To improve the ability of diglycolamide extractants for the extraction of Sr(II) from high-level waste liquid, N,N,N',N'-tetracyclohexyldiglycolamide (TCHDGA) was proposed and studied to extract Sr(II) from nitrate media. TCHDGA was prepared and characterized by ¹H nuclear magnetic resonance spectroscopy (NMR), ¹³C NMR, and fourier transform infrared spectroscopy (FT-IR). Various factors affecting extraction were studied systematically. In just 20 s, the extraction rate can reach approximately 98.2%. The extraction capacity of cyclohexyl-substituted extractant TCHDGA is tens of times higher than that with linear or branched chain alkyl. The chemical structure of the complex has been demonstrated to be [Sr 3TCHDGA]·(NO₃)₂, based on FT-IR, X-ray photoelectron spectroscopy (XPS), and crystal structure analysis. The crystal belongs to the monoclinic system, space group P21, and a strontium ion coordinates with nine oxygen atoms, all of which contribute from TCHDGA. The stripping rate can reach over 99% when using distilled water or 0.50 mol·L^-1 oxalic acid as stripping agents.

Simultaneous recovery of Ni and Co from Fe(III) and Al is a critical challenge in hydrometallurgical processes. Recognized solvent extraction systems often struggle with selectivity and effective performance in mixed metal ion environments. Herein, a new synergistic solvent extraction (SSX) system comprised of a novel pyridine analog, N,N-bis(pyridin-2-ylmethyl) dodecan-1-amine (BPMDA), and dinonylnaphthalene sulfonic acid (DNNSA) with tributyl phosphate as phase modifier is introduced. The SSX system demonstrates high extraction performance achieving >90% for Ni and >97% for Co in a single-stage extraction process, with high selectivity. Under optimal conditions, the selectivity sequence is observed as Co²⁺ (>97%) > Ni²⁺ (>90%) > Mn²⁺ (<20%) > Fe³⁺ (<10%) > Mg²⁺ (<5%) > Al³⁺ (<2%) > Ca²⁺ (<1%). Spectroscopic analysis evidences the preferential binding of BPMDA with Ni and Co in the presence of DNNSA, concurrently achieving a significant reduction in the co-extraction of Fe(III) and Al. The selective complexation of Ni and Co using the SSX system offers a highly efficient and selective approach for their extraction, with promising potential for applications in recovery-based processes.

The effects of internals on liquid mixing and gas—liquid mass transfer have rarely been investigated in bubble columns, and the commonly used measurement method overestimates significantly overall gas holdup. Firstly, gas holdup measurement method is improved by conducting multi-point liquid level measurement and using net fluid volume instead of bed volume to calculate gas holdup. Then, a stable conductivity method for liquid macromixing has been established by shielding large bubbles using #16 nylon mesh. Subsequently, the influences of internal coverage (=12.6%, 18.9% and 25.1%) on macroscopic fluid dynamics in a bubble column with a free wall area are systematically investigated. It is found that the presence of internals has a notable effect on macroscopic fluid dynamics. The overall gas holdup and gas—liquid volumetric mass transfer coefficient decrease, and the macromixing time decreases with the increase of internal cross-sectional area coverage. These are mainly caused by the uneven distribution of airflow due to the low resistance in the free wall area. This design makes maintenance easier, but in reality, the reactor performance has decreased. Further improvements will be made to the reactor performance based on such a configuration through flow guidance using baffles.

