Reaction Chemistry & Engineering最新文献

Microfluidics is a very attractive discipline for implementing more versatile high-throughput screening methods to improve enzymes. However, state-of-the-art microfluidics set-ups are mainly devoted to screening enzymes in solution, while screening of enzyme immobilisation protocols using microfluidics is scarce. In this work, we develop a versatile wall-coated microreactor (WCμR) plate for transaminase screening, integrating up to 32 poly(methyl methacrylate) (PMMA) WCμR functionalised with different metal chelates. The device is validated by screening His-tagged and His-clustered amine transaminase (ATA) variants that result in different orientations, evaluating a total of 30 unique biocatalyst-functionalisation combinations for activity, stability, and immobilisation efficiency. In batch mode reactions, H3A, H2A, and H4 ATA variants from Pseudomonas fluorescens, Chromobacterium violaceum, and Haelomonas elongata, respectively, immobilised on copper-chelates exhibit the highest scores based on fluorometer assays. This WCμR plate can be easily integrated with optical microscopes for spatiotemporal assays. Alternatively, these WCμRs are readily adapted for continuous biotransformation operating as flow microreactors. This capability is tested with a His-tagged ATA immobilised on the microchannels to continuously aminate 5-hydroxymethyl furfural, achieving a specific productivity of 0.49 mol_HMFA mol_ATA⁻¹ s⁻¹ and a total turnover number of 9 × 10³, with a maximum space–time yield (STY) of 0.077 g L⁻¹ d⁻¹. This study highlights the potential of WCμRs for high-throughput enzyme screening and continuous biocatalysis, offering precise control over reaction conditions.

The growing accumulation of non-biodegradable plastics worldwide is causing environmental havoc that needs to be effectively addressed immediately by providing a sustainable solution. In this regard, a Cu–PTA metal–organic framework (MOF) was synthesized from discarded PET bottles and waste copper (Cu) metal derived from CHNS analyzer oxidation tubes and utilized to remove Congo red (CR) from aqueous solutions. The synthesized Cu–PTA–MOF was analyzed using various characterizations to reveal their crystal lattices and compositional and morphological features. Subsequently, the efficacy of the synthesized MOF in the adsorption of Congo red dye (20 mg L⁻¹) was investigated. The optimized conditions were determined to be pH 7, an adsorbent dosage of 10 mg, and a contact time of 60 min, which resulted in a 95% removal efficiency and demonstrated the potential of the MOF for adsorption applications. Furthermore, the data were fitted to different isotherm models, which correlated with the Redlich–Peterson adsorption model, indicating monolayer and multilayer adsorption. The kinetic data also fitted well with the pseudo-second-order kinetic model, while thermodynamic analysis revealed that the adsorption of Congo red was exothermic, spontaneous and physisorption process. This study adds to the larger goal of promoting resilience and long-term viability in materials science and environmental engineering through waste valorization, as well as environmental remediation for adsorption applications.

Crude oil emulsions are challenging to break due to their complex and variable composition. While high-performance demulsifiers exist, many conventional systems still face limitations such as poor stability under harsh conditions or insufficient separation efficiency for specific emulsion types. It is thus essential to develop new demulsifiers that combine high salt resistance with effective destabilization capability. Carbon materials, known for their strong adsorption capacity and chemical stability, can efficiently capture emulsified droplets, enabling significantly enhanced demulsification performance even under harsh conditions. The integration of TiO₂–carbon heterostructures with fluorinated polyether grafting into magnetic demulsifiers represents a previously unreported strategy. Building on this background, our research innovatively modified the magnetic substrate Fe₃O₄ by incorporating TiO₂ and three types of carbon materials (carbon nanospheres, graphene oxide, and carbon nanotubes). Through a sol–gel approach, fluorinated polyether chains were covalently grafted onto the surface of modified Fe₃O₄ nanoparticles, leading to the successful synthesis of three novel magnetic composite demulsifiers: Fe₃O₄@Ti/C–F, Fe₃O₄@Ti/G–F and Fe₃O₄@Ti/CN–F. The results demonstrate that these three demulsifiers exhibit excellent demulsification efficiency, acid resistance, and excellent recyclability. They achieve demulsification rates exceeding 85% in neutral and acidic environments. Notably, Fe₃O₄@Ti/G–F stands out with the best performance. After five cycles of recovery from a biphasic system, its demulsification efficiency remains above 70%. When used at a concentration of 600 mg L⁻¹, it can achieve a demulsification rate of 93.44% within just 30 minutes. In summary, this innovative magnetic nanodemulsifier not only provides an efficient and stable solution for crude oil emulsion separation but also offers significant ecological benefits, holding great potential for application in the treatment of oily wastewater.

The textile industry is one of the most polluting sectors worldwide, generating large amounts of post-consumer and industrial waste with limited recycling options and significant greenhouse gas emissions. This study assesses the environmental viability of energy recovery from textile waste through fluidized bed combustion and oxycombustion, followed by post-combustion catalytic treatment, thermal plasma application, and carbon capture. A gate-to-gate life cycle assessment (LCA) was performed using process simulation data for textile waste with a composition of 50% cotton and 50% polyester, integrating selective catalytic reduction for NO_x abatement, CaO-based treatment for CO₂ capture, and also incorporating real thermal plasma data for the destruction of dioxins and furans. Environmental impacts were quantified using the ReCiPe 2016 Midpoint (H) method. Results show that combustion with carbon capture and thermal plasma application achieved a global warming potential (GWP) of 3.6 kg CO₂ eq. per kg textile. In comparison, oxycombustion with carbon capture and thermal plasma application achieved 4.3 kg CO₂ eq. per kg textile, representing reductions of 27–57% compared to textile waste disposal in landfills, incineration, or mechanical/chemical recycling. CO₂ capture and thermal plasma were the primary contributors to environmental burdens, whereas steam generation provided significant offsetting credits. Oxycombustion increased NO_x and particulate emissions but reduced eutrophication and aquatic ecotoxicity. Overall, combustion and oxycombustion with post-combustion catalytic treatment, thermal plasma application, and carbon capture offer a promising route for the energetic valorization of non-recyclable textile waste, combining greenhouse gas reduction, energy recovery, and lower environmental impacts, supporting circular economy strategies.

