Showing papers in "Green and Sustainable Chemistry in 2018"
TL;DR: In this article, a review of recent literature on the factors, barriers and motivations that influence the generation and management of CDW is presented, and two indicators are calculated for selected countries using the latest available data and an explanatory model is developed with a view to identifying the factors affecting CDW generation.
Abstract: Construction and demolition activities and natural disasters generate vast quantities of waste materials. Globally, it is estimated that about 35% of the quantities of construction and demolition waste (CDW) produced are directed to landfills, without any further treatment, although efforts to recycle and reuse CDW are increasingly being made. This paper, through a review of recent literature, focuses on the factors, barriers and motivations that influence the generation and management of CDW. Based on the analysis, two indicators are calculated for selected countries using the latest available data and an explanatory model is developed with a view to enabling identification of the factors affecting CDW generation. Most importantly, a concept map is created involving thirty-six different nodes that represents existing knowledge with respect to the components of the CDW system, and the positive or negative relationships between them.
205 citations
TL;DR: In this paper, the authors provide an overview of the current and future potential of the recycling of rare earth elements (REE), including the significant but currently unrealised potential for increased amounts of REE recycling from end-uses such as permanent magnets, fluorescent lamps, batteries, and catalysts.
Abstract: The rare earth elements (REE) are vital to modern technologies and society and are amongst the most critical of the critical elements. Despite these facts, typically only around 1% of the REE are recycled from end-products, with the rest deporting to waste and being removed from the materials cycle. This paper provides an overview of the current and future potential of the recycling of the REE, including outlining the significant but currently unrealised potential for increased amounts of REE recycling from end-uses such as permanent magnets, fluorescent lamps, batteries, and catalysts. This future potential will require a significant amount of research but increasing the amount of REE recycling will contribute to the overcoming some of the criticality issues with these elements. These include increased demand, issues over security of supply, and overcoming the balance problem where primary mine-derived sources overproduces lower demand REE without necessarily meeting demands for the higher demand REE.
196 citations
TL;DR: The mechanisms of bio-recycling have been particularly emphasized in the present article as discussed by the authors, where the bio-degradability and renewability of biopolymers have been discussed.
Abstract: Recycling is groundwork of the worldwide efforts to diminish the amount of plastics in waste. Mostly around 7.8–8.2 million tons of poorly-used plastics enter the oceans every year. Non-biodegradable plastics settlements in landfills are uncertain, which hinders the production of land resources. Non-biodegradable plastic solid wastes, carbon dioxide, greenhouse gases, various air pollutants, cancerous polycyclic aromatic hydrocarbons and dioxins, released to the environment cause severe damage and harmfulness to the inhabitants. Due to the bio-degradability and renewability of biopolymers, petroleum-based plastics can be replaced with bio-based polymers in order to minimize the environmental risks. In this review article, bio-degradability of polymers has been discussed. The mechanisms of bio-recycling have been particularly emphasized in the present article.
166 citations
TL;DR: In this paper, a review article gives an overview of plastics solid waste with particular emphasis on the recent progress in polystyrene based plastics, which is becoming a great challenge for the society as plastic solid waste creates big threat to our environment.
Abstract: Due to their superior properties, plastics derived from petroleum have been extensively used almost in everyday life since last few decades. Because of lack in the manageability of plastic solid waste, their volume is increasing steadily in the natural world. Unfortunately, the disposal of plastics wastes in the oceans and land filling has led to a global issue. To effectively and efficiently deal with plastic solid waste is becoming a great challenge for the society as plastic solid waste creates big threat to our environment. Recycling of plastics solid waste should be performed to produce products having same quality to original plastics. This review article gives an overview of plastics solid waste with particular emphasis on the recent progress in polystyrene based plastics.
109 citations
TL;DR: Four classes of (nano)particles that can be employed as Pickering emulsion stabilizers: minerals, polysaccharides, synthetic polymers and proteins, and proteins are reviewed.
