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Correction for ‘Towards sustainable synthesis: a life cycle assessment of polymer of intrinsic microporosity (PIM-1) by green mechanosynthesis’ by Ching Yoong Loh et al., RSC Sustainability, 2023, http://doi.org/10.1039/d3su00340j.

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The development of efficient catalysts for hydrodeoxygenation of vanillin to 5-methylguaiacol is highly desirable. Herein, we show a construction of Pd–TiOx interfaces by loading Pd nanoparticles on ETS-10 zeolite. These interfaces in the Pd/ETS-10 sample are quite efficient for the cleavage of CO bonds in vanillin, exhibiting >99.9% vanillin conversion and 95.2% 5-methylguaiacol yield at 120 °C. Characterization and kinetic studies have confirmed that the unique Pd–TiOx interfaces activated the CO bond of the intermediates in the reaction. This work might be helpful for the preparation of efficient catalysts for the hydrodeoxygenation of biomass-derived materials in the future.

Dietary fiber provides organisms with key nutrients and allows for transport of small molecules and metabolic products. Due to being biocompatible, sustainable, and positively influencing microbial communities, dietary fiber is utilized in the design of many materials in applications such as biomedical or agricultural. In this work, the feasibility of using randomly collected, mixed food waste from a local restaurant as a feedstock for extracting native cellulose is explored. The extraction procedure adapts previously utilized acid/base extraction procedures for the extraction of cellulose from single source fruit and vegetables and is tailored in both sequencing and concentration to account for the complexity of the feedstock. Despite being collected at random over a period of a year, extraction of cellulose from restaurant waste led to products with reproducible yield and chemical properties. FTIR spectroscopy and XRD revealed that the extracted cellulose has a chemical structure similar to commercially available cellulose products, but that the extracted cellulose was less crystalline, due to the presence of lower molecular weight species. Thermal analysis confirmed that the extracted cellulose contained lower molecular weight species and residual lignin, indicating a trade-off between yield and purity when using a complex feedstock such as mixed food waste in current extraction methodologies. Besides obtaining cellulose, other biopolymers, specifically pectin, hemicellulose, and lignin, can be recovered as viable products. This research demonstrates the feasibility of diverting real-world food waste streams from local restaurants to provide a sustainable, environmentally friendly feedstock for the extraction of biopolymers and to decrease the production of greenhouse gases in landfills.

Chemical recycling offers a convenient solution for the disposal of plastic items made of polyethylene terephthalate (PET); however, there is still much room for improvement in terms of integration into the current waste treatment cycles. Recently, deep eutectic solvents (DESs) have exhibited interesting properties in PET glycolysis and hydrolysis, in some cases under mild conditions. In particular, we recently reported good results with Lewis/Brønsted acidic DESs (LBDESs) containing iron(III) chloride and sulfonic acids. However, the choice of weaker acids, such as acetic acid, is more cost effective and sustainable, with an associated reduced risk of corrosion and improved safety. In this study, we demonstrate that a simple post-reaction procedure significantly enhances the yield of terephthalic acid (TA) using FeCl3·6H2O/acetic acid (molar ratio 1 : 1) LBDES from 4% (literature value) to 54% under the same experimental conditions. Furthermore, we investigate the effect of chloride salts as additives and microwave irradiation on the reaction, achieving quantitative conversion and a high yield of TA in 10 minutes at 180 °C.

Hydrogen peroxide (H2O2) with strong oxidizing properties and a volatile nature has a potential role in biological systems and industrial applications. Developing an optical “on–off–on” probe for the efficient detection of H2O2 is crucial for health, environmental safety, and diagnostic applications. Herein, sustainable N-doped carbon quantum dots (N-CQDs) were explored as optical probes for the selective discrimination of H2O2 and aspartic acid in aqueous media based on simple photoluminescence “turn on” and “turn off” mechanisms. N-CQDs were synthesized from Moringa oleifera (drumstick leaves) used as both a carbon and nitrogen source. The synergistic effect of N-doping, oxygenous surface functional groups and structural advantages lead to high selectivity and good sensing performance with a LOD value of 26.4 mM and 134.2 nM for H2O2 and aspartic acid, respectively. The simple synthesis process and structural advantage of N-CQDs showed the potential for the detection of reactive oxygen species and biomolecules with high sensitivity and selectivity in an aqueous medium for diagnostic applications and human health monitoring.

