Eco-friendly Route Research Articles

Solvent-dependent selective oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid under neat conditions

An eco-friendly and economical route for the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) with atmospheric dioxygen as the sole oxidant under acid-, base-, metal-, and external initiator-free conditions in minimal solvent was reported. In the present reaction, the 1,2-diethoxyethylane has a dual role: reaction medium and free-radical initiator. The FDCA easily crystallizes during the reaction and was simple purified via recrystallization to provide the pure FDCA.

Calcium ions enhanced mussel-inspired underwater superoleophobic coating with superior mechanical stability and hot water repellence for efficient oil/water separation

The presented study proposed a simple, eco-friendly, and inexpensive route for improvement in mechanical robustness and hot solutions resistance of underwater superoleophobic mesh. The robustly underwater superoleophobic mesh was fabricated by introducing polydopamine (PDA)-calcium (Ca) complex aggregations to form hierarchical micro/nano-structures on the mesh surface. The wettability, appearance, roughness, and chemical composition of the obtained mesh were investigated. The generated coating reveals ultralow underwater oil adhesion and superior resistance to ultraviolet irradiation, hot water, oils, mechanical abrasion and folding. Moreover, the fabricated mesh can separate all sorts of oil/hot (95 ℃) water mixtures with high efficiencies (>97.8%) and satisfactory oil intrusion pressure. Especially, the decorated mesh can maintain high efficiency (>98.2%) after the separation of 80 cycles to oil/hot water mixtures, showing outstanding stability. Besides, the developed mesh can be applied as a separation material for gravity driven penetration of corrosive water from oil with high efficiency (>97%). We believe that the fabricated mesh with good stability and excellent separation performance has great potential to solve large-scale water contamination resulted from oil leaking accidents and oily water emission.

Preparation and characterization of Curcumin niosomal nanoparticles via a simple and eco-friendly route

In this investigation, curcumin niosomal nanoparticles were prepared via a simple, efficient and eco-friendly route, thin film hydration (TFH), in the presence of different mixture of the surfactants (tween 60 and span 60). Cholesterol ratio to surfactant, as effective factor, was altered to obtain the optimal nanoparticles. The size, zeta potential, size distribution, entrapment efficiency of the prepared nanoparticles were examined and compared. The optimum nanoparticles were chosen to examine the release from the dialysis membrane. Ratio of cholesterol to surfactant was found to have key and notable influence on the size, zeta potential, size distribution, entrapment efficiency of the prepared nanoparticles. The nanoparticles prepared with Formulations 3 and 5 as optimum nanoparticles were chosen to examine the release from the dialysis membrane. The results denoted that by increasing the ratio of cholesterol to surfactant, the rate of curcumin release was enhanced from the membrane. High quantities of cholesterol in the formulation 3, in addition to explosive release, can lead to slow release.

Au nanoparticles by instant green chemicals and optimising key synthesis parameters using Taguchi method

In the recent years, functionalised Au nanoparticles using eco-friendly chemical routes are under the focus for developing several technological applications. However, a simple, reproducible, and controlled synthesis of high-quality nanoparticles is challenging in these approaches. In this work, readily available green chemicals were utilised and the usefulness of and Taguchi approach for optimisation of synthesis procedure was designed for the synthesis of possible lower size Au nanoparticles of size 93 ± 7 nm. L16 orthogonal array, by which the influence of four factors in four levels may well be tested, was chosen. Analysis of variance was done on the attained results and optimum condition suggested by statistical estimations was tested through a verification test. The identified key parameters for synthesising lower size Au nanoparticles are reducing agent (curcumin + cinnamic acid + citric acid), additive (zero), sonication time (30 min), and temperature (50°C) after performing the optimisation technique. Furthermore, this study also provides a selective approach to obtain different shape/shape Au nano to colloidal structures through different trail selection within the Taguchi experimental array.