The removal of cesium-137 (¹³⁷Cs) from nuclear wastewater remains crucial due to its radioactivity and high solubility in water, which pose serious risk to human health and the environment. Aiming at selective capture of Cs⁺ from wastewater, a core-shell adsorbent, Prussian blue analog@γ-alumina (PBA@Al₂O₃) pellets were synthesized using the hydrothermal-stepwise deposition method. The core-shell PBA@Al₂O₃ pellets showcased a PBA loading of 25% and demonstrated a maximum adsorption capacity of 15.65 mg·g^-1. The adsorption data was consistent with the pseudo-second-order kinetic model and the Langmuir isotherm model. It effectively reduced bulk Cs⁺ concentrations from an initial 6.62 mg·L^-1 to 2 μg·L^-1, achieving a removal efficiency of 99.97% and distribution coefficient (K_d) of 1.265×10⁶ ml·g^-1, surpassing the performance of other PBA-based materials. The material also indicated good mechanical properties and cesium ion removal rates of 99.7% across a wide pH range (1.82 to 11.12). Furthermore, PBA@Al₂O₃ exhibited consistent removal rate of over 99% and good selectivity (SF=50—1600) towards Cs⁺ even in the presence of interfering ions such as Na⁺, K⁺, Mg²⁺, and Ca²⁺ ions. The K_d(Cs⁺) for PBA@Al₂O₃ in simulated seawater and groundwater were 9.92×10³ and 2.23×10⁴ ml·g^-1, where the removal rates reached 96.1% and 98.2%, respectively. XPS confirms that the adsorption mechanism is the ion exchange between Cs⁺ and K⁺ ions. This study underscores the significant potential of inorganic core-shell pellets adsorbents as promising agents for the selective capture of Cs⁺ from wastewater.

Combining the advantages of high efficiency, low-pressure drop, and large throughput, the pore array-enhanced tube-in-tube microchannel (PA-TMC) is a promising microreactor for industrial applications. However, most of the mass transfer takes place in the upstream pore region, while the contribution of the downstream annulus is limited. In this work, helical wires were introduced into the annulus by adhering to the outer surface of the inner tube. Mixing behavior and mass transfer of liquid—liquid two-phase flow in PA-TMC with different helical wires have been systematically studied by a combination of experiments and volume of fluid (VOF) method. The introduction of helical wires improves the overall volumetric mass transfer coefficient K_La by up to 133% and the mass transfer efficiency E by up to 117%. The simulation results show that the helical wire brings extra phase mixing regions and increases the specific interface area, while accelerating the fluid flow and expanding the area of enhanced turbulent dissipation rate. Influences of helical wires in various configurations are compared by the comprehensive index I concerning the pressure drop and mass transfer performance simultaneously and a new correlation between K_La and specific energy consumption ϕ is proposed. This research deepens the understanding of the mixing behavior and mass transfer in the PA-TMCs and provides practical experience for the process intensification of microchannel reactors.

Exploring modification methods for enhancing the adsorption performance of biochar-based adsorbents for effective removal of methylene blue (MB), biochar-loaded CeO₂ nanoparticles (Ce/BC) were synthesized by pomelo peels through co-precipitation combined with the pyrolysis method. Ce/BC showed a higher specific surface area and disorder degree than that of BC. The 0.5Ce/BC (mass ratio of Ce(NO₃)₃·6H₂O/BC = 0.5/1) showed the best performance to adsorption of MB solution at different reaction conditions (MB concentration, Ce/BC composites dosage, and initial pH). Adsorption kinetics and equilibrium isotherms were well-described with a pseudo-first-order equation and Langmuir model, respectively. In addition, the maximum adsorption capacity of 0.5Ce/BC for MB was 105.68 mg·g^-1 at 328 K. The strong adsorption was attributed to multi-interactions including pore filling, π-π interactions, electrostatic interaction, and hydrogen bonding between the composites and MB. This work demonstrated that the modified pomelo peels biochar, as a green promising material with cost-effectiveness, exhibited a great potential for broad application prospectively to dyeing-contaminated wastewater treatment.

Due to the low transport resistance, mullite hollow fiber (HF) could be regarded as a promising support for preparation of NaA zeolite membranes. However, insufficient coverage and undesired seed penetration often occur in the seeding step of the mullite support due to the rough surfaces with ultra-large macropores (2—4 μm). This leads to poor intergrowth of the membrane layer. To solve this issue, cationic polyacrylamide (CPAM) was employed to modify the chemical and electrostatic properties of the mullite HF surface, where the electrostatic attraction between the surface and seed crystals could significantly promote the coating effect. In the seeding, the original seeds (3.2 μm) were mixed with the ball-milled seeds (0.3 μm) to improve the seed coverage, i.e., the original seed was used to block the macropores on the support surface to prevent the penetration of small seeds, while the decked ball-milled seed was used to provide sufficient active sites to induce the intergrowth of the zeolite crystals. The effects of the concentration of CPAM, mixed mass ratio of seeds, and seed concentration on the preparation of NaA zeolite membranes were systematically examined, where the separation performances were characterized by pervaporation (PV) dehydration of 90% (mass) ethanol/water mixtures at 75 ℃. The results indicated that under a CPAM concentration of 0.7% (mass), an equivalent mass ratio of mixed seeds in a seed concentration of 1.0% (mass), the prepared mullite HF supported NaA zeolite membrane yielded the best PV performance, where the permeation flux and separation factor corresponded to 5.45 kg·m^-2·h^-1 and 10000, respectively, being sufficient for industrial applications.