Heterostructure materials are intriguing because they may combine two or more building blocks that produce novel heterointerfaces with exceptional features. By exposing more interfaces and active sites, their utility in electrochemical applications is further expanded when they are used to form large-scale 3D frameworks. This study uses improved graphene oxide (IGO) and GO to form a heterojunction (ZIF-8/IGO). The interface between ZIF-8 and IGO accelerated the transfer of thermally obtained electrons from ZIF-8-NC to IGO. We focus on developing a 2D heterostructure mixed porous system based on differences in the density of oxygen-containing functional groups of improved graphene oxide (IGO) and commercially accessed graphene oxide (GO) while forming a composite with ZIF-8. IGO@ZIF-8-NC exhibited a very high capacitance of 352.8 F g−1 as compared to 287.5 F g−1 for GO@ZIF-8-NC at a scan rate of 5 mV s−1 confirming that the former is an excellent supercapacitor electrode owing to the synergistic behaviour at the heterojunction interface. The results on IGO-based electrodes pave the way forward for sustainable capacitive devices.

Organic dyes dissolved in water are of major concern, due to their characteristic persistence and accumulation in the environment and living organisms, leading to harmful effects such as mutagenicity, and carcinogenicity. To address this concern, this study aimed to explore the effectiveness of a bio-adsorbent prepared from spent coffee grounds and calcium alginate, referred to as SCG_ALG, in the removal of methylene blue (MB) from water. SCG_ALG exhibited an impressive Langmuir maximum adsorption capacity of 1601.85 mg g−1, besides a strong stability within a pH range of 2–10 and outstanding cyclability. The adsorption process was examined through kinetics and adsorption data, which were best fitted to PFO and Temkin's models, indicating weak physicochemical interactions. The thermodynamic study confirmed that the adsorption was a physisorption process. The possible interaction mechanism between MB and SCG_ALG was proposed through XPS spectroscopy and pH analysis. Electrostatic and π–π interactions were suggested to be involved in the adsorption mechanism. As a result, SCG_ALG emerges as a promising, cost-effective, environmentally friendly, and non-toxic adsorbent for removing MB from water-sourced and natural sources, highlighting the easy separation of the material from the solution, owing to its high adsorption capacity, reusability, and broad applicability.

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In recent years, the synthesis of carbon quantum dots (CQDs) through green methods for environmental remediation has gained significant interest owing to their benefits of reducing toxic by-products and minimising the usage of hazardous chemicals. CQDs are a new type of zero-dimensional carbon nanomaterials having a size less than 10 nm. They have attracted much attention considering their outstanding optical characteristics, non-toxicity, low-cost synthesis, biocompatibility, uniform particle size, high photostability and highly tuneable photoluminescence. The synthesis of CQDs from biodegradable and renewable resources, such as biowastes and biomass, provides an eco-friendly and sustainable alternative to conventional synthesis methods. The synthesized CQDs possess unique optical and electronic properties, including a high selectivity and sensitivity, making them promising for metal ion sensing. This review highlights the recent progress in the green synthesis of CQDs, including their synthesis methods, optical properties and potential use in sensing applications for the detection of heavy metal ions, such as iron(III), copper(II), mercury(II), chromium(IV), lead(II), silver(I), arsenic(III) and gold(III), which are considered as major environmental pollutants. A comparison based on the quantum yield, sensitivity, selectivity, detection limit, linear range concentration and sensing mechanisms is also presented. In addition, the effect of heteroatom doping on CQD performance for heavy metal detection is also discussed. In conclusion, this review emphasizes the importance of employing eco-friendly and sustainable methodologies for CQD synthesis, which not only benefits the environment but also makes these materials more accessible and cost-effective for widespread use in detecting harmful pollutants.

Lignin is the most abundant source of renewable aromatics on Earth, yet its enormous potential remains underexploited in current biorefinery and pulping processes. The extensive degree of condensation of the lignin fractions produced via the most widely adopted biomass pretreatments (i.e. “technical lignin”) poses a prominent limitation to their subsequent conversion toward valuable products. In this work, a broad range of methods for biomass pretreatment are reviewed, illustrating the impact of each strategy on the properties of the isolated lignin and carbohydrate fractions. The main pathways for the valorization of the obtained lignin streams (i.e. toward polymeric materials or chemicals) are critically discussed, and the relationship existing between (i) native lignin structure, (ii) pretreatment conditions, and (iii) lignin processability is rationalized. A key aspect for producing lignin streams amenable to further upgrading is the prevention of condensation reactions between lignin fragments during biomass fractionation. In this respect, a class of so-called “lignin-first” pretreatments, targeting the prompt stabilization of reactive lignin intermediates to minimize lignin condensation, has recently gained momentum. Herein, lignin-first approaches are reviewed, discussing in detail the fate of lignin, cellulose, and hemicellulose for each strategy. The potential of lignin-first biorefineries to realize a more complete valorization of lignocellulose and the current limitations of each method are highlighted. Overall, this work provides a comprehensive overview of the technologies that are available or currently emerging for lignin isolation and subsequent valorization.