Biogenic synthesis of green and cost effective iron nanoparticles and evaluation of their potential biomedical properties

This present study for the first time reports a facile and ecofriendly route for synthesis of IONPs. The IONPs were simply synthesized using Rhamnella gilgitica leaves extract as both reducing and stabilizing agents. The color change of the reaction mixture from dark brown to reddish black determined the biofabrication of IONPs which was further confirmed by the presence of an absorbance peak at 341 nm. The biogenic IONPs were further studied using various microscopic and spectroscopic techniques; SEM, TEM, XRD, DLS, FT-IR, EDX and Raman spectroscopy. The IONPs were further evaluated for anticancer potential against HepG2 cancer cells (IC50: 14.30 μg/mL) in concentrations range of 5.47–700 μg/mL. Dose-dependent cytotoxicity assay was performed against Leishmanial amastigotes (IC50: 26.91 μg/mL) and promastigotes (IC50: 9.63 μg/mL). In addition, cytotoxicity assay was evaluated against brine shrimps (IC50: 34.45 μg/mL). The disc diffusion method showed significant antibacterial and antifungal activities. Significant antioxidants and enzyme inhibition potentials were revealed. Biocompatibility tests were performed against human RBCs and macrophages and determined the hemocompatible nature of IONPs. Overall, IONPs have played significant role in multiple biological applications. In future, we suggest different in vivo studies on toxicity aspects in different animal models and for once the biosafety is maintained, then these nanoparticles can be utilized in nano-pharma industries for the treatment of different diseases.

Novel fabrication of gelatin-encapsulated copper nanoparticles using Aspergillus versicolor and their application in controlling of rotting plant pathogens.

The fabrication of copper nanoparticles (CuNPs) with smallest size and more stability, with potential effects in plant disease management, may need a modified protocol for green synthesis. In this study, we could biosynthesize stable CuNPs extracellularly by an eco-friendly route using A. versicolor. The biosynthesis of nanoparticles was confirmed by UV-visible spectroscopy, Fourier transform infrared (FTIR), transmission electron microscope (TEM) and dynamic light scattering (DLS) techniques. CuNPs have a size range of 23-82nm with round to polygonal shape. Antifungal study showed that CuNPs have potential antifungal activity against rotting plant pathogens, where 3.2 and 2.8µgml-1 of nanoparticle solution totally inhibited the growth of both Fusarium oxysporum and Phytophthora parasitica, respectively. Damaged hyphae with limited deformed spores were detected through scanning electron microscope (SEM) analysis after the treatment of both pathogens with CuNPs. Between all tested polymers, gelatin-encapsulated nanoparticles were characterized 'by their smallest size, 7-33nm, and regular spherical shape at all experimental conditions. After 6months of storage, gelatin-CuNPs maintained full nanoscale and antifungal properties compared with uncoated particles which lost these properties after only 1month. It is concluded that CuNPs can be biosynthesized by an eco-friendly cheap method using A. versicolor and can be preserved stably for a long time with the smallest size and full antifungal activity by their encapsulation with gelatin as a natural polymer. These nanoparticles can be used safely in the management of plant rotting fungi.

Electrocatalytic oxygen evolution and photoswitching functions of tungsten-titanium binary oxide nanostructures

Tungsten-titania (WO3-TiO2) based binary oxide was fabricated by an eco-friendly chemical route for electrocatalytic water splitting and photoelectrical applications. Ambiguous evidence for the coexistence of W/Ti oxides and their binary feature were extensively studied by different analytical tools and also affirmed using high-resolution microscopy. The existence of multiple defects in the binary material and their 2.68 eV optical band gap was evaluated using the room-temperature photoluminescence data and Tauc's plot, respectively. Nature of conductivity in WO3-TiO2 and its flat band potential was inferred using Mott–Schottky type electrochemical impedance spectroscopic results. The enhanced photosensitivity in WO3-TiO2 was demonstrated using a flip-chip Schottky diode architecture and reasoned to the improved charge transfer kinetics across the same. Next, the potential of WO3-TiO2 for stable water splitting functions was examined. Here, WO3-TiO2 interface was found to provide an enriched surface area for effective charge transfer, complementing towards the effective oxygen evolution reaction (OER) performance. The results demonstrated a smaller overpotential of 270 mV, authenticating the oxide system as an effective anode material for water splitting reactions with excellent stability.

