Green Way Research Articles

Fatty Acid Epoxidation on Enzymes: Experimental Study and Modeling of Batch and Semibatch Operation

Biolubricants, plasticizers, bio-based rigid foams, and non-isocyanate polyurethanes can be made in a green way from epoxidized fatty acids. The classical technology for fatty acid epoxidation requires a reaction carrier, which acts as the real epoxidation agent. The process is complicated and involves a safety risk because of the appearance of percarboxylic acids. Therefore, the direct epoxidation of fatty acids in the presence of an immobilized enzyme is an attractive pathway to epoxidized fatty acids. Oleic acid was used as the model compound is this work, and commercial immobilized lipase Novozym 435 was used as the catalyst and hydrogen peroxide as the epoxidation agent. Batch and semibatch operation modes were tested in a laboratory-scale stirred tank reactor. The experimental results showed that almost complete conversions of the double bonds in oleic acid were achievable under isothermal batch and semibatch operation, with low concentrations of ring-opening byproducts. Semibatch operation gave an improvement of the product yield. Mathematical modeling of the experimental data was based on the reaction stoichiometry OA + HP → POA + W and OA + POA → EOA + OA, where OA = oleic acid, HP = hydrogen peroxide, POA = peroleic acid, W = water, and EOA = epoxized OA. Rate equations for the formation of peroleic acid and epoxide were derived, and the numerical values of the kinetic and adsorption parameters were estimated with nonlinear regression analysis. The reactor models consisted of ordinary differential equations, which were solved numerically during the parameter estimation until the optimal parameter values were reached. The model gave a very good description of the experimental data.

Design of novel transition-metal-doped C4N4 as highly effective electrocatalysts for nitrogen fixation with a new intrinsic descriptor

Electrocatalytic nitrogen reduction reaction (NRR) is an efficient and green way to produce ammonia, which offers an alternative option to the conventional Haber-Bosch process. Unfortunately, the large-scale industrial application of NRR processes is still hindered by poor Faraday efficiency and high overpotential, which need to be overcome urgently. Herein, combined with density functional theory and particle swarm optimization algorithm for the nitrogen carbide monolayer structural search (CmN8-m, m = 1–7), the surprising discovery is that single transition metal-atom-doped C4N4 monolayers (TM@C4N4) could effectively accelerate nitrogen reduction reaction. TM@C4N4 (TM = 29 transition metals) as single-atom catalysts are evaluated via traditional multi-step screening method, and their structures, NRR activity, selectivity and solvation effect are investigated to evaluate their NRR performance. Through the screening steps, W@C4N4 possesses the highest activity for NRR with a very low limiting potential of −0.29 V. Moreover, an intrinsic descriptor φ is proposed with machine learning, which shortens the screening process and provides a new idea for finding efficient SACs. This work not only offers promising catalysts W@C4N4 for NRR process but also offers a new intrinsic and universal descriptor φ.

Dissociative electron transfer mechanism and application in the electrocatalytic activation of organic halides

The electrochemical dehalogenation of organic halides has been a widely investigated topic in primis for fundamental investigations of dissociative electron transfer (DET) and as a green way for the electrosynthesis of organic compounds and environmental remediation. The main drawback associated with the electrochemical activation of C-X is the very negative potentials required, and this is particularly true in the case of organic chlorides, which represent the most investigated ensemble among organic molecules containing a leaving group. This has boosted over the last decades the research of electrode materials that are active toward C–X bond breaking, and without any doubt, Ag possesses extraordinary electrocatalytic properties, so far unsurpassed by any other electrode material. In this paper, we will attempt to brush up on important concepts related to DET in organic halides, while also evaluating recent developments in terms of electrode materials used in electrosynthesis based on organic halides and RX degradation processes.