Abstract: Emulsions are used widely in formulated consumer products, paints and coatings, foods, and pharmaceutical preparations to name just a few examples Frequently surfactants are employed as emulsifiers, but the use of particles, including nanoparticles, can offer advantages Naturally derived, or synthetic, particles that are biodegradable can reduce end-of-life environmental impact, while offering advantages such as lack of irritancy in use (eg, on skin) and, in some cases, the use of particle supported Pickering emulsions may provide more environmentally friendly processes (eg, biphasic catalysis mitigating use of solvents) or environmental cleanup solutions (eg, oil spill dispersion) Here we review four classes of (nano)particles that can be employed as Pickering emulsion stabilizers: minerals, polysaccharides, synthetic polymers and proteins
109 citations
TL;DR: In this paper, the authors present the recent trends in green and sustainable chemistry, as well as waste valorization and their applicability to understand and realize the concept of a circular economy.
Abstract: The review presents the recent trends in green and sustainable chemistry, as well as waste valorization and their applicability to understand and realize the concept of a circular economy. It also provides a comprehensive global perspective of the linear plastics economy and makes the case for its transformation into a circular plastics economy. Furthermore, bioconversion in a food waste biorefinery to produce fructose as an example of a high value-added product is given as a case study to demonstrate the feasibility of a circular economy.
105 citations
TL;DR: In this article, the authors review some of the notable existing and emerging technologies such as microfactories being employed for e-waste plastics and present their limitations, advantages and potential for future development.
Abstract: Electronic waste (e-waste) is the fastest growing waste on the planet, with an annual growth rate of 3–4%. It is estimated that e-waste generation will reach 52.2 million tonnes per annum by 2021. Presently, only 15% of e-waste is recycled. One of the most significant constituents of e-waste is plastics, accounting for almost for 20% of it. Despite several technological developments, their recycling is largely hindered due to presence of flame retardants. In this paper, we review some of the notable existing and emerging technologies such as microfactories being employed for e-waste plastics. Furthermore, we present their limitations, advantages and potential for future development.
103 citations
TL;DR: In this paper, reactions in aqueous micellar media are clearly governed by new rules, in contrast to those that prevail in traditional organic synthesis performed in organic solvents.
Abstract: Several examples are discussed where reactions in aqueous micellar media are clearly governed by new rules, in contrast to those that prevail in traditional organic synthesis performed in organic solvents.
88 citations
TL;DR: The United Nations Sustainable Development Goals (SDG's) have exceptional value in identifying key areas of challenge that need urgent improvement if we are to move away from the unsustainable trajectory that we are on as mentioned in this paper.
Abstract: The United Nations' Sustainable Development Goals (SDG's) have exceptional value in identifying key areas of challenge that need urgent improvement if we are to move away from the unsustainable trajectory that we are on. The place that is a major shortcoming of these goals is that they take a highly integrated and inextricably linked system, and express them as individual areas such as food, water, poverty, materials, empowerment, etc. In the absence of systems thinking, there is an excellent chance of noble intentions bringing about unintended and perhaps counter-productive consequences. As we employ sustainable chemistry and the tools of its scientific basis, green chemistry, to address so many of these challenges, it is important to integrate these tools not as isolated individual principles or methods, but rather as an integrated interconnected system as well.
84 citations
TL;DR: In this paper, the main byproduct of the cocoa harvest, the pod husk (CPH), is used for animal feed, as a starting material for soap making and activated carbon.
Abstract: Cocoa pod husk (CPH) is the main by-product (ca. 70–75% weight of whole fruit) of the cocoa harvest, an important and economic crop in developing countries. It is a rich source of minerals (particularly potassium), fibre (including lignin, cellulose, hemicellulose and pectin) and antioxidants (e.g. phenolic acids). An existing practise is the return of CPH to soil with potential benefits (or disadvantages) for cocoa productivity and soil sustainability that have not been fully characterised. Currently, alternative low-value applications of CPH include its use as animal feed, as a starting material for soap making and activated carbon. Other biotechnological valorisation potentials for CPH and its fractions include the production of bio-fuels and their incorporation in food systems. Physical, chemical or biological pre-treatment approaches are needed in order to achieve desirable fractions in a cost-effective and sustainable manner for novel applications in food and non-food sectors.
