Green Chemistry最新文献

Microalgae-based carbon sequestration is emerging as a green and sustainable way to achieve negative carbon while recycling CO₂ into biomass used for the production of bioenergy and value-added products. However, its successful implementation is still to be realized due to the low solubility of CO₂ and ion accumulation with the addition of bicarbonate in the culture medium. In this study, we proposed, developed and verified a novel system integrating electrolysis and ionic membranes (EIMs) that enables the artificial recycling of CO₂ utilization and alleviation of metal cation stress in microalgae cultivation. HCO₃⁻ was selected to transfer from the cathode chamber to the culture pond with sodium bicarbonate as the catholyte, while Na⁺ cations were blocked with the anionic membrane in EIMs, accompanied by a gradually decreasing pH value, which facilitates microalgae growth. The reliability and universality of EIMs was further verified with both a cation-tolerant marine strain, Dunaliella salina HTBS, and cation-sensitive freshwater strains, Chlamydomonas and Chlorella. In particular, the cell densities of cation-sensitive strains in EIMs were much higher than those in the NaHCO₃ group in both 800 mL- and 150 L-scale applications, demonstrating their great potential. Moreover, the intracellular metabolites were not affected when microalgae were cultured in EIMs, implying their feasibility for commercial cultivation. Therefore, we established robust EIMs that facilitate both the efficient utilization of CO₂ and commercial application, which will shed light on the development of green technology for microalgae-based carbon sequestration in the future.

The comprehensive utilization of agro-industrial residues poses a persistent global challenge. Microbial fermentation is an efficient way to convert agro-industrial residues into valuable products. Trichoderma reesei is a traditional cellulase and other protein producer using agro-industrial residues as substrates. The potential of T. reesei as a chassis to produce small natural products remains untapped. Here, we successfully employed T. reesei to efficiently synthesize different terpene types. To optimize the chassis for metabolite synthesis, we deleted major (hemi-)cellulase genes along with the global regulator Lae1 to improve the efficiency of secondary metabolite biosynthesis, and overexpressed the constitutively activated transcriptional factor XYR1^A824V in MC3 (a uridine auxotrophic strain derived from T. reesei Rut-C30) to alleviate glucose repression. Through glucose, lactose, and corn steep as substrates, the production of ophiobolin F using the modified chassis was increased to 1187.06 mg L⁻¹ in shake flask fermentation and up to 3072.45 mg L⁻¹ under fed-batch fermentation. We further demonstrated the versatility of the Δlae1::xyr1/MC3-Δ10 chassis by successfully producing other fungal and plant terpenes. Collectively, our results demonstrated the potential of the Reducing Outflow and Broadened Upstream Substrate Type (ROBUST) T. reesei chassis for efficient terpene production utilizing agro-industrial residues, with important implications for terpene biosynthesis and sustainable biofabrication.

α-Chiral amines are key intermediates for scalable preparation of bioactive compounds; herein we present a novel palladium-based nanocatalyst capable of selectively catalyzing the reductive amination of carbonyl compounds, which enables the in situ regeneration of amino donors from wasteful co-products in a one-enzyme cascade using ω-transaminase, without the requirement of the expensive coenzyme NAD(P)H. The cascade network combines a ω-transaminase-assisted transamination with a selective reductive amination reaction facilitated by a heterogeneous palladium-based nanocatalyst. Nitrogen is sourced from hydroxylamine ions to convert generated co-products back into amino donors, yielding chiral amines with exceptional yields of up to 99% and excellent enantioselectivity. This chemoenzymatic one-enzyme transamination-reductive amination cascade network is highly atom-efficient and generates H₂O as its sole by-product, demonstrating its potential impact in synthetic chemistry and beyond.

Efficient activation and oxidative transformation of C(sp³)–H into value-added compounds by O₂ represents a sustainable synthetic pathway with high atom economy and environmentally friendly features. However, both C(sp³)–H and O₂ must be activated effectively, and this may be difficult to achieve with catalysts that contain only one type of active site. Herein, dual active-sites comprising oxygen vacancies and cobalt species were constructed in cobalt-doped nanorods of ceria for the respective activation of O₂ and C(sp³)–H, enabling efficient toluene oxidation for subsequent Knoevenagel condensation with malononitrile to yield benzylidenemalononitrile under mild conditions. Extensive experiments and theoretical simulations revealed that the oxidation of C(sp³)–H in toluene to aldehyde intermediates was realized through the spillover of active oxygen species from the oxygen vacancies to cobalt sites owing to the high capacity for oxygen mobility in the defective CeO₂. Subsequently, the facile condensation with malononitrile on CeO₂ was also promoted by the presence of cobalt sites. This dual-active-sites process provides an alternative approach for the effective oxidation of C(sp³)–H by O₂/air for subsequent transformations.

Precious metal (PM) catalysts have been widely used in the chemical industry owing to their high activity, selectivity and stability. The key problems are their scarcity and high cost. Therefore, the recycling of PMs from deactivated catalysts becomes a critical step in industry. Here, we developed a novel recycling method for the photoresponsive carrier-supported Au-based PM catalyst through an eco-friendly photocatalytic dissolution technique. Au is recovered effectively from deactivated Au/CeO₂ using itself as the photocatalyst and re-deposited on the remaining CeO₂. The revived Au/CeO₂ exhibits comparable performance with the fresh catalyst during ethane dehydrogenation either in the absence or in the presence of CO₂. Similar results can also be obtained over the Pt/CeO₂ catalyst recovered from a deactivated catalyst using this all-in-one dissolution–deposition technique. In comparison with the conventional methods, this recycling preparation offers a more environmentally friendly and long-lasting method for efficiently recycling PMs and producing regenerated PM catalysts.

