Frontiers of Chemical Science and Engineering最新文献

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.

Zeolites, with their exquisite microporous frameworks and tailorable acidities, serve as ubiquitous catalysts across a diverse spectrum of industrial applications, ranging from petroleum and coal processing to sustainable chemistry and environmental remediation. Optimizing their performance hinges on a thorough understanding of the structure-performance relationship. In situ solid-state nuclear magnetic resonance spectroscopy has emerged as a critical tool, providing unparalleled atomic-level insights into both structure and dynamic aspects of zeolite-catalyzed reactions. Herein, we review recent progress in the development and application of the in situ solid-state nuclear magnetic resonance technique to zeolite catalysis. We first review the in situ nuclear magnetic resonance techniques used in zeolite-catalyzed reaction, including batch-like and continuous-flow reaction modes. The conditions and limitations for these techniques are thoroughly summarized. Subsequently, we review the applications of in situ nuclear magnetic resonance techniques in zeolite-catalyzed reaction, focusing on some important catalytic reactions like methanol-to-hydrocarbons, ethanol dehydration, alkane activation, and beyond. Emphasis is placed on the strategies of specific in situ nuclear magnetic resonance methodologies to tackle critical challenges encountered in these fields, such as probing intermediates and unraveling reaction mechanisms. Additionally, we discuss the burgeoning opportunities and prospective challenges associated with in situ nuclear magnetic resonance studies of zeolite-catalyzed processes.

The rapid migration and separation of photoinduced carriers is a key factor influencing photocatalytic efficiency. Constructing an S-scheme heterojunction is a strategic technique to enhance the separation of photo-generated carriers and boost overall catalytic activity. Herein, a simple physical stirring technique was adopted to successfully fabricate a novel NiCo₂S₄/CoTiO₃ S-scheme heterojunction photocatalyst. Upon exposure to light, the NiCo₂S₄/CoTiO₃-10 specimen demonstrated an outstanding hydrogen evolution rate of 2037.76 µmol·g⁻¹·h⁻¹, exceeding twice the rate observed for the pristine NiCo₂S₄ (833.72 µmol·g⁻¹·h⁻¹). The experimental outcomes reveal that the incorporation of CoTiO₃ significantly enhances the charge separation and transfer within the system. Concurrently, the formation of the S-scheme mechanism facilitates the separation of carriers while maintaining high redox capabilities. This work introduces an innovative approach to forming S-scheme heterojunctions based on bimetallic sulfides, thereby offering new prospects for the efficient utilization of solar energy.

Biochar belongs to the category of low-cost, stable, and environmentally benign carbon-based materials. In this article, the reasons that highlight the advantages of biochar materials to be used in carbon dioxide (CO₂) adsorption are briefly viewed with recent examples. Also, the issues to be solved for recommending biochar materials in the practical applications are listed.

The dynamics of methanol within prototype methanol synthesis catalysts were studied using quasi-elastic neutron scattering. Three Cu-exchanged zeolites (mordenite, SSZ-13 and ZSM-5) were studied after methanol loading and showed jump diffusion coefficients between 1.04 × 10⁻¹⁰ and 2.59 × 10⁻¹⁰ m²·s⁻¹. Non-Arrhenius behavior was observed with varying temperature due to methoxy formation at Brønsted acid sites and methanol clustering around copper cations.

The lateral dispersion of bed material in a bubbling fluidized bed is a key parameter in the prediction of the effective in-bed heat transfer and transport of heterogenous reactants, properties important for the successful design and scale-up of thermal and/or chemical processes. Computational fluid dynamics simulations offer means to investigate such beds in silico and derive effective parameters for reduced-order models. In this work, we use the Eulerian-Eulerian two-fluid model with the kinetic theory of granular flow to perform numerical simulations of solids mixing and heat transfer in bubbling fluidized beds. We extract the lateral solids dispersion coefficient using four different methods: by fitting the transient response of the bed to (1) an ideal heat or (2) mass transfer problem, (3) by extracting the time-averaged heat transfer behavior and (4) through a momentum transfer approach in an analogy with single-phase turbulence. The method (2) fitting against a mass transfer problem is found to produce robust results at a reasonable computational cost when assessed against experiments. Furthermore, the gas inlet boundary condition is shown to have a significant effect on the prediction, indicating a need to account for nozzle characteristics when simulating industrial cases.

Nowadays, global warming caused by the increasing levels of CO₂ has become a serious environmental problem. Membrane separation technology has demonstrated its promising potential in carbon capture due to its easy operation, energy-efficientness and high efficiency. Interfacial polymerization process, as a facile and well-established technique for preparing membranes with a thin selective layer, has been widely used for fabricating commercial reverse osmosis and nanofiltration membranes in water treatment domain. To push forward such an interfacial polymerization process in the research of CO₂ separation membranes, herein we make a review on the regulation and research progress of the interfacial polymerization membranes for CO₂ separation. First, a comprehensive and critical review of the progress in the monomers, nanoparticles and interfacial polymerization process optimization for preparing CO₂ separation membrane is presented. In addition, the potential of molecular dynamics simulation and machine learning in accelerating the screen and design of interfacial polymerization membranes for CO₂ separation are outlined. Finally, the possible challenges and development prospects of CO₂ separation membranes by interfacial polymerization process are proposed. It is believed that this review can offer valuable insights and guidance for the future advancement of interfacial polymerization membranes for CO₂ separation, thereby fostering its development.

A class of supramolecular binary hydrogels is formed from dodecylamine or tridecylamine and sparing carboxylic acids (with amine/acid molar ratio ⩾ 18). These hydrogels exhibit a remarkable thermally reversible four-phase transition. On heating, they transition from gel one (G¹)-to-sol one (Sol¹), then to gel two (G²)-to-sol two (Sol²). On cooling, they revert from Sol²-to-G²-to-Sol¹-to-G¹. Additionally, several G¹ and G² hydrogels undergo thermally reversible gel-to-gel phase transitions, which are reflected by translucent-opaque and opaque-translucent changes in their appearance. The nature of the four-phase transformation was analyzed using a range of techniques. Scanning electron microscopy images confirmed that the fibers of the opaque hydrogel at high temperatures were considerably larger than those of its translucent counterpart at low temperatures. Fluorescence emission spectra demonstrated that higher temperatures, higher amine/acid ratios, and greater acid hydrophobicity increased the hydrophobic interactions. Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopic analyses confirmed the existence of hydrogen-bonding interactions and aggregation in the hydrogels. X-ray diffraction profiles indicated that the hydrogels adopt lamellar structures. The findings advance our current understanding of the phase transition of supramolecular gels and facilitate the constitution of binary or multicomponent gels, providing a practical way to create new smart functional materials.