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Non-enzymatic electrochemical blood glucose sensors often suffer from issues such as requiring an alkaline environment, limited monitoring range, and poor anti-interference properties. Carbon substrates have been demonstrated to improve the performance of non-enzymatic sensors, but complex and energy-consuming manufacturing processes restrict their use. Herein, a simple and green approach for the preparation of 3D porous Au/Au-Pt networks (PAAPNs) is proposed using tissue paper for recycling as the nanomaterial substrate to deposit Au-Pt bimetallic nanoparticles. The unique structure of the PAAPNs sensor allows for low-potential operation (-1.0 V) with a wide monitoring range (-0.25 to 36 mM) in a neutral environment. Moreover, the sensor exhibited excellent selectivity (<10% response of interference) even without the use of an anti-interference outer membrane. Further investigation using density functional theory (DFT) simulation revealed the synergistic effect between Au and Pt in promoting glucose oxidation. Overall, this work provides a simple and low-carbon footprint method for creating carbon substrates from tissue paper for recycling, offering new opportunities for fabricating novel value-added nanomaterials for medical sensing applications. [ABSTRACT FROM AUTHOR]

The current open-loop practices employed to render paper substrates water- and oil-repellent for packaging and non-packaging applications have generated ocean pollution and have placed daunting burdens on landfills. In this study, we report a green, unique and facile approach for the fabrication of grease- and water-resistant paper products with 100% recyclability of the paper pulp. Low surface energy polydimethylsiloxane (PDMS) was grafted onto a biobased chitosan polymer via urea linkages to prepare the graft copolymer chitosan-graft-polydimethylsiloxane (chitosan-g-PDMS). Chitosan-g-PDMS was then applied as a coating onto an unbleached Kraft paper substrate from an aqueous solution. The coated paper substrates exhibited good hydrophobic properties with a water contact angle of 120.53 ± 0.96° and a Cobb 60 value of 9.89 ± 0.32 g m−2. The coated paper substrates also showed good oil-resistance as evident from the kit rating value of 11.7/12. The tensile strength, crushing resistance, bending stiffness, and internal tearing resistance of the paper before and after coating treatment was determined. Scanning electron microscopy (SEM) analysis was used to characterize changes in the porosity of the paper before and after the coating. The pulp recyclability of the coated paper was validated by subjecting the coated paper samples to repulping and washing treatment. This novel and practical approach can provide significant environmental benefits by offering plastic-free, fluorine-free and fully-recyclable water- and grease-resistant paper; thus promoting sustainability due to its unique closed-loop nature. [ABSTRACT FROM AUTHOR]

Petroleum-based plastics are useful, but they pose a huge threat to the environment and human health. The development of sustainable cellulose paper materials with excellent mechanical and water-resistance properties to replace plastics is highly desirable but also challenging. Herein, we report a new kind of rosin-based modifier synthesized from fully hydrogenated rosin and (3-glycidoxypropyl)triethoxysilane, which can covalently bind with cellulose fiber networks to improve the hydrophobicity and weaken the capillarity of cellulose paper. The rosin-grafted cellulose composite paper shows a unique combination of water resistance (water absorption of 19.2% and 37.9% in 25 and 90 °C water, respectively) and high strength (tensile strength of 47.9 MPa and Young's modulus of 2.32 GPa). Moreover, the rosin-grafted cellulose composite paper can be completely degraded when buried in soil for up to 100 days, and it can be recycled when treated with an alkali. These impressive performances make rosin-grafted cellulose composite paper a promising eco-friendly alternative material to replace plastics in straws, boxes, cups, bags and so on. [ABSTRACT FROM AUTHOR]

Waterproof coating is necessary for paper-based packaging materials, especially as a plastic substitute in single-use applications. Currently, most paper-based packaging employs hazardous fluorocarbon coatings or other petroleum-based additives, which has caused a lot of concerns over safety. Herein, a novel edible waterproof coating was fabricated by a beeswax-in-water Pickering emulsion using hemicellulose-grafted-lauric acid (H-LA) micelles as nano-stabilizers. The fully biomass-based waterproof coating agent presented a uniform and stable water dispersion with a droplet size of around 1 μm. And compared with conventional surfactants, H-LA micelles stabilized at the oil–water interfaces and formed Pickering emulsions with enhanced stability. The Pickering emulsion was then applied as a coating of paper. The coated paper exhibited excellent water-resistance with a water contact angle of 130 ± 2.89° and an effective waterproof time of up to 6 h. The coated paper also showed good moisture barrier properties; the water vapor transmission rate was lower than 5.05 g mm m−2 day−1. Moreover, the waterproof coating was non-toxic, environmentally friendly and biocompatible, and could completely biodegrade in soil within 2 months. This work may provide an alternative solution for safe, cost-effective and sustainable paper-based packaging materials to replace traditional disposable plastics. [ABSTRACT FROM AUTHOR]

Polymers and surfactants are used in many technological and industrial applications such as the manufacture of functional materials and coatings, personal care and pharmaceutical products, food science, paints, anti-icing fluids, tertiary oil recovery and the paper industry. Polymer–surfactant mixtures are particularly important in shampoos and conditioners. However, as in almost every other industry over the past five or more decades, the performance of hair care formulations has been significantly improved by the use of petrochemical-derived ingredients. As a result, cosmetic formulations, and hair care formulations in particular, have been based primarily on polymers and surfactants that are neither renewable, nor derived from environmentally friendly processes, nor have a positive environmental impact. This contrasts with the extensive use of natural and renewable products, mainly plant extracts, in cosmetics in ancient times. Therefore, the substitution of currently used ingredients with others of natural origin has been a top priority for the cosmetic industry over the last two decades, and in order to achieve greater consumer acceptance, it is crucial to maintain and, where possible, improve the technical performance of such products. This paper describes the complexities and challenges of developing greener shampoo and conditioner ingredients and formulations to meet current and future needs, and outlines a methodological approach based on model hair surfaces and a selection of appropriate experimental and numerical techniques to achieve our goals. Some encouraging technical routes using biosurfactants, biopolymers and bio-based polymers are presented, along with the significant opportunity to obtain a wide range of green ingredients through molecular design and well-controlled biotechnological processes. Similar concerns apply to other cosmetic products such as waxes, fragrances, bleaching agents, etc. [ABSTRACT FROM AUTHOR]