Due to its distinct electrical structure and environmental compatibility, graphitic carbon nitride (g-C3N4) has become a viable photocatalyst for various applications. Significant initiatives are currently being implemented to enhance the photocatalytic activity of g-C3N4 by adding oxygen dopants to its structure. The unique characteristics of oxygen-doped g-C3N4 (O@g-C3N4), including enhanced charge carrier mobility and changed electronic structure, make it especially appealing for photocatalytic applications. The synthetic techniques used to create O@g-C3N4 are thoroughly examined in this paper, along with the structural changes brought on by oxygen doping and the processes underpinning its increased photocatalytic activity. The methods for adding oxygen atoms to the g-C3N4 lattice are covered in the synthesis section, including solid-state processes, chemical vapor deposition, hydrothermal synthesis, co-precipitation, and post-treatment procedures. Using these techniques, the type and density of oxygen functional groups may be precisely controlled, allowing O@g-C3N4's photocatalytic characteristics to be tailored. O@g-C3N4's characteristics are discussed, emphasizing its modified electronic band structure, better surface reactivity, and enhanced light absorption abilities. Recent developments in the field are also presented, exhibiting cutting-edge techniques, including heteroatom doping, nanostructuring, and co-catalyst integration that further enhance O@g-C3N4's photocatalytic capabilities. As a versatile photocatalyst, O@g-C3N4 has been extensively reviewed in this study, emphasizing its synthesis processes, structural characteristics, and current developments in improving its photocatalytic activity. Our understanding of O@g-C3N4 is deepened by this review's insights, which also open the door for future research into using the compound in environmentally friendly and sustainable technology.

The full oxidation of lithium metal (4Li + O2 ⇌ 2Li2O) offers a mass normalised Gibbs energy change greater than that for the combustion of carbon (C + O2 ⇌ CO2) or any hydrocarbon fuel (). This thermodynamic comparison promises a lithium–oxygen (air) battery with a petrol comparable energy density. Similar analyses apply to other abundant alkali and alkaline earth metals (AAEMs) which all feature very high specific charge capacity and the most negative electrode potentials. The success of lithium ion batteries (LIBs) in both research and commercial development confirms these thermodynamic predictions. However, the experimentally demonstrated energy capacities of all AAEM-based batteries are only small fractions of the thermodynamic values. A main cause is that a satisfactory oxygen positive electrode (positrode) is still to be developed, whilst the very few options of AAEM storage positrodes still do not match AAEM negative electrodes (negatrodes) in charge capacity. Another challenge results from the complicated interactions between AAEMs and the currently used organic carbonate electrolytes that not only reduce the negatrode capacity but also exert restrictions on both electron and ion transfers. The flammability of currently used organic electrolytes is another major concern with respect to the safety of AAEM batteries. Herein, we introduce the concept and potential, and review the relevant practices of a promising ionic liquid supercapattery that couples an AAEM negatrode with a supercapacitor positrode to bypass the thermodynamic and kinetic difficulties of an oxygen or AAEM storage positrode. The further discussion aims at the selection of ionic liquid-based electrolytes that can enable the reversible anodic dissolution of AAEMs and a wide potential window for the supercapacitor positrode. The use of molten salt-based electrolytes is also postulated and analysed, not only because of their high ionic conductivity, low cost and unique applications, but also their high temperatures that eliminate dendritic growth on the liquid AAEM negatrode and heat buildup in the cell.

Genipap (Genipa americana L.), also known as caruto, is a fruit native to Central and South America and presents a novel source of a crosslinking substance containing genipin for biopolymers in various applications. In this study, the fruit's core was used to extract the genipin-rich genipap oil, and a complete characterization of the oil as an inexpensive replacement for commercial genipin powder is included. The extracted genipap oil shows a high phenolic content and remarkable non-hemolytic, antioxidant, and antimicrobial activity. The potential of genipap oil is further demonstrated by its advantage over commercial genipin powder, which did not show antioxidant activity. The crosslinking capacity of the genipap oil was tested with chitosan films and hot-pressed sheets of protein blends from agro-industrial biomass, including zein, wheat gluten, and potato protein. The results indicated that incorporating genipap oil in these blends allowed for manufacturing homogenous structures and improved their mechanical performance compared to the non-crosslinked blends. The use of the oil represents an advantage from a material engineering perspective as it allows for better distribution of genipin during the thermal processing of the materials compared with the commercial genipin. Further, commercial genipin requires solvents and extensive purification processes, which hinders its upscalability. These results support the use of the extracted fruit oil as a green, inexpensive, efficient crosslinking agent, opening new avenues for several applications.

