Reaction Systems Research Articles

Recent Progress in Electrochemical Conversion from Biomass Derivatives into High‐Value‐Added Chemicals

Selective and efficient electrochemical conversion of cheap and abundant biomass derivatives into high‐value‐added products can provide a way to store large‐scale renewable intermittent energy such as wind energy, solar energy, etc. Although a large amount of research is devoted to developing highly efficient catalysts or disclosing the reaction processes, there are always challenges of conversion rate and selectivity, and the relevant comprehensive and in‐depth discussion is relatively scarce. This review introduces the basic principles and reaction processes from the charge transfer pathway of biomass electrochemical conversion. Then, for the design of the anode, the representative work is summarized and discussed in detail from the point of view of material adjustment, theoretical calculations, and in situ characterizations. Finally, insights for further optimization of the reaction systems are put forward. It is believed that this review provides guidance for the selection, design, and application of materials for high‐value‐added organic electrochemical synthesis.

TEMPO-Grafted Polystyrene/Polymethacrylate Organosiloxane Janus Nanohybrids as Efficient Pickering Interfacial Catalyst for Selective Aerobic Oxidation of Cinnamyl Alcohol.

The novel 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) groups immobilized on functional polymers or nanoparticles emerged as potential Pickering interfacial catalysts (PICs) for effective catalysis in biphasic systems. In this study, a snowman-shaped Janus-structured polymer with TEMPO-anchored nanohybrid particles (SM-JPP-TEMPO) was prepared and employed as a potential PIC in the Anelli-Montanari system for the selective oxidation of alcohol. The amphiphilic character of SM-JPP-TEMPO particles plays a dual role as an emulsifier and catalyst in the Pickering emulsion. As a result, it enables smaller droplets (102 μm) at the water-in-oil (W/O) interface and reduces the interfacial tension from 26.58 to 17.38 mN/m, which improves the stability of the Pickering emulsion system. This constructed Pickering emulsion microreactor offers a larger interface contact area and shortens the mass transfer distance of the substrate of cinnamyl alcohol, which significantly enhances the catalytic conversion at the Anelli-Montanari oxidation system, thus achieving remarkable conversion efficiency of (92.3%) with excellent selectivity (99%) in static (stirring-free) condition. It was found that the Janus nanohybrid catalyst (SM-JPP-TEMPO) enhanced 1.29-fold catalytic efficiency compared to the TEMPO grafted spherical polystyrene nanoparticle (PS-NPs-TEMPO) catalyst (72%). Moreover, after seven consecutive cycles, the Janus nanocatalyst (SM-JPP-TEMPO) maintained the conversion significantly. Hence, these results collectively highlight that the amphiphilic SM-JPP-TEMPO catalyst provides an efficient and eco-friendly strategy for the intensification of liquid-liquid biphasic reaction systems for potential applications in industries.

Insight into the stabilization/solidification of Cd, Pb and Zn in MSWI FA by three stages: Vulcanization, precipitation and bio-oxidation