In continuation of previously reported results, the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene-1-ium acetate was also found to be a powerful non-derivatizing solvent for cellulosic waste such as paper and cardboard. The ionic liquid could dissolve all the present bio-polymers (cellulose, hemicellulose, and lignin) in high concentrations, resulting in solutions with visco-elastic properties that were suitable for dry-jet wet fiber spinning. The cellulosic raw materials were refined gradually to identify the influence of residual components on the spinnability of the respective solution. Polymer degradation and losses in the spinning process could be avoided nearly entirely. With the exception of virtually unrefined cardboard, all the samples showed excellent spinnability, resulting in fibers with high tensile strength. Prototype textiles were produced to validate the quality of the fibers and demonstrate the possibility of using residual lignin in cardboard as a natural dye. [ABSTRACT FROM AUTHOR]

There has been a huge demand for low-cost, eco-friendly, flexible and wearable electronics which find applications in personal health monitoring. Flexible electronics based on plastic substrates have been extensively studied in this regard because of their versatility. However, their fabrication involves energy consuming complex procedures and processing of eco-unfriendly materials which limit their use to certain specific applications. Here we report the fabrication of a flexible all-carbon field effect transistor (FET) using a low-cost, recyclable and biodegradable cellulose paper as both the substrate and the dielectric and pencil graphite as the source, drain, channel and gate without using any expensive, toxic or non-biodegradable materials. The FET transfer characteristics show ambipolar behavior which can be utilized in analog electronics applications like rectifiers, mixers and frequency multipliers and its mobility was found to be very high compared to reduced graphene oxide based FETs. The FET was utilized as a strain sensor which shows excellent sensitivity for very low strains (of both tensile and compressive type) which is comparable to and even better than recently reported carbon nanotube and graphene based strain sensors. The sensitivity of the FET based strain sensor can be modulated by varying the gate voltage under strain. Furthermore, we investigated the performance of the sensor by integrating it with hand gloves to detect human motion. The results indicate that the sensor can be utilized in patient surveillance in healthcare and human–machine interface (HMI) applications. The successful fabrication of this paper based all-carbon transistor using only paper and pencil graphite and its application in human motion detection using strain sensing indicate that this approach can be used for developing highly scalable, low cost, low energy, flexible electronics for healthcare without using any sophisticated fabrication methods or toxic chemicals. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) are widely implemented to power portable electronic devices and are increasingly in demand for large-scale applications. One of the major obstacles for this technology is still the low cost-efficiency of its electrochemical active materials and production processes. In this work, we present a novel impregnation–carbothermal reduction method to generate a LiFePO4–carbon paper hybrid electrode, which doesn't require a metallic current collector, polymeric binder or conducting additives to function as a cathode material in a LIB system. A shell of LiFePO4 crystals was grown in situ on carbon fibres during the carbonization of microcrystalline cellulose. The LiFePO4–carbon paper electrode achieved an initial reversible areal capacity of 197 μA h cm−2 increasing to 222 μA h cm−2 after 500 cycles at a current density of 0.1 mA cm−2. The hybrid electrode also demonstrated a superior cycling performance for up to 1000 cycles. The free-standing electrode could be potentially applied for flexible lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A single-step protocol was developed for the hydrolytic hydrogenation of microcrystalline cellulose into sorbitol over commercial carbon-supported Ru, in the presence of gaseous CO2 as an acid source and molecular hydrogen as a reductant. Under these conditions, cellulose was first hydrolysed to glucose by reversibly formed carbonic acid in water and then instantaneously hydrogenated on Ru/C. By tuning the reaction parameters, such as temperature, time and the relative pressure of CO2 and hydrogen gas, cellulose was fully converted at 220 °C in 18 h under 30 and 40 bar of H2 and CO2, respectively, with a sorbitol yield of 81%. Blank experiments revealed that without a catalyst and hydrogen, the reaction exhibited <5% conversion and glucose was the only detected product when the reaction was performed under CO2 pressure. XRD measurements on CO2-treated cellulose surprisingly revealed no noticeable changes in the crystallinity index (<10% with respect to microcrystalline cellulose), suggesting that hydrolytic hydrogenation took place on crystalline, not amorphous, cellulose. Furthermore, not only several cellulosic feedstocks, including filter paper, cotton wool, and cotton fiber, but also typical cellulose-based wastes such as a cardboard pizza box were also tested and under the optimized conditions sorbitol was obtained with yields ranging from 56% up to 72% in all cases. No less significant was the Ru/C catalyst stability, which could be recycled at least six times without any noticeable activity loss. [ABSTRACT FROM AUTHOR]

As a main stream of waste from the paper and pulp industry, paper sludge is regarded as a threat to environmental safety as most of it is disposed via landfill or incineration, which can cause severe soil, water or air pollution. However, alkaline paper sludge has the potential to be a catalyst in biomass pretreatment, and also contains a large amount of fiber that can be used as a feedstock for ethanol production. The dissolved lignin in alkaline pretreatment can be recovered as a good quality co-product such as lignin pellets. The ash in paper sludge can also be recovered to replace sand as a raw material in mortar production. However, the use of paper sludge for commercialized ethanol production is currently a challenge due to its low solid content and high pH. This paper therefore proposes a novel conceptual design for combining paper sludge and agricultural residues (e.g. rice straw in this study) to produce ethanol and other co-products. The net present value is used to assess the economic potential of two proposed process designs: (1) a current technology of turning C5 sugars into biogas; and (2) a prospective technology of co-fermenting both C5 and C6 sugars into ethanol. It is found that both approaches could be economically feasible, but at different scales of production. A sensitivity analysis is also conducted to investigate the effects of plant size, feedstock stream composition (the ratio between rice straw and paper sludge) and subsidies on the economic performance of the proposed projects. [ABSTRACT FROM AUTHOR]

