doped TiO2 nano-catalyst by utilizing TiO2 as precursor and AgNO3, ZnNO3 as doping agents. A strong UV–Vis spectra peak confirmed the Ag–Zn doped TiO2 formation. Furior transformed infrared spectroscopy analysis revealed the role of phenolics in the N. tabacum leaves extract for the formation of Ag–Zn-doped TiO2 nano-catalyst. Moreover, Ag–Zn doped TiO2 nano-catalyst formation was confirmed by X-ray diffraction analysis, which reveals the cubic and tetragonal geometries with average size of 5.66 nm. The scanning electron microscopy analysis also confirmed the poly-morphological structure of prepared Ag–Zn doped TiO2 nano-catalyst. The nano-catalyst was used for the remediation of dyes and conditions were optimized for maximum removal of dyes using NaBH4 reducing agent. The catalytic activity results revealed that Ag–Zn doped TiO2 showed promising features versus individual counterparts, which is correlated with reduced bandgap of doped nano-catalyst. The N. tabacum leaves extract efficiently stabilized Ag–Zn doped TiO2 nano-catalyst that exhibited remarkable catalytic activity and have potential to treat the dyes in wastewater.

Highly efficient synthesis of benzyl benzoate directly from self-coupling of benzyl alcohol in water

Benzyl benzoate (BB), an important ester, still demands for green synthesis routes. In this work, by size regulation and proper functionalization of carbon nanotubes (CNTs) as the support of gold catalyst, this ester can be synthesized very efficiently directly from benzyl alcohol via oxidative coupling. More attractively, the reaction is performed using water as green solvent and molecular oxygen as green oxidant. Simultaneously, very high selectivity to BB can be obtained near full conversion within very short reaction time (just 0.5 h), while the low-value benzoic acid byproduct is negligible. This is very different from many reported gold catalysts that yield much benzoic acid and/or benzaldehyde in water. The results show that, besides the size of CNTs (length and diameter), the functionalization of CNTs is also critical for improving both conversion and the selectivity to BB. In addition, the reaction mechanism for forming BB ester is put forward as well.

Green Route Synthesis and Molecular Docking of Azines Using Cellulose Sulfuric Acid under Microwave Irradiation

A novel catalytic approach for the synthesis of symmetric and asymmetric azines has been developed. The environmentally benign protocol was achieved via condensation of 1-[(2-thienyl)ethylidene]hydrazine (1) with different aromatic aldehydes 2a–h and acetyl heterocyclic compounds (4, 6, 8, 10, and 12) in the presence of cellulose sulfuric acid (CSA) as the green catalyst. These procedures offer an interesting method for the large-scale industrial manufacture of azines due to their high percentage yield, mild reaction conditions, broad substrate range, and utilization of an economical and environmentally acceptable catalyst. Additionally, the molecular docking of the products to the monoamine oxidase (MAO-A) target protein was achieved to highlight the possible binding interaction with the amino acid residues Arg51, Glu43, Gly22, Gly49, Gly443, Ala272, Ile335, and Tyr407 at the point of binding. The binding interaction energy was discovered to be (− 6.48 kcal/mol) for the protein MAO-A (PDB ID: 2Z5X). The most effective azine derivatives 7 and 13 revealed some major conserved interactions between the MAO-A protein’s binding site amino acid residues and the PDB co-crystal ligand 2Z5X. Moreover, azine derivatives 3a and 3f showed the lowest binding activity with the target MAO-A.

A review on biological synthesis of ZnO nanostructures and its application in photocatalysis mediated dye degradation: An overview.

Zinc oxide (ZnO) has several industrial applications due to its versatile properties, which lead to its continuously increasing demand in different industrial sectors. Additionally, ZnO nanostructures possess unique photocatalytic activity, and because of this, they are being applied to degrade organic dyes through photocatalysis for wastewater treatment. Nevertheless, chemical synthesis methods to develop ZnO nanostructures have raised concerns related to environmental issues, furthermore, these methods are found to be costly and tedious. As a result, the synthesis of ZnO nanostructures using green methods is gaining popularity due to its low cost and eco-friendly mode, while avoiding the use of toxic chemicals. Green synthesis of ZnO nanostructures using different biological approaches involving plants, algae, and different microorganism-derived bioactive compounds has been well reported for diverse applications. Among different applications, ZnO nanostructures that enable photocatalysis to degrade dye have been found to be imperative for wastewater treatments. Therefore, the current review explores recent studies on green synthesis approaches to prepare ZnO nanostructures via adopting different biological methods that rely on plants, algae, and bacterial microorganisms. The properties of ZnO nanostructures, along with their green synthesis routes and feasible mechanisms, have also been discussed in this review. This review focuses on the use and efficiency of green route synthesized ZnO nanostructures as nanophotocatalysts for the degradation of organic dyes in wastewater treatment. Additionally, existing challenges in green synthesis methods and the efficiency of ZnO nanostructures to degrade organic dyes following photocatalysis has been discussed.