79 citations
TL;DR: The textile industry uses over 8000 chemicals in its supply chain and today faces the challenging demand to move towards cleaner production as mentioned in this paper, which is why the industry has taken strong initiatives to address this challenge.
Abstract: With exponential increase in global population and innovations in chemistry during the past century, chemical production has grown enormously. The textile production, which started in the West, gradually moved to low cost developing countries. Inadequate legislation and control in these countries has led to the pollution of the natural water bodies there. The textile industry uses over 8000 chemicals in its supply chain and today faces the challenging demand to move towards cleaner production. NGOs have challenged the industry to achieve the goal of Zero Discharge of Hazardous Chemicals across all pathways by 2020. The industry has taken strong initiatives to address this challenge. In the long term, sustainable chemistry will be the only solution and innovation is the key.
TL;DR: In this paper, the importance of new strategies in biorefineries, based on food waste nutrients and their interactions, is discussed, where the authors state that interactions between FW nutrients, their derivates and subsequent treatment methodologies may lead to negative effects and a low yield.
Abstract: Waste management is one of the most significant challenges of EU policies for the coming decades. Our changing food habits carries an inherent increase in waste nutrients, that worth recycling. The traditional method of waste management is not adapted to meet future energy and environmental requirements. Food waste (FW)-based biorefinery allows new approaches in waste recovery, while improving industrial processes. However, interactions between FW nutrients, their derivates and subsequent treatment methodologies may lead to negative effects and bioprocess low yield. This work aims to state the importance of new strategies in biorefineries, based on FW nutrients and their interactions.
TL;DR: In this paper, the synthesis of gold and silver nanoparticles was evaluated using green chemistry metrics, with an emphasis on process mass intensity (PMI). Opportunities for improving synthetic methods were identified based on these metrics.
Abstract: The synthesis of gold and silver nanoparticles was evaluated using green chemistry metrics, with an emphasis on process mass intensity (PMI). Opportunities for improving synthetic methods were identified based on these metrics. Solvent usage was identified as the biggest challenge among nanoparticle syntheses, including those otherwise deemed as green, with PMIs that were typically in the thousands. The synthesis of ligated metal nanoparticles by arrested precipitation was identified as the best opportunity for making impactful improvements, since they are the most industrially relevant but the least green. Although this review focuses on gold and silver nanoparticles, much of the discussion also pertains to inorganic nanomaterials synthesis in general.
TL;DR: In this paper, TEMPO-oxidized cellulose nanofibers (TOCNs) with homogeneous widths (∼3nm) and high aspect ratios are described.
Abstract: The development of green and sustainable routes to liberate crystalline cellulose microfibrils from plant cell walls is of utmost importance to enable development of the large-scale production of sustainable nanomaterials based on renewable resources. The catalytic oxidation of cellulose using 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) under aqueous conditions at room temperature is a position-selective and efficient chemical modification. TEMPO-mediated oxidation of plant cellulose fibers, followed by gentle mechanical disintegration of the oxidized celluloses in water, results in the formation of TEMPO-oxidized cellulose nanofibers (TOCNs) with homogeneous widths (∼3 nm) and high aspect ratios. TOCNs are characteristic bio-based materials with high tensile strengths and elastic moduli. Sodium carboxylate groups are densely present on the crystalline TOCN surfaces and can undergo counterion exchange from sodium to other metal or alkylammonium ions under aqueous conditions. The hydrophilic/hydrophobic, stable/biodegradable, super deodorant, catalytic, and other functionalities of TOCNs can be controlled through counterion exchange.
TL;DR: A large number of chemicals and products have been developed starting from cashew nut shell liquid by taking advantage of the three reactive sites, namely, phenolic hydroxyl, aromatic ring and unsaturation(s) in the alkenyl side chain this article.
