Transfer Capacity Research Articles

Modified eco‐friendly and biodegradable chitosan‐based sustainable semiconducting thin films

AbstractSemiconducting materials are pivotal in various fields, such as solar cells, LEDs, photovoltaic cells, etc. A nature‐friendly chitosan is a good film‐forming, water‐soluble polymer that is modified to a small band‐gap polymer for various optoelectronic applications. Choline chloride:ethylene glycol:glycerin (1:1:1) deep eutectic solvent (DES)‐modified activated carbon is incorporated into the chitosan matric and this composite is fabricated into thin films via spin coating methodology. The obtained films are subjected to multiple studies such as scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), impedance spectroscopy, and UV–vis spectroscopy to perceive the thin‐films microstructure, morphology, conductance, band gap, and optical nature. The integration of DES‐modified activated carbon has significantly improved the charge transfer capacity of chitosan by reducing the band gap from 4.0 to 2.0 eV. These notable characteristics exhibited by the modified films can be key to sustainable semiconducting materials and have the potential to transform several optoelectronic applications.

Adaptations to nitrogen availability drive ecological divergence of chemosynthetic symbionts.

Bacterial symbionts, with their shorter generation times and capacity for horizontal gene transfer (HGT), play a critical role in allowing marine organisms to cope with environmental change. The closure of the Isthmus of Panama created distinct environmental conditions in the Tropical Eastern Pacific (TEP) and Caribbean, offering a "natural experiment" for studying how closely related animals evolve and adapt under environmental change. However, the role of bacterial symbionts in this process is often overlooked. We sequenced the genomes of endosymbiotic bacteria in two sets of sister species of chemosymbiotic bivalves from the genera Codakia and Ctena (family Lucinidae) collected on either side of the Isthmus, to investigate how differing environmental conditions have influenced the selection of symbionts and their metabolic capabilities. The lucinid sister species hosted different Candidatus Thiodiazotropha symbionts and only those from the Caribbean had the genetic potential for nitrogen fixation, while those from the TEP did not. Interestingly, this nitrogen-fixing ability did not correspond to symbiont phylogeny, suggesting convergent evolution of nitrogen fixation potential under nutrient-poor conditions. Reconstructing the evolutionary history of the nifHDKT operon by including other lucinid symbiont genomes from around the world further revealed that the last common ancestor (LCA) of Ca. Thiodiazotropha lacked nif genes, and populations in oligotrophic habitats later re-acquired the nif operon through HGT from the Sedimenticola symbiont lineage. Our study suggests that HGT of the nif operon has facilitated niche diversification of the globally distributed Ca. Thiodiazotropha endolucinida species clade. It highlights the importance of nitrogen availability in driving the ecological diversification of chemosynthetic symbiont species and the role that bacterial symbionts may play in the adaptation of marine organisms to changing environmental conditions.

Heat and mass transfer analysis of desiccant-coated heat exchanger with desiccants and metal-organic framework for bus air conditioning applications

Desiccant-coated heat exchangers (DCHEs) in air conditioning offer advantages like independent temperature and humidity control, reduced energy consumption, and high performance. However, the availability of desiccants with high water adsorption and low thermal energy requirements is limited. The present study proposes that aluminum fumarate (Al-Fum) MOF-coated heat exchangers will outperform conventional desiccants, especially at low regeneration temperatures (around 50°C). In order to evaluate this hypothesis, the performance of DCHEs was evaluated with a validated analytical model for different solid desiccant coatings: silica gel, zeolite, and Al-Fum MOF. Water vapor sorption characteristics, heat and mass transfer, and adsorption and desorption capacities were determined. The results showed that the Al-Fum MOF-coated heat exchanger outperformed silica gel and zeolite at low regeneration temperatures under adiabatic conditions. The MOF exhibited superior water uptake capacity (0.39 g/g) between 20% and 80% RH compared to the other studied conventional desiccants. Moreover, the MOF achieved the lowest outlet air temperature. At 19.5 g/kgda, the MOF demonstrated higher adsorption rates (4 % and 0.3 %) than zeolite and silica gel. These findings highlight the potential of Al-Fum MOFs as energy-efficient solutions for controlling indoor air humidity, particularly for latent-sensible heat separation systems with conventional vapor compression bus air-conditioning systems.

The transformation of Cure4Kids: Expanding knowledge transfer capacity.

Global survival disparities among children with cancer and other catastrophic diseases are the driving force behind Cure4Kids' sustained outreach to healthcare professionals. Congruent with this need, Cure4Kids was redesigned to meet the emergent demands of diverse healthcare professionals seeking free, web-based pediatric hematology/oncology education. Herein, we present an overview of each phase of the design and development process for the transformation and describe key features of the new Cure4Kids and future opportunities for expansion.

Non-uniform boiling heat transfer characteristics and calculation evaluation in U-tube steam generator tube bundle

U-tube steam generator, as one of the core equipment in nuclear power plants, has lateral non-uniform heating on the secondary side, which complicates the progress