High electrochemical performance supercapacitors require activated carbon with high specific surface area, suitable pore size distribution and surface properties, and high electrical conductivity as electrode materials, whereas there exists a trade-off relationship between specific surface area and electrical conductivity, which is not well met by a single type of carbon source. To solve this problem, the coal and sargassum are adopted to obtain the coupling product via co-thermal dissolution, followed by carbonization and KOH activation. The effects of mixing mass ratio and activation temperature on the prepared activated carbon (AC) are investigated using single factor experimental method. The experimental results show that AC_1/3-800 has abundant micropore and mesopore content, good pore structure connectivity, high electrical conductivity and good wettability, and superior electrochemical properties compared with other activated carbons prepared in this experiment. Its total specific surface area is up to 2098.5 m²·g^-1, the pore volume is up to 1.33 cm³·g^-1, the content of mespores with diameter of 6—8 nm is significantly increased, and the pore size distribution is wide and uniform. When the current density increases from 0.1 to 10 A·g^-1, the gravimetric capacitance decreases from 219 to 186 F·g^-1 with a capacitance retention of 84.9%, the equivalent series resistance is very small, and the rate performance and reversibility of charging and discharging have also been excellent.

Polystyrene (PS) waste was depolymerized using a low-temperature pyrolysis treatment (LTPT) to increase its caking index. The mechanism of caking index modification was revealed by using Fourier transform infrared spectroscopy, thermogravimetric (TG) analysis, pyrolysis-gas chromatography with mass spectrometric detection, and solid-state ¹³C nuclear magnetic resonance spectroscopy. The crucible coal-blending coking tests were carried out using an industrial coal mixture and the treated-PS with the highest caking index (PS300) or raw PS. Some properties of the resultant cokes were also analyzed. It was demonstrated that the caking index of PS dramatically increased by LTPT; however, exceeding 300 ℃ did not yield any benefit. The caking index increased due to the formation of the caking components, whose molecules are medium in size, caused by LTPT. Additionally, the coke reactivity index of the coke obtained from the mixture containing PS300 decreased by 5.1% relative to that of the coke made from the mixture with PS and the coke strength after reaction index of the former increased by 7.3% compared with that of the latter, suggesting that the ratio of depolymerized PS used for coal-blending coking could increase relative to that of PS.

To optimize secondary air nozzle structure in purifying burner, this study focused on the comparison of purification, combustion and NO_x emission characteristics of pulverized coal preheated by a 30 kW purifying burner with coaxial and centrosymmetric structures. Centrosymmetric structure shifted the position of main burning region down in high-temperature reduction unit (HTRU), and the number of branches differently influenced the temperature in different regions with this structure. For reductive gas components, CO concentration with centrosymmetric structure was higher compared to coaxial structure, while the differences in H₂ and CH₄ concentrations were smaller. Centrosymmetric structure was more disadvantageous to improve physicochemical properties of pulverized coal compared to coaxial structure, and this structure with four branches further deteriorated its properties compared to two branches. In mild combustion unit (MCU), the temperature at top was lower with centrosymmetric structure, while was higher in the rest. Centrosymmetric structure more effectively reduced NO_x emission compared to coaxial structure, but with slight sacrifice of combustion efficiency (η). Moreover, both two-branch and four-branch centrosymmetric structures realized ultra-low NO_x emission (<50 mg·m^-3) with high η of over 98.50%, and the former was more advantageous. With this optimal structure, η and NO_x emission were 99.25% and 40.42 mg·m^-3.