Eco-Friendly Synthesized of CuO Nanoparticles Using Anchusa strigosa L. Flowers and Study its Adsorption Activity

Environmentally friendly copper oxide nanoparticles (CuO NPs) were prepared with a green synthesis route via Anchusa strigosa L. Flowers extract. These nanoparticles were further characterized by FTIR, XRD and SEM techniques. Removing of Gongo red from water was applied successfully by using synthesized CuO NPs which used as an adsorbent material. It was validated that the CuO NPs eliminate Congo red by means of adsorption, and the best efficiency of adsorption was gained at pH (3). The maximum adsorption capacity of CuO NPs for Congo red was observed at (35) mg/g. The equilibrium information for adsorption have been outfitted to the Langmuir, Freundlich, Temkin and Halsey adsorption isotherm types. The temperature thermodynamic parameters like ΔG°, ΔH° and ΔS° have been calculated.

Nano coloration and functionalization of cellulose drive through in-situ synthesis of cross-linkable Cu2O nano-cubes: A green synthesis route for sustainable clothing system

The textile and clothing industry is under great stress and subjected to the huge utilization of toxic dyes. Metal oxide nanoparticles are getting great attention in textiles as a promising alternative to toxic dyes and organic pigments with added functionality. Unfortunately, the utilization of toxic precursors in the synthesis of nanoparticles and their poor bonding interaction with the textile still offers an open challenge for nano-coloration. The lack of bonding interaction not only leads to the release of nanoparticles in common laundering but also vanishes the functional properties. Herein, we demonstrated a robust, and sustainable process for one-step coloration and functionalization of cotton fabric through an in-situ synthesis of cross-linkable functional Cu2O nanocubes. The nano-cubes to fabric interaction was established through FTIR spectroscopy, while the proposed chemical mechanism provides the theoretical conjecture in support of interaction. The as-prepared nano-dyed fabric presented an attractive yellowish-orange color with excellent dyeing fastness, and wash durability along with the retained hydrophilicity with a water contact angle (WCA) value of as low as 59°. Additionally, the eminence of the development was validated by mapping the processing traits with UN sustainable development goals (SDGs) as a blueprint for easy commercial adaptation. With added functionality of easy-care, antimicrobial and photocatalytic performance while maintaining comfort and color aesthetic (in the absolute absence of toxic reagents) such a process can find tremendous utilization in sustainable clothing needs.

Application of Biobased Substances in the Synthesis of Nanostructured Magnetic Core-Shell Materials

We propose here a novel green synthesis route of core-shell magnetic nanomaterials based on the polyol method, which uses bio-based substances (BBS) derived from biowaste, as stabilizer and directing agent. First, we studied the effect of BBS concentration on the size, morphology, and composition of magnetic iron oxides nanoparticles obtained in the presence of BBS via the polyol synthesis method (MBBS). Then, as a proof of concept, we further coated MBBS with mesoporous silica (MBBS@mSiO2) or titanium dioxide (MBBS@TiO2) to obtain magnetic nanostructured core-shell materials. All the materials were deeply characterized with diverse physicochemical techniques. Results showed that both the size of the nanocrystals and their aggregation strongly depend on the BBS concentration used in the synthesis: the higher the concentration of BBS, the smaller the sizes of the iron oxide nanoparticles. On the other hand, the as-prepared magnetic core-shell nanomaterials were applied with good performance in different systems. In particular, MBBS@SiO2 showed to be an excellent nanocarrier of ibuprofen and successful adsorbent of methylene blue (MB) from aqueous solution. MBBS@TiO2 was capable of degrading MB with the same efficiency of pristine TiO2. These excellent results encourage the use of bio-based substances in different types of synthesis methods since they could reduce the fabrication costs and the environmental impact.

Antibacterial Activities of Biosynthesized Zinc Oxide Nanoparticles and Silver-Zinc Oxide Nanocomposites using Camellia Sinensis Leaf Extract

Green route of nanomaterials synthesis is increasing in demand due to ecofriendly to the environment. In this research, objective is to biosynthesize and evaluate the antibacterial performance of pure ZnO and Ag/ZnO nanocomposites using Camellia sinensis leaf extracts. Pure ZnO nanoparticles and Ag/ZnO nanocomposites were synthesized using Camellia sinensis leaf extract. The antibacterial effectiveness against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria were examined and compared with 1 % Chlorox as a commercial disinfectant by well diffusion method based on the zone of inhibition. Pure ZnO nanoparticles and Ag/ZnO nanocomposites had hexagonal shape ZnO nanoparticles and rectangular shape Ag nanoparticles in Ag/ZnO nanocomposites with a particle crystal size between 20 - 30 nm with carboxylic and phenolic functional group attached on it. Ag/ZnO nanocomposites exhibited antibacterial effectiveness against both gram-positive and gram-negative bacteria, while pure ZnO nanoparticles exhibited antibacterial effectiveness against only gram-positive bacteria. Conversely, 1 % Chlorox and 1 % DMSO showed no significant antibacterial activity against gram-positive and gram-negative bacteria. Camellia sinensis mediated ZnO and Ag/ZnO nanoparticles showed antibacterial potential against S. aureus and E. coli suggesting that green route to synthesis of antibacterial nanoparticles can be an excellent strategy to develop eco-friendly disinfectant products HIGHLIGHTS Zinc oxide nanocomposites biosynthesis by Camellia sinensis at low pH, Antibacterial properties of ZnO nanoparticles and Ag/ZnO nanocomposites on Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538P strains, Disinfection application. GRAPHICAL ABSTRACT

