Green Pathway Research Articles

Anticancer, antimicrobial and antioxidant activity of CuO–ZnO bimetallic nanoparticles: green synthesised from Eryngium foetidum leaf extract

In the present study, green synthetic pathway was adapted to synthesize CuO–ZnO bimetallic nanoparticles (BNPs) using Eryngium foetidum leaf extract and their anti-cancer activity against MCF7 breast cancer cell lines, anti-microbial activity and in vitro anti-oxidant activity were evaluated. Various bio-active compounds present in leaf extract were responsible for the reduction of CuO–ZnO NPs from respective Cu2+ and Zn2+ metal precursors. In the present study, the involvement of bio-active compounds present in E. foetidum extract before and after green synthesis of BNPs were evaluated for the first time. Rod-shaped and spherical structural morphology of synthesized BNPs were revealed by using FESEM, TEM, and XRD analysis with particle size ranged from 7 to 23 nm with an average size of 16.49 nm. The distribution of Cu and Zn were confirmed by elemental mapping. The green synthesized CuO–ZnO NPs showed significant cytotoxic effect with the inhibition rate 89.20 ± 0.03% at concentration of 500 μg/mL. Again, good antioxidant activity with IC50; 0.253 mg/mL and antimicrobial activity of BNPs were also evaluated with the increasing order of MIC; E. coli (7.81 μg/mL) < B. subtilis (62.5 μg/mL) < S. aureus (31.25 μg/mL).

Supercritical Fluids: An Innovative Strategy for Drug Development.

Nanotechnology plays a pivotal role in the biomedical field, especially in the synthesis and regulation of drug particle size. Reducing drug particles to the micron or nanometer scale can enhance bioavailability. Supercritical fluid technology, as a green drug development strategy, is expected to resolve the challenges of thermal degradation, uneven particle size, and organic solvent residue faced by traditional methods such as milling and crystallization. This paper provides an insight into the application of super-stable homogeneous intermix formulating technology (SHIFT) and super-table pure-nanomedicine formulation technology (SPFT) developed based on supercritical fluids for drug dispersion and micronization. These technologies significantly enhance the solubility and permeability of hydrophobic drugs by controlling the particle size and morphology, and the modified drugs show excellent therapeutic efficacy in the treatment of hepatocellular carcinoma, pathological scarring, and corneal neovascularization, and their performance and efficacy are highlighted when administered through multiple routes of administration. Overall, supercritical fluids have opened a green and efficient pathway for clinical drug development, which is expected to reduce side effects and enhance therapeutic efficacy.

Elucidating the degradation mechanisms of perfluorooctanoic acid and perfluorooctane sulfonate in various environmental matrices: a review of green degradation pathways.

Given environmental persistence, potential for bioaccumulation, and toxicity of Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), the scientific community has increasingly focused on researching their toxicology and degradation methods. This paper presents a survey of recent research advances in the toxicological effects and degradation methods of PFOA and PFOS. Their adverse effects on the liver, nervous system, male reproductive system, genetics, and development are detailed. Additionally, the degradation techniques of PFOA and PFOS, including photochemical, photocatalytic, and electrochemical methods, are analyzed and compared, highlighted the potential of these technologies for environmental remediation. The biotransformation pathways and mechanisms of PFOA and PFOS involving microorganisms, plants, and enzymes are also presented. As the primary green degradation pathway for PFOA and PFOS, Biodegradation uses specific microorganisms, plants or enzymes to remove PFOA and PFOS from the environment through redox reactions, enzyme catalysis and other pathways. Currently, there has been a paucity of research conducted on the biodegradation of PFOA and PFOS. However, this degradation technology is promising owing to its specificity, cost-effectiveness, and ease of implementation. Furthermore, novel materials/methods for PFOA and PFOS degradation are presented in this paper. These novel materials/methods effectively improve the degradation efficiency of PFOA and PFOS and provide new ideas and tools for the degradation of PFOA and PFOS. This information can assist researchers in identifying flaws and gaps in the field, which can facilitate the formulation of innovative research ideas.