The membrane aeration biofilm reactor (MABR) represents an innovative approach to wastewater treatment, integrating gas separation membranes with biofilm process and demonstrating effectiveness in treating wastewater rich in ammonia nitrogen. In this system, hollow fiber membranes are essential, serving as a substrate for biofilm attachment while facilitating oxygen transfer to microorganisms through aeration, hydrophobic microporous membranes are utilized in MABR applications. This study focuses on the use of poly-4-methyl-1-pentene (PMP) hollow fiber membranes, which exhibit superior oxygen permeation capabilities compared to traditional hydrophobic microporous membranes. To overcome the challenges posed by the hydrophobic nature and low bubble point of PMP microporous membranes, a hydrophilic modification was conducted using dopamine/poly(ethyleneimine) (DOPA/PEI) co-deposition to enhance microbial adhesion on the membrane surface. The composite membrane modified with DOPA/PEI exhibited an approximately 20% higher NH₄⁺-N removal efficiency than the unmodified membrane. These findings suggest that the incorporation of DOPA/PEI significantly improves MABR performance, underscoring its potential for further research and development in membrane technology for MABR.

Covalent organic skeletons (COFs) have been widely used in gas separation due to their excellent pore structure, high crystallinity, and high specific surface area. In this work, Dha Tab-COF was synthesized by solvothermal method and filled in polyether block polyamide (PEBAX) to form mixed matrix membranes (MMMs). Various characterization methods such as Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffractometry (XRD) were used to characterize the structure of Dha Tab-COF as well as the MMMs. The effects of operating pressure, operating temperature and the content of Dha Tab-COF particles on the CO₂/CH₄ separation performance of the membranes were investigated. The best separation performance with a CO₂ permeability of 295.8 barrer (1 barrer = 7.52×10^-18 m³·(STP)·m^-2·m·s^-1·Pa^-1) and a CO₂/CH₄ selectivity of 21.6 was achieved when the Dha Tab-COF content is 2% (mass), which were 45.7% and 108.1% higher than that of the pure PEBAX membrane, respectively.

Sunscreen agents derived from plants have been regarded as promising alternatives to artificial compounds. In this work, carbon dots (CDs) were prepared from carrot juice via a continuous microflow-based approach, where the influence of process parameters was studied and optimized. Complimentary characterization revealed the CDs not only have small size, narrow size distribution, and good water solubility, but also have abundant functional groups as well as excellent UV absorption performance. Relying on these properties, the CDs were used as UV absorbers, suggesting they have strong long-term UV absorption ability over a broad pH range. The UV-absorption properties of the CDs were confirmed by incorporating the CDs in polyvinyl alcohol (PVA) to get C-CDs@PVA films of different thickness, in which significantly enhanced UV absorption performance was observed. Besides, the sun protection performance is also related to the film thickness. Afterwards, the practical application of the CDs was evaluated by adding them in a typical skin cream. With the addition of the CDs, the cream has drastically reduced UV transmittance in both UVA and UVB regions, and exhibits better UV absorption performance than commercial sunscreen agents. The CDs also demonstrated low cytotoxicity and high DPPH radical scavenging activity, making them promising as green sunscreen absorbers. This work is expected to provide a guidance for the development of green and effective natural sunscreen agents via microflow-based method.

The pollution especially organic dyes pollution of water resources is an urgent issue to be solved. It is crucial to develop highly efficient, low cost and recyclable heterogeneous catalysts for wastewater treatment. In this study, a heterogeneous Fenton catalyst loaded with Fe₃O₄ nanoparticles was prepared by one step pyrolysis using natural crop waste corncob as carbon source. The prepared porous carbon catalyst can effectively degrade methyl orange (MO, 25 mg·L^-1) at room temperature, and the degradation rate is 99.7%. In addition to high catalytic degradation activity, the layered porous carbon structure of the catalyst also provides high stability and reusability. The degradation rate can be maintained above 93% after 10 cycles. Furthermore, the prepared catalyst is magnetic, which makes the catalyst easy to recycle in practical applications. In addition, the prepared Fe₃O₄/RCC catalyst has efficient Fenton degradation activity for bisphenol A (BPA) (96.9%) and antibiotic tetracycline hydrochloride (TC-HCl) (95.5%), which proves that it has universal applicability for the degradation of most organic pollutants. This study provides a feasible and scalable strategy to prepare a heterogeneous Fenton catalyst treating wastewater and high-value utilization of biomass waste.