Abstract: Among the renewable resource materials, cashew nut shell liquid (CNSL) is considered as an important starting material due to its unique structural features, abundant availability and low cost. A large number of chemicals and products have been developed starting from CNSL by taking advantage of the three reactive sites, namely, phenolic hydroxyl, aromatic ring and unsaturation(s) in the alkenyl side chain. Increasing attention is paid to promising cardanol-based products that could be have potential interest in industry, such as epoxy and acrylic monomers, plasticizers and surfactants.
TL;DR: Glycerol carbonate as mentioned in this paper is a bio-derived compound that results from the cyclo-condensation of glycerol, arguably the best studied and most promising biomass derived compound.
Abstract: Glycerol carbonate results from the cyclo-condensation of glycerol, arguably the best studied and most promising biomass-derived compound. Glycerol is highly abundant and relatively cheap as it is produced as a waste stream within the biodiesel industry. The direct reaction of carbon dioxide with glycerol is possible, and the prospect of combining these two abundant waste products into such a versatile and exciting molecule has resulted in a linear increase in the number of patents and scientific publications in the last ten years. Glycerol carbonate has already been commercialised, but many opportunities to develop better production routes and new applications exist. In this critical review, we examine the relevance of this bio-derived compound and the recent advances in preparation methods and recent applications.
TL;DR: Important factors for the assessment and implementation, as well as future perspectives of biocatalysis in the pharmaceutical industry are presented.
Abstract: Enzymes are essential tools in the pharmaceutical industry rooting in historic processes for steroids and antibiotics. Recently new processes, based on engineered catalysts for asymmetric ketone reduction and reductive aminations, have been established and highlighted the potential for greener synthesis routes. While enzymatic processes can contribute to an increased sustainability in the synthesis of active pharmaceutical ingredients (APIs) it is important to use established tools for correctly measuring their impact. Important factors for the assessment and implementation, as well as future perspectives of biocatalysis in the pharmaceutical industry are presented.
TL;DR: In this article, the authors introduce the range of renewable precursors available and current state-of-the-art performances of supercapacitors and explore the challenges regarding flexibility and sustainability.
Abstract: At present, supercapacitors constitute, along with batteries, one of the most promising electrochemical energy storage technology. The recent emerging generation of bendable portable electronic devices has boosted the research of new materials, new processing techniques and new designs that can meet the demands in terms of mechanical stability upon bending or stretching, without compromising their electrochemical performance, at an acceptable cost. Among all the electrode materials currently explored, biomass-derived carbons hold a great potential, due to their low-cost, easy processing techniques, stability and versatility. Here we introduce the range of renewable precursors available and current state-of-the-art performances, and explore the challenges regarding flexibility and sustainability.
TL;DR: These issues are addressed, some recent advances in the production and use of cellulases from the genera Aspergillus, Penicillium and Trichoderma are discussed, and molecular biology tools are used to favor the enzyme production economics.
Abstract: Lignocellulosic biomass is an excellent raw material for the production of fuels, chemicals and energy. However, its use in a more productive way is conditioned to the use of highly efficient enzymatic cocktails, which can be produced by a plethora of microorganisms. Among them, strains of the genera Aspergillus, Penicillium and Trichoderma are some of the most relevant, corresponding to over 50% of the studies related to cellulases. In this context, molecular biology tools should be used to favor the enzyme production economics, whereas approaches such as product engineering and supplementation with additives (e.g. surfactants or accessory proteins) should be used to increase the efficiency of the hydrolytic process. In this paper, we shortly address these issues, and discuss some recent advances in the production and use of cellulases from the abovementioned fungal genera.
TL;DR: In this paper, a review of recent developments and pioneering work in the field of electrochemical lignin degradation to bio-based fine chemicals is presented, which is a powerful and green tool for the depolymerization and utilization of the renewable feedstock Lignin.