Bio-oxidation has been perceived as a promising treatment for the solidification/stabilization (S/S) of heavy metals (HMs) in mining soils. Nonetheless, no research exists on the integration of the iron-sulfur oxidizing bacterium Acidithiobacillus ferrooxidans as a microbial agent into the treatment of municipal solid waste incineration-fly ash (MSWI-FA). The effect of vulcanization (Stage I), precipitation (Stage II) and bio-oxidation (Stage III) on the stabilization of HMs in MSWI-FA was unexplored. This study investigated the stabilization effects of Stage I and Stage II by utilizing Na2S and FeSO4 to adjust the Fe/S ratio. The findings contributed to identifying suitable methods to enhance the stabilization effect of the microbial agent on MSWI-FA (Stage III). The results indicated that the vulcanization (Stage I) increased the compressive strength of MSWI-FA to 1.87 MPa when the concentration of Na2S reached 0.03 mM. The leaching toxicity of Cd, Pb, and Zn at 28 days after Stage II was 0.12 mg/L, 0.99 mg/L, and 356 mg/L, respectively, which improved by 96.3%, 94.8%, and 26.9% compared to the untreated samples. The compressive strength of the samples peaked at 1.97 MPa when the Fe/S ratio was 0.25 (precipitation (Stage II)). Despite the inhibitory effect of MSWI-FA on microbial activity, the leaching toxicity of Cd, Pb, and Zn in the presence of Acidithiobacillus ferrooxidans decreased to 0.07 mg/L, 0.17 mg/L and 97.3 mg/L at 28 days after Stage III, with no significant further increase in compressive strength. This study suggested that bio-oxidation utilizing iron sources may change the formation of iron oxides, thereby impacting the mechanical and chemical properties of MSWI-FA-based materials. The treatment sequence of vulcanization, precipitation and bio-oxidation proved effective in immobilizing HMs, particularly Pb, Cd, and Zn in MSWI FA. This research highlighted the potential of employing this technique to treat MSWI FA, yet it is essential to identify suitable reaction systems with appropriate additives to further enhance the long-term effectiveness and mechanical properties of MSWI-FA-based materials.

On the spectrum between reaction systems and string rewriting

On the spectrum between reaction systems and string rewriting

Hydroxylamine supplementation accelerated the rates of cell growth, aerobic denitrification and nitrous oxide emission of Pseudomonas taiwanensis EN-F2

Hydroxylamine can disrupt the protein translation process of most reported nitrogen-converting bacteria, and thus hinder the reproduction of bacteria and nitrogen conversion capacity. However, the effect of hydroxylamine on the denitrification ability of strain EN-F2 is unclear. In this study, the cell growth, aerobic denitrification ability, and nitrous oxide (N2O) emission by Pseudomonas taiwanensis were carefully investigated by addition of hydroxylamine at different concentrations. The results demonstrated that the rates of nitrate and nitrite reduction were enhanced by 2.51 and 2.78 mg/L/h after the addition of 8.0 and 12.0 mg/L hydroxylamine, respectively. The N2O production from nitrate and nitrite reaction systems were strongly promoted by 4.39 and 8.62 mg/L, respectively, through the simultaneous acceleration of cell growth and both of nitrite and nitrate reduction. Additionally, the enzymatic activities of nitrate reductase and nitrite reductase climbed from 0.13 and 0.01 to 0.22 and 0.04 U/mg protein when hydroxylamine concentration increased from 0 to 6.0 and 12.0 mg/L. This may be the main mechanism for controlling the observed higher denitrification rate and N2O release. Overall, hydroxylamine supplementation supported the EN-F2 strain cell growth, denitrification and N2O emission rates.

Recent Advancements in Continuous-Flow Suzuki-Miyaura Coupling Utilizing Immobilized Molecular Palladium Complexes.

Immobilized Pd-catalyzed Suzuki-Miyaura coupling under continuous-flow conditions using a packed-bed reactor, representing an efficient, automated, practical, and safe technology compared to conventional batch-type reactions. The core objective of this study is the development of an active and durable catalyst. In contrast to supported Pd nanoparticles, the attachment of Pd complexes onto solid supports through well-defined coordination sites is considered a favorable approach for preparing highly dispersed and stabilized Pd species. These species can be directly employed in various flow reactions without the need for pre-treatment. This concept paper explores recent achievements involving the application of immobilized Pd complexes as precatalysts for continuous-flow Suzuki-Miyaura coupling. Our focus is to elucidate the significance of the designed catalyst structures in relation to their catalytic performance under flow conditions. Additionally, we highlight various reaction systems and catalyst packing methods, emphasizing their crucial roles in establishing a practical synthesis process.

Counter-regulatory RAS peptides: new therapy targets for inflammation and fibrotic diseases?