We synthesized CN11, a carbon nitride material rich in sp³ hybrid graphitic nitrogen (sp³-N), employing a facile oxalic acid-assisted melamine molecular assembly strategy. CN11 promoted the formation of Pd nanoparticles (NPs) predominantly exposing {2 0 0} facets, termed Pd/CN11-2. This facet-specific configuration significantly boosted hydrogen adsorption, leading to notable improvements in catalytic activity. Compared to Pd/XC-72-2 and Pd/g-C₃N₄-2, Pd/CN11-2 exhibited a remarkable two-fold and nineteen-fold increase in catalytic yield for hydrazo compound hydrogenation, respectively. Pd/CN11-2 also demonstrated robust performance across a range of reaction conditions, maintaining excellent yield. This study emphasizes the critical role of tailored support structures in controlling Pd NPs facets, thereby enhancing hydrogenation efficiency. It provides valuable insights for advancing the industrial application of Pd-based catalysts, underscoring the importance of strategic support modulation for optimizing catalytic performance.

As a kind of novel environmental-friendly surfactant, Gemini surfactant has attracted extensive research interests in its effects on gas hydrate formation. We investigated the effects of dioctyl sodium sulfosuccinate (AOT) on the formation thermodynamics/kinetics of CH₄ and CO₂ hydrates. Experimental results indicate that while AOT does not exhibit significant thermodynamic promotion for hydrate formation, it demonstrates favorable kinetic promotion effects. Its promotion effect surpasses that of the traditional kinetic promoter SDS and can enhance the gas storage capacity of hydrates. Utilizing the Chen-Guo hydrate model and adsorption kinetic model, we established a kinetic model for AOT with a predictive deviation of 7.17% and fitted key parameters accordingly.

Constructing a framework carrier to stabilize protein conformation, induce high embedding efficiency, and acquire low mass-transfer resistance is an urgent issue in the development of immobilized enzymes. Hydrogen-bonded organic frameworks (HOFs) have promising application potential for embedding enzymes. In fact, no metal involvement is required, and HOFs exhibit superior biocompatibility, and free access to substrates in mesoporous channels. Herein, a facile in situ growth approach was proposed for the self-assembly of alcohol dehydrogenase encapsulated in HOF. The micron-scale bio-catalytic composite was rapidly synthesized under mild conditions (aqueous phase and ambient temperature) with a controllable embedding rate. The high crystallinity and periodic arrangement channels of HOF were preserved at a high enzyme encapsulation efficiency of 59%. This bio-composite improved the tolerance of the enzyme to the acid-base environment and retained 81% of its initial activity after five cycles of batch hydrogenation involving NADH coenzyme. Based on this controllably synthesized bio-catalytic material and a common lipase, we further developed a two-stage cascade microchemical system and achieved the continuous production of chiral hydroxybutyric acid (R-3-HBA).

The process of deep hydrodesulfurization (HDS) in gasoline typically results in the saturation of olefins, leading to significant reductions in octane number. In this work, Y-supported Co(Ni)—Mo catalysts that with different Ni—Co content were prepared by the incipient wetness impregnation method, the structure and properties were characterized and analyzed using HRTEM, XPS, H₂-TPR, and NH₃-TPD. The isomerization of 1-hexene and 1-octene as well as the HDS of thiophene were studied by using model FCC naphtha. The incorporation of Ni was found to enhance the number of MoS₂ stacking layers, thereby improving the degree of sulfurization in Mo and subsequently increasing the desulfurization rate, with a maximum achieved desulfurization rate of 94.7%. When employing a Ni/Co ratio of 3:2, optimal synergy between Ni and Co is achieved, resulting in a greater presence of multi-layer stacked II-Co(Ni) MoS active phases. Additionally, appropriate Brønsted acidity levels are maintained to facilitate efficient olefin isomerization while preserving high HDS activity. As a result, the current isomerization yield stands at 58.2%(mass). These understandings shed light on the development of highly HDS and olefin isomerization catalysts.