Optical and electrochemical studies of silver nanoparticles biosynthesized by Haplophyllum tuberculatum extract and their antibacterial activity in wastewater treatment

Silver nanoparticles (AgNPs) were biosynthesized through simple, fast, elegant and ecofriendly route using AgNO3 as a precursor and Haplophyllum tuberculatum aqueous extract. Transmission Electron Microscopy (TEM) and energy-dispersive x-ray spectroscopy (EDX) were used to determine the morphological properties, while Fourier Transform Infrared spectroscopy (FTIR) and zeta potential were used to identify the capping molecules and the stability of the nanoparticles, respectively. AgNPs were electrochemically detected using cyclic voltammetry (CV) and its optical properties were investigated using UV–Vis and fluorescence spectroscopy. Our findings showed that AgNPs size ranges from 20 to 60 nm. FTIR studies referred to the role of polyphenolics in AgNPs stability. Zeta potential value (−42 mV) confirmed the high stability of AgNPs, while CV value (0.42 mV) explain the electrochemical behavior of the nanoparticles. Additionally, biosynthesized AgNPs have a brilliant antibacterial activity against total and fecal coliform in addition to the potent antibacterial activity against clinically isolated Gram positive and Gram negative bacteria. The employment of these AgNPs in disinfection protocols can potentially help us in various applications such as biological treatment of wastewater.

Crystal phase effect of iron oxides on the aerobic oxidative coupling of alcohols and amines under mild conditions: A combined experimental and theoretical study

Selective catalytic oxidation using air as the terminal oxidant is an ecofriendly route for the synthesis of fine and commodity chemicals. However, the catalyst generally faces the challenges of the inertness of molecular oxygen, limited substrate scope, poor selectivity, and high cost. Moreover, the toxicity of the catalyst should also be considered when the products are used in pharmaceutical or biotechnological areas. Here, upon investigating the dependence of catalytic oxidation on the crystal phases of iron oxides, we find that naked γ-Fe2O3 particles exhibit excellent catalytic activity, selectivity, and stability in a series of imine synthetic reactions. The performance of γ-Fe2O3 particles is significantly better than that of α-Fe2O3 and Fe3O4 under mild reaction conditions, and the γ-Fe2O3 catalyst can be separated from the reaction mixture magnetically. Both experimental and theoretical calculation results show that γ-Fe2O3 possesses supercapability for oxygen activation. The inverse spinel structure of γ-Fe2O3 has abundant cation vacancies, which confers unique electronic properties on surface Fe species. These Fe species tend to transfer electrons to molecular oxygen to form O2− or O22− species. These oxygen species are favorable for the dehydrogenation of alcohols, which is responsible for the high activity of γ-Fe2O3 in this coupling reaction.

Synthesis of 2-(Prop-2-ynyloxy) Benzaldehyde using Salicyl Aldehyde and Propargyl Bromide in Aqueous Micellar Media

Abstract Advances in science and technology are promoting eco-friendly synthesis routes, green chemicals, and non-hazardous solvents. A suitable method for the synthesis of 2-(prop-2-ynyloxy) benzaldehyde was developed using three different aqueous micellar media. The targeted product ether is completely immiscible in water, but in combination with interface active surfactants it has been possible to produce the hydrophobic organic compound in water. Micelles function as a pseudocellular organic environment to isolate species from the main solvent and favor compartmentalization of reagents. There is an increase in the local concentration and consequently the reactivity increases. The use of such unique chemo-, regio-, and stereoselectivity renders this reaction new. Organic species added to a micellar media are distributed between water and micelles depending on polarity, charge, and size. In the experiments it was observed that salicylaldehyde and propargyl bromide interacted best in CTAB media and the yield of the formed product was 96 %.

