Frontiers of Chemical Science and Engineering最新文献

Traditional open circulating cooling water systems use a lot of water and electricity to remove waste heat. In coastal areas, closed seawater circulating cooling water systems have been used as an alternative to improve cooling efficiency. However, a comprehensive comparison of the design and advantages of the two types of cooling systems is lacking. Also, the best way to match and optimize the seawater system with the circulating water system in the closed seawater circulating cooling water system has not been fully explored. In this paper, a closed seawater cooling system under multiperiod is constructed, taking into account monthly changes in environmental factors. The mixed integer nonlinear programming model is solved by using GAMS software to evaluate and compare the economics and operability of the two cooling schemes. Meanwhile, the matching relationship of the internal subsystems of the closed seawater circulating cooling water system after coupling the air coolers is studied in depth, and the cooling load is allocated reasonably. The cases show that seawater cooling saves 9.22% of circulating water and reduces the total cost by 8.93% compared with cooling tower. The cost of the closed seawater cooling system can be reduced by 24.37% after coupling air coolers, and there is a direct corresponding matching relationship between circulating water and seawater.

To achieve fire-resistant epoxy resin (EP), a UiO-66-based novel flame retardant coating (CS@APP@UiO-66) was prepared by modifying UiO-66 with chitosan (CS) and ammonium polyphosphate (APP) through a layer-by-layer (LbL) self-assembly method, which was then introduced into an EP system to improve its fire safety. The results of scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy show that the unsaturated Zr atoms in the UiO-66 framework provide many active sites conducive to modification, so that the UiO-66 particles, which originally had a regular octahedral structure, are more dispersed by LbL modification without causing doping or distortion issues. The thermogravimetric analysis results indicate that the char residue of EP/2% UiO-66 is increased by 2.52% compared with that of pure EP, indicating that the thermal properties of the EP composite are improved after modification. In addition, the cone test results indicate that EP/2%UiO-66-5L has good flame retardancy and smoke suppression properties, and the peak heat release rate, total smoke production and rate of CO generation values are 25.2%, 5.7% and 38.5% lower than those of the unmodified EP. Moreover, it can be concluded from the Raman test that the graphitization degree of the modified EP composite is strengthened. The above results indicated that after the incorporation of CS@APP@UiO-66 into the EP composites, more char layers formed as physical barriers to prevent the transfer of mass and heat, thus reducing the speed of flame propagation. Therefore, the flame resistance and smoke suppression of the EP composites improved. These favorable characteristics, including high flame retardant efficiency and good smoke suppression, make LbL-functionalized UiO-66 promising for flame retardant polymer applications.

Single-atom catalysts are highly effective in catalyzing a wide range of reactions owing to their capacity to have precise coordination patterns and fully leverage the potential of metal atoms. Although several techniques have been reported for the preparation of single-atom catalysts, adopting a convenient method to construct them still has a challenge. In this work, we report a convenient method for the preparation of Zr-based single-atom catalyst that takes advantage of the nanoconfined environments between the template and silica wall in template-occupied silica SBA-15. After introducing Zr-containing precursor into the nanoconfined environments of the template-occupied silica SBA-15 using solid-phase milling, Zr-based single-atom catalysts were produced via the following calcination step. Density functional theory calculations and experimental findings show that Zr atoms form Zr–O–Si structure in the silica walls. The Zr single-atom catalyst synthesized using the nanoconfined environments exhibited notably superior catalytic performance in the synthesis of benzyl acetate from the esterification reaction between acetic acid and benzyl alcohol (63.3% yield), outperforming the counterpart that synthesized without such nanoconfined environments (19.8% yield).