Red mud (RM) is a solid waste generated in the aluminum industry after the extraction of alumina oxide; its multiple elements and higher pH value likely pose a severe threat to the environment after treatment. However, RM's higher concentrations of metal components, particularly Fe₂O₃ and rare earth elements (REEs), render RM promising for catalytic application. Hence, this work showed an efficient high-speed RM to catalyze electrocatalytic nitrate-to-ammonia reduction reaction (NARR). RM calcined at 500 ℃ (RM-500) exhibited excellent catalytic performance. Faradaic efficiency of ammonia (FE_NH3) in an electrolyte solution containing 1 mol·L^-1 NO₃^- achieved a maximum value of 92.3% at -0.8 V (vs. RHE). Additionally, 24-h cycle testing and post-reaction PXRD and SEM indicated that the RM-500 electrocatalyst is stable during NARR. The RM-500 demonstrated a high FE of NH₃-to-NO₃^- of 89.7% at 1.85 V (vs. RHE), showing great potential in the ammonia fuel cells technology and achieving the nitrogen cycle.

This study explores the unique role of CO₂ as an oxidant in stainless steel smelting, focusing on its effectiveness in decarbonization and chromium retention. The research begins by theoretically demonstrating that although the introduction of CO₂ increases the CO partial pressure in the reaction system, the decarburization and chromium (Cr) retention capabilities of CO₂ can still be stably maintained through the rational adjustment of the molten steel composition, temperature, and inert gas proportions. Further experimental findings indicate that chromium does not exhibit significant oxidation losses when the carbon (C) content exceeds 1.0% (mass). Finally, a novel CO₂ recovery and utilization approach is proposed, integrating CO₂ capture from smelting flue gas and recycling it for smelting, reducing O₂ consumption and energy costs. This innovative process, compatible with existing smelting plants, presents a promising pathway towards carbon neutrality in the iron and steel industry, bridging theoretical insights with practical applications.

In this context, the present study proposes the use of microwave irradiation to improve the dehydration rate and efficiency of strontium hydroxide octahydrate (Sr(OH)₂·8H₂O) without introducing contaminants. This study revealed that the use of microwave irradiation to dehydrate Sr(OH)₂·8H₂O is feasible and surprisingly efficient. The effects of this approach on important parameters were investigated using response surface methodology (RSM). The results revealed that the microwave dehydration process follows a linear polynomial model. In addition, compared with the heating time and material thickness, the microwave-assisted dehydration of Sr(OH)₂·8H₂O is sensitive to the microwave power and not to the material mass. The relative dehydration percentage reached 99.99% when heated in a microwave oven at 950 W for just 3 min. In contrast, a relative dehydration percentage of 94.6% was reached when heated in an electric furnace at 180 ℃ for 120 min. The XRD spectra also revealed that most of the Sr(OH)₂·8H₂O transformed into Sr(OH)₂ after dehydration via microwave irradiation, whereas a significant portion of the Sr(OH)₂·H₂O remained after conventional electric dehydration. The experimental data were fitted and analyzed via the thin-layer drying dynamics model, and the results indicated that the dehydrating behavior of Sr(OH)₂·8H₂O could be well described by the Page model.

The effects of the structure and concentration of impurities on the alkylation of naphthalene with 1-octene catalyzed by chloroaluminate ionic liquid (IL) were investigated. The presence of impurities containing oxygen and nitrogen led to a decrease in the catalytic performance of chloroaluminate IL. As the water concentration increased to 65 mg·g^-1, the total selectivity of multi-octylnaphthalene gradually decreased to 42.33%, and the average friction coefficient of the multi-octylnaphthalene base oil gradually increased to 0.201. When the concentration of impurities increased to a critical value, the chloroaluminate IL began to deactivate, leading to a decrease in naphthalene conversion. The critical concentrations for ethanolamine, water, methanol, ether, and diisopentyl sulfide were 33 mg·g^-1, 65 mg·g^-1, 67 mg·g^-1, 87 mg·g^-1, and 123 mg·g^-1, respectively. Impurities with higher basicity resulted in an earlier onset of chloroaluminate IL deactivation. The changes of Lewis and Brønsted acids in chloroaluminate IL under the influence of impurities were investigated using in situ IR and ²⁷Al NMR spectroscopy. 2,6-dimethylpyridine as an indicator could detect the changes of Brønsted acid in chloroaluminate IL better, but the changes of Lewis acid were not obvious because of the overlap between the characteristic peaks. 2,6-dichloropyridine as an indicator could exclusively detect the changes of Lewis acid in chloroaluminate IL. With the increase in water concentration, the Lewis acid in chloroaluminate IL was continuously consumed and converted into Brønsted acid, and the Lewis acid gradually decreased, while the Brønsted acid showed a change of increasing first and then decreasing.