Leather is made of collagen protein polymer, which is used in the manufacture of a variety of products including footwear, automotive upholstery, garments, and sports equipment. Animal skins/hides are converted into leather using a series of chemical processes. Of them, the tanning process is the most important chemical process that converts animal skins into leather by stabilising collagen fibre so that they do not putrefy. However, it is a hazardous process because of the use of various toxic chemicals in tanning, re-tanning and fatliquoring treatments producing toxic effluent. Over the years many tanning treatments based on chromium sulphate, and vegetable and synthetic tannins in combination with heavy metals, have been developed but tanning with chromium sulphate (known as Cr-tanning) is still the most effective, cheap, and widely used tanning process in the leather industry. Although the development of various improved Cr-tanning methods highly reduced the chemical and water consumption in leather tanning, it is still under scrutiny because of the production of effluent containing a harmful level of Cr and there is strong evidence that when the treated leather is disposed into the environment, part of the released trivalent chromium is converted into carcinogenic hexavalent chromium. Many sustainable alternatives to Cr-tanning based on chemical and enzymatic crosslinking, various bio-derived polymers, enzymes, modified zeolites, and nanostructured materials have been developed over the years with limited success. The alternative methods are either not as effective as Cr-tanning, affect the dyeability and other functional and organoleptic properties of leather, and or are cost-prohibitive. In this comprehensive review article, various tanning methods used in industry or studied in the laboratory are critically reviewed, and their advantages and disadvantages are outlined. The consumption of tanning agents, total chemicals including various auxiliaries and fatliquoring agents, and water in tanning, and the tanning performance and mechanical properties of the processed leather are compiled and compared. The reaction mechanisms of novel tanning agents with leather collagens and the future directions to make leather tanning more sustainable are outlined. This review article will be a guide for academicians/researchers/manufacturers involved in leather processing to develop more sustainable leather materials.

A new homogenous silylation method of cellulose is developed by mixing it with monohydrosilane in an ionic liquid. In this concise reaction with high atom economy, the ionic liquid acts as both the solvent and catalyst, and the only formal by-product generated is the clean fuel of molecular hydrogen.

A cellulose conductor with biodegradability and renewability is a charming candidate to construct state-of-the-art electronic devices toward artificial intelligence and the Internet of things. However, the poor bonding between conductive materials and cellulose film, or high cost and complex processes for realizing the robustness (high stability of its conductivity) functions as the obvious defect, preventing the broad utilization of a cellulose conductor in advanced electronic devices. Herein, a solution-processable, robust, and scalable cellulose conductor with a high conductivity (15 Ω sq⁻¹) and transmittance (85%) is developed via coating a blending starch and silver nanowires (AgNWs) on as-prepared cellulose film (namely, CSA film). In such a cellulose conductor, starch plays the natural “glue” to effectively fasten AgNWs on the cellulose film, which endows the desirable robustness to our CSA film. Despite robustness, more importantly, the CSA film features a promising recyclability via cellulose degradation to re-harvest the AgNWs, or by boiling CSA the film to independently separate the AgNWs and cellulose film, both of which are reused to produce a second CSA film with a conductivity of 18 Ω sq⁻¹. The high performance allows the CSA film to construct advanced electronic devices, such as inorganic electroluminescent and organic light-emitting diode devices. Our starch-gluing–AgNW strategy paves the way for developing a robust yet green, recyclable cellulose conductor toward advanced electronic devices.

Herein, we report a green and sustainable electrochemical strategy for α-alkylation of tertiary amines with halogenated alkanes under undivided electrolytic conditions. A Barbier–Grignard-type reaction at the cathode produces an organozinc reagent that reacts with an iminium ion produced at the anode to provide the α-alkylated amine. The reaction proceeds under mild reaction conditions with wide-ranging functional-group and substrate compatibilities, affording the products in good yields. More importantly, convergent pair electrolysis, an ideal but challenging electrochemical technique, is effectively utilized in this reaction system. Detailed mechanistic study indicated that an imine ion intermediate is involved in the reaction process.

Precise and efficient separation of molecules and ions is important in many fields, including the chemical industry, textiles, and medicine. Two-dimensional (2D) materials with high specific surface areas and atomic thickness are an excellent choice for membrane building blocks. However, stacking nanosheets face-to-face usually prevents the transport of molecules or ions across such 2D membranes, thereby reducing their flux. Supramolecular macrocyclic hosts contain cucurbiturils, cyclodextrins, pillararenes, crown ethers, and calixarenes, which afford macrocyclic cavities with rigid structures that are easy to be functionalized. Thus, it is possible to construct membranes using 2D materials as “beams” and supramolecular macrocyclic compounds as “columns”. This strategy has been applied to overcome challenges related to the permeability–selectivity trade-off. Supramolecular 2D membranes have been widely used in a wide range of critical separations, including water purification, enantiomer separation, ion extraction and separation, and gas separation. This review provides a new perspective to inspire researchers to develop promising 2D supramolecular membranes with high selectivity, mild flux, and appreciable reversibility.