Hybrid hydrogels containing one-step biosynthesized silver nanoparticles: Preparation, characterization and catalytic application

Silver nanoparticles (AgNPs) were synthesized using an innovative strategy that makes use of tangerine peels extract, which acts as a reducing and stabilizing agent. This eco-friendly synthetic route allowed obtaining spherical nanoparticles with narrow size distribution (19.2±6.7nm) within a short reaction time (40min). Later, the AgNPs suspension was entrapped in a poly(vinyl alcohol) (PVA) matrix forming a hybrid hydrogel (PVA-gel/AgNPs), which was characterized by different techniques. Its catalytic activity was explored in the reduction of nitrobenzene to aniline in aqueous media. The reaction catalyzed by PVA-gel/AgNPs exhibited kinetics (kapp≈2.07×10−3min−1) and energy of activation (Ea≈50.36kJmol−1) comparable to or lower than similar reactions catalyzed by other metals. Moreover, a better catalytic performance was noticed to the hybrid hydrogel as compared to “free” AgNPs, highlighting their entrapment within the hydrogel. The anchoring of the AgNPs in the hydrogel network, prevents their aggregation and leaching. The hybrid hydrogel is recovered quickly from the reaction medium, and it can be successfully reused for six consecutive runs without significant loss of its activity. Overall, it is presented here a cheap, efficient, and eco-friendly methodology to synthesize AgNPs and newly hybrid hydrogels, which have the potential to catalyze the reduction of nitroaromatic compounds.

One-pot grinding method to BiO(HCOO)xI1−x solid solution with enhanced visible-light photocatalytic activity

Considering that conventional hydrothermal route to prepare photocatalysts is energy-consumable and difficult to scale-up, herein, uniform bismuth oxide formate (BiOHCOO; BiOR) nanosheets were firstly prepared from solid-state chemical reaction by a facile room-temperature grinding method. Furthermore, since BiOR could only respond to UV light, thin-nanosheet-based flowerlike BiO(HCOO)xI1−x solid solutions were synthesized via a one-pot method by adding KI into the BiOR reaction mixture and continuously grinding for an additional duration. As compared with BiOR, the resulting solid solution with x = 0.57 possessed narrower band gap, optimal energy levels and higher surface areas, leading to much higher visible-light photocatalytic activity for multiple pollutants degradation including rhodamine B (RhB), malachite green (MG) and colorless bisphenol A (BPA). This work demonstrates an easily-handling and eco-friendly solid-state reaction route to solid solutions with excellent visible-light photocatalytic activity. Good photocatalytic performance was also confirmed by electrochemical techniques.

Optimising an eco-friendly vehicle routing problem model using regular and occasional drivers integrated with driver behaviour control

Vehicle routing problem (VRP) research has recently improved dramatically to simulate more real-life circumstances. Nevertheless, the typical VRP models proposed have been isolated from the most important factor determining the success of the VRP plan on the ground, i.e. the human factor (driver). Thus, this research investigates the effect of drivers' behaviours on the optimal VRP plan by integrating the level of autonomy of both planner and drivers as represented by risk-taking parameters. To enhance the model configuration's practicability, the concept of ‘ridesharing’ – which has been introduced before – has also been integrated to expand the logistical services, improve customer satisfaction, and compensate for shortages in service. Moreover, to ensure environmentally-friendly logistical practices, a velocity maximisation policy and environmental penalty enforcement on the chosen velocity range have been considered. In general, the model improves drivers' satisfaction, customers' perceived quality, and the firm's financial objectives. Additionally, it achieves a better supply chain strategic fit by planning at the three levels: strategic, tactical, and operational. A numerical example was solved using the Eclipse Java 2018-09 solver through two heuristic methods, the Greedy and the Intra-route neighborhood heuristic, and both revealed the same near-optimal solutions. Sensitivity analyses showed that the resulting insignificant increase in the VRP costs due to assigning autonomy for drivers is still reasonable, and the total costs' objective function weight has an insignificant effect on the total near-optimal solution, while that of the energy consumption objective function has the largest impact.