Based on the experimental data of Mn₁Co_0.5Cr_0.5O_x catalysts and the component transport model in computational fluid dynamics (CFD), a kinetic model for the standard NH₃-SCR (NH₃ selective catalytic reduction) process was effectively established. The objective of the model development was to predict the denitrification reaction rate of the catalyst, which incorporates various factors such as the Arrhenius parameters (pre-exponential factor and activation energy), inertial resistance, viscous resistance, and surface-to-volume ratio. To verify the practicability of the model, simulation results were compared with actual experimental data. The effects of NH₃, NO, O₂ concentrations, and gas hourly space velocity (GHSV) on NO conversion were simulated and analyzed. Subsequently, the NO conversion prediction model was trained and established using a combination of numerical simulation results, back-propagation neural network, and genetic algorithm (BP-GA). Furthermore, the significance of the impact that various factors had on the denitrification activity of the catalyst was determined.

Waste heat generation, upgrading, and refrigeration are the fundamental ways to recover and utilize waste heat. Rationalizing the use of refrigerants also contributes to creating energy savings and minimizing carbon emissions. This study evaluates the thermodynamics, economics, and environment of different refrigerants in three waste heat recovery schemes: generate electricity, heat pump, and refrigeration. Based on this, the entropy weight and technique for order preference by similarity to an ideal solution are combined to assess the overall performance of the refrigerants. A thorough analysis reveals that R1234ze(E) could replace R245fa and R123 in the organic Rankine cycle. The best refrigerant for vapor compression refrigeration and high-temperature heat pump systems is R1243zf. In addition, the multi-objective decision analysis shows that the performance difference among the nine selected refrigerants is the total cost, followed by the environmental impact. The approach successfully recognizes the variations between different refrigerants in the same waste heat recovery scheme and gives a thorough evaluation. It sets instructions for the future use of eco-friendly refrigerants and their application of waste heat recovery schemes.

The operational state of distillation columns significantly impacts product quality and production efficiency. However, due to the complex operation and diverse influencing factors, ensuring the safety and efficient operation of the distillation columns becomes paramount. This research combines passive acoustic monitoring with artificial intelligence techniques, proposed a technology based on residual network (ResNet), which involves the transformation of the acoustic signals emitted by three distillation columns under different operating states. The acoustic signals were initially in one-dimensional waveform format and then converted into two-dimensional Mel-Frequency Cepstral Coefficients spectrogram database using fast Fourier transform. Ultimately, this database was employed to train a ResNet for the purpose of identifying the operational states of the distillation columns. Through this approach, the operational states of distillation columns were monitored. Various faults, including flooding, entrainment, dry-tray, etc., were diagnosed with an accuracy of 98.91%. Moreover, an intermediate transitional state between normal operation and fault was identified and accurately recognized by the proposed method. Under the transitional state, the acoustic signals achieved an accuracy of 97.85% on the ResNet, which enables early warnings before faults occur, enhancing the safety of chemical production processes. The approach presents a powerful tool for the monitoring and diagnosis of chemical equipment, particularly distillation columns, ensuring the safety and efficiency.

Steam power systems (SPSs) in industrial parks are the typical utility systems for heat and electricity supply. In SPSs, electricity is generated by steam turbines, and steam is generally produced and supplied at multiple levels to serve the heat demands of consumers with different temperature grades, so that energy is utilized in cascade. While a large number of steam levels enhances energy utilization efficiency, it also tends to cause a complex steam pipeline network in the industrial park. In practice, a moderate number of steam levels is always adopted in SPSs, leading to temperature mismatches between heat supply and demand for some consumers. This study proposes a distributed steam turbine system (DSTS) consisting of main steam turbines on the energy supply side and auxiliary steam turbines on the energy consumption side, aiming to balance the heat production costs, the distance-related costs, and the electricity generation of SPSs in industrial parks. A mixed-integer nonlinear programming model is established for the optimization of SPSs, with the objective of minimizing the total annual cost (TAC). The optimal number of steam levels and the optimal configuration of DSTS for an industrial park can be determined by solving the model. A case study demonstrates that the TAC of the SPS is reduced by 220.6×10³ USD (2.21%) through the arrangement of auxiliary steam turbines. The sub-optimal number of steam levels and a non-optimal operating condition slightly increase the TAC by 0.46% and 0.28%, respectively. The sensitivity analysis indicates that the optimal number of steam levels tends to decrease from 3 to 2 as electricity price declines.

