ACS Sustainable Chemistry & Engineering最新文献

Sustainable production of cellulose nanofibrils (CNFs) from bast fibers offers a promising route to high-value biobased materials. Despite their high cellulose content (70–92%), hemp fibers remain underexplored for nanofibrillation. Here, hemp cellulose was nanofibrillated for the first time using a choline chloride–lactic acid deep eutectic solvent (DES) followed by shear mixing. Response surface methodology (RSM) was employed to model the effects of DES treatment and shear mixing time on the fibril diameter, yield, and aspect ratio. The quadratic models an exhibited excellent predictive capability (R² > 0.99), confirming their robustness. Fibril diameter decreased under harsher conditions, reaching 10–12 nm, while the aspect ratio increased up to ∼145. Yield declined with increasing severity, highlighting the trade-off between fibrillation efficiency and material recovery. SEM and AFM confirmed progressive fibrillation from coarse bundles under mild conditions to highly individualized nanofibrils with narrow distributions (<20 nm) under optimized conditions. Sedimentation and gel point analysis indicated enhanced suspension stability and network formation for the optimized sample, with gel points as low as 0.15 wt % and a zeta potential of −30.3 mV. Energy analysis revealed shear mixing as the dominant contributor to consumption, yet optimization achieved superior fibrillation at a reduced demand of ∼1.5 kWh for the whole process. FTIR confirmed cellulose esterification by DES, while XRD verified retention of cellulose I structure with crystallinity indices of 71–79%. The solvent was successfully reused for three consecutive cycles without loss of the treatment performance. Overall, this study demonstrates an efficient, low-energy route for producing high-quality hemp nanofibrils by integrating DES pretreatment, shear processing, and statistical optimization.

The development of high-strength and high-toughness wood-based composites remains a crucial but challenging goal in industrial applications, as these two properties are often mutually exclusive in traditional material design. Inspired by the multiscale structure of spider silk rigid β-sheet crystals and dynamic amorphous matrix, we propose a biomimetic holocellulose material (HEODW) with a dynamic covalent network. Through the selective oxidation of cellulose and the Schiff base reaction with ethylenediamine, a dynamic imine bond network was constructed in the wood cell wall. The network can undergo reversible fractures and recombination in the stress concentration area and achieve efficient energy dissipation through finite molecular slip. HEODW exhibits excellent mechanical properties: a tensile strength of 479.51 MPa, a Young’s modulus of 17.61 GPa, and a toughness of 14.85 MJ/m³, which are 6.3 times, 4.6 times, and 15.7 times higher than those of natural wood, respectively. The flexural strength and flexural modulus reached 216.49 MPa and 23.02 GPa, respectively. In addition, the chemical vapor deposition organic silane modification gives the material persistent hydrophobicity, expanding its application in humid environments. This study demonstrates a feasible spider silk-like strategy that can break through the trade-off between the strength and toughness of holocellulose materials and provide a sustainable path for the development of high-performance structural wood composites.

This study reports the development of a sustainable solid-state fluorescent chemosensor for selective detection of zirconium ions (Zr⁴⁺) by covalently grafting quercetin onto chitin via a Mannich reaction. The chitin-quercetin (Ch-Q) film exhibits a distinct “turn-on” yellow-green fluorescence response at 540 nm upon Zr⁴⁺ binding, attributed to chelation-enhanced fluorescence (CHEF) and the suppression of excited-state intramolecular proton transfer (ESIPT). The sensor exhibits exceptional selectivity for Zr⁴⁺ over competing metal ions, along with a low detection limit (1.157 μM), rapid response (<60 s), and broad operational pH range (2–8). Density functional theory (DFT) calculations confirm the optimal Zr⁴⁺ binding site and elucidate the underlying ligand-to-metal charge transfer (LMCT) mechanism. This biomass-derived platform offers a simple, sustainable, and eco-friendly solution for real-time Zr⁴⁺ monitoring in environmental applications.