Abstract: Lignin, one of the most abundant polymers in nature, qualifies itself by the polyphenolic structure as potential renewable feedstock for the production of bio-based aromatic fine chemicals. However, the natural complexity and degradation stability of lignin make the depolymerization a highly challenging task. Several efforts have been pursued for the selective degradation of the biopolymer into suitable compounds. However, there are only a few technical approaches for the degradation of lignin to aromatic fine chemicals. Organic electrosynthesis is the synthetic method that enables the direct use of electricity for the production of valuable compounds. Moreover, electro-organic synthesis represents a sustainable and modern technology. In addition, it is a powerful and “green” tool for the depolymerization and utilization of the renewable feedstock lignin. In general, if electro-conversion is driven to significant extent then a plethora of products is obtained, whereas the selective electrochemical degradation results in a low yield. Because of the inexpensive and abundant nature of lignin, the latter is of technical interest. This review surveys recent developments, and pioneering work in the field of electrochemical lignin degradation to bio-based fine chemicals.
TL;DR: The recent lignin depolymerization techniques that yield phenolic aldehydes and phenolics such as alkaline oxidation, fast pyrolysis, hydrogenolysis, and hydrolysis are summarized and novel upgrading approaches via biological and chemo-catalytic pathways from lignIn monomers to targeted bulk chemicals are described.
Abstract: Lignin is a complex aromatic heteropolymer that harbors great potential to serve as a basis for the production of chemicals, biofuels, and materials. In a bio-economy, lignin valorization through depolymerization to monomers and upgrading of these monomers to targeted chemicals is highly challenging, but attractive and important for the chemical industry. To address current limitations of lignin valorization and further upgrading, we will summarize the recent lignin depolymerization techniques that yield phenolic aldehydes and phenolics such as alkaline oxidation, fast pyrolysis, hydrogenolysis, and hydrolysis. In addition, this review describes novel upgrading approaches via biological and chemo-catalytic pathways from lignin monomers to targeted bulk chemicals, including cis,cis-muconic acid, adipic acid, and terephthalic acid, and to fine chemicals, and then discuss future prospects.
TL;DR: In this article, photoredox catalytic trifluoromethylation of aromatic and especially heteroaromatic compounds is particularly interesting for application in pharmaceutical industry, and the synthesis of fluoroorganic compounds is important for the preparation of biologically active products.
Abstract: Photocatalytic reactions are useful tools for organic synthesis. Photooxygenation of furan derivatives have been successfully applied to the synthesis of complex nitrogen containing heterocycles. Enzyme catalyzed asymmetric oxidations are simplified when combined with photoredox processes. The synthesis of fluoroorganic compounds is important for the preparation of biologically active products. Thus, photoredox catalytic trifluoromethylation of aromatic and especially heteroaromatic compounds is particular interesting for application in pharmaceutical industry.
TL;DR: In this article, the benefits and challenges associated with polymer recycling are highlighted, not least being the strategies required to encourage industry and society to recycle resources rather than dispose and renew, and a review presents current research and technology that aims to embrace plastics and polymer composites into a circular economy.
Abstract: It is reported that plastic waste is accumulating in the oceans at an alarming rate. A significant proportion of this waste is plastic packaging materials, even though recycling routes and options are available to retain and reuse this oil-based resource. In addition to thermoplastic materials, fibre reinforced polymer materials are finding increased use and soon will become a concern with respect to disposal. This review presents current research and technology that aims to embrace plastics and polymer composites into a circular economy. The benefits and challenges associated with polymer recycling are highlighted, not least being the strategies required to encourage industry and society to recycle resources rather than dispose and renew.
TL;DR: In this paper, a review introduces a new approach of completely marine based bioethanol production by analyzing and evaluating the recent trends in bio-ethanol fermentations using algae, marine microorganisms and the replacement of freshwater with seawater.
Abstract: This review introduces a new approach of completely marine based bioethanol production by analyzing and evaluating the recent trends in bioethanol fermentations using algae, marine microorganisms and the replacement of freshwater with seawater. Both macroalgae and microalgae have been successfully used for bioethanol production. Marine yeasts showed excellent tolerance to salt and inhibitors, and fit for seawater fermentation. The combination of marine biomass, marine microorganism and seawater has a potential for a greener bioethanol production.