The electrocatalytic hydrogenation of aromatic rings in benzoic acid derivatives has arisen as a notionally engaging substitute for thermal catalysis under mild conditions. However, the utilization of organic solvents and low faradaic efficiency are incompatible with the principles of green chemistry and energy conservation. Herein, bimetallic PtRu supported on carbon paper developed by co-electrodeposition with optimized atomic ratios maintains an inspiring high conversion of 92.9%, high selectivity of 100% and a high faradaic efficiency of 62.2% for the hydrogenation of benzoic acid to cyclohexanecarboxylic acid in an acidic aqueous electrolyte without external H2, which is the best result to date. The optimized electrocatalyst also exhibits outstanding stability and universality for the electrocatalytic hydrogenation of benzoic acid derivatives. In situ Raman results and theoretical calculations prove that the synergistic effect generated by Ru modifying the electronic structure of Pt simultaneously enhances the capture of benzoic acid molecules and interfacial active hydrogen species and lowers the reaction energy barrier. After adsorbing benzoic acid, more accumulation of electrons around the Ru atom reduces the electron density of phenyl, thereby activating the reaction. Meanwhile, the uniform alloy nanoclusters anchored to the carbon paper surface ensure highly efficient electronic transmission and high dispersion of active components, reducing excessive agglomeration. A proton-exchange membrane reactor is also used to certify the potential of the electrocatalytic hydrogenation of benzoic acid derivatives for large-scale application. [ABSTRACT FROM AUTHOR]

Wood bark is a structurally complex by-product of the pulp and paper industry, which focuses primarily on the valorization of structurally more regular wood xylem components. The aim of this study was the elucidation of the less valorised willow wood counterparts (whole bark, inner bark, sclerenchyma bundles, and parenchymatous tissues) by NMR spectroscopic techniques. This allowed a better understanding of the structural features of macromolecular components of bark (i.e. pectin, hemicellulose, and lignin), thus providing a base for a more rational design of the customized biochemical processes prior to chemical processing of bark. This crucial knowledge contributed to the creation of a protocol/decision tool to select tailored enzymes (discarding the slightest substrate binding) for the biological pre-treatment of bark to a state suitable for chemical pulping. Such a protocol/decision-making tool would significantly improve the efficiency of enzyme selection by 60–70% due to the specific catalytic activity of the enzymes involved. [ABSTRACT FROM AUTHOR]

Papermaking is a highly energy-consuming industry. The growth in paper demand will further intensify the need for energy and the stress of GHG emissions. Papermaking involves complex processing routes, and energy is required for collecting raw materials, producing chemicals, and pulp and papermaking. Previous investigations of energy consumption in the papermaking industry have focused primarily on the analysis of one single product or one single pathway, lacking a comprehensive and systematic comparison of various products and pathways. Herein, the results of a life cycle energy consumption analysis of major paper products in China using an extensive system boundary are presented. When 1 tonne of paper was produced in China in 2015, the maximum energy consumption was 38.17 GJ for tissue paper, with a minimum energy consumption of 15.90 GJ for corrugated medium. This study also predicts energy-related GHG emissions and a mitigation target in the papermaking industry in China by 2050. Although the energy consumption assumed to be distributed to the papermaking industry can meet its development requirements, the GHG emissions will exceed the mitigation target by about 101 Mt CO2 eq. in 2050 under current policy. The target can be achieved by changing the energy structure and promoting low-carbon technology. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass, especially lignin and extractives, has the potential to substitute fossil precursors in the chemical industry. The conversion of lignin has been intensively researched, but challenges remain as high temperatures and increased pressure are commonly used, which is not energy efficient. Lignin and wood extractives bear chromophoric groups that can absorb light in the ultraviolet (UV) region, which enables photochemical reactions. Ultraviolet light emitting diodes (UV-LEDs) are an emerging technology; they are cheap, versatile, and energy-efficient compared to existing mercury lamps. UV-LEDs were used in this study as a proof of concept for the valorisation of a lignocellulosic residual stream from the pulp and paper industry, sawdust. In a process at ambient temperature and pressure and without the use of a catalyst, we have shown that lignin and extractives can be valorised using light from UV-LEDs. Simplified lignin model compounds were used to pinpoint chemical reactions during irradiation, and to ease the analysis of the sawdust samples. The rate of conversion upon irradiation of the model compounds was found to be 0.7–2.3 g L−1 h−1, depending on the concentration of the starting compounds. [ABSTRACT FROM AUTHOR]

Recent progress in portable and wearable electronics has promoted a growing demand for high-performance and flexible energy-storage devices that are abundant and affordable. Because reduced graphene oxide (rGO), originating from inexpensive graphite, serves as a higher-performance energy-storage electrode than conventional activated carbons and carbon nanotubes, research and development of rGO/polymer composite electrodes for flexible supercapacitors have become a center of attraction. However, the fabrication of rGO-based flexible electrodes frequently requires a long time with high-temperature treatment or toxic chemical treatment, resulting in the lack of scalability and eco-friendliness. Here we show a fast, scalable, and environment-compatible route to fabricate a high-performance rGO/cellulose paper supercapacitor electrode. Single-layer graphene oxide (GO) sheets and recycled waste pulp fibers were successfully fabricated into a paper composite by a well-established scalable papermaking process, followed by a room-temperature, additive-free, and millisecond-timescale flash reduction process. The as-prepared rGO/paper electrode had a high specific capacitance, up to 212 F g−1, for an all paper-based flexible supercapacitor, comparable to those of state-of-the-art rGO-based electrodes, while dramatically decreasing the reduction time of GO from the conventional hour timescale to milliseconds. This work will pave the way for green, flexible, and mass-producible energy-storage paper in future wearable electronics. [ABSTRACT FROM AUTHOR]