MOF-initiated imprinted self-supporting basswood membranes for precise recognition and separation of artemisinin

Membrane-based separations can lessen the environmental effect of conventional techniques while increasing energy efficiency. Conventional adsorbents, on the other hand, enclose the majority of their functional sites in their dense structures, which causes problems with limited selectivity and adsorption capacity. By top-down method, based on the molecular structure and properties of artemisinin (Ars), a three-dimensional porous basswood membrane and a Metal-organic framework (MOF)-based modified layer were used as a dot-matrix initiator. The combination design of hydrophobic bond and complex bond interaction synergistic imprinting strategy was used to construct high density and high selectivity Ars molecularly imprinted polymers (MIPs) on the membrane, thus achieving the preparation of MOF-initiated imprinted self-supporting basswood membranes (MPIBSMs). When combined with the superhydrophilicity of the TiO2 modified layer and the numerous accessible imprinting sites that MOF previously grown in situ on basswood provided, the resulting MPIBSMs displayed good adsorption capacity (81.2 mg g−1), selectivity coefficient (greater than 4.9), and ultrahigh water flux, eliminating the "trade-off" effect between membrane flux and selectivity. Additionally, the MPIBSMs are synthesized in a straightforward, pollution-free manner. Additionally, MPIBSMs were created in a green way. Finally, the aforementioned experimental findings and the environmentally sound synthetic technique imply that MPIBSMs have a wide range of possible applications in several fields, including environmental protection and selective separation.

A Brief Review on Flexible Electronics for IoT: Solutions for Sustainability and New Perspectives for Designers.

The Internet of Things (IoT) is gaining more and more popularity and it is establishing itself in all areas, from industry to everyday life. Given its pervasiveness and considering the problems that afflict today's world, that must be carefully monitored and addressed to guarantee a future for the new generations, the sustainability of technological solutions must be a focal point in the activities of researchers in the field. Many of these solutions are based on flexible, printed or wearable electronics. The choice of materials therefore becomes fundamental, just as it is crucial to provide the necessary power supply in a green way. In this paper we want to analyze the state of the art of flexible electronics for the IoT, paying particular attention to the issue of sustainability. Furthermore, considerations will be made on how the skills required for the designers of such flexible circuits, the features required to the new design tools and the characterization of electronic circuits are changing.

Multicomponent Approaches Involving Carbon Disulfide

AbstractIn present scenario, innovative carbon disulfide‐involving multicomponent protocols are extremely advantageous for practical and efficient construction of acyclic as well as heterocyclic building blocks. Carbon disulfide is well recognized synthetic component and has achieved the desirability of scientific community for the preparation of a variety of highly functionalized organic scaffolds. Carbon disulfide involving MCRs mostly advantage from other features such as bond‐forming efficiency, resource effectiveness, the use of easily obtainable starting compounds, and atom‐economy, which make these protocols useful environmentally benign alternatives, in care with the greener way in which organic chemistry is going on. In this review article, we have discussed the noteworthy topical advances in the promising region of carbon disulfide‐involving multicomponent reactions. It highlight the prospects and confronts, emphasizing the diverse approaches established previously.

Covalent Crosslinking Cellulose/Graphene Aerogels with High Elasticity and Adsorbability for Heavy Metal Ions Adsorption.

With the fast development of modern industry, heavy metal contaminant became more severe. How to remove heavy metal ions in water in a green and efficient way is a prominent problem in current environmental protection. The adsorption of cellulose aerogel as a novel heavy metal removal technology has many advantages, including abundant resources, environmental friendly, high specific surface, high porosities and without second pollution, which means it has a wide application prospect. Here, we reported a self-assembly and covalent crosslinking strategy to prepare elastic and porous cellulose aerogels using PVA and graphene and cellulose as precursor. The resulting cellulose aerogel had a low density of 12.31 mg cm-3 and excellent mechanical properties, which can recover to its initial form at 80% compressive strain. Meanwhile, the cellulose aerogel had strong adsorption capacity of Cu2+ (80.12 mg g-1), Cd2+ (102.23 mg g-1), Cr3+ (123.02 mg g-1), Co2+ (62.38 mg g-1), Zn2+ (69.55 mg g-1), and Pb2+ (57.16 mg g-1). In addition, the adsorption mechanism of the cellulose aerogel was investigated using adsorption kinetics and adsorption isotherm, and the conclusion was that the adsorption process was mainly controlled by chemisorption mechanism. Therefore, cellulose aerogel, as a kind of green adsorption material, has a very high application potential in future water treatment applications.