The renin-angiotensin system (RAS) is an important cascade of enzymes and peptides that regulates blood pressure, volume, and electrolytes. Within this complex system of reactions, its counter-regulatory axis has attracted attention, which has been associated with the pathophysiology of inflammatory and fibrotic diseases. This review article analyzes the impact of different components of the counter-regulatory axis of the RAS on different pathologies. Of these peptides, Angiotensin-(1-7), angiotensin-(1-9) and alamandine have been evaluated in a wide variety of in vitro and in vivo studies, where not only they counteract the actions of the classical axis, but also exhibit independent anti-inflammatory and fibrotic actions when binding to specific receptors, mainly in heart, kidney, and lung. Other functional peptides are also addressed, which despite no reports associated with inflammation and fibrosis to date were found, they could represent a potential target of study. Furthermore, the association of agonists of the counter-regulatory axis is analyzed, highlighting their contribution to the modulation of the inflammatory response counteracting the development of fibrotic events. This article shows an overview of the importance of the RAS in the resolution of inflammatory and fibrotic diseases, offering an understanding of the individual components as potential treatments.

Surface wettability control and electron transport regulation in zerovalent iron for enhanced removal of emerging polystyrene microplastics-heavy metal contaminants

Emerging microplastics-heavy metal (MPs-HM) contaminants in wastewaters pose an emerging health and environmental risk due to their persistence and increasing ecological risks (e.g., “Trojan horse” effect). Hence, removing MPs in solution and preventing secondary releases of HM has become a key challenge when tackling with MPs pollution. Leveraging the hydrophobic nature of MPs and the electron transfer efficiency from Fe0 to HM, we demonstrate an alkylated and sulfidated nanoscale zerovalent iron (AS-nZVI) featuring a delicate “core-shell-hydrophobic film” nanostructure. Exemplified by polystyrene (PS) MPs-Pb(II) removal, the three nanocomponents offer synergistic functions for the rapid separation of MPs, as well as the reduction and stabilization of Pb(II). The outmost hydrophobic film of AS-nZVI greatly improves the anticorrosion performance of nanoscale zerovalent iron and the enrichment abilities of hydrophobic MPs, achieving a maximum removal capacity of MPs to 2725.87 mgMPs·gFe−1. This MPs enrichment promotes the subsequent reductive removal of Pb(II) through the electron transfer from the iron core of AS-nZVI to Pb(II), a process further strengthened by the introduced sulfur. When considering the inevitable aging of MPs in wastewaters due to mechanical wear or microbial degradation, our study concurrently examines the efficiencies and behaviors of AS-nZVI in removing virgin-MPs-Pb(II) and aged-MPs-Pb(II). The batch results reveal that AS-nZVI has an exceptional ability to remove above 99.6 % Pb(II) for all reaction systems. Overall, this work marks a pioneering effort in highlighting the importance of MPs-toxin combinations in dealing with MPs contamination and in demonstrating the utility of nZVI techniques for MPs-contaminated water purification.

A review of copper-based Fenton reactions for the removal of organic pollutants from wastewater over the last decade: different reaction systems.

In recent years, as global industrialization has intensified, environmental pollution has become an increasingly serious problem. Improving water quality and achieving wastewater purification remain top priorities for environmental health initiatives. The Fenton process is favored by researchers due to its high efficiency and ease of operation. Central to the Fenton process is a catalyst used to activate hydrogen peroxide, rapidly degrading pollutants, improving water quality. Among various catalysts developed, copper-based catalysts have attracted considerable attention due to their affordability, high activity, and stable performance. Based on this, this paper reviews the development of copper-based Fenton systems over the past decade. It mainly involves the research and application of copper-based catalysts in different Fenton systems, including photo-Fenton, electro-Fenton, microwave-Fenton, and ultrasonic-Fenton. This review provides a fundamental reference for the subsequent studies of copper-based Fenton systems, contributing to the goal of transitioning these systems from laboratory research into practical environmental applications.

Abiotic Methane Production Driven by Ubiquitous Non-Fenton-Type Reactive Oxygen Species.