Green pathways for biomass transformation: A holistic evaluation of deep eutectic solvents (DESs) through life cycle and techno-economic assessment

The utilization of renewable biomass resources to manufacture biofuels, chemicals, and materials has garnered considerable attention. Deep eutectic solvents (DESs) have surfaced as a promising instrument within the realm of biomass conversion, owing to their distinctive attributes such as biodegradability, negligible toxicity, easier fabrication, liquid-phase stability and renewability as opposed to ionic liquids (ILs). Research into DESs, particularly those derived from natural sources, is expanding to advance affordable and sustainable biomass conversion. However, the bottlenecks of DES are its limited solubility for certain biomass constituents, cost and availability. To overcome these hurdles, ongoing research and technological innovations strive to tap into the complete potential of DESs in biomass conversion. This review underscores the importance of evaluating DESs' eco-friendly potential comprehensively, encompassing ecological, financial, and technological standpoints which aims to illuminate how DESs can effectively contribute to sustainable biomass utilization, fostering an environmentally conscious circular bio-based economy.

Multi-omics analysis of green lineage osmotic stress pathways unveils crucial roles of different cellular compartments

Maintenance of water homeostasis is a fundamental cellular process required by all living organisms. Here, we use the single-celled green alga Chlamydomonas reinhardtii to establish a foundational understanding of osmotic-stress signaling pathways through transcriptomics, phosphoproteomics, and functional genomics approaches. Comparison of pathways identified through these analyses with yeast and Arabidopsis allows us to infer their evolutionary conservation and divergence across these lineages. 76 genes, acting across diverse cellular compartments, were found to be important for osmotic-stress tolerance in Chlamydomonas through their functions in cytoskeletal organization, potassium transport, vesicle trafficking, mitogen-activated protein kinase and chloroplast signaling. We show that homologs for five of these genes have conserved functions in stress tolerance in Arabidopsis and reveal a novel PROFILIN-dependent stage of acclimation affecting the actin cytoskeleton that ensures tissue integrity upon osmotic stress. This study highlights the conservation of the stress response in algae and land plants, and establishes Chlamydomonas as a unicellular plant model system to dissect the osmotic stress signaling pathway.

Microwave-assisted catalytic rapid pyrolysis of soybean straw for the preparation of high-value indole-rich bio-oils

Microwave-assisted catalysed rapid pyrolysis of soybean straw to prepare high-value bio-oils rich in indoles achieved value-added use of biomass. The effects of different urea doping ratios, two typical Al-based catalysts (γ-Al2O3, HZSM-5), and different HZSM-5 doping ratios on the preparation of N-rich bio-oils (NCBs) from soybean straw by microwave-assisted pyrolysis were investigated. It was shown that the yield of the liquid product at 40 % urea addition was 39.63 %, in which pyridine compounds were enriched to the extent of 20.86 %. On this basis, the effects of γ-Al2O3 and HZSM-5 on N-containing compounds (NCCs) in bio-oil were analyzed in detail. The yield of NCCs increased significantly with the addition of HZSM-5. The best parameter combinations were obtained through orthogonal experiments: urea addition of 50 %, HZSM-5 catalyst type, and catalyst doping ratio of 200 %. At this point, the bio-oil yield reached 29.575 wt%. Among them, indole yield reached 41.66 wt% and exhibited high selectivity of 68.92 % in NCCs. The formation mechanism of indoles during microwave-assisted N-rich pyrolysis was further investigated on the basis of experimental studies. In addition, the inhibitory effect of the HZSM-5 catalyst on the formation of pyridine compounds during pyrolysis process and the enhancement mechanism of the formation of indole compounds were deeply investigated. This provided a green pathway for the preparation of indoles by microwave-assisted fast pyrolysis directional catalytic conversion of biomass.