Green Synthesis Of Zinc Oxide Nanoparticles Using Sapindus Mukorossi Fruit Extact, Characterization And Their Antioxidant Activity

In this paper we presented a biogenic method for the synthesis of zinc oxide nanoparticles (ZnO NPs) using Sapindus mukorossi fruit extract. Currently, green synthesis route is most promising route for the synthesis of metallic nanoparticles in which various plant parts are being used. Nanomedicine utilizes biocompatible nanomaterials for diagnostic and therapeutic purposes. The synthesized zinc oxide nanoparticles were initially noticed through visual colour change from dark brown to yellow and further confirmed by surface plasmonic resonance band at 341 nm using UV-Visible spectroscopy. Morphology and size were determined by TEM, XRD analysis revealed the crystalline nature and spherical shape with less than 16 nm average size of synthesized ZnO NPs. The stability of ZnO NPs was due to capping of oxidized polyphenols which was established by Fourier transform infrared spectroscopic study. It could be concluded that S. mukorossi can be used efficiently in the production of potential antioxidant ZnO NPs for commercial application. The antioxidant activity of zinc oxide nanoparticles was determined using a DPPH free radical scavenging assay. Results indicated that synthesized zinc oxide nanoparticles of S. mukorossi fruit could effectively scavenge the free radicals which shows effective antioxidant activity

Green Synthesis of Silver Nanoparticles; A Sustainable Approach with Diverse Applications.

Silver nanoparticles (AgNPs) have garnered significant attention in recent years due to their unique properties and diverse applications across various industries. This review provides an overview of the synthesis methods, characterization techniques, applications, regulatory guidelines, and challenges associated with AgNPs. Green synthesis routes, utilizing natural extracts or biomolecules, have emerged as environmentally sustainable alternatives for producing AgNPs with reduced environmental impact. Characterization techniques such as spectroscopy, microscopy, and chromatography are employed to analyze the physicochemical properties of AgNPs and ensure their quality and stability. AgNPs find applications in biomedical, environmental, and consumer product sectors, including wound dressings, water purification filters, cosmetics, and medical devices, owing to their antimicrobial, catalytic, and optical properties. Regulatory guidelines play a crucial role in ensuring the safe and responsible use of AgNPs, addressing concerns related to biocompatibility, toxicity, and environmental impact. However, challenges remain in standardization, scalability, and long-term safety assessment of AgNP-based products. Future research efforts should focus on optimizing synthesis methods, enhancing characterization techniques, and addressing regulatory gaps to unlock the full potential of AgNPs while ensuring their safety and sustainability. Overall, AgNPs offer promising opportunities for addressing global challenges and driving technological innovation across diverse sectors.

Water-resistance chitosan film through enzymatic treatment and layer-by-layer assembly with bacterial cellulose for food packaging materials.

The pervasive presence of plastic packaging has led to significant environmental contamination due to excessive reliance on petrochemicals and the inherent non-biodegradability of these materials. Both bacterial cellulose (BC) and chitosan (CT) films offer a promising option for food packaging purposes due to their sturdy mechanical strength, biodegradability, environmentally friendly manufacturing process, and non-toxic composition. However, the considerable moisture absorption capacity of these eco-friendly materials has hindered their extensive use, as it leads to a reduction in their strength and ability to serve as a barrier. In the present study, we introduced a composite material of BC reinforced with a lauryl gallate grafted CT coating. After grafting CT with lauryl gallate (CT-LG) through enzymatic modification, it showed excellent hydrophobic properties also in a green route of chemistry synthesis. Based on the results of the study, the duration of the water droplet test of the pure CT-LG film and BC coated with CT-LG (BC/CT-LG) films was more than 15 min, showing that water droplets can be completely blocked by the CT-LG coating without water penetration. For the mechanical properties, the wet flexural strength and wet tensile strength of BC/CT-LG films have improved 400% and 70% compared with the original BC. This method produces a composite material with enhanced hydrophobicity and green properties and shows great potential for use in drinking straws or packaging bags.

Enhanced ammonia selectivity on electrochemical nitrate reduction: Cu–Ni metal–organic frameworks with tandem active sites for cascade catalysis

A Cu–Ni metal–organic framework is proposed as a cascade catalyst to eliminate the nitrite product in nitrate reduction, providing an effective route for high-value green ammonia synthesis.