ACS Sustainable Chemistry & Engineering最新文献

The chemical recycling of chlorinated plastics is industrially challenging due to the release of corrosive HCl and char formation. In this work, a novel upcycling route for chlorinated plastics, including polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and chlorinated polyethylene (CPE), is developed. When ZnCl₂-catalyzed dehydrochlorination (DHC) is combined with tandem DHC-hydrogenation, using a homogeneous Ru hydrogenation catalyst and metal oxides as a HCl trap, each plastic type can be selectively converted into an unsaturated polyolefin (UPO), which can be chemically split via metathesis. By rational design of reaction conditions, CPE (25 or 35 m% Cl) as a model substrate, a PVDC–PVC copolymer (66 m% Cl) and PVC (57 m% Cl) were consecutively converted into partially and fully dechlorinated UPOs. Both of these UPO products contained −CH₂–CH₂–sequences and up to 11 double bonds per 100 carbons. They were chemically split into α,ω-dienes using a second-generation Grubbs catalyst. Via this procedure, chlorinated plastics can be converted into valuable chemical building blocks, while the released HCl is sequestered.

Coal washing plays a vital role in improving coal quality and reducing atmospheric pollutant emissions from coal combustion. However, the water footprint burdens caused by substantial freshwater consumption and wastewater discharge remain poorly understood. In this study, a comprehensive water footprint framework for coal washing was developed and used for a bottom-up analysis based on firsthand data from 2,367 coal washing plants across China in 2022. Compared with the scenario where coal was not washed, the national coal washing industry increases the water footprint by 7.38 Gm³, bringing the total water footprint of China’s coal supply chain to 27.68 Gm³, with gray water accounting for 90.9%. The water footprint intensities of commercial coal varied between 6.93 and 27.33 m³/t depending on the washing technologies, with a national average of 8.73 m³/t. Among the various technologies, jigging and jigging-based combined processes demonstrated relatively low water footprint intensities. From a production perspective, the spatial distribution of water footprint intensities in China exhibits a “high in the south and low in the north” pattern. However, an interprovincial transfer of 12.72 Gm³ of water footprint exacerbated the spatial mismatch between coal resources and water availability, owing to mismatches between production and consumption centers and prevailing trade flows. This study highlights the significant contribution of coal washing to the total water footprint of the coal life cycle and underscores the urgent need to incorporate water footprint balance into policies and decision-making regarding coal washing practices.

While anatase-TiO₂/α-Fe₂O₃ (ATAF) composites are promising visible-light photocatalysts, their conventional synthesis is hindered by prolonged processing and high-temperature calcination, which limits scalability and increases energy consumption. This work demonstrates a rapid, single-step microwave-hydrothermal strategy to fabricate phase-pure ATAF composites within 10 min, entirely without calcination. This method facilitates the heterogeneous nucleation of anatase-TiO₂ onto α-Fe₂O₃ particles, creating an intimate interface. By optimizing the α-Fe₂O₃ content with uniform TiO₂ decoration on it, an ATAF composite exhibiting superior charge separation, as evidenced by significant photoluminescence quenching, is prepared. This optimal interface engineering results in a remarkable 99.9% photocatalytic degradation of methylene blue under visible light, significantly outperforming the individual constituents. This energy-efficient approach potentially reduces synthesis energy consumption by one to 2 orders of magnitude compared to conventional calcination routes, while the use of aqueous solvents and a closed system aligns with the principles of clean production. The combined advantages of rapid processing, energy efficiency, and scalability position this method as a viable pathway for the industrial-scale production of high-performance photocatalytic composites. The microwave-assisted hydrothermal synthesis demonstrates process electrification by transitioning from conventional furnace-based thermal treatment to direct microwave heating, resulting in reduced energy consumption and associated CO₂ emissions.