Factors affecting the economy of green hydrogen production pathways for sustainable development and their challenges.

In a hydrogen economy, the primary energy source for industry, transportation, and power production is hydrogen gas. Green hydrogen can be generated and utilized in an environmentally friendly and sustainable manner; it seeks to displace fossil fuels. Finding a clean alternative energy source is becoming more crucial due to the depletion of fossil fuels and the major environmental pollution issues they bring when utilized extensively. The paper's objective is to analyze the factors affecting the economy of green hydrogen production pathways for sustainable development to decarbonize the world and the associated challenges faced in terms of technological, social, infrastructure, and people's perceptions while adopting green hydrogen. To achieve this, the research looked at a variety of areas relevant to green hydrogen, such as production techniques, industry applications, benefits for society and the environment, and challenges that need to be overcome before the technology is widely used. The most recent methods of producing hydrogen from fossil fuels, such as steam methane, partial oxidation, autothermal, and plasma reforming, as well as renewable energy sources including biomass and thermochemical reactions and water splitting. Grey hydrogen is now the least expensive type of hydrogen, but, in the future, green hydrogen's levelized cost of hydrogen (LCOH) is expected to be less than $2 per kilogram of hydrogen.

Performance of Green Desymmetrization Methods toward Bioactive Cephalostatin Analogues.

Since the discovery of cephalostatins, which have shown remarkable activity against human cancer cells, they have attracted the attention of researchers to target the synthesis of such impressive, complicated molecules using the green desymmetrization approach. In the current review, we report the progress in the desymmetrization of symmetrical bis-steroidal pyrazines (BSPs) as an approach toward potentially active anti-- cancer agents, namely cephalostatins/ ritterazines. The achievement of synthesizing a gram-scaled prodrug with comparable activity to the potent natural cephalostatins using green methods is our primary target. These synthetic methods can be scaled up based on the symmetrical coupling (SC) of two steroidal units of the same type. Our secondary target is the discovery of new green pathways that help in structural reconstruction programming toward the total synthesis of at least one potentially active family member. The strategy is based on functional group interconversions with high flexibility and brevity using green selective methods. The introduction of controlling groups using nontrivial reconstruction methodologies forms the backbone of our work. After certain modifications to the symmetrical BSP starting material, the resulting analogs underwent several chemoselective transformations through three main routes in rings F, D, and C. One of these routes is the chemoselective spiroketal opening (ring-F). The second route was the functionalization of the Δ14,15 bond (ring-D), including chlorination/dechlorination, in addition to epoxidation/ oxygenation processes. Finally, the introduction of the C-11 methoxy group as a directing group on ring-C led to several chemoselective transformations. Moreover, certain transformations on C-12 (ring-C), such as methylenation, followed by hydroboration- oxidation, led to a potentially active analog. The alignment of these results directs us toward the targets. Our efforts culminated in preparing effective anti-cancer prodrugs (8, 24, 30, and 31), which are able to overcome cancer drug resistance (chemoresistance) by inducing the atypical endoplasmic reticulum-mediated apoptosis pathway, which works through the release of Smac/Diablo and the activation of caspase-4.

The African fulcrum to bend the curve of the climate crisis to a just transition

From a current impact of under 4% of global greenhouse gas emissions, rapid industrialization and population growth in Africa could dramatically change the continent’s emissions profile. In this study, we develop an analytic framework to quantify future scenarios and project that, in mid- and green-growth scenarios, Africa’s emissions would amount to just 4%–13% of the planned carbon savings in major economies. However, in a high-growth scenario without climate-conscious development, African emissions could jeopardize global mitigation efforts. Less than 20 nations could account for 80%–90% of the continent’s emissions, highlighting the critical role of green growth pathways centered on rapid clean energy adoption in just a few countries to transform the continent’s energy landscape. A 20-fold increase in investment and project completion rates is required to meet the renewable energy targets in these countries’ Nationally Determined Contributions (NDCs). Our analysis underscores the need for nuanced country-specific strategies that prioritize equity and financial support for optimal climate and development progress in Africa.