The pulp and paper industry together with lignocellulosic biofuel production provides plentiful streams of lignin and lignin-derived molecules (LDMs) that currently remain underutilized. The heterogeneity and complexity of lignin along with the lack of convenient tools significantly hamper its utilization. Selective separation of these LDMs from streams using specific tools would allow the recovery of aromatic compounds, as well as facilitate biological processes aiming at lignin valorization. To this end, here we report the isolation and characterization of single-chain variable fragment (scFv) antibodies against ferulate, coumarate, and caffeate, which are the molecular representatives of LDMs. Binders for the target LDMs were enriched by interrogating a synthetic scFv library with the phage display technique. As a result, scFv binders specific against each of the target molecules were obtained with affinities in the micromolar range. The selectivity of scFvs towards specific LDMs was proved by recovering caffeate from simulated LDM solution, Kraft lignin, and rice straw hydrolysate samples. Further proof of concept studies with model compounds demonstrated the applicability of antibody-based binders as a detection tool for monitoring microbial LDM conversion. Overall, this study demonstrates the potential of scFv binders as a specific toolset for lignin compound recovery and analysis. [ABSTRACT FROM AUTHOR]

The conversion of waste office paper (printed or photocopied) to bio-oil via low temperature (<200 °C) microwave-assisted pyrolysis, and its utilisation as an adhesive for aluminium-aluminium bonding are reported. The yields for the organic and aqueous phase bio-oil are 19% and 23%, respectively. The pyrolysis products were characterized by ICP-MS, ATR-IR, GC-MS and NMR to reveal broad categories of compounds indicative of sugars (carbohydrates), aromatics and carbonyl-containing moieties. Application of the organic phase bio-oil (70 mg) to Al plates (50 mm x 50 mm) followed by curing at different temperatures and time periods revealed that a maximum tensile strength of approximately 2300 N could be attained at 160 °C for 8 h cure. Also, at a fixed temperature, the tensile strength increased with increasing curing time. To gain an in-depth understanding of the adhesive properties of bio-oil, a liquid-liquid fractionation of the organic phase bio-oil was conducted. The 'acidic' fraction showed far better adhesion properties than the 'neutral' fraction with no bonding achieved for the aqueous fraction. A combination of the 'acidic' and 'neutral' fraction gave better adhesion, thus suggesting a possible synergistic or co-operative effect. [ABSTRACT FROM AUTHOR]

Cu–Pd bimetallic catalysts were fabricated on carbon paper (CP) by the electrodeposition method via a dynamic hydrogen bubble template approach. At a potential of −1.2 V vs. RHE, the Faradaic efficiency (FE) of C2H4 could reach 45.2% with a current density of 17.4 mA cm−2 in an H-type electrolytic cell. Detailed studies suggest that the enhanced performance of Cu–Pd/CP was attributed mainly to the synergistic effect, low interfacial charge transfer resistance, and the 3D architecture of the catalysts. [ABSTRACT FROM AUTHOR]

This paper describes the chemistry of green materials synthesized with supercritical fluids. First, the properties and some specific features of supercritical water are summarized. Then, supercritical hydrothermal synthesis of nanoparticles is explained, and various applications of green materials are described. The surface control of nanoparticles in supercritical water is also explained. Green processes involving chemical recycling of waste polymers and a combination of hydrothermal synthesis and supercritical water oxidation are also discussed. Finally, commercialization of supercritical water processes is discussed. [ABSTRACT FROM AUTHOR]

Exploitation of hydrogen as an energy carrier requires the development of systems for its storage and delivery. Formic acid has been proposed as valuable hydrogen carrier compound, due to its relatively high hydrogen content (53 g L−1), the latter being easily and cleanly released in catalytic reactions under mild conditions (HCOOH → H2+ CO2). Ionic liquids are interesting solvents for homogeneous catalyzed formic acid decomposition systems as their extremely low volatility avoids solvent contamination of the produced hydrogen stream. In this paper an outstandingly simple, robust and active catalyst system is presented, namely RuCl3dissolved in 1-ethyl-2,3-dimethylimidazolium acetate (RuCl3/[EMMIM][OAc]). This system proved to be fully recyclable over 10 times. Turnover frequencies (TOF) of 150 h−1and 850 h−1were obtained at 80 °C and 120 °C, respectively. [ABSTRACT FROM AUTHOR]

Supercritical carbon dioxide (scCO2) was used to extract components of interest from Scenedesmus dimorphus, a microalgae species, under varied algal harvesting and extraction conditions. Liquid chromatography-mass spectrometry (LC-MS) was used to quantify the concentration of fatty acid methyl esters (FAME) and the FAME profile of transesterified lipids, phospholipids and pigments extracted under varied supercritical temperatures and pressures. The scCO2extraction results are compared with conventional solvent extraction to evaluate differences in the efficiency and nature of the extracted materials. Algae harvested by centrifugation (vs.lyophilization) demonstrated a similar extraction efficiency in scCO2, indicating potential energy benefits by avoiding conventional algal mass dehydration prior to extraction. Centrifuged algae and optimized extraction conditions (6000 psi; 100 °C) resulted in comparable FAME yields to conventional processes, as well as increased selectivity, reflected in the decreased pigment, nitrogen and phospholipid contamination of the FAME. Cell pre-treatments—sonication, microwave, bead beating and lyophilization—showed an enhancement in extraction yield in both conventional solvent and scCO2extraction, allowing for improved extraction efficiencies. This study suggests that scCO2, a green solvent, shows great potential for algal lipid extraction for the sustainable production of biodiesel. [ABSTRACT FROM AUTHOR]

