Green Chemical Engineering最新文献

There are lots of biochemical reactions in the biosynthetic pathway without associated enzymes. Reactions predicted by retro-biosynthetic tools are not assigned gene sequences. Besides, non-natural reactions designed with novel functions also lack suitable enzymes. All these reactions can be categorized as orphan reactions. The absence of protein-encoding genes in these orphan reactions limits their direct experimental implementation. Computational tools have been developed to find candidate enzymes for these orphan reactions. Herein, we discuss recent advances in these computational tools, including reaction similarity-based methods for calculating the substructural similarity between orphan reactions and known enzymatic reactions; sequence-based tools combine metabolic knowledge base and phenotypic information with genomic, transcriptomic, and metabolomic data to mine appropriate enzymes for orphan reactions; and approaches based on the creation of enzyme variants for orphan reactions as enzyme engineering modifications and de novo design of enzymes. We believe that our review will greatly facilitate the design of microbial cell factories and contribute to the development of the biomanufacturing field.

Industrial pharmaceutical wastewater usually contains butyl acetate (BA) with a concentration of 1 wt%–7 wt%, and the traditional method for BA recovery is distillation with high energy consumption. Adsorption method is developed to recover BA with low concentration for the high efficiency and low energy consumption. Medium polar polyacrylate resins with macroporous structure of 233.1 nm and average particle size of about 526.5 μm are successfully synthesized by suspension polymerization and used for the BA adsorption and desorption. The maximum adsorption capacity reaches 171.1 mg g⁻¹ with relative standard deviation (RSD) value of 0.2%, which is more than twice the results in the literature. The BA desorption rate is 97.0% at 100 °C with RSD value of 0.4%, and the resins are beneficial to the reuse in the adsorption-desorption cycle. The adsorption thermodynamics and kinetics are investigated, and the BA adsorption is a spontaneous and endothermic process with the increase of disorder degree. This process is mainly contributed by physical absorption and agree well with Freundlich model and pseudo-first-order adsorption kinetic model. The adsorption method avoids boiling a large amount of wastewater and hopefully provides a novel alternative technology for the BA recovery.

Interactions of cellulose- and lignin-derived intermediates have been well documented during pyrolysis of lignocellulosic biomass. The reaction network for the interactions is rather complex, as cellulose-derived volatiles could interact/react with not only lignin-derived volatiles but also lignin-derived char and vice versa. To probe specifically the impacts of cellulose-derived volatiles on the lignin-derived char or the opposite, herein the sequential pyrolysis was performed by arranging cellulose in the upper bed with lignin in the lower bed or lignin above with cellulose below at 350 and 650 °C, respectively. The results indicated that the sequential pyrolysis of cellulose→lignin or lignin→cellulose at 350 °C induced increased char yield from formation of carbonaceous deposits via volatiles-char interactions. Compared with the lignin-derived volatiles, the cellulose-derived volatiles, especially aldehyde fractions, were more reactive towards the lignin-derived char at 350 °C, forming oxygen-rich lignin-derived char with a higher yield, an abundance of aliphatic structures and consequently lower thermal stability. In sequential pyrolysis of lignin→cellulose, more aromatics-rich species were deposited on cellulose-derived char, but the lignin-derived volatiles were less reactive for enhancing the char yield. At 650 °C, instead of polymerisation of the volatiles on the char, either the cellulose- or lignin-derived char catalyzed the cracking of the counterpart volatiles to remove the aliphatic functionalities, which made the char more aromatic and thermally more stable.

Coumarin and its derivatives, presenting in many organisms (plants, fungi, and bacteria), are critical metabolites composed of fused benzene and α-pyrone rings. With unique biological and chemical properties, coumarin derivatives possess great technological potential in the agrochemicals, pharmaceuticals, food, and cosmetic industries. The increasing demand for coumarin derivatives accelerates the research in biological and chemical synthesis to provide stable and scalable sources of coumarins. However, the complex structures and unknown pathways have limited the progress in the biosynthesis of coumarin derivatives. Here, we summarize recent developments and provide a detailed analysis of coumarin derivative biosynthetic pathways in different organisms.

Poly(ionic liquids) (PILs) combined with the macromolecular structure and unique properties of ionic liquids show unlimited potential in catalysis. In this work, a series of metal-based PIL with different ionic ratios were prepared for the selective oxidation of cyclohexane. Characterization analysis reveals that different degrees of ionization could adjust the Co–N sites of the catalysts efficiently, leading to significant changes in their electronic structure, which strongly relate to catalytic performance in oxidation. 20.07% cyclohexane conversion and 13.06% cyclohexanone and cyclohexanol (KA oil) yield can be achieved by metal-based PILs that are better than other commercial catalysts. Compared with CoCl₂, metal-based PILs perform well, with superior conversion and KA oil yield. More interestingly, the catalyst created in this study features a malleable Co–N site, which may potentially have an impact on how oxygen species adsorb and desorb from the catalyst. Therefore, the catalyst studied in this work is used as molecular oxygen for the selective oxidation of cyclohexane to produce KA oil, and its application prospect is promising.