TL;DR: In this article, a review highlights the key reasons that make these manufacturing routes unsustainable and presents alternatives, with special emphasis on bottom-up techniques, such as biological and biochemical-inspired routes.
Abstract: Inorganic nanomaterials are widely used in e.g. healthcare,
electronics and energy sectors (worth several billion $), but
their manufacturing is highly wasteful and hence unsustainable.
This review highlights the key reasons that make these
manufacturing routes unsustainable. We present alternatives,
with special emphasis on bottom-up techniques. Biological and
bioinspired routes feature as emerging solutions that can be
sustainable yet with the ability to produce high-value nanomaterials.
Finally, the review identifies future challenges in
developing these routes such that they become commercially
attractive manufacturing methods.
TL;DR: In this article, a review of the chemical industry's efforts to support the realization of the United Nations Sustainable Development Goals (SDGs) has been presented, together with an evaluation of the approaches and tools some companies are using to support realisation of the goals.
Abstract: Since their launch in 2015, the United Nations Sustainable Development Goals have been adopted by a wide range of businesses to capture their efforts in corporate sustainability. This review highlights specific examples from the chemical industry, together with an evaluation of the approaches and tools some companies are using to support the realisation of the goals. A view towards the efforts required by the chemical industry in order to maximise the impact of the goals is also provided.
TL;DR: In this paper, the conversion of sugars derived from waste polysaccharide biomass to commodity chemicals by fermentation or catalytic hydrogenation, oxidation or dehydration or combinations thereof is reviewed.
Abstract: The conversion of sugars, derived from waste polysaccharide biomass, to commodity chemicals by fermentation or catalytic hydrogenation, oxidation or dehydration or combinations thereof are reviewed.
TL;DR: In this article, a review article aims to shed light on the advancement in the carbon fiber recycling techniques from used composite materials and the disadvantages of mechanical and thermal recycling approaches over chemical recycling such as production of low quality fibres, low tensile strength, char deposition, etc.
Abstract: The recycling of carbon fibre reinforced polymers (CFRPs) is much needed due to the environmental challenges posed by traditional landfilling. Although, various recycling techniques have been used for the recovery of carbon fibres from waste materials, the recycled fibres have limited applications due to partial deterioration of mechanical properties and shortening of fibre lengths. This review article aims to shed light on the advancement in the carbon fibre recycling techniques from used composite materials. Further, the disadvantages of mechanical and thermal recycling approaches over chemical recycling such as production of low quality fibres, low tensile strength, char deposition, etc. have been brought out concisely.
TL;DR: In this paper, the authors review recent advances towards understanding the nature of this nanostructure in ionic liquids and related mixtures and solutions, both in bulk and at or near macroscopic interfaces.
Abstract: Many ionic liquids (ILs), and their mixtures and solutions are amphiphilically nanostructured. Here we review recent advances towards understanding the nature of this nanostructure in ionic ILs and related mixtures and solutions, both in bulk and at or near macroscopic interfaces. We propose nanostructure is key for realising the designer solvent promise of ILs, and highlight its potential for translation to new generations of low-cost and environmentally sustainable cation and anion motifs for large-scale applications.
TL;DR: Inorganic nanomaterials are at the heart of some of the most exciting research developments of the day as mentioned in this paper, and their synthesis with high control over their size, shape, and composition is essential to achieve the desired properties.
Abstract: Inorganic nanomaterials are at the heart of some of the most exciting research developments of the day. Their synthesis with high control over their size, shape, and composition is essential to achieve the desired properties. Recently mechanochemistry and aging have emerged as powerful methodologies to produce such nanomaterials. Interestingly, methods relying on molecular precursors, as opposed to bulk or micro-sized phases, allow the seeding and growth of nanoparticles in the absence of solvent, with remarkable control, to achieve unusually small size and monodispersity. These emerging methods are reviewed in this opinion article.