Experiments were conducted to study the effects of reaction conditions on the hydrolysis of miscanthus dissolved in 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) catalyzed by H2SO4. It was determined that while there is a small co-inhibition effect associated with the simultaneous hydrolysis of the cellulosic and hemicellulosic portions of miscanthus, the largest rate decreases were observed for the hydrolysis of the hemicellulosic portion. This rate decrease was attributed to the chemical linkage between hemicellulose and lignin in miscanthus, which could be broken with chemical pretreatment. While chemical pretreatment increased the rate of the hydrolysis of the hemicellulosic component, delignification showed no further benefit. The rate of hydrolysis was determined to be first order in concentrations of β-1,4 glycosidic linkage and acid, and zero order in water concentration. The activation energy for the hydrolysis of the glycosidic linkages in the cellulosic and hemicellulosic components were determined to be 95 kJ mol−1and 114 kJ mol−1respectively. Progressive addition of water during the first hour of the reaction increased conversion and selectivity to saccharine products, while limiting dehydration of the sugars formed. The conversion of the cellulosic portion of miscanthus could be increased after the first hour of the reaction by increasing the reactor temperature. While miscanthus is only partially soluble in [Emim][Cl], it was found that the initial miscanthus loading could be increased to 9 wt% before significant yield decreases attributed to solubility limitations of the cellulosic component were observed. By proper adjustment of reaction conditions, it was possible to achieve yields of sugars approaching 84% from the cellulosic and hemicellulosic components of miscanthus, with minimal dehydration of the sugars to furans. [ABSTRACT FROM AUTHOR]

A new approach to improve the cellulase stability against 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]), based on coating of immobilized enzyme particles with hydrophobic ILs, is proposed. The stability of commercial cellulase (Celluclast®), immobilized onto a polymeric support (Amberlite XAD4), was first studied in ten different ionic liquids (ILs) at 50 and 80 °C. Hydrophobic ILs clearly enhanced the enzyme thermal stability. Butyltrimethyl-ammonium bis(trifluoromethylsulfonyl)imide ([N1114][NTf2]) enhances half-life time of the immobilized enzyme at 50 °C up to 4 times, while [Bmim][Cl] behaved as a powerful enzyme deactivating agent. Thus, the stability of cellulase in hydrophobic IL/[Bmim][Cl] mixtures was greatly improved with respect to [Bmim][Cl] alone. A stabilized cellulase derivative obtained by coating immobilized enzyme particles with [N1114][NTf2], has been then successfully used for the saccharification of dissolved cellulose in [Bmim][Cl] (i.e. up to 50% hydrolysis in 24 h) at 50 °C and 1.5 w/v water content. [ABSTRACT FROM AUTHOR]

Continuous-flow rhodium-catalysed hydroformylation of long chain alkenes has been achieved with selectivities to the desired linear aldehyde of 92% and minimum rhodium loss, using a xantphos-derived ligand attached to an imidazolium salt in a supercritical fluid–ionic liquid system. The effect of oxygen in the system can be ameliorated to some extent by adding a simple sulfonated triphenylphosphine to the catalytic solution. [ABSTRACT FROM AUTHOR]

We present an ionic liquid (IL) strategy for the reactive dissolution of star anise seeds using different Brønsted-acidic ionic liquids as the solvent and reaction media towards the isolation of important pharmaceutical intermediates; this procedure provides a single-step, higher yielding and environmentally benign strategy towards the synthesis of the anti-influenza drug Tamiflu™. [ABSTRACT FROM AUTHOR]

The ruthenium catalysed cross-metathesis of terpenoids with methyl acrylate and methyl methacrylate was used to prepare new terpenoids and to improve, to a large extent, the synthesis of known terpenoids. In particular, the cross-metathesis of mono-unsaturated terpenoids was very efficient whereas the transformation of terpenoids incorporating two double bonds was more difficult due to side reactions. The cross-metathesis reactions were carried out under environmentally friendly conditions either in dimethyl carbonate or under solvent-free conditions. [ABSTRACT FROM AUTHOR]

Algae are being explored as a sustainable energy feedstock, having potential to reduce dependence on petrofuels and offset greenhouse gas emissions. Economic considerations and principles of green design suggest that if algae-to-fuel technology is to be successful, biofuels must be produced simultaneously with value-added co-products. At present, the algae industry is centered around a limited number of products, such as low-volume/high-value speciality nutrients. New products for medium- and high-volume markets will be needed as biomass production increases in scale. This Perspective highlights non-fuel applications of algal biomass that have received relatively little attention to date but are promising for future development. It is our goal to draw attention to some of the unique opportunities that algae present with respect to biochemical composition as compared to lignocellulosic energy crops. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are widely discussed as alternative green solvents not only because of their unique chemical properties, but also because of their extremely low vapour pressure and – at least in some cases – relatively high thermal stability. Two complementary methods are analyzed and compared to determine both the rate constant of decomposition and the vapour pressure of four ILs: (1) thermogravimetrical analysis at ambient pressure (TGap) with an overflow of inert gases, and (2) high vacuum (HV) experiments with a magnetic suspension balance (MSB). At ambient pressure, [EMIM][MeSO3] and [EMIM][CF3SO3] decompose without a significant contribution of evaporation, which leads to the rate constant of thermal degradation. For both ILs, the vapour pressure can only be determined at HV by the MSB, because the evaporation rate is then higher than the decomposition rate. For the relatively volatile ILs [EMIM][NTf2] and [BMIM][NTf2] the vapour pressure can be derived both by the MSB at HV as well as by TGap. General strategies to determine the volatility and stability of ILs and criteria for the maximum operation temperature with regard to decomposition and evaporation are presented. [ABSTRACT FROM AUTHOR]