Covalent organic frameworks (COFs) hold great promise for solar-driven H₂O₂ production due to their designable donor–acceptor (D–A) structures. However, leveraging side-chain engineering to precisely control these D–A interactions for enhanced performance remains a key challenge. In this study, we introduced a side-chain engineering strategy to optimize D–A COFs for efficient photocatalytic H₂O₂ production. The strategy involves systematically tuning the electron density of the acceptor units by introducing methoxy, hydrogen, or fluorine substituents into the molecular scaffolds, yielding FMP-COF, FPB-COF, and DFF-COF, respectively. The synthesized methoxy-functionalized FMP-COF exhibited significantly enhanced crystallinity, a narrowed bandgap, and optimized D–A interactions, leading to a notable H₂O₂ production rate of 5384 μmol g^–1 h^–1 in pure water, surpassing its hydrogen- and fluorine-substituted counterparts (FPB-COF and DFF-COF, respectively). Comprehensive in situ characterization and theoretical simulations revealed that electron-donating methoxy groups not only facilitate charge carrier separation and migration but also promote a dual-path reaction mechanism. In this mechanism, polarized hydrazone linkages serve as active sites for the water oxidation half-reaction, whereas the optimized electronic structure directs electrons efficiently toward the oxygen reduction pathway. This study established a clear structure–activity relationship, demonstrating that side-chain electronic properties are pivotal in steering photocatalytic efficiency, thereby providing a molecular-level design principle for advanced COF photocatalysts.

The ruthenium-catalyzed Murai reaction represents a fundamental C–H activation process wherein the nucleophilic ruthenium(0) catalyst oxidatively inserts into inert C–H bonds, which has been broadly utilized in all areas of chemical science. Herein, we report the first ruthenium-catalyzed decarbonylative cross-coupling of indole carboxylic acid esters via Murai carbon–carbon bond cleavage under solventless mechanochemical conditions. A key feature of this reaction involves mechanochemical carbon–carbon bond activation, a process that has been elusive despite a very significant progress in mechanochemical C–H bond activation. The catalytic system enables the simultaneous activation of ester C–O/C–C bonds through ruthenium catalysis, achieving a highly chemoselective decarbonylative coupling with common arylboronic acids. Notably, the reaction proceeds without added ligands, bases, or organic solvents, establishing a sustainable platform for ruthenium-catalyzed transformations. The mechanistic insights lay the groundwork for the future design of catalytic Murai activation methodologies under solventless mechanochemical conditions. This mechanochemical decarbonylative coupling represents an innovative and green strategy to access structurally diverse indole derivatives─privileged motifs in pharmaceuticals and functional materials.

The hydrothermal liquefaction (HTL) process offers an energetic advantage over pyrolysis because it does not require prior drying of the biomass feedstock. However, there are significant challenges in simultaneously estimating both the yields and characteristics of products from the HTL of biomass with theoretical support. This study developed a unique element-based kinetic model to predict the yields, higher heating values, and fuel characteristics of solid residue and heavy bio-oil, based on the temperature, residence time, solid loading, and elemental composition (C, H, N, and O) of corn stover. Furthermore, the model predicted the weights of dissolved carbon and nitrogen in the aqueous phase. HTL experiments were conducted using corn stover at temperatures ranging from 250 to 350 °C for residence times between 5 and 60 min. The resulting solid and liquid products were analyzed for the elemental composition and ash content. The experimental data and MATLAB program were used to predict the products. The fuel characteristics derived from predicted elemental weight data of solid residues followed the trend line of the observed data on the van Krevelen diagram. In those of heavy bio-oil, the H/C atomic ratio of the average predicted data matched the one calculated from the observed data. Additionally, power function relationships between the amounts of corn stover and obtained product fractions were identified under identical temperature and residence time conditions by varying solid loading, providing insights into the partial nonlinear behavior of the reaction system.

Through an element-based kinetic model, the yields and characteristics of bioproducts are predicted, and plausible reaction orders are suggested.