Evaluation on photocatalytic activity of bismuth nitrate derived materials at different calcination temperatures using paper microzones method

Our work reveals for the first time that directly calcined bismuth nitrate derivatives (BNDs) possess significant photocatalytic activity towards rhodamine B (RhB). As the calcination temperature increased, the Bi(NO3)3·5H2O powder gradually ruptured and transformed into different bismuth nitrate products and their mixtures, finally into stable α-Bi2O3 at 500 °C. Among them, BNDs-100 could achieve 100 % photocatalytic degradation of 10 mg/L RhB solution under UV irradiation for 6 min. The ImageJ-led paper microzones (PMZs) method is introduced for the first time into the performance evaluation process of photocatalysts, which can achieve the green chemistry pathway and the rapid evaluation of different catalysts. The accuracy of the results of the PMZs method relative to the spectrophotometric method was up to 91.14 %, which has a better reliability and is suitable for qualitative analysis, and a certain ability when used for quantitative analysis. The results showed that the PMZs method was used to assess the photocatalytic degradation of rhodamine B by bismuth nitrate-derived materials at different calcination temperatures with well reliability, and the preparation of BNDs by direct calcination was a simple and effective strategy.

Development of environmentally friendly glyoxal-based adhesives with outstanding water repellency utilizing wheat gluten protein

To reduce the release of volatile organic compounds (VOCs) from formaldehyde-based adhesives at the source, the use of low-toxicity and biodegradable glyoxal instead of formaldehyde for the preparation of novel urea-glyoxal resins is a simple and promising strategy. The limited water resistance and adhesive strength of the new urea-glyoxal resins (UG) restrict their extensive application. This study prepared a high-performance, water-resistant WP-UG wood adhesive by combining UG prepolymer with wheat gluten protein (WP). FTIR, XRD, and XPS confirmed the existence of a chemical reaction between the two components, and thermal analysis showed that WP-UG plywood had better thermal stability. Evaluation of the gluing properties revealed that the dry and wet strengths of WP-UG adhesive bonded plywood reached 1.39 and 0.87 MPa, respectively, which were significantly higher than those of UG resin by 35 % and 314 %. The bond strength increased from 0 to 0.89 MPa after immersion in water at 63 °C for 3 h. The results indicated that the introduction of WP promoted the formation of a more complex and tightly packed crosslinking network and developed a glyoxal-based adhesive with high bond strength and water resistance. This study provides a new green pathway for novel urea-formaldehyde binders to replace harmful formaldehyde-based binders, which helps to increase their potential application value in the wood industry.

RATE OF COVID-19 INFECTION AND 30-DAY MORTALITY BETWEEN BLUE AND GREEN (DEDICATED COVID-19 FREE) PATHWAYS: RESULTS FROM UK-FALCON AUDIT

ObjectivesThe primary aim was to determine the differences in COVID-19 infection rate and 30 day mortality in patients undergoing foot and ankle surgery between different treatment pathways over the two phases of the UK-FALCON audit, spanning the first and second national lockdowns.DesignMulticentre retrospective national audit.SettingThis was a combined retrospective (Phase 1) and prospective (Phase 2) national audit of foot and ankle procedures in the UK in 2020.ParticipantsAll adult patients undergoing foot and ankle surgery in an operating theatre during the study period included from 46 participating centres in England, Scotland, Wales and Northern Ireland. Patients were categorised as either a green pathway (designated COVID-19 free) or blue pathway.Results10,846 patients were included, 6,644 from phase 1 and 4,202 from phase 2. Over the 2 phases the infection rate on a blue pathway was 1.07% (69/6,470) and 0.21% on a green pathway (9/4,280). In phase 1, there was no significant difference in the COVID-19 perioperative infection rate between the blue and green pathways in any element of the first phase (pre-lockdown (p = .109), lockdown (p = .923) or post-lockdown (p = .577)). However, in phase 2 there was a significant reduction in perioperative infection rate when using the green pathway in both the pre-lockdown (p &lt; .001) and lockdown periods (p &lt; .001). There was no significant difference in COVID-19 related mortality between pathways.ConclusionsThere was a five-fold reduction in the perioperative COVID-19 infection rate when using designated COVID-19 green pathways; however the success of the pathways only became significant in phase 2 of the study. The study shows a developing success in using green pathways in reducing the risk to patients undergoing foot and ankle surgery.