Using non-substituted and long-chain substituted cyclic anhydrides as the esterifying agents and dimethyl sulfoxide as the solvent, high water vapor/oxygen/bacterial resistant, mechanically/thermally strong, and biodegradable bacterial cellulose (BC) films have been fabricated according to a simple, efficient, and low-pollution surface modification protocol. The anhydride loading, reaction time and characterization in terms of the esterification degree, crystallinity, microstructures, transparency, barrier resistance, mechanical and thermal properties of the films, and fruit preservation tests were investigated. Modification with 10 wt% dodecenyl succinic anhydride (DSA) increased the dry tensile strength (TS) of the film to 124 MPa and the wet TS to 81 MPa in 30 min. Modification with 10 wt% octadecenyl succinic anhydride (OSA) reduced the water vapor permeability of the film by 84% and yielded the highest antimicrobial effect on the film surface. The film modified with 3 wt% of maleic anhydride (MA) had the strongest oxygen barrier and preserved strawberries most effectively. These films were totally biodegraded in soil within one month and exhibit strong potential to be bio-based and biodegradable food packaging materials.

The Remembrance Poppy is an iconic artificial flower that is prevalently worn in Commonwealth countries in the period preceding the Remembrance Day to commemorate their military personnel. The current version of the Remembrance Poppy is a multi-material design made of fossil plastic (i.e., light-density polyethylene, LDPE) and paper; this prevents its widespread recycling and ascribes the Poppy to the realm of single-use plastics. In this study, we quantify the environmental performance of the current and alternative designs of the Remembrance Poppy via a detailed Life Cycle Assessment (LCA), with the objective of supporting decision-making by the Royal British Legion Group, whose group charities provide the Remembrance Poppy across the UK. We consider two alternative designs: (i) one envisaging an increased recycled content (30% for LDPE and 50% for paper) compared to the current design and (ii) a novel, mono-material design fully made of paper. For the latter we consider three sub-scenarios with increasing recycled content from 50% to 100%, as well as two options considering or not recycling of the Poppy at the end of its life. The system boundaries are cradle-to-grave. The inventory data combines primary data collected from RBL group and a paper supplier, and secondary data from LCA databases. The environmental impacts are quantified via the Environmental Footprint 2.0 method. The LCA study indicates that the paper-based design is overall the environmentally preferable option, yielding environmental benefits (after normalization and weighting) ranging from 39% to 59% compared to the current design, according to the specific scenario. The recycled-content plastic-based design is also preferable but by a smaller amount (11%). The study highlights the importance of using increasing percentages of recycled content, as well as that of designing product that are recyclable at the end of their life, which are tenets of the Circular Economy paradigm.

This research aims to evaluate waste cotton and polyester as effective potential adsorbents for the removal of crystal violet (CV) from aqueous phases. Carbonaceous materials (VCP1000 or VC1000) from waste cotton and polyester were prepared at different calcination temperatures, and their characteristics were assessed using scanning electron microscopy, pHpzc, surface functional groups, and specific surface areas. The values of the parameters of VCP1000 or VC1000 were greater than those of other adsorbents. Additionally, adsorption experiments were performed in batch mode, and various parameters, including initial concentration, adsorption temperature, contact time, and pH, were demonstrated in this study. The amount of CV adsorbed onto VCP1000 and/or VC1000 was higher than those onto other VCP and/or VC adsorbents. The adsorption equilibrium of CV was achieved within 24 h. These data were fitted to the pseudo-second-order model (correlation coefficient: 0.991–0.995). The adsorption capacity increased with increasing adsorption temperatures (7 °C < 25 °C < 45 °C). The adsorption isotherm data were fitted to both the Langmuir and Freundlich models as well. The adsorption of CV using VCP1000 or VC1000 was significantly influenced by pH under our experimental conditions. Finally, elemental distribution and binding energy analyses were conducted to elucidate the adsorption mechanisms of CV. The obtained results indicate that the adsorbed CV was presented onto the VCP1000 and/or VC1000 surface. Collectively, these obtained results show that VCP1000 or VC1000 holds promise for the removal of CV from aqueous phases.