The development of environmentally benign methods for synthesizing carbon nanomaterials from biomass is gaining momentum due to growing concerns about sustainability and industrial pollution. In this study, Pinus roxburghii biomass was utilized as a renewable precursor for the hydrothermal synthesis of functionalized carbon nanotubes (f-CNTs). Natural deep eutectic solvents (NADESs), formulated using various hydrogen bond donors (HBDs) and choline chloride (ChCl) as a hydrogen bond acceptor (HBA), were explored as green, structure-directing, and functionalizing agents. Among the tested combinations, [ChCl/oxalic acid] (1 : 1 molar ratio) proved most effective in directing the formation of well-defined tubular nanostructures under optimized conditions (120 °C, 5 h). The synthesized f-CNTs were subsequently applied for the adsorption of reactive orange 16 (RO16), a persistent azo dye commonly found in industrial effluents from textile-dense regions. Adsorption performance was evaluated through studying the adsorption isotherms and kinetic models, revealing that the process followed chemisorption. The thermodynamic analysis of the process was also conducted, depicting the endothermic (ΔH = 6783.47 J mol⁻¹) and spontaneous nature of the process. The synthesized f-CNTs offered a maximum adsorption capacity of 111.11 mg g⁻¹. Thus, this study illustrates the green route for the synthesis of CNTs using NADESs while meeting the sustainable development goals and also curbing the water pollution caused by reactive dyes.

Hydrogenated bisphenol A is a high-performance, long-term color-stable, safe and environmentally friendly monomer material for epoxy resins. This research demonstrates the in-depth investigation of the reaction mechanism for the hydrogenation of bisphenol A over a highly dispersed ultra-small ruthenium nanoparticle catalyst in a continuous fixed-bed hydrogenation reactor. Findings reveal that the acidic support promotes the adsorption of aromatic functional groups, ultimately enhancing the hydrogenation activity in coordination with the highly dispersed ultra-small ruthenium nanoparticle catalyst. Interestingly, the acidity regulation of the catalyst support by MgO modification not only favors the formation of highly dispersed ultra-small Ru nanoparticles but also inhibits the side reactions of C–OH and C–C cleavage, finally leading to an improved selectivity for the target product. Furthermore, an ingeniously controllable three-stage hydrogenation reaction is designed, which provides valuable insights into the reaction mechanism.

In this paper, we present the development of a kinetic model for multi-step transformations, comprising of a Paal–Knorr pyrrole reaction followed by a nucleophilic aromatic substitution within a continuous-flow process, utilizing data obtained from sequential dynamic flow experiments. The reaction networks were fitted to achieve successful parameter estimation (7 parameters in total) with a R² of 0.974 for the desired Paal–Knorr product and a R² of 0.998 for the nucleophilic aromatic substitution product. Model validation based on dynamic flow experiments was extended beyond the previously explored experimental space. In silico simulation involving a threefold higher concentration of the nucleophile than previously studied resulted in approximately 7% model predicted difference to the experimental results.

Isocyanides are of relevance to several scientific fields; however, over the last 150 years only a limited number of synthetic strategies have been reported for preparing them. In a newly developed flow approach, a neglected method for preparing isocyanides, the Hofmann carbylamine reaction, has been revisited and revitalised. The approach developed afforded the preparation of a diverse library of isocyanides in good conversions while only requiring a 15 min residence time at 70 °C. In addition, the method is operationally easy to apply, and it affords several advantages over the more commonly employed strategy of preparing isocyanides which involves the conversion of amines to formamides followed by dehydration to an isocyanide.

Molecular-level reactions predominantly dictate all macro-level properties in the materials world. Understanding nano-level molecular reactions opens up the door to grasping how bottom-up building blocks lead to novel molecules and thus materials. Here, free radicals from the thermal decomposition of peroxide molecules were pursued to explore different plausible reactions with polyethylene oxide as a macromolecular polymer model. Many chemical compounds with different functional groups, such as acetals or hemiacetals, alkoxy ethers, geminal diols, aldehydes, ketenes and orthoesters, were detected. An important observation was chain scission due to tertiary radical formation that created oligomers with carboxylic end groups, a plausible sign of the deterioration of the final product's mechanical properties. Additionally, theoretical prediction enhanced our understanding of intermediate outcomes and revealed hydrogels with the potential to degrade in dilute acids due to vulnerable acetal, hemiacetal or orthoester functional groups, with profound effects on the macroscopic-level properties.

Improving access to functionalized N-aryl amides efficiently remains a key challenge in organic synthesis, particularly when starting from nitroaromatic compounds. Direct amidation of nitroarenes has emerged as an attractive alternative to multistep synthetic sequences; however, existing methods often require long reaction times, transition metals, and harsh and inert conditions, and exhibit limited functional group tolerance. Herein, we describe a fast, metal-free, and scalable flow protocol for the synthesis of functionalized N-aryl amides directly from nitroarenes. This protocol integrates an electrochemical reduction of nitroarene with a CO₂-mediated amidation of carboxylic acids, enabling the synthesis of twenty amides in yields of up to 89% while containing valuable yet reducible functional groups, in a semi-telescoped fashion.