Spontaneous α‐C−H Carboxylation of Ketones by Gaseous CO2 at the Air‐water Interface of Aqueous Microdroplets

AbstractWe present a catalyst‐free route for the reduction of carbon dioxide integrated with the formation of a carbon‐carbon bond at the air/water interface of negatively charged aqueous microdroplets, at ambient temperature. The reactions proceed through carbanion generation at the α‐carbon of a ketone followed by nucleophilic addition to CO2. Online mass spectrometry reveals that the product is an α‐ketoacid. Several factors, such as the concentration of the reagents, pressure of CO2 gas, and distance traveled by the droplets, control the kinetics of the reaction. Theoretical calculations suggest that water in the microdroplets facilitates this unusual chemistry. Furthermore, such a microdroplet strategy has been extended to seven different ketones. This work demonstrates a green pathway for the reduction of CO2 to useful carboxylated organic products.

A green EC/ECL dual-mode biosensing platform for detection of Vibrio parahaemolyticus

Here, a green EC/ECL dual-mode biosensing platform was designed for sensitive and accurate detection of Vibrio parahaemolyticus (VP). When VP was present, Apt on Fe3O4@SiO2-cDNA/Apt was specifically bound to VP and detached to obtain Fe3O4@SiO2-cDNA. Subsequently, aDNA on Zn-TCPP@AgNPs-aDNA was hybridized with cDNA on Fe3O4@SiO2-cDNA to obtain magnetic conjugates, which were quickly collected by magnetic force and then one-step assembled onto a magnetic glassy carbon (MGCE) electrode for EC/ECL dual-mode measurement. Under the optimal experimental conditions, the detection linear range of VP was 10 ∼ 107 CFU/mL, and the detection limits (LOD) were as low as 7 CFU/mL (EC) and 3 CFU/mL (ECL), respectively, with good repeatability, storage stability and selectivity. In addition, Fe3O4@SiO2-cDNA/Apt and Zn-TCPP@AgNPs-aDNA could be regained by adding Apt into the magnetic conjugates recovered after EC/ECL test, thus the biosensing platform was regenerated with the signal still remaining up to 91.7% (EC) and 92.8% (ECL) after 10 cycles of recovery. With homogeneous recognition and good regeneration, this EC/ECL dual-mode sensing platform provides a green, simple and reliable pathway for the analysis of VP or other foodborne pathogens.

Thymus vulgaris-assisted growth of nickel nanoparticles onto Luffa fibers: A robust and recyclable catalyst for the reduction of organic pollutants

A green and efficient synthetic pathway was developed to prepare nickel@Luffa nanocomposite. Thymus vulgaris extract was used to functionalize the surface of Luffa fibers with hydroxyl, carbonyl, and amide groups, which assisted in the adsorption of nickel ions. The scanning electron microscope images revealed that nickel nanoparticles grew as aggregates of semi-spherical particles and randomly dispersed on the Luffa fibers. The X-ray diffraction pattern of the nickel@Luffa nanocomposite showed the diffraction pattern of a face-centered cubic Ni crystal. XPS spectrum indicated the formation of metallic Ni at the Luffa surface. The prepared nickel@Luffa was used to catalyze the degradation of 4-nitrophenol, methyl orange, bromophenol blue and a mixture of both. The reaction rate constant for nickel@Luffa nanocomposite was calculated as 15.47 × 10−3 s−1 at pH = 10 and even after ten cycles its conversion was about 90%. The nickel nanoparticles could be recycled/reused for ten catalytic cycles with adequate catalytic activity. Such synthetic pathways encourage the application of renewable natural resources to fabricate separable/recyclable heterogeneous catalyst for many important reactions. The proposed nanocomposite is industrially applicable and environmentally-benign, fulfilling the requirements for the sustainable development.