Biodegradation of p-hydroxybenzoic acid in Herbaspirillum aquaticum KLS-1 isolated from tailing soil: Characterization and molecular mechanism

The wide distribution of p-hydroxybenzoic acid (PHBA) in the environments has attracted great concerns due to its potential risks to organisms. Bioremediation is considered a green way to remove PHBA from environment. Here, a new PHBA-degrading bacterium Herbaspirillum aquaticum KLS-1was isolated and its PHBA degradation mechanisms were fully evaluated. Results showed that strain KLS-1 could utilize PHBA as the sole carbon source and completely degrade 500 mg/L PHBA within 18 h. The optimal conditions for bacterial growth and PHBA degradation were pH values of 6.0–8.0, temperatures of 30 °C-35 °C, shaking speed of 180 rpm, Mg2+ concentration of 2.0 mM and Fe2+ concentration of 1.0 mM. Draft genome sequencing and functional gene annotations identified three operons (i.e., pobRA, pcaRHGBD and pcaRIJ) and several free genes possibly participating in PHBA degradation. The key genes pobA, ubiA, fadA, ligK and ubiG involved in the regulation of protocatechuate and ubiquinone (UQ) metabolisms were successfully amplified in strain KLS-1 at mRNA level. Our data suggested that PHBA could be degraded by strain KLS-1 via the protocatechuate ortho-/meta-cleavage pathway and UQ biosynthesis pathway. This study has provided a new PHBA-degrading bacterium for potential bioremediation of PHBA pollution.

Combining Blue Light and Yellow Curcumin to Obtain a "Green" Tool for Berry Preservation against Bacterial Contamination: A Preliminary Investigation.

Background: According to recent studies, tens of millions of tons of fruit are wasted each year in Europe in primary production and home/service consumption. Among fruits, berries are most critical because they have a shorter shelf life and a softer, more delicate, and often edible skin. Curcumin is a natural polyphenolic compound extracted from the spice turmeric (Curcuma longa L.) which exhibits antioxidant, photophysical, and antimicrobial properties that can be further enhanced by photodynamic inactivation of pathogens when irradiated with blue or ultraviolet light. Materials and methods: Multiple experiments were performed in which berry samples were sprayed with a complex of β-cyclodextrin containing 0.5 or 1 mg/mL of curcumin. Photodynamic inactivation was induced by irradiation with blue LED light. Antimicrobial effectiveness was assessed with microbiological assays. The expected effects of oxidation, curcumin solution deterioration, and alteration of the volatile compounds were investigated as well. Results: The treatment with photoactivated curcumin solutions reduced the bacterial load (3.1 vs. 2.5 colony forming units/mL (UFC/ml) in the control and treated groups; p-value = 0.01), without altering the fruit organoleptic and antioxidant properties. Conclusions: The explored method is a promising approach to extend berries' shelf life in an easy and green way. However, further investigations of the preservation and general properties of treated berries are still needed.

GO Treated with Aminoethyl‐Piperazine as a Reusable and Eco‐friendly Organocatalyst for Synthesis of Some Xanthen and Pyran Derivatives

AbstractGraphene Oxide (GO) containing 1‐(2‐aminoethyl) piperazine as a reusable, highly efficient and heterogeneous organocatalyst was prepared using a simple and green way. Epoxide groups on the surface of GO layers were replaced with 1‐(2‐aminoethyl) piperazine by an easy and green technique in a mild condition. The prepared catalyst (GO‐A.P.) was characterized using diverse microscopic and spectroscopic techniques. The presence of organic functional groups on the surface of GO‐A.P. was confirmed by Fourier transform infrared and Raman spectroscopy. X‐ray diffraction analysis showed an increase in the catalyst's interlayer spaces which confirm the successful presence of 1‐(2‐aminoethyl) piperazine molecules on the GO surface. Also interaction between the organic molecules and GO was established by thermogravimetric analysis via weight loss steps. Then, the capability of this catalyst was evaluated in a three‐component coupling reaction for one‐pot synthesis of 12‐aryl‐8,9,10,12‐tetrahydrobenzo[a]xanthen‐11‐one (A1–A7) and also 2‐amino‐4H‐pyrans (B1–B8) derivatives. The target products were obtained in high isolated yields. Furthermore, our catalyst was reusable at least for 5 runs with no significant decrease in its activity.