Mesoporous carbon nitrides (MCN) were prepared by a nano-casting method using mesoporous silica as a template with different carbon and nitrogen sources like melamine only (MS-MCN), urea-formaldehyde (UF-MCN) and melamine-glyoxal (MG-MCN). These mesoporous carbon nitride materials possess nitrogen moieties which behave like a CO2-philic surface facilitating oxidation of cyclic olefins by molecular oxygen in the co-presence of CO2below supercritical conditions. The co-presence of CO2augmented the conversions of cyclic olefins at low pressures of CO2, depicting a promotional effect. Approaches towards quantification of promotional effects and insights into the promotional aspects have been studied. [ABSTRACT FROM AUTHOR]

A series of hydrophilic N,N-dimethylpyrrolidinium- and N,N-dimethylpiperidinium-based ionic liquids (ILs) have been prepared and applied as reaction media in the Wacker oxidation of styrene by hydrogen peroxide using PdCl2as the catalyst. The efficiency of these ILs was compared with hydrophilic and hydrophobic imidazolium systems (including those with nitrile functionalities). The nature of the ionic liquid strongly influences the product distribution. In particular, in hydrophobic ILs, relevant amounts of 1,3-diphenyl-1-butene arising from styrene dimerization were detected, in addition to the expected phenylmethylketone. The formation of 1,3-diphenyl-1-butene may be attributed to the formation of Pd(0) species from “ClPdOH” (probably formed during the Wacker process) in a side-reaction. Consequently, the ability of the IL to favor or disfavor the reoxidation of “ClPdOH” to “ClPdOOH” by hydrogen peroxide, giving an homogeneous phase or a biphasic system, appears to be the main factor affecting selectivity. [ABSTRACT FROM AUTHOR]

Academic research in the area of green solvents is focused on neither the industries that use solvents most nor the types of solvents that the research community believes have the best hope of reducing solvent-related environmental damage. Those of us who are primarily motivated by a desire to reduce such damage would do well to look at the major uses of solvents, to determine the problems that currently make those applications less-than-green and focus our research efforts on potential solutions to those problems. As a contribution to such efforts, I present four grand challenges in the field of green solvents: finding a sufficient range of green solvents, recognizing whether a solvent is actually green, finding an easily-removable polar aprotic solvent and eliminating distillation. [ABSTRACT FROM AUTHOR]

The continuous biocatalytic synthesis of (R)-2-octanol carried out in an enzyme membrane reactor showed an excellent process stability of the biocatalysts, resulting in a turnover number of 15 million for the applied alcohol dehydrogenase. Utilisation of the ionic liquid AMMOENG™ 101 as a feasible cosolvent increased substrate concentration, and improved space time yields and turnover numbers of the cofactor by factors of 3 and 6, respectively. Moreover, 80% less waste was generated, while producing the same amount of product. Integrated product separation was realized viasolid phase extraction. Extraction of the applied solid phase with supercritical carbon dioxide allowed more than 30 reuses of the solid phase. [ABSTRACT FROM AUTHOR]

“The best catalyst is no catalyst.” With growing public concern over global warming and the amount of greenhouse gases, it is important to reduce the amount of chemicals and eliminate waste, to obtain better results in a simple, selective, safe, and environmentally benign fashion compared to conventional tedious chemical synthesis. Herein, we disclose an environmentally benign, rapid, catalyst/promoter/coupling reagent-free cyclization procedure of free amino acids to furnish exclusively cyclic dipeptides (2,5-diketopiperazines, DKPs) in excellent or even quantitative yield, along with their solid state self-assembling properties. This process is extremely simple and highly efficient with little or no traditional synthetic skills and without any chromatographic purification. Synthesis of structurally diverse DKPs has been achieved with a dramatic decrease in the reaction time, the amount/number of solvents used, a significant increase in the yield and nearly complete elimination of waste. As a result, this is an excellent example for the environmentally benign, clean and green chemistry concept. The most exciting outcome of our investigation is an unusual case of chiral self-recognition encountered upon the cyclization of rac-pipecolic acid, which resulted in the formation of the meso-product exclusively. [ABSTRACT FROM AUTHOR]

Concrete production is a large scale process that involves high energy consumption. In order to increase the sustainability of this process, the reduction of energy input is necessary. Bio-glycerol was demonstrated to be a highly efficient renewable-based additive in the grinding process for concrete production and helped reduce energy costs and improve the quality of the resulting product. In order to understand its excellent aiding properties, the interaction of glycerol with cement clinkers was investigated; both chemical and physical interactions were taken into account. The results of this investigation points to surface tension modification of the clinker particles as one of the main effects of bio-glycerol addition during the grinding process. [ABSTRACT FROM AUTHOR]

The present study describes the first-time usage of an isolated thermostable Baeyer–Villiger monooxygenase (phenylacetone monooxygenase, PAMO) in the presence of ionic liquids. The stability, activity and selectivity of PAMO as an oxidative enzyme in the presence of different ionic liquids were studied. This revealed that the addition of some specific ionic liquids, such Ammoeng™ 102 and [bmim]MeSO4, can significantly enhance the E-value in the oxidation of racemic benzylketones. Moreover, the use of ionic liquids increases the optimal substrate concentration for performing Baeyer–Villiger oxidation, thereby extending the biocatalytic repertoire of PAMO for synthetic applications. [ABSTRACT FROM AUTHOR]

The immobilization of N-sulfonyl-(Ra)-binam-d-prolinamide using polystyrene as a support allows the recovery of an efficient catalytic system for the enantioselective direct aldol reaction between different ketones and aldehydes under solvent-free or aqueous conditions. The polystyrene-supported N-sulfonyl-(Ra)-binam-d-prolinamide catalyst in combination with benzoic acid showed similar results to those obtained with unsupported N-tosyl-binam-derived prolinamide under similar reaction conditions. The aldol products were obtained at room temperature and using only 2 equivalents of the ketone with high yields, regio-, diastereo- and enantioselectivities. The aldol reaction between aldehydes can also be performed under these reaction conditions with moderate results. The recovered catalyst can be reused up to six times without having a detrimental effect on the achieved results. [ABSTRACT FROM AUTHOR]