Flexible aqueous zinc-air batteries with high energy density and safety have garnered significant attention. Gel polymer electrolytes have emerged as the preferred option over conventional liquid electrolytes due to their ability to prevent electrolyte leakage. In this study, a composite PANa-PVP-TiO₂(NH₂) hydrogel with high alkaline resistance and ionic conductivity is designed, where the inorganic TiO₂(NH₂) nanoparticles are evenly distributed and integrated into the organic dual network of polyacrylate sodium and polyvinyl pyrrolidone. The organic-inorganic hybrid structure enhances the absorption and retention capabilities for electrolyte solution, leading to impressive ionic conductivity of the gel polymer electrolyte throughout the operation of flexible aqueous zinc-air batteries. Additionally, the incorporation of TiO₂(NH₂) nanoparticles and the dual network construction effectively strengthen the mechanical strength and flexibility of the gel polymer electrolyte, suppressing by-products and zinc dendrite formation. The enhancements lead to the extended cycling longevity of zinc symmetric batteries and excellent power density, as well as the prolonged cycle life of flexible aqueous zinc-air batteries.

Polylactic acid, a biodegradable polymer derived from renewable resources, is increasingly used in food packaging due to its transparency, renewability, and food safety. However, its mechanical properties, heat resistance, and barrier performance present significant challenges that limit its application. Currently, there is a lack of comprehensive literature addressing methods to optimize polylactic acid’s performance for various food packaging application. Hence, this review provides an overview of polylactic acid production processes, including the synthesis of lactic acid and lactide, as well as methods such as polycondensation and ring-opening polymerization. We critically examine the advantages and limitations of polylactic acid in various food packaging contexts, focusing on strategies to enhance its mechanical properties, barrier performance against oxygen and water vapor, surface hydrophobicity, thermal stability, and resistance to ultraviolet light. Furthermore, we summarize recent advancements in polylactic acid applications for food packaging, highlighting innovations in antioxidant, antimicrobial, and freshness indicator packaging. These developments underscore the significant potential of polylactic acid in the food packaging sector and offer valuable insights for future research directions.

This paper proposes an innovative simultaneous optimization approach for single and multi-component mass exchanger network synthesis (MENS). A retrofitted stage-wise superstructure and a parallelized random walk algorithm with compulsive evolution (RWCE) are adopted. An iterative calculation method is designed to satisfy the requirements of multi-component mass transfer, with a relaxation for the outlet composition of the lean streams. The parametric analysis shows that the relaxation coefficient plays a major role in driving the convergence of the method. To improve the robustness of the established model, an adaptive relaxation coefficient strategy is implemented for multi-component MENS problems. In a divergence situation, the outlet concentration of the lean stream can be adjusted automatically by a random relaxation coefficient. Finally, three industrial MENS examples are considered in this work, whose total annual cost (TAC) are reduced by 7179, 2212, and 551 $·year⁻¹. The corresponding optimization times are obtained to be 336, 125, and 145 s. The results indicate improvements in the economy and time, demonstrating that the parallelized RWCE can yield an optimal TAC and optimization efficiency compared to previous results. Overall, the adaptive relaxation coefficient strategy enhances the convergence for multi-component MENS problems.

The use of metal-organic frameworks (MOFs) as CO₂-gas-capture materials has attracted extensive research attention. In this study, two types of MOFs—Zn-MOF and ZnCe-MOF—were synthesized utilizing the microchannel reaction method, with water being employed as the solvent. The specific surface area, pore size, and pore volume of Zn-MOF and ZnCe-MOF were 1566.4 and 15.6 m²·g⁻¹, 0.65 and 7.32 nm, as well as 1.65 and 0.03 cm³·g⁻¹, respectively. Furthermore, Ce doping not only increased the pore size of ZnCe-MOF but also its adsorption energy from −0.19 eV (Zn-MOF) to −0.53 eV (ZnCe-MOF). At 298 K, the adsorption capacities of Zn-MOF and ZnCe-MOF were 0.66 and 0.74 mmol·g⁻¹, respectively. In addition, the CO₂ adsorption behaviors of Zn-MOF and ZnCe-MOF were linear and logarithmic, respectively. Theoretical calculations show that the results of adsorption thermodynamic simulations were consistent with the experiments. Thus, the preparation of ZnCe-MOF materials using a microchannel reactor provides a new approach for the continuous preparation of MOFs.