Abiotic CH4 production driven by Fenton-type reactive oxygen species (ROS) has been confirmed to be an indispensable component of the atmospheric CH4 budget. While the chemical reactions independent of Fenton chemistry to ROS are ubiquitous in nature, it remains unknown whether the produced ROS can drive abiotic CH4 production. Here, we first demonstrated the abiotic CH4 production at the soil-water interface under illumination. Leveraging this finding, polymeric carbon nitrides (CNx) as a typical analogue of natural geobattery material and dimethyl sulfoxide (DMSO) as a natural methyl donor were used to unravel the underlying mechanisms. We revealed that the ROS, photocatalytically produced by CNx, can oxidize DMSO into CH4 with a high selectivity of 91.5 %. Such an abiotic CH4 production process was further expanded to various non-Fenton-type reaction systems, such as electrocatalysis, pyrocatalysis and sonocatalysis. This work provides insights into the geochemical cycle of abiotic CH4, and offers a new route to CH4 production via integrated energy development.

Enhanced ammonia oxidation by a photoelectrocatalysis‑chlorine system: The role of ClO• and free chlorine

The decomposition of ammonia-N to environmental-friendly N2 remains a fundamental problem for water treatment. We proposed a way to selectively and efficiently oxidize ammonia to N2 through an integrated photoeletrocatalysis‑chlorine reactions (PECCl) system based on a bifunctional TiO2 nanotube photoanode. The ·OH and HClO can be simultaneously generated on the TiO2 nanotube photoanode in this system, which can in situ form ClO· for efficient ammonia removal. Compared with electrochemical‑chlorine (EC-Cl), photocatalysis‑chlorine (PC-Cl) and photoelectrocatalysis (PEC) systems, the PEC-Cl system exhibited much higher electrocatalytic activity due to the synergetic effect of photoelectrocatalyst and electrocatalyst in bifunctional TiO2 nanotube electrode. The removal efficiency of ammonia-N and total-N reached 100.0 % and 93.3 % at 0.3 V (vs Ag/AgCl) in the PEC-Cl system. Moreover, the system was efficient under various pH conditions. The reactions between ClO−/ClO· and the N-containing intermediates contributed to the high performance of the system, which expanded the reactions from the electrode surface to the electrolyte. Furthermore, radical scavenging and free chlorine determination experiments confirmed that ClO· and free chlorine were the main active species that enabled the ammonia oxidation. This study presents new understanding on the role of active species for ammonia removal in wastewater.

Solving subset sum and SAT problems by reaction systems

Solving subset sum and SAT problems by reaction systems

Enzymatic Preparation, In-Depth Molecular Analysis, and In Vitro Digestion Simulation of Palmitoleic Acid (ω-7)-Enriched Fish Oil Triacylglycerols.

In this study, an enzymatic reaction was developed for synthesizing pure triacylglycerols (TAG) with a high content of palmitoleic acid (POA) using fish byproduct oil. The characteristics of synthesized structural TAGs rich in POA (POA-TAG) were analyzed in detail through ultrahigh-performance liquid chromatography Q Exactive orbitrap mass spectrometry. Optimal conditions were thoroughly investigated and determined for reaction systems, including the use of Lipozyme TL IM and Novozym 435, 15 wt % lipase loading, substrate mass ratio of 1:3, and water content of 2.5 and 0.5 wt %, respectively, resulting in yields of 67.50 and 67.45% for POA-TAG, respectively. Multivariate statistical analysis revealed that TAG 16:1/16:1/20:4, TAG 16:1/16:1/16:1, TAG 16:1/16:1/18:1, and TAG 16:0/16:1/18:1 were the main variables in Lipozyme TL IM and Novozym 435 enzyme-catalyzed products under different water content conditions. Finally, the fate of POA-TAG across the gastrointestinal tract was simulated using an in vitro digestion model. The results showed that the maximum release of free fatty acids and apparent rate constants were 71.44% and 0.0347 s-1, respectively, for POA-TAG lipids, and the physical and structural characteristics during digestion depended on their microenvironments. These findings provide a theoretical basis for studying the rational design of POA-structural lipids and exploring the nutritional and functional benefits of POA products.