Mechanochemistry has been recognized as an efficient and sustainable methodology to provide a unique driven force and reaction environments under ambient and neat conditions for the construction of functionalized materials possessing promising properties. Among them, highly porous conjugated scaffolds with attractive electronic conductivities and high surface areas are one of the representative categories exhibiting diverse task-specific applications, especially in electrochemical energy storage. In recent years, the mechanochemistry-driven procedures have been deployed to construct conjugated scaffolds with engineered structures and properties leveraging the tunability in chemical structures of building blocks and polymerization capability of diverse catalysts. Therefore, a thorough review of related works is required to gain an in-depth understanding of the mechanochemical synthesis procedure and property-performance relationship of the as-produced conjugated scaffolds. Herein, the mechanochemistry-driven construction of conjugated porous networks (CPNs), the carbon-based materials (e.g., graphite and graphyne), and carbon supported single atom catalysts (CS-SACs) are discussed and summarized. The electrochemical performance of the afforded conductive scaffolds as electrode materials in supercapacitors and alkali-ion batteries is elucidated. Finally, the challenges and potential opportunities related to the construction of conjugated scaffolds driven by mechanochemistry are also discussed and concluded.

To realize economical and effective removal of hazardous 4-nitrophenol from the environment, we developed an easily recyclable ZnO nanowire array decorated with Cu nanoparticles. Its salix argyracea-shaped structure not only provides a platform to achieve stable and good dispersion of Cu nanoparticles, but also offers a great deal of catalytically active sites. The density functional theory calculations reveal that ZnO and Cu have a very beneficial synergistic effect on their catalytic capability. This synergy is ascribed to the electronic localization occurring at ZnO/Cu interface, which helps improve Cu nanoparticle's ability to adsorb electro-negatively 4-nitrophenolate ions and to capture hydrogen radicals, thereby accelerating the hydrogen transfer from metal hydride complex to 4-nitrophenol. Benefiting from these characteristics, it exhibits high efficiency and reusability towards the catalytic reduction of waste 4-nitrophenol to valuable 4-aminophenol with a rate constant of 43.02 × 10⁻³ s⁻¹ and an average conversion of 96.5% in 90 s during 10 cycles. This activity is superior to that of most reported noble- or non-noble-metal powder, bulk, coating, and array catalysts, indicating its competitive advantages in cost and efficiency, as well as enticing application prospects.

Biomass and plastics are two of the most common municipal solid wastes globally that have continuously placed a burden on the environment. It is therefore important that they are properly recycled. Thermochemical co-conversion offers a valuable opportunity to recycle biomass and plastics simultaneously into biochar, which reduces the time and cost of recycling them individually while producing a material with a wide range of applications. This study is a review of published literature that discusses the thermochemical co-processing of biomass and plastic wastes into biochar. It was observed that co-pyrolysis and co-hydrothermal carbonization are the most commonly utilized technologies for this process. The characteristics of different biomass and plastics that have been thermochemically converted into biochar were compared. The properties of the resulting biochar are affected by the feedstock composition, pre-treatment and blending ratio, the reactor’s configuration, reaction temperature, and the presence of a catalyst. Most studies found that treating the feedstocks separately resulted in a lower yield of biochar than processing them together. The biochar created by this procedure has been used as a soil additive and as an adsorbent for water treatment. Future perspectives and suggestions, such as the necessity for some technical advancement, biochar's economic benefits, improved government participation, and raised social awareness, were also made. These factors have the potential to propel this field of study to great horizons.

Soft strain sensors that can transduce stretch stimuli into electrical readouts are promising as sustainable wearable electronics. However, most strain sensors cannot achieve highly-sensitive and wide-range detection of ultralow and high strains. Inspired by bamboo structures, anti-freezing microfibers made of conductive poly(vinyl alcohol) hydrogel with poly(3,4-ethylenedioxythiphene)-poly(styrenesulfonate) are developed via continuous microfluidic spinning. The microfibers provide unique bamboo-like structures with enhanced local stress to improve both their length change and resistance change upon stretching for efficient signal conversion. The microfibers allow highly-sensitive (detection limit: 0.05% strain) and wide-range (0%–400% strain) detection of ultralow and high strains, as well as features of good stretchability (485% strain) and anti-freezing property (freezing temperature: −41.1 °C), fast response (200 ms), and good repeatability. The experimental results, together with theoretical foundation analysis and finite element analysis, prove their enhanced length and resistance changes upon stretching for efficient signal conversion. By integrating microfluidic spinning with 3D-printing technique, the textiles of the microfibers can be flexibly constructed. The microfibers and their 3D-printed textiles enable high-performance monitoring of human motions including finger bending and throat vibrating during phonation. This work provides an efficient and general strategy for developing advanced conductive hydrogel microfibers as high-performance wearable strain sensors.