Enhancing nitrogen removal is a very active branch in municipal wastewater treatment research, toward this end, anammox technology is a sustainable solution. This review systematically outlines the strategies employed to enhance mainstream anammox performance, including nitrite accumulation and microbial enrichment based on partial nitrification coupled anammox and partial denitrification coupled anammox, developed to address the challenges of low ammonium content in wastewater, nitrate accumulation in the effluent, and the influence of organic matter. The characteristics and advantages of novel anammox-coupled processes, including partial nitrification and partial denitrification coupled anammox, endogenous partial denitrification coupled anammox, and denitrifying anaerobic methane oxic coupled anammox are also comprehensively discussed; these aim to ensure the highly efficient and stable operation of anammox under diverse wastewater conditions by constructing a composite biological nitrogen removal system based on anammox, supplemented by nitrification-denitrification and other processes. Additionally, a novel anammox application route including mainstream partial denitrification/anammox and absorptionbiodegradation as well as sidestream partial nitrification/anammox is proposed, and its application pathway in conceptual wastewater treatment plants is outlined, aiming to foster the development of cost-effective, efficient, and energy-saving advanced wastewater treatment processes. Finally, prospects are presented that indicate the gaps in contemporary research and potential future research directions. Overall, this review provides a reference for treating municipal wastewater with anammox and sheds new light on related strategies and nitrogen removal mechanisms.

Coal utilization, as a major energy source, raises sustainability concerns and environmental impacts, prompting researchers to explore blending it with other feedstocks. This study discusses hydrochar coal-water slurry (HC-CWS) preparation conditions, emphasizing apparent viscosity and exploring the influence of high ash content on char reactivity. The study highlights that the presence of free water in sludge is moderately influential, while high amounts of free water in raw sewage sludge (SS) and its near absence during hydrothermal carbonization (HTC) of SS are both unfavorable for enhancing the overall performance of coal-water slurry (CWS). HTC reduces the concentration of hydroxyl functional group, enhancing slurry performance and reducing ash content in HC-CWS, indicating that coal complements hydrochar (HC). High-temperature HC preparation is unsuitable for HC-CWS due to increased viscosity and decreased stability. In terms of ash content, the optimal pH and HC ratio for CWS are determined at 30% HC. The gasification reactivity of HC, prepared at 180 °C with a 30% HC ratio in CWS at R_0.5 is 6 × 10⁻³ and at R_0.9 is 9 × 10⁻³. However, increasing HC to 50% diminishes reactivity under CO₂ atmosphere. The inhibitory effect was observed with an increasing percentage of HC in CWS and the synergy factor decreased in the following order: 10% HC > 30% HC > 50% HC, i.e., from 1.04 to 0.35. The possible reason is the presence of high ash content and their similar initial gasification rates during its early stages.

Direct air capture (DAC) using amine-functionalized solid adsorbents holds promise for achieving negative carbon emissions. In this study, a series of additive-incorporated tetraethylenepentamine-functionalized SiO₂ adsorbents with varying tetraethylenepentamine and additive contents were prepared via a simple impregnation method, characterized by various techniques, and applied in the DAC process. The structure-performance relationship of these adsorbents in DAC was investigated, revealing that the quantity of active amine sites (or the tetraethylenepentamine content in the exposed layer), as determined by CO₂-TPD measurement, was an important factor affecting the adsorbent performance. This factor, which varied with the tetraethylenepentamine content, additive type, and additive content, showed a positive correlation with the CO₂ adsorption capacity of the adsorbents. The optimal adsorbent, 40TEPA-10PEG/SiO₂ containing 40 wt % tetraethylenepentamine and 10 wt % polyethylene glycol (Mn = 200), exhibited a stable CO₂ capacity of 2.1 mmol·g⁻¹ and amine efficiency of 0.22 over 20 adsorption–desorption cycles (adsorption at 400 ppm CO₂/N₂ and 30 °C for 60 min, and desorption at pure N₂ and 90 °C for 20 min). Moreover, even after deliberate accelerated oxidation treatment (pretreated in air at 100 °C for 10 h), the CO₂ capacity of 40TEPA-10PEG/SiO₂ remained at 2.0 mmol·g⁻¹. The superior thermal and oxidative stability of 40TEPA-10PEG/SiO₂ makes it a promising adsorbent for DAC applications.