Photoswitching and photocatalytic functions of SnxCu1−xS nanostructures

Ultra-thin semiconducting nanostructures are garnering strategic importance in energy and environment remediation applications. In this regard, SnxCu1−xS nanostructures were processed through an eco-friendly chemical route and investigated in detail for photoswitching and photocatalytic functions. X-ray diffraction, FT-IR, Raman, UV–vis absorbance and high-resolution microscopic tools were initially used to examine the physico-chemical traits of SnxCu1−xS nanostructures. Ambiguous evidence for the substitution of Sn ions in place of Cu ions was attained through X-ray photoelectron spectroscopy. The photocatalytic performance of SnxCu1−xS systems was investigated through effective remediation of organic dye molecules under visible light. Scavenger based photocatalytic experiments were additionally carried out to infer the degradation mechanism. Type II p-n SnxCu1−xS/In2S3 heterojunction diodes were also demonstrated for the first time with improved electrical conductivity and photoelectrical performances. The rectification ratio, forward current values and photo switching capabilities of these diodes were noted to improve in the Current vs. Voltage (I-V) and Current vs. Time (I-T) curves as a function of Sn composition and applied bias potential. The excellent photo switching stability augments the photo generated carriers to be effectively separated along the p-n junctions. The enhanced photoelectronic and photocatalytic functionalities in SnxCu1−xS has finally been reasoned to the improved charge transfer kinetics in the respective architectures, resulting from the effective Sn interaction in hexagonal host lattice.

In situ decoration of Ag@AgCl nanoparticles on polyurethane/silk fibroin composite porous films for photocatalytic and antibacterial applications

An efficient Ag@AgCl-polyurethane/silk fibroin (Ag@AgCl-PU/SF) composite photocatalyst was synthesized by an eco-friendly and practical multistep route, including a wet phase inversion technique, to prepare polyurethane/silk fibroin (PU/SF) composite porous films as a substrate. An impregnation-precipitation-photoreduction process was used to decorate Ag@AgCl nanoparticles in situ on the PU/SF composite porous films. The obtained samples exhibited high photocatalytic activity for the degradation of Rhodamine B (RhB) under ultraviolet and visible light. Meanwhile, the photocatalytic activity of the samples decreased only slightly after 4 runs of photodegradation of RhB. Importantly, the Ag@AgCl-PU/SF films could be recycled without centrifugation and filtration. The Ag@AgCl-PU/SF films also exhibited excellent antibacterial activity. Possible mechanisms for photocatalysis were proposed. This work may provide a new approach for the design of novel porous polyurethane film photoreactors that possess excellent photocatalytic and antibacterial activities for multifunctional applications.

A simple and eco-friendly route for fabricating iron-based coating on metal mesh for efficient oil/water separation

Although many underwater superoleophobic surfaces for separating immiscible oil/water mixtures have been constructed, the fabrication process of most of surfaces is non-green, complex, and time-consuming. Herein, a novel underwater superoleophobic stainless steel mesh (SSM) with eco-friendly coating was successfully prepared by simple and rapid one-step liquid phase chemical reduction route. The reduction treatment produces the iron (Fe) coating with micro/nano-structure, resulting in the underwater superoleophobicity, with oil contact angle as high as 152°. Such special wettability makes the surface to be readily wetted by water phase while repelling immiscible oil phase simultaneously. For this, the effective separation (separation efficiency: >96.2%) of oil/room temperature water and oil/hot (90 °C) water mixtures can be achieved by the decorated mesh. Specially, oil/hot corrosive water mixed liquid can be efficiently separated, and the mesh still maintains good separation efficiency (>94.6%) even after 30 cycles of separation. This research work provides a green, facile, and cost-effective strategy to construct the coating for oil/water filtration on metal mesh. It is expected that the as-fabricated mesh can be used as the filtration material for oily wastewater purification and oil spill treatment.

Water-Responsive and Mechanically Adaptive Natural Rubber Composites by in Situ Modification of Mineral Filler Structures.

A new biomimetic stimuli-responsive adaptive elastomeric material, whose mechanical properties are altered by a water treatment is reported in this paper. This material is a calcium sulphate (CaSO4) filled composite with an epoxidized natural rubber (ENR) matrix. By exploiting various phase transformation processes that arise when CaSO4 is hydrated, several different crystal structures of CaSO4· xH2O can be developed in the cross-linked ENR matrix. Significant improvements in the mechanical and thermal properties are then observed in the water-treated composites. When compared with the untreated sample, there is approximately 100% increase in the dynamic modulus. The thermal stability of the composites is also improved by increasing the maximum degradation rate temperature by about 20 °C. This change in behavior results from an in situ development of hydrated crystal structures of the nanosized CaSO4 particles in the ENR matrix, which has been verified using Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and X-ray scattering. This work provides a promising and relatively simple pathway for the development of next generation of mechanically adaptive elastomeric materials by an eco-friendly route, which may eventually also be developed into an innovative biodegradable and biocompatible smart polymeric material.