The hydrogenation of CO₂ to methanol serves as a practical approach extensively applied in achieving carbon cycling utilization and reducing carbon emissions. Nevertheless, the rational design of Cu-based catalysts with satisfactory catalytic performance and corresponding structure–activity relationship understanding still remains a challenging goal. Inspired by the characteristics of both hydrotalcite structures and active Cu species for CO₂ hydrogenation, a series of hydrotalcite-derived Cu nanocatalysts with highly dispersed Cu nanoclusters and tunable electronic and geometric structures are obtained via simply controlling structural topological transformation process temperature, verified by a comprehensive study including Bader charge analyses, TG-MS, HAADF-STEM, in situ CO–DRIFTS, and XAFS experiments. The optimized catalyst demonstrates an exceptional normalized CO₂ reaction rate of 30.6 mmol·g_cat^–1·h^–1 and a methanol selectivity of 92%, yielding an excellent methanol space-time yield (∼0.9 g·g_cat^–1·h^–1) and a stability of 100 h under mild conditions (220 °C, 3 MPa). This is approximately twice that of the control catalyst and ranks among the top outcomes reported so far for Cu-based systems. Operando FTIR, structure–activity relationship, and DFT studies elucidate that the active Cu species at the Cu–ZnO interface function as intrinsic active centers, accelerating the formation of key intermediates (HCOO* and H₃CO*), leading to a lower activation-energy barrier. Therefore, this work presents an effective strategy for fabricating Cu nanocatalysts featuring a precisely controllable Cu–ZnO interface via a facile LDH topological transformation, offering a promising application path in the large-scale synthesis of methanol from CO₂ hydrogenation.

The transition toward sustainable plastics calls for biodegradable polymers with enhanced performance and scalable processing routes. Plant-derived nanofibers are promising reinforcements, yet their adoption is hindered by energy-intensive isolation, incompatibility with hydrophobic matrices, and aggregation during drying. Here, we report a dual-function reactive extrusion strategy that combines nanofibrillation and surface modification in a single step. Lignocellulosic fibers are prefunctionalized with maleic anhydride to introduce carboxyl groups while retaining native lignin, and in-situ transesterification during melt compounding generates well-dispersed cellulose nanofibrils covalently bonded to PBAT. This integrated approach removes the need for costly nanocellulose isolation and drying while simultaneously ensuring compatibility and mechanical integrity through both chemical bonding and the hydrophobic contribution of lignin. The resulting composite films exhibit a 30% increase in stiffness while maintaining superior tensile strength and strain at failure, along with a 42% and 56% reduction in water vapor and oxygen permeability, respectively, compared to neat polymers. Additionally, the preserved lignin imparts over 90% antibacterial activity, enabling improved fruit preservation, while many film trials confirmed effective soil moisture retention and good biodegradability. Overall, this work establishes a scalable, industry-ready route to transform raw biomass into multifunctional nanofillers, providing a green pathway toward high-performance composite films for packaging and agricultural applications.

Washing and thermal treatment are among the most promising technologies for managing municipal solid waste incineration fly ash (FA). However, the fate of residual ash after treatment remains uncertain and requires further investigation to achieve full resource utilization. In this study, the feasibility of using raw fly ash (RFA), washed fly ash (WFA), and thermally activated fly ash (TFA) as partial replacements for cement in composite cementitious materials was investigated. The macroscopic properties, strength development, environmental safety, and hydration mechanisms of FA-based composites were systematically examined. After the removal of hazardous substances, the physicochemical properties of WFA and TFA became closer to those of ordinary Portland cement (OPC). The mechanical performance of the composites followed the order TFA > WFA > RFA. At a 30% replacement level, the compressive strength of TFA reached 64.2 MPa, slightly higher than that of pure OPC and 103% greater than that of RFA. The corresponding carbon emission calibrated by strength is 29.5% lower than that of pure OPC, reaching 672.5 kgCO₂e/t. In terms of environmental performance, heavy-metal leaching from all FA-based composites met the relevant standards, and the chloride immobilization efficiency exceeded 90%. The crystalline phases of hydration products included ettringite (AFt), calcium silicate hydrate [C-(A)-S-H], and Friedel’s salt. During hydration, the formation of portlandite, precipitation of AFt, and deposition of C-(A)-S-H led to an interlaced microstructure in the TFA-derived composites, effectively refining the microstructure and thereby enhancing the macroscopic performance. These findings provide a reference pathway for the utilization of FA and contribute to the sustainable management of FA.