ACS Sustainable Chemistry & Engineering最新文献

Ethyl levulinate (EL) is a crucial biomass-derived compound with diverse applications in pesticides, rubber, pharmaceuticals, and fuel. The efficient conversion of straw into EL presents significant challenges, primarily due to the interference of inorganic components (IOCs). In this study, we aim to enhance the alcoholysis of straw by identifying the specific inhibitory factors and mechanisms of IOCs. A case study on rice straw as a reactant in ethanol over Al(OTf)₃ revealed that K⁺ is a critical inhibitory factor impeding the hydrolysis of cellulose into glucose. Specifically, K⁺ is adsorbed on O of S–O–Al in [Al(EtOH)_m](OTf)₃, thus inhibiting the release of H⁺ and the cleavage of the glycosidic bond. Further, simulating computation reveals that K⁺ exhibits stronger electrophilicity than H of O–H in [Al(EtOH)_m](OTf)₃, thus inhibiting the cleavage of H from O–H in ethanol. Consequently, a simple, green acetic acid pretreatment strategy has been developed to enhance the alcoholysis of straw by efficiently eliminating K⁺, resulting in an EL yield of more than 10 times that of the pristine straw. In conclusion, this study improves the alcoholysis activity of straw and provides novel insights and potential strategies for biorefinery.

The sustainable utilization of hemihydrate phosphogypsum (HPG) in building materials is crucial for reducing industrial waste and promoting eco-friendly practices. However, its performance is sensitive to pH variations, which can impede its engineering applications. To understand the effect of pH on phosphogypsum hydration, this study examined the strength, hydration heat, hydration rate, ion concentration, phase composition, and microstructure of HPG and hemihydrate flue gas desulfurization gypsum (HFGD) under varying pH conditions. The results showed that pH had little effect on HFGD but significantly affected HPG. At pH 6.13, HPG had a 2 h strength of 6.57 MPa, a single hydration peak, and a 90% hydration rate in 1 h. At pH 8.53, the strength dropped to 0.93 MPa, the hydration peak almost disappeared, and the hydration rate was 57.62% in 10 h. At pH 11.62, strength increased to 5.67 MPa, with two hydration peaks and a 90% hydration rate in 2 h. Further ion analysis in the slurry indicates that the release and transformation of HPO₄^2– under different pH conditions mainly affect phosphogypsum properties. In low acidity (pH = 5–7), low HPO₄^2– content minimally impacts hydration. In low alkalinity (pH = 7–10), substantial HPO₄^2– release severely hinders hydration. At higher alkalinity (pH = 10–12), abundant HPO₄^2– gradually converts to insoluble calcium phosphate, reducing inhibition and causing a second exothermic peak. This research highlights the importance of controlling alkalinity and HPO₄^2– content to optimize the HPG cementitious performance, thereby supporting cleaner production methods and advancing sustainable construction practices.

PdCu alloy nanoparticles stabilized by a secondary diamine ligand (L) bearing C16-alkyl chains at the nitrogen atoms were successfully synthesized. The PdCuL supported on Vulcan XC-72 (C^v) with a very low metal loading (1 wt %) was applied in alkaline glycerol electroreforming experiments for both hydrogen generation and chemicals. The PdCuL/C^v electrocatalyst exhibited excellent activity as an anode material for glycerol oxidation with a specific activity of 6 A mg_Pd^–1 at 1 V and a notable selectivity (up to 95%) for high-value C3 oxidation products (glycerate and tartronate). Sterically demanding L allows the obtaining of small and stable size-controlled nanoparticles (d_m 1.9 ± 0.7 nm) observed through high-resolution transmission electron microscopy (TEM) analysis before and after catalysis testing. The catalyst was also thoroughly investigated by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) techniques. The Pd–Cu synergistic effect on alcohol oxidation catalysis was verified through electrochemical experiments, which highlight the superior catalytic activity of PdCuL/C^v (up to 3 times) compared to a monometallic catalyst.

Cobalt phthalocyanine (CoPc) is a widely utilized molecular catalyst for converting CO₂ to CO in the CO₂ reduction reaction (CO₂RR). However, achieving high selectivity at high current densities remains significant challenges, such as mass transport and interfacial microenvironment. In this study, CoPc-based gas diffusion electrodes with thermal induction treatments are investigated to reach high performance and stability. At a current density of 300 mA/cm², the cell voltage is 2.9 V, with a CO selectivity of 95%, representing nearly a 5-fold improvement compared to the pristine electrode. Additionally, at a current density of 150 mA/cm², the electrode demonstrates long-term durability, maintaining stable performance for 45 h. The structural changes and underlying mechanisms of the Nafion ionomer induced by thermal treatment are investigated via microscopic characterization and molecular dynamics simulations. It is revealed that thermal induction at temperatures slightly above Nafion’s glass transition point could enhance ionomer phase separation, resulting in the formation of additional hydrophilic–hydrophobic interfaces that facilitate CO₂ mass transport. Moreover, the rearrangement of Nafion chains during thermal induction produces a denser structure that restricts OH^– release. This localized retention of OH^– raises the pH near the catalyst, thereby improving the efficiency of the CO₂RR. This work offers valuable insights into the design of CoPc-based gas diffusion electrodes with high selectivity at elevated current densities and provides guidance for post-treatment processes in the field of CO₂RR.

Recently, there has been much interest in editing polymers to either endow them with improved properties or facilitate their deconstruction post-use. Such editing often requires the addition of functional groups, which can be especially challenging in the case of highly crystalline and recalcitrant polymers. Herein, we introduce a relatively simple dual-step technique for functionalizing high-density polyethylene (HDPE) using ozone. The method involves first treating the polymer in either supercritical carbon dioxide or paraffinic solvents such as isobutane or n-hexane at 110–120 °C to enhance ozone’s accessibility to the C–H bonds. This step is then followed by exposing the pretreated polymer to ozone either in a gaseous form or dissolved in liquid carbon dioxide at ambient temperature. Nitrogen sorption results and scanning electron micrographs confirmed increased porosity in the solvent-pretreated HDPE samples. Infrared and NMR spectroscopic analyses reveal the formation of carbonyl groups in the pretreated polymer samples upon ozonation. Further, high-temperature GPC analyses indicate that ozonation reduced the molecular weights of the pretreated HDPE samples, suggesting that ozone also induces C–C scission. This method uses benign reagents to induce porosity in the polymer and its functionalization. Our results demonstrate the need to improve ozone utilization to maximize resource efficiency.

The development of biobased composites with enhanced properties represents a timely research approach toward the obtainment of functional and sustainable materials for different end-use applications as an alternative to conventional non-renewable resources. Here, biocomposites based on the embedding of Croatina grape skins, rich in antioxidants, in poly(butylene succinate-co-adipate) are presented. Croatina grape skins were treated with a solvent-free, eco-friendly, mechanochemical process in order to obtain particles with reduced sizes, thus improving their homogeneous dispersibility in the polymeric matrix. The biomass was then sieved in different fractions according to their size and characterized in terms of chemical composition and morphology. The skins were added to the melt-mixed polymer matrix with varying filler sizes and amounts. The realized composites were characterized by examining their morphological, mechanical, barrier and antioxidant properties. Finally, the biodegradability of the biocomposites was assessed through soil burial degradation tests. Results demonstrate that the composites show remarkable antioxidant activity combined with an improved biodegradation rate. Interestingly, the processing of the biomasses and the composites completely avoided complex extraction procedures and the use of organic solvents, thus highlighting the environmental sustainability of this approach.