Solar-driven Bi6O5(OH)3(NO3)5(H2O)3/Bi2WO6 heterojunction for efficient degradation of organic pollutants: Insights into adsorption mechanism, charge transfer and degradation pathway

Actualizing controllable construction of efficient heterojunction nanocomposites remains a challenge in the field of photocatalytic water remediation, which can be got over through exploiting in-situ attachment approaches between different semiconductors. Based on this, we successfully fabricated a unique separable Z-scheme Bi6O5(OH)3(NO3)5(H2O)3/Bi2WO6 (BON/BW) nanoflowers by an in-situ growth strategy. The profitable photogenerated carriers transfer mediated by Z-scheme heterojunction greatly accelerated the generation of •O2– and •OH. The strong adsorption of 4-nitrophenols (4-NP) with parallel configuration on side Bi2WO6 in BON/BW nanocomposites also provides great convenience for subsequent degradation steps. By optimizing multiple steps in the photocatalytic reaction process, BON/BW showed far superior photodegradation performance compared to single components. The causes and consequences of 4-NP photodegradation were explored through LC-MS tests, theoretical calculations, and toxicity analysis, and a green and safe degradation pathway was proposed. More experiments have confirmed that the synthesized BON/BW composites also have excellent degradation ability against other pollutants under sunlight, demonstrating excellent universality. With any luck, the logical design of heterojunction photocatalysts for effective photocatalytic water remediation should be aided by this study.

Metal-support interface engineering for stable and enhanced hydrogen evolution reaction

Hydrogen has emerged as a green and sustainable pathway towards achieving global decarbonization and net-zero emissions, intensely driving the need for efficient hydrogen production protocols. Electrocatalytic hydrogen evolution reaction (HER) holds great potential as a scalable, eco-friendly and safe avenue for efficient hydrogen production. However, the large-scale implementation of electrocatalytic HER is substantially challenged by the high-cost and unstable materials that are mainly fabricated from noble metals, e.g., Pt and Pd. Given this challenge, we adopted an interface engineering strategy to immobilize nanoscale Pt particles within the framework of nitrogen-doped CNTs, namely Pt@N-CNTs, where electronic metal-support interaction (EMSI) plays an important role in enabling orbital rehybridization and regulating the charge transfer through the metal-support interface, thereby considerably improving the electrocatalytic activity. With limited content of noble metals, our developed Pt@N-CNTs delivered superior HER performance with an ultralow overpotential of 5.8 mV at 10 mA cm−2 and demonstrated a high mass activity of 12.72 A mgPt−1 at an overpotential of 50 mV as well as excellent stability under harsh acidic conditions. At 500 mA cm−2, Pt@N-CNTs surprisingly exhibited an overpotential of 55.2 mV, outperforming that of commercial 20 wt% Pt/C catalysts (131.5 mV). Importantly, we established a straightforward, scalable, and time-saving microwave reduction strategy, alluding to its promising commercial viability. This work therefore sheds light on the development of high-performance electrocatalysts for hydrogen evolution and water electrolysis.