The biological synthesis of metal nanoparticles from ions has recently emerged as a novel technique for an environmentally benign recovery of heavy metals. Bacteria are known to recover palladium(0) in the form of nanoparticles that are catalytically active. However, the extent of the reactions that can be catalysed by bio-recovered palladium has not been investigated. This study demonstrates that the Suzuki–Miyaura and Mizoroki–Heck reactions can be catalysed by bio-generated palladium nanoparticles formed on the surface of Gram-negative bacteria. The results suggest that the range of applications of this catalyst can be extended to the realm of carbon–carbon bond formation in synthetic organic chemistry. [ABSTRACT FROM AUTHOR]

The kinetic resolution (KR) and dynamic kinetic resolution (DKR) of racemic 1-phenylethanol with the acyl donor vinyl acetate catalysed by Pseudomonas cepacialipase ATCC 21808 (PCL) (this has recently been reclassified as Burholderia cepacialipase), either as the suspended native protein (PCL) or immobilised on ceramic particles (commercial lipase Amano PS CI) has been examined, as batch reactions, in supercritical carbon dioxide (scCO2). The yields and enantioselectivities achieved in these reactions were comparable to experiments conducted in hexane. The immobilised lipase PS CI displayed excellent yields (48–49%) and enantioselectivities (98–99%) to give (R)-phenylethyl acetate after 2.5 hours reaction at 40 °C in scCO2. The acylated product was obtained in higher yield in scCO2compared to the reaction carried out in hexane (yield 30–35%; ee 98–99%) under comparable conditions. Unlike PCL, the immobilised lipase PS CI could then be successfully reused with no loss of activity or selectivity observed over four reaction cycles. Combining lipase PS CI with a chemical catalyst (either the metal catalyst [Ru(p-cymene)Cl2]2or the acid catalyst Nafion SAC 13) to catalyse the racemisation of the unreacted alcohol caused an increase in the yield of the (R)-acyl phenylethanol product to 70 and 85%, respectively, in scCO2indicating a viable dynamic kinetic resolution system had been established. The enantioselectivities of the products in these reactions were slightly higher in scCO2(96% Ru-catalyst; 85% Nafion) compared to those observed in hexane (91%; 81%). The lower enantioselectivity with the acidic Nafion SAC 13 catalyses indicates that some non-enzymic acid catalysed esterification was occurring. [ABSTRACT FROM AUTHOR]

Both softwood (southern yellow pine) and hardwood (red oak) can be completely dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim]OAc) after mild grinding. Complete dissolution was achieved by heating the sample in an oil bath, although wood dissolution can be accelerated by microwave pulses or ultrasound irradiation. It has been shown that [C2mim]OAc is a better solvent for wood than 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and that variables such as type of wood, initial wood load, particle size, etc.affect dissolution and dissolution rates; for example, red oak dissolves better and faster than southern yellow pine. Carbohydrate-free lignin and cellulose-rich materials can be obtained by using the proper reconstitution solvents (e.g., acetone/water 1 : 1 v/v) and approximately 26.1% and 34.9% reductions of lignin content in the reconstituted cellulose-rich materials (from pine and oak, respectively) have been achieved in one dissolution/reconstitution cycle. The regenerated cellulose-rich materials and lignin fractions were characterized and compared with the original wood samples and biopolymer standards. For pine, 59% of the holocellulose (i.e., the sum of cellulose and hemicellulose) in the original wood can be recovered in the cellulose-rich reconstituted material; whereas 31% and 38% of the original lignin is recovered, respectively, as carbohydrate-free lignin and as carbohydrate-bonded lignin in the cellulose-rich material. [ABSTRACT FROM AUTHOR]

Silica supported platinum catalysts coated with a thin film of 1-butyl-2,3-dimethyl-imidazolium trifluoromethane sulfonate (BDiMIm) were investigated with respect to the interaction of the ionic liquid with the oxide support and the metal clusters. IR, inelastic neutron scattering and NMR spectroscopy indicate that the vibrations of the imidazolium ring of ionic liquid are less restricted when supported on SiO2, while the viscosity of the supported ionic liquid increased. The presence of Pt particles enhances the electron density of the ionic liquid at the nitrogen atom inducing higher basicity. The coverage of the catalyst surface and the metal particles by the ionic liquid protects the metal against oxidation. The catalysts are active and stable for hydrogenation of ethene. [ABSTRACT FROM AUTHOR]

It has been demonstrated that the pharmaceutical molecule, Ibuprofen, can be loaded into mesoporous silica using liquid (near-critical) carbon dioxide as the solvent, and that the resulting material had a high Ibuprofen content (300 mg Ibuprofen/g SiO2). A high enrichment (300 times) of Ibuprofen in the pores was observed in comparison to the Ibuprofen concentration in the solution. When similar experiments were performed in CO2(l) mixed with minor amounts (5 mol-%) of other organic cosolvents (cyclohexane, acetone or methanol), a significantly lower loading capacity of Ibuprofen into the mesoporous material was achieved. The drug-loaded mesoporous silica material was analyzed with Thermogravimetric Analysis (TGA), confocal Raman microscopy, X-ray Powder Diffraction (XRPD) and Scanning Electron Microscopy (SEM). It was found that the Ibuprofen loaded into the mesoporous silica host was amorphous and that Ibuprofen was present both at the surface and in the centre of the mesoporous silica particles. Furthermore, the SEM images did not reveal any large flakes of Ibuprofen molecules outside the mesoporous silica particles. [ABSTRACT FROM AUTHOR]