Green synthesis of MoSe2 nanosheets based on hydrogen bond with high photodegradation performance

MoSe2 is listed as a very promising photocatalyst candidate due to its unique 2D nanostructure and narrow band gap, yet how to obtain it in a green and facile way is still a challenge. In this work, multilayered MoSe2 nanosheets were successfully prepared by a hydrothermal method using a hydrogen bond-based melamine-oxalic acid polymer as the reducing agent, surfactant and template. X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Bruno-Emmett-Taylor (BET), X-ray photoelectron spectroscopy (XPS) and UV–Vis spectroscopy were used to characterize the composition, morphology, specific surface area and band gap of the product. In addition, the photodegradation experiments of Rhodamine B and methylene blue were carried out by using such MoSe2 nanosheets. The degradation of Rhodamine B reached 94.4% in 40 min, while the degradation of methylene blue reached 95.1% in 50 min, respectively. After four cycles of degradation, it still maintained a high catalytic activity. The formation mechanism of the MoSe2 nanosheets and the photocatalytic mechanism have also been explained.

A fast, efficient, inexpensive and green way to outdoor photopolymerization

A series of environmentally friendly photoinitiating systems operating under mild conditions of visible light (Vis-PIs) were tested for vinyl polymerization using sunlight as a free of charge radiation source. These Vis-PIs based on water soluble xanthene dyes showed good performances after deaerating with an inert gas, obtaining colorless polymers with gravimetric yields up to 80–90% after short irradiation times (2–15 min). Aqueous solutions of the materials were highly viscous and viscosimetric measurements yielded molecular weights up to 106. Surprisingly, the evaluated Vis-PIs also worked successfully under ambient air atmosphere, obtaining similar polymer yields in the same irradiation times. Photolysis experiments and transient spectroscopy were used to shed light on the mechanism of the process, allowing both triplets and radicals formation of the dyes to be identified even in the presence of air. The kinetics of photopolymerization was studied following the monomer conversion at several irradiation times by FTIR. The results were interpreted based on kinetic data collected as competitive quenching mechanisms between the co-initiator and oxygen for the excited dyes. The present report represents a breakthrough in the search for fast, efficient and inexpensive Vis-PIs with low ecological impact, which can be very useful in outdoor coating applications among others.

Dry heating affects the multi-structures, physicochemical properties, and in vitro digestibility of blue highland barley starch.

As a physical method for starch modification, dry heating treatment (DHT) at high temperatures (150 and 180°C, respectively) was applied to blue highland barley (BH) starch with different durations (2 and 4 h). The effects on its multi-structures, physicochemical properties, and in vitro digestibility were investigated. The results showed that DHT had changed the morphology of BH starch, and the diffraction pattern remained an "A"-type crystalline structure. However, with an extension of DHT temperature and time, the amylose content, gelatinization temperature, enthalpy value, swelling power, and pasting viscosity of modified starches decreased, while the light transmittance, solubility, and water and oil absorption capacities increased. Additionally, compared with native starch, the content of rapidly digestible starch in modified samples increased after DHT, whereas those of slowly digestible starch and RS decreased. Based on these results, the conclusion could be drawn that DHT is an effective and green way to transform multi-structures, physicochemical properties, and in vitro digestibility of BH starch. This fundamental information might be meaningful to enrich the theoretical basis of physical modification on BH starch and extend the applications of BH in the food industry.