In situ Raman spectroscopy study of the oxidative polymerization of aniline in media of different acidity

In situ Raman spectroscopy was used for the first time to study the reaction intermediates/products of the oxidative polymerization of aniline to polyaniline (PANI) with peroxydisulfate in aqueous solutions of different initial acidity. Raman spectra were recorded for the drops of reaction mixture taken at various reaction times. Five reaction systems with different pH of the monomer solution (pHmon), leading to 1-D nanostructured PANIs (pHmon =5.8, 4.6 and 4.5) and granular PANIs (pHmon= 3.4 and 1.0) were explored. Spectral characteristics of different reaction phases - athermal, exothermic and post-propagation were identified and correlated with the proposed mechanisms of aniline polymerization and nanostructures formation. For the nanostructured PANIs, the athermal phase was characterized by pronounced strengthening of the δ(N−H)/ν(CN)Q band at 1510–1520 cm−1, while the characteristic of the second exothermic phase was the strengthening of the ν(C∼C)B/ν(C∼C)Phz band at c.a. 1636 cm−1 which becomes stronger than the ν(CC)Q/ν(C∼C)SQ band at c.a. 1590 cm–1. For granular PANIs, the band at 1590 cm–1 was stronger than that at 1630 cm–1 for all reaction phases. For all reaction systems, characteristic feature of the post-propagation phase was strengthening of the ν(C∼N+•) band at 1330–1340 cm−1 due to delocalized polarons. For granular PANIs, the band associated with phenazine-like units at c.a. 1415 cm−1 disappeared after the exothermic phase, while for nanostructured PANIs it was seen until the end of the reaction. The obtained results are expected to be useful in further investigations of the intermediates/products and mechanisms of polymerizations of other aromatic amines.

Structural reconstruction of electrocatalysts

Efficient and durable electrocatalysts are essential for achieving high electrocatalytic efficiency in electrocatalytic reactions, forming the bedrock of effective electrochemical energy technologies. Electrocatalysis is a complex process, marked by intricate reaction system and crucial interfacial interactions, leading to diverse degrees of reconstruction changes in electrocatalysts, affecting both catalytic capabilities and structural integrity. This review delves into the development and prospects of electrocatalyst reconstruction within the electrochemical energy conversion and storage technologies. It elucidates the underlying motivation and mechanism driving reconstruction in various oxidation/reduction reaction systems. Moreover, it elucidates the evolution and comprehension of highly effective electrocatalysts that emerge as a result of this reconstruction phenomenon. The characterizations of catalyst reconstruction are thoroughly examined through the cutting-edge imaging/spectroscopy technologies, enabling dynamic reconstruction tracking and identification. Finally, this work highlights the challenges and opportunities associated with advancing reconstructed electrocatalysts. The primary objectives are to fathom the intricacies of reconstruction and its structural evolution for precise catalyst design. Additionally, it aims to regulate the reconstruction process to enhance the electrocatalyst longevity, stabilize catalytic reactions, and ultimately facilitate the implementation of electrochemical technologies.

On categorical approach to reaction systems

On categorical approach to reaction systems

Degradation of Orange G Using PMS Triggered by NH2-MIL-101(Fe): An Amino-Functionalized Metal-Organic Framework.

As an azo dye, OG has toxic and harmful effects on ecosystems. Therefore, there is an urgent need to develop a green, environmentally friendly, and efficient catalyst to activate peroxymonosulfate (PMS) for the degradation of OG. In this study, the catalysts MIL-101(Fe) and NH2-MIL-101(Fe) were prepared using a solvothermal method to carry out degradation experiments. They were characterized by means of XRD, SEM, XPS, and FT-IR, and the results showed that the catalysts were successfully prepared. Then, a catalyst/PMS system was constructed, and the effects of different reaction systems, initial pH, temperature, catalyst dosing, PMS concentration, and the anion effect on the degradation of OG were investigated. Under specific conditions (100 mL OG solution with a concentration of 50 mg/L, pH = 7.3, temperature = 25 °C, 1 mL PMS solution with a concentration of 100 mmol/L, and a catalyst dosage of 0.02 g), the degradation of OG with MIL-101(Fe) was only 36.6% within 60 min; as a comparison, NH2-MIL-101(Fe) could reach up to 97.9%, with a reaction constant k value of 0.07245 min-1. The NH2-MIL-101 (Fe)/PMS reaction system was able to achieve efficient degradation of OG at different pH values (pH = 3~9). The degradation mechanism was analyzed using free-radical quenching tests. The free-radical quenching tests showed that SO4•-, •OH, and 1O2 were the main active species during the degradation of OG.