A series of task-specific ionic liquids (TSILs) based on glycerylimidazolium cations have been prepared by reaction of 1-chloropropanediol, a compound obtainable from glycerol (a widely available and in-expensive waste product), with the appropriate base (1-H-imidazole, 1,2-dimethylimidazole and 1-methyl-1-H-imidazole). The reaction of 3-(1H-imidazol-1-yl)propane-1,2-diol with chloroalkanes, bromoalkanes and alkyl mesylates gave the corresponding salts which were characterized. The possibility to use these ILs in palladium catalyzed reactions was evaluated, evidencing good catalyst stability and a high recyclability. [ABSTRACT FROM AUTHOR]

A new and environmentally friendly technology has been used successfully to produce thermoresponsive polysulfone membranes with good performance in terms of valve mechanism in the pores, with a complete on-off control of water permeability. Membranes were prepared using a CO2-assisted phase inversion method and their pores were coated/impregnated with a thermoresponsive polymer – poly(N-isopropylacrylamide) – using a new methodology for the preparation of these type of structures. The coating/impregnation efficiency was assessed by SEM and XPS analysis that confirmed the presence of nitrogen due to the thermoresponsive hydrogel. Contact angle measurements and phosphate buffer solution permeability were determined in order to characterize the structure hydrophobicity variations with temperature. The on-off mechanism was tested using a model protein (BSA) as a proof of concept for the ability to control pore apertures by temperature stimulus. A diffusion model based on Fick's law and Langmuir adsorption was developed. [ABSTRACT FROM AUTHOR]

The aqueous-biphasic hydroformylation of higher alkenes catalyzed by Rh/TPPTS has been carried out in the presence of imidazolium, pyridinium and triethylammonium salts. High reaction rates are achieved with imidazolium and triethylammonium salts provided that their alkyl “tail” is ≥C8.Fast and complete phase separation, and good retention of the metal in the aqueous phase could be achieved with an octyl “tail”. Imidazolium salts were found to give the highest rate enhancement. The nature of the anion showed a moderate influence on the reaction. Evidence suggests that the additive can act as weak surfactant allowing emulsions to be formed and broken by simply switching the stirring on and off. [ABSTRACT FROM AUTHOR]

In the chemical industry organic solvents should be avoided wherever possible. They are often toxic to marine organisms and plants as well as to higher organisms and humans. Moreover, volatile organic compounds (VOC) cause air pollution which leads to the necessity of expensive separation technologies like waste water or exhaust gas treatments. Solutions for these problems are either the development of processes without the use of any solvent or the use of environmentally benign solvents such as water. In this contribution it is shown how versatile water can be, used as a solvent in homogeneously catalysed processes, for example, telomerisation reactions with methanol, diethylamine, ethylene glycol and glycerol. In this context another positive effect of the solvent water is the ecologically and economically required retention of the transition metal catalyst inside the process. Furthermore, different reactor types, a loop reactor and a mixer-settler reactor, are presented to cope with the challenges of mass transport limitations and selectivity control in aqueous biphasic systems. [ABSTRACT FROM AUTHOR]

Pressurized hot (subcritical) water and ethanol were used to extract betulin and antioxidants from birch bark. Betulin was found to be the major compound (around 26% (w/w)), which was able to be extracted with ethanol (120 °C, 50 bar, 15 minutes) but not with water at any of the temperatures tested (40–180 °C, 50 bar). The obtained extraction result for betulin is supported by theoretical solvation parameter calculations. Furthermore, high antioxidant activity of the extract was obtained using both ethanol and water as solvent. The antioxidant activity, as determined by a DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, was found to be highest for the water extract of finely ground bark and it markedly increased with elevated extraction temperatures (90–180 °C). To elucidate if this was due to increased extraction efficiency or chemical reactions, a set of experiments was performed in which the samples were pre-treated with water at different temperatures before extraction. Results from liquid chromatography showed some differences in molecular composition between samples pre-treated at ambient and 180 °C, respectively. However, more detailed studies have to be performed to distinguish between hot-water extraction and reaction kinetics. [ABSTRACT FROM AUTHOR]

A metal-free phosphazenium cation-catalyzed direct dehydrative condensation of phosphoric acid with alcohols has been developed for the environmentally benign synthesis of phosphoric acid monoesters. [ABSTRACT FROM AUTHOR]

Microwave heating was found to have a beneficial effect on the enzymatic esterification of lactic acid (LA) with ethanol in Cyphos 202 ionic liquid (IL) medium. Microwave irradiation caused hydrolysis of lactoyllactic acid (the linear dimer of LA) during the reaction, thus, as a result, more lactic acid was available as substrate and a higher ester yield was achieved in the esterification. [ABSTRACT FROM AUTHOR]

A lack of renewable resources and their inefficient use is a major challenge facing the society. Lignin is a natural biopolymer obtained mainly as a by-product from the pulp- and paper-making industries, and is primarily burned to produce energy. However, interest for using lignin in more advanced applications has increased rapidly. In particular, lignin based nanoparticles could find potential use in functional surface coatings, nanoglue, drug delivery, and microfluidic devices. In this work, a straightforward method to produce lignin nanoparticles from waste lignin obtained from kraft pulping is introduced. Spherical lignin nanoparticles were obtained by dissolving softwood kraft lignin in tetrahydrofuran (THF) and subsequently introducing water into the system through dialysis. No chemical modification of lignin was needed. Water acts as a non-solvent reducing lignin's degrees of freedom causing the segregation of hydrophobic regions to compartments within the forming nanoparticles. The final size of the nanoparticles depended on the pre-dialysis concentration of dissolved lignin. The stability of the nanoparticle dispersion as a function of time, salt concentration and pH was studied. In pure water and at room temperature the lignin nanoparticle dispersion was stable for over two months, but a very low pH or high salt concentration induced aggregation. It was further demonstrated that the surface charge of the particles could be reversed and stable cationic lignin nanoparticles were produced by adsorption of poly(diallyldimethylammonium chloride) (PDADMAC). [ABSTRACT FROM AUTHOR]