Machine learning-assisted retrosynthesis planning aims to utilize machine learning (ML) algorithms to find synthetic pathways for target compounds. In recent years, with the development of artificial intelligence (AI), especially ML, researchers’ interest in ML-assisted retrosynthesis planning has rapidly increased, bringing development and opportunities to the field. In this review, we aim to provide a comprehensive understanding of ML-assisted retrosynthesis planning. We first discuss the formal definition and the objective of retrosynthesis planning, and organize a modular framework which includes four modules: data preparation, data preprocessing, pathway generation and evaluation, and pathway verification. Then, we sequentially review the current status of the first three modules (except pathway verification) in the ML-assisted retrosynthesis planning framework, including ideas, methods, and latest progress. Following that, we specifically discuss large language models in retrosynthesis planning. Finally, we summarize the extant challenges that are faced by current ML-assisted retrosynthesis planning research and offer a perspective on future research directions and development.

A cylindrical chamber with a rotating bottom holds significant potential for application in cell culture bioreactors due to its ability to generate more stable swirling flows. In order to control vortex breakdown within the chamber, this study first establishes a computational fluid dynamics simulation coupled with the level set method. Verified by experimental results in literature, this method accurately simulates the position and shape of vortex breakdown, and also predicts the critical Reynolds numbers for the appearance and detachment of vortex breakdown bubbles from the center. Additionally, it precisely captures the gas—liquid interface and depicts the vortex breakdown phenomenon in the air above the liquid for the first time. Finally, it predicts the impact of physical property of gas—liquid systems on vortex breakdown in response to significant changes in viscosity of microbial process systems.

Simultaneous nitrification and denitrification (SND) is considered an attractive alternative to traditionally biological nitrogen removal technology. Knowing the effects of heavy metals on the SND process is essential for engineering. In this study, the responses of SND performance to Zn(II) exposure were investigated in a biofilm reactor. The results indicated that Zn(II) at low concentration (≤2 mg·L^-1) had negligible effects on the removal of nitrogen and COD in the SND process compared to that without Zn(II), while the removal of ammonium and COD was strongly inhibited with an increasing in the concentration of Zn(II) at 5 or 10 mg·L^-1. Large amounts of extracellular polymeric substance (EPS), especially protein (PN), were secreted to protect microorganisms from the increasing Zn(II) damage. High-throughput sequencing analysis indicated that Zn(II) exposure could significantly reduce the microbial diversity and change the structure of microbial community. The RDA analysis further confirmed that Azoarcus-Thauera-cluster was the dominant genus in response to low exposure of Zn(II) from 1 to 2 mg·L^-1, while the genus Klebsiella and Enterobacter indicated their adaptability to the presence of elevated Zn(II). According to PICRUSt, the abundance of key genes encoding ammonia monooxygenase (EC: 1.14.99.39) was obviously reduced after exposure to Zn(II), suggesting that the influence of Zn(II) on nitrification was greater than that of denitrification, leading to a decrease in ammonium removal of SND system. This study provides a theoretical foundation for understanding the influence of Zn(II) on the SND process in a biofilm system, which should be a source of great concern.

Leveraging big data signal processing offers a pathway to the development of artificial intelligence-driven equipment. The analysis of fluid flow signals and the characterization of fluid flow behavior are of critical in two-phase flow studies. Significant research efforts have focused on discerning flow regimes using various signal analysis methods. In this review, recent advances in time series signals analysis algorithms for stirred tank reactors have been summarized, and the detailed methodologies are categorized into the frequency domain methods, time-frequency domain methods, and state space methods. The strengths, limitations, and notable findings of each algorithm are highlighted. Additionally, the interrelationships between these methodologies have also been discussed, as well as the present progress achieved in various applications. Future research directions and challenges are also predicted to provide an overview of current research trends in data mining of time series for analyzing flow regimes and chaotic signals. This review offers a comprehensive summary for extracting and characterizing fluid flow behavior and serves as a theoretical reference for optimizing the characterization of chaotic signals in future research endeavors.