The alkylation of benzene with cyclohexene provides a direct and atom-efficient route to cyclohexylbenzene (CHB), a key intermediate for advanced chemical manufacturing. The role of Lewis acid sites (LAS) in homogeneous alkylation is well established; however, their function and synergy with Brønsted acid sites (BAS) in solid acid catalysts remain elusive. Herein, we proposed a dual-acid-site engineering strategy to construct titanium-incorporated β zeolites (Hβ-at-x) via sequential dealumination and titanation. Structural and spectroscopic characterizations confirmed that Ti was anchored in silanol nests, generating electron-deficient Ti-LAS while tuning the Al-BAS to establish synergetic dual-acid-site. It was demonstrated that Ti-modified Al-BAS facilitated the protonation of cyclohexene, and benzene was adsorbed and enriched on Ti-LAS via π-complexation adjacent to BAS. The optimized Hβ-at-50 catalyst achieved complete cyclohexene conversion, even under the currently lowest benzene-to-cyclohexene volume ratio of 7:1. Furthermore, it demonstrated a significantly enhanced CHB formation rate of 18.6 mmol_CHB·g_cat^–1·h^–1, surpassing that of the parent Hβ catalyst (2.98 mmol_CHB·g_cat^–1·h^–1) and the Hβ-at catalyst (2.29 mmol_CHB·g_cat^–1·h^–1). The superior activity was corroborated by a reduced apparent activation energy (Ea = 35.1 kJ·mol^–1) compared to the parent Hβ catalyst (Ea = 57.3 kJ·mol^–1). The catalytic stability decreased during cycling due to the light olefin polymerization, and its activity could be fully restored via thermal treatment. This work provides mechanistic insight into dual-site catalysis and a design framework for high-performance zeolite catalysts for hydrocarbon upgrading.

Despite the natural abundance of peach gum (PG), its efficient and large-scale utilization remains limited. Inspired by the Maillard reaction, this study successfully developed a high-performance PG-based wood adhesive through controlled acid degradation of PG and a subsequent reaction with a polyamine polymer. The three-layer plywood bonded with the resulting adhesive exhibited a hot-water shear strength of 0.94 MPa after hot-pressing at 120 °C, meeting the requirements for Type II plywood according to the Chinese National Standard (GB/T 9846-2015), and maintained durable adhesion in warm water (60 °C) for up to 120 days. Even after 12 h of exposure to harsh environments, including acidic (pH = 5) and alkaline (pH = 9) conditions, acetone, ethanol, and simulated seawater, the bonding strength remained around 1.0 MPa. Moreover, the adhesive displayed broad and superior bonding performance toward diverse substrates such as composites and metal and nonmetal substrates, with bonding strengths ranging from 2.02 to 17.01 MPa. Additionally, the adhesive exhibited a limiting oxygen index of 30.6%, indicating favorable flame retardancy. This work provides a viable route for the high-value and scalable utilization of PG in wood adhesives and offers an environmentally friendly alternative to conventional formaldehyde-based resins for the wood industry.

Forced Chicory Roots (Cichorium intybus L.) are the main byproduct of the Belgian endive culture and also a great source of caffeoylquinic acids (CQAs), valuable bioactive polyphenols with high potential applications in the cosmetic, food, and pharmaceutical fields. The aim of the present study was to selectively recover chlorogenic acid (5-CQA) and dicaffeoylquinic acid (diCQAs) from a forced chicory roots aqueous extraction. To do so, four different macroporous resins XAD4, XAD7, XAD16, and FPX66 were screened for CQAs adsorption. FPX66 leads to the highest recovery ratio (55% 5-CQA and 73.8% diCQAs) and extract purity (19.6%). CQAs adsorption kinetics and isotherms were performed on FPX66 resin. CQAs adsorption followed a pseudo-second-order kinetic model, while equilibrium data were well-described by a refined multicomponent Langmuir isotherm (R² 0.993–0.999) accounting for competitive adsorption. The total resin capacity for both compounds was 0.55 mmol/g. Better adsorption performances were observed at 25 °C. Optimal CQAs recovery was achieved with an adsorption at pH 2 and a desorption with 50% EtOH eluant. Finally, FPX66 macroporous resin increased CQAs purity 25-fold, from 0.8% to 19.6%. This study highlights the efficiency of adsorption as a green and sustainable technology for purifying bioactive compounds from biomass.