RSC sustainability最新文献

Upcycled waxes are blended with poly(ethylene-co-vinyl acetate) (EVA) to make hot-melt adhesives (HMAs). Herein, we report partially recycled HMAs that were prepared by blending EVA with upcycled waxes obtained from mix waste polyolefins. First, waste mixed polyolefins (such as high-density, low-density, and linear low-density polyethylene and polypropylene) were converted into waxes in high yields reaching up to 92%. The obtained upcycled waxes were used as an additive for HMAs along with gum rosin. The thermal properties and seal strength of the HMAs containing upcycled waxes were compared with those of commercially available HMAs. The HMA made from upcycled wax was found to be as efficient in seal strength as the commercially available HMA. This upcycling of plastic waste for use in HMAs is yet another way of promoting circularity in single-use plastics.

Catalysis is a crucial tool to efficiently address the recycling and upgrading of polymeric waste within the context of a circular economy, providing affordable and selective methods for waste valorization in alignment with the principles of green chemistry. Various catalysts, including metals, metal–organic frameworks, and biocatalysts, have been explored for the degradation of chemical poly(ethylene terephthalate) (PET) and polyurethane (PU) waste through processes like hydrolysis or alcoholysis. This critical review specifically focuses on catalytic tools, examining both homogeneous systems (such as metal salts or coordination organometallic complexes) and heterogeneous systems where the catalysts are immobilized on solids, including metal oxides, layered or porous solids, or inorganic–organic coordination polymers as well as biocatalytic counterparts from 2017 to the present. We provide a comparative analysis of the chemo-catalysts researched, evaluating their performance relative to biocatalysts using a SWOT analysis of both technologies to highlight their strengths and limitations in the context of sustainable waste management practices.

The transition to widespread adoption of electric vehicles (EVs) is leading to a steep increase in lithium ion battery production around the world. With this increase it is predicted there will not only be a large increase in end of life batteries needing to be recycled, but also a substantial amount of production scrap, particularly in the early stages of gigafactory set-up. The recycling of such battery electrode materials has a number of challenges which need to be considered, in particular the delamination from the current collector and removal of the binder, e.g. mainly polyvinylidene fluoride (PVDF) for cathode materials. Traditional pyrometallurgy or hydrometallurgy approaches require multiple separation steps to obtain pure metal salts before resynthesising the cathode active material, and so can be high cost, high CO₂ and high waste processes. Production scrap in particular, however, offers the potential for lower cost and lower environmental impact direct recycling processes to be employed, which preserves the manufactured value of the electrode material. To illustrate the potential of such an approach, here we demonstrate a direct recycling approach on EV production scrap cathode materials which utilises a low temperature heat treatment to decompose the binder and allow delamination of the cathode material from the Al current collector. A further higher temperature heat treatment is then employed to ensure complete binder removal and regenerate the cathode, with the results showing that the addition of a small amount of Li is required to improve electrochemical performance (first cycle discharge capacity (2.5–4.2 V) of 129(2) mA h g⁻¹ and 146(4) mA h g⁻¹ with 0 wt% and 10 wt% added lithium, respectively). Electrochemical performance can be further improved by increasing the upper voltage window to 4.3 V (first cycle discharge capacity of 146(4) mA h g⁻¹ and 164(2) mA h g⁻¹ at 2.5–4.2 V and 2.5–4.3 V, respectively).

Catalytic reductive processes facilitate deconstruction of lignins into value-added aromatics. This study explores the novel use of glycerol-derived ethers (GDEs), specifically 1-3-dimethoxypropan-2-ol (DMP) and 1,3-diethoxypropan-2-ol (DEP), as hydrogen transfer solvents for reductive catalytic fractionation (RCF) of softwood biomass, marking a departure from conventional use of high-pressure molecular hydrogen and short-chain alcohols. The influence of process conditions, namely, batch holding time, temperature, catalyst species and dosage, solvent-to-biomass ratio, acidic medium (by acetic acid addition), and water volumes as a co-solvent on the yield of aromatic monomers and delignification were evaluated. Under optimal conditions, GDE-mediated RCF of softwood achieved aromatic monomer yields and delignification up to 24.9 wt% and 90.7 wt%, respectively. Aromatic monomers with unsaturated and oxygenated side chains were observed including value-added species, such as vanillin, isoeugenol, coniferaldehyde, eugenol, and vanillic acid. This observation contrasts with prior RCF studies applying ex situ hydrogen which yield monomers with saturated alkyl side chains (e.g., 4-propylguaiacol, 4-ethylguaiacol). Mass-based green chemistry metrics (e.g., solvent intensity, process mass intensity) demonstrate GDEs supported material-efficient, catalytic deconstruction of softwood lignins into value-added aromatic monomers. MALDI-TOF analyses of resultant lignin oils revealed the occurrence of sidechain dehydration and decarbonylation of oligomeric species. HSQC NMR of lignin oils indicated the absence of native linkages, especially β-O-4 bonds, post RCF treatment. Furanic monomers derived from carbohydrate fractions were identified and furan yields were higher under neat solvent conditions (∼8 wt%) than in the presence of redox catalyst (∼2 wt%). This study demonstrated successful and optimized utilization of GDEs as hydrogen transfer solvents for RCF of softwood biomass, resulting in competitive yields of functionalized aromatics within the confines of green chemistry.

We have custom-engineered dye-sensitized solar cells (DSCs) by eliminating spacers and holes, fabricating hole-free, spacer-free (HF-SF) DSCs with a 96% active area to total area ratio. These newly engineered HF-SF dye cells provide better scalability, lower cost, and improved aesthetics with enhanced device performance delivering more than 30% efficiency under indoor/ambient illumination. Two serially interconnected HF-SF DSCs fabricated using D35:XY1b co-sensitized organic dyes and [Cu^(I/II)(dmp)₂] electrolyte were able to autonomously power an indoor temperature and humidity monitoring unit free of batteries at realistic indoor illumination intensities below 200 lux.

Compressed carbon dioxide energy storage (CCES) emerges as a promising alternative among various energy storage solutions due to its numerous advantages, including straightforward liquefaction, superior energy storage density, and environmental compatibility. This review delves into the recent advancements, economic viability, technological feasibilities, and operational aspects of CCES systems comprehensively. It encapsulates the evaluation methodologies, examines the intricacies of compressed carbon dioxide storage, and explores the avenues for performance optimization within CCES technology. A comparative analysis reveals that among trans-critical, supercritical, and liquid CCES systems, the supercritical variant exhibits enhanced thermodynamic properties and a more straightforward configuration, positioning it as the preferred choice for large-scale applications. Additionally, this review incorporates recent advancements in CO₂-related conversion technologies, such as photocatalytic and photothermal CO₂ reduction, which further enhance the potential of CCES systems. The review highlights the future direction for CCES development, emphasizing the need for optimal compression–expansion ratios, refined analytical models, and integrated multi-disciplinary approaches. This discussion aims to serve as a foundational reference for the effective design and implementation of CCES systems.