Green preparation of flake nano porous carbon: For sulfur scaffolds in high-performance lithium sulfur batteries

In this report, we describe the creation of 2D porous nitrogen-doped carbon nanosheets using carbon precursors derived from silkworm cocoon biomass and CaCl2, a non-toxic and environmentally friendly material. The resulting carbon material exhibits a unique structure of nitrogen-doped nanosheets, extensive pore structure, and a significant specific surface area of 675 m2 g−1, which is attributed to the effect of Ca2+ on the structural conformation of silk glue protein. The high nitrogen doping, thin carbon sheets, and dense pore structure of the electrode material contribute to its excellent electrochemical performance. When used in a lithium‑sulfur composite electrode, it demonstrates exceptional electrochemical properties, including a very high initial capacity of 1403 mAh g−1, good multiplicity performance, and excellent cycling performance (700 mAh g−1 after 100 cycles at 0.1 C, 319 mAh g−1 after 1000 cycles at 1 C, and a capacity decay rate of 0.07 % per cycle). Importantly, the preparation strategy avoids the use of strong acid and alkaline structural restructuring agents, and provides an effective and green way to prepare advanced porous carbon electrode materials for lithium‑sulfur batteries.

Visible Light-Driven Conversion of Carbon-Sequestrated Seawater into Stoichiometric CO and HClO with Nitrogen-Doped BiOCl Atomic Layers.

Seawater is one of the most important CO2 sequestration media for delivering value-added chemicals/fuels and active chlorine; however, this scenario is plagued by sluggish reaction rates and poor product selectivity. Herein, we first report the synthesis of nitrogen-doped BiOCl atomic layers to directly split carbon-sequestrated natural seawater (Yellow Sea, China) into stoichiometric CO (92.8 μmol h-1 ) and HClO (83.2 μmol h-1 ) under visible light with selectivities greater than 90 %. Photoelectrons enriched on the exposed BiOCl{001} facet kinetically facilitate CO2 -to-CO reduction via surface-doped nitrogen bearing Lewis basicity. Photoholes, mainly located on the lateral facets of van der Waals gaps, promote the selective oxidation of Cl- into HClO. Sequestrated CO2 also maintains the pH of seawater at around 4.2 to prevent the alkaline earth cations from precipitating. The produced HClO can effectively kill typical bacteria in the ballast water of ocean-going cargo ships, offering a green and safe way for onsite sterilization.

Visible Light‐Driven Conversion of Carbon‐Sequestrated Seawater into Stoichiometric CO and HClO with Nitrogen‐Doped BiOCl Atomic Layers

AbstractSeawater is one of the most important CO2 sequestration media for delivering value‐added chemicals/fuels and active chlorine; however, this scenario is plagued by sluggish reaction rates and poor product selectivity. Herein, we first report the synthesis of nitrogen‐doped BiOCl atomic layers to directly split carbon‐sequestrated natural seawater (Yellow Sea, China) into stoichiometric CO (92.8 μmol h−1) and HClO (83.2 μmol h−1) under visible light with selectivities greater than 90 %. Photoelectrons enriched on the exposed BiOCl{001} facet kinetically facilitate CO2‐to‐CO reduction via surface‐doped nitrogen bearing Lewis basicity. Photoholes, mainly located on the lateral facets of van der Waals gaps, promote the selective oxidation of Cl− into HClO. Sequestrated CO2 also maintains the pH of seawater at around 4.2 to prevent the alkaline earth cations from precipitating. The produced HClO can effectively kill typical bacteria in the ballast water of ocean‐going cargo ships, offering a green and safe way for onsite sterilization.

Room Temperature Synthesis Mediated Porphyrinic NanoMOF Enables Benchmark Electrochemical Biosensing.

Leveraging size effects, nanoparticles of metal-organic frameworks, nanoMOFs, have recently gained traction, amplifying their scopes in electrochemical sensing. However, their synthesis, especially under eco-friendly ambient conditions remains an unmet challenge. Herein, an ambient and fast secondary building unit (SBU)-assisted synthesis (SAS) route to afford a prototypal porphyrinic MOF, Fe-MOF-525 is introduced. Albeit the benign room temperature conditions, Fe-MOF-525(SAS) nanocrystallites obtained are of ≈30nm size, relatively smaller than the ones conventional solvothermal methods elicit. Integrating Fe-MOF-525(SAS) as a thin film on a conductive indium tin oxide (ITO) surface affords Fe-MOF-525(SAS)/ITO, an electrochemical biosensor. Synergistic confluence of modular MOF composition, analyte-specific redox metalloporphyrin sites, and crystal downsizing contribute to its benchmark voltammetric uric acid (UA) sensing. Showcasing a wide linear range of UA detection with high sensitivity and low detection limit, this SAS strategy coalesces ambient condition synthesis and nanoparticle size control, paving a green way to advanced sensors.

Recycling Spent Lithium-Ion Batteries Using Waste Benzene-Containing Plastics: Synergetic Thermal Reduction and Benzene Decomposition.

Spent lithium-ion batteries (LIBs) and benzene-containing polymers (BCPs) are two major pollutants that cause serious environmental burdens. Herein, spent LIBs and BCPs are copyrolyzed in a sealed reactor to generate Li2CO3, metals, and/or metal oxides without emitting toxic benzene-based gases. The use of a closed reactor allows the sufficient reduction reaction between the BCP-derived polycyclic aromatic hydrocarbon (PAH) gases and lithium transition metal oxides, achieving the Li recovery efficiencies of 98.3, 99.9, and 97.5% for LiCoO2, LiMn2O4, and LiNi0.6Co0.2Mn0.2O2, respectively. More importantly, the thermal decomposition of PAHs (e.g., phenol and benzene) is further catalyzed by the in situ generated Co, Ni, and MnO2 particles, which forms metal/carbon composites and thus prevent the emissions of toxic gases. Overall, the copyrolysis in a closed system paves a green way to synergistically recycle spent LIBs and handle waste BCPs.

Towards Green Synthesis of Fluorescent Metal Nanoclusters.

In the modern development of nanoscience and nanotechnology, metal nanoclusters have emerged as a foremost category of nanomaterials exhibiting remarkable biocompatibility and photo-stability having dramatically distinctive optical, electronic, and chemical properties. This review focuses on synthesizing fluorescent metal nanoclusters in a greener way to make them suitable for biological imaging and drug delivery application. The green methodology is the desired route for sustainable chemical production and should be utilized for any form of chemical synthesis including nanomaterials. It aims to eliminate harmful waste, uses non-toxic solvents, and employs energy-efficient processes for the synthesis. This article provides an overview of conventional synthesis methods, including stabilizing nanoclusters by small organic molecules in organic solvents. Then we focus on the improvement of properties, applications of green synthesized metal nanoclusters, challenges involved, and further advancement required in the direction of green synthesis of MNCs. There are plenty of problems for scientists to solve to make nanoclusters suitable for bio-applications, chemical sensing, and catalysis synthesized by green methods. Using bio-compatible and electron-rich ligands, understanding ligand-metal interfacial interactions, employing more energy-efficient processes, and utilizing bio-inspired templates for synthesis are some immediate problems worth solving in this field that requires continued efforts and interdisciplinary knowledge and collaboration.

Recycled brick powder from construction and demolition waste as waterborne coating filler with robust scrubbing resistance

During the daily use of waterborne coatings, it was unavoidable to be scratched so that it was required to have the property of scrubbing resistance. This study explored the use of recycled red bricks as a substitute filler for waterborne coatings. The prepared red brick powder (RBP) waterborne coating exhibited exceptional scrubbing resistance, with a maximum resistance of over 9000 times, which was approximately 4.5 times higher than the national standard in China. The addition of pigment volume concentration (PVC) between 40 ∼ 53% significantly improved the coating’s performance. The use of RBP as a coating framework also enhanced the coating’s hardness, which was found to be 85–103 times better than that of commercial coatings (75–90 times). Moreover, the water absorption of RBP waterborne coating was only 14.4%, which is significantly lower than that of commercial coatings (25.2–32.0%). These two key factors, low water absorption and high hardness, were found to be crucial in improving the scrubbing resistance of coatings. The incorporation of emulsion, such as styrene acrylic, further improved the compactness of coating, by strengthening the benefits of the good hardness and low water absorption. The use of construction and demolition waste as a resource for waterborne coating would be a green and efficient way to eliminate massive land resource occupation and potential environmental risks.