A sustainable and highly efficient photocatalytic and supercapacitor electrode for biogenic nickel oxide nanoparticle infused graphene oxide

Energy-storage device manufacturing focuses on cost-effective, efficient, and stable solutions. Electrodes based on graphene oxide (GO) and nickel oxide (NiO) have enhanced electrochemical characteristics, such as high specific capacitance and prolonged cycle stability, which are desirable in supercapacitors. Moreover, a green synthesis pathway was developed for the production of NiO/graphene oxide composites (GO-NiO). FESEM, HRTEM, FTIR, XRD, XPS, UV–Vis, and Raman spectroscopy were among the many methods used to characterize the as-prepared nanocomposites. Since both NiO and the GO-NiO nanocomposite displayed estimated optical band gaps of about 3.45 eV, they were regarded to be semiconductors with potential applications as photocatalysts. GO-NiO nanocomposite was used to adsorb and photodegrade Acridine orange (AO) and Rhodamine-B (Rh-B) from an aqueous solution. In the presence of visible light, the GO-NiO nanocomposite undergoes photodegradation and adsorption at a much quicker rate and with a greater removal efficiency than when exposed to darkness. In under 90 min, GO-NiO composite removed 86.81% of Acridine orange and 86.12% of Rhodamine-B. Photodegradation and adsorption in visible light remove Acridine orange and Rhodamine-B more effectively than adsorption alone. Electrochemical studies of GO-NiO nanocomposites showed that the samples are very stable over numerous cycles and have a specific capacitance of about 228.78 Fg−1 at a scan rate of 10 mV s−1. The NiO-infused GO nanocomposites for photocatalytic and supercapacitor applications are new because of their synergistic features, which efficiently degrade pollutants and store energy, with extensive environmental and energy applications.

Simultaneous geraniol and citronellol transesterification using Pseudomonas fluorescens lipase for the production of fragrance and flavour esters: A kinetic study

This study aims to develop, for the very first time, a kinetic model for the simultaneous transesterification of geraniol and citronellol using Pseudomonas fluorescens lipase to produce their respective esters. This allows us to test the feasibility of the bioprocess and comprehend the enzyme behaviour, fine-tune process efficiency, and predict process performance. Geranyl and citronellyl esters are key ingredients in fragrance and flavour formulations in the food sector, as well as bioactive compounds for pest and insect repellents in the agricultural sector. Unlocking a greener and sustainable production of these terpene esters directly from plant-derived essential oil is crucial to meet the 2050 net zero targets to produce bio-based chemicals. The simultaneous transesterification of geraniol and citronellol in a batch reactor successfully achieved conversions of 66 % for citronellol and 94 % for geraniol within 5 h. Key optimum conditions were 1:8 molar ratio (geraniol:vinyl acetate), an enzyme loading of 10 wt % of geraniol, temperature of 40 °C, and a stirring speed of 250 RPM. The results indicated that simultaneous transesterification followed a ternary complex mechanism with competitive inhibition by alcohol. Initial testing of rose geranium oil under optimised conditions yielded 32 % citronellol and 50 % geraniol conversion after 30 h. Overall, this study shows promise as a green pathway utilising enzyme catalysis to selectively produce esters from diverse terpene mixtures and can be extended to terpene alcohols derived from flower essential oils.

Green ammonia production: Process technologies and challenges

Ammonia, a vital player in the global economy, propels economic growth through its key role in fertilizer production, boosting agricultural output significantly. While traditional methods dominate its production, recent efforts focus on sustainable pathways like green ammonia, produced using renewable energy. This colourless gas, beyond agriculture, becomes a versatile input in chemical manufacturing, finding applications in solvents and fertilizers. Industries are increasingly adopting green pathways to reduce carbon footprints, exploring methods using green hydrogen and CO2 by-products. Green ammonia, a beacon for decarbonization, surpasses hydrogen in volumetric energy density, making it a preferred energy carrier. Power-to-Ammonia technology supports energy storage and transfer capabilities, aiding renewable energy integration. Despite challenges like low reactivity, NOx emissions, and toxicity, ammonia's global demand is projected to rise to 350 million tonnes/year by 2050. This review article emphasizing the need for sustainable ammonia production to achieve economic competitiveness, environmental sustainability, and a carbon–neutral future.