Streamlined synthesis of superstructure Ni-benzimidazole MOFs: Glucose electrochemical analysis

The design and synthesis of efficient electrochemical sensors are crucial transformation technologies in electrochemistry. We successfully synthesize a three-dimensional Ni-metal–organic framework (MOF) nanostructured material with a superior architecture using benzimidazole and nickel nitrate as precursors at room temperature which is being applied in glucose electrochemical sensors. The reaction mechanism of M-6 during glucose detection is thoroughly studied using various characterization techniques, such as in situ Raman spectroscopy, in situ ultraviolet–visible spectrophotometry, synchrotron radiography, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The research findings demonstrate that the M-6 material exhibits high sensitivity for glucose detection, with a sensitivity of 2199.88 mA M−1 cm−2. This study provides an important reference for designing more efficient electrochemical reaction systems and optimizing material performance. Furthermore, the superstructural design offers new ideas and possibilities for the development and application of similar materials.

Quantized Proportional-Integral Tracking Control for Two-Stage Chemical Reactor Systems

Abstract This paper is concerned with the problem of proportional-integral tracking control of a two-stage chemical reactor system subject to time delays, disturbances, uncertainties, and input quantization. In this work, an improved equivalent-input-disturbance estimator is incorporated into the proportional-integral tracking control system to compensate for the disturbances in the addressed model. Moreover, to minimize the communication congestion in the control networks, the quantized control input signals are considered while designing the controller. Further, a robust stability condition for the addressed system is established in the form of linear matrix inequalities by employing asymmetric Lyapunov–Krasovskii functional and Jensen's integral inequalities. Moreover, in accordance with the derived conditions, the control and observer gain matrices are determined. Finally, a numerical example is provided to demonstrate the validity of the proposed control scheme.

Confined Synthesis of Noble Metal Clusters Assisted by Liquid Film for Photocatalytic CO2 Reduction.

The important concept of confined synthesis is considered a promising strategy for the design and synthesis of definable nanostructured materials with controllable compositions and specific morphology, such as highly loaded single-atom catalysts capable of providing abundant active sites for photocatalytic reactions. In recent years, researchers have been working on developing new confined reaction systems and searching for new confined spaces. Here, we present for the first time the concept of a bubble liquid film as a novel confined space. The liquid film has a typical sandwich structure consisting of a water layer, sandwiched between the upper and lower surfactant layers, with the thickness of the intermediate water layer at the micro- and nanometer scales, which can serve as a good confinement. Based on the above understanding and combined with the photodeposition method, we successfully confined synthesized Ag/TiO2, Au/TiO2, and Pd/TiO2 photocatalysts in liquid film. By HAADF-STEM, it can be seen that the noble metal morphologies are all nanoclusters of about 1 nm and are highly uniformly dispersed on the TiO2 surface. Compared with photodeposition in solution, we believe that the surfactant molecular layer restricts a limited amount of precursor to the liquid film, avoiding the accumulation of noble metals and the formation of large particle size nanoparticles. The liquid film, meanwhile, restricts the migration path of noble metal precursors, allowing for thorough in situ photodeposition and enables the complete and uniform dispersion of noble metal precursors, greatly reducing the photodeposition time. The uniform loading of the three noble metals proved the universality of the method, and the catalysts showed high activity for photocatalytic CO2 reduction. The rates of reduction of CO2 to CO over the Ag/TiO2 photocatalytic reached 230 μmol g-1 h-1.This study provides a new idea for the expansion of the confined reaction system and a reference for the study of liquid film as the confined space.