Synthesis and characterization of 3D flower-like nickel oxide entrapped on boron doped carbon nitride nanocomposite: An efficient catalyst for the electrochemical detection of nitrofurantoin

It is a great challenge to design and develop a new kind of cost-effective electrode with excellent activity and high stability for the electrochemical sensors. In this presented research, an eco-friendly sonochemical route was utilized to synthesize the flower-like nickel oxide entrapped on boron doped carbon nitride (NiO/BCN) nanocomposite for the application towards electrochemical detection of nitrofurantoin (NFT). The as-synthesized NiO/BCN nanocomposite was detailedly characterized by FESEM, TEM, elemental mapping, EDX, XRD and FT-IR analysis. The electrochemical studies presented that the new sensing probe using the NiO/BCN modified electrode possesses rapid mass transport, superior electrocatalytic activity and high electrical conductivity for the detection of NFT. Furthermore, the NiO/BCN nanocomposite on a glassy carbon electrode displayed a wide dynamic linear response range (0.05–230 μM), very low detection limit (10 nM) and good sensitivity (1.15 μA μM−1 cm2) with excellent selectivity. The proposed electrochemical sensor has been successfully applied to the determination of NFT in biological samples with satisfactory results.

Novel synthesis of flame-retardant magnetic nanoparticles/hydroxy acid cellulose-6-phosphate composite

In the present paper, an eco-friendly synthesis route is proposed to produce fire-retardant magnetic nanoparticles (MNPs; Fe3O4)/hydroxyl acid cellulose phosphate (HACP) composite. Dialdehyde cellulose phosphate (DACP) experienced an intramolecular Cannizzaro reaction during the in situ preparation of MNPs and produced HACP. The (Fe3+/Fe2+) co-precipitation method was employed to prepare the MNPs/HACP composite from DACP. The microstructural properties of the produced composite were assessed through FT-IR, Raman spectroscopy, x-ray diffraction (XRD), SEM, TGA, and DTA. The XRD analysis revealed a significant change in the DACP phase of the MNPs/HACP composite, and SEM images confirmed a homogenous distribution of MNPs in hydroxyl acid. Furthermore, DSC and TGA proved that char yield increased from 8% in DACP to 25% in the composite in the temperature range of 600 °C–800 °C; hence, it indicates that MNPs significantly increased the flame retardancy of the composite as compared to cellulose phosphate (CP) and DACP.

Synthesis and characterization of new class of geopolymer hybrid composite materials from industrial wastes

Geopolymer belongs to a new class of emerging materials for a number of applications owing to the advantages such as low cost; higher compressive strength; improved fire & acid resistance as well as reduced greenhouse gas emission. In this work, we explore the effective utilization of marble waste as a reactive filler and binder for the development of fly ash based geopolymer hybrid composite materials using extrusion process. The effect of marble waste content on the physico–chemical and mechanical characteristics of prepared hybrid materials was studied through various characterization techniques. The geopolymerization was conducted at two different molarities of sodium hydroxide in which the effects of materials properties were studied. The results indicate that the materials prepared at higher molarity exhibits better performance in terms of compressive strength (4.61–6.52 MPa) (2–4M). The silicon dioxide present in fly ash reacts with calcium hydroxide present in marble waste forming calcium silicate hydrate network and possibly contributes to the increment in the interfacial bonding in marble waste infiltrated geopolymer matrix. Overall, this improved interfacial adhesion yielded an increase in compressive strength and bulk density but also decreased the water absorption of the developed material. The results of this study not only indicate an effective utilization of marble waste for the production of geopolymer hybrid composite materials via an eco–friendly route but also provide an economical and sustainable route for management of marble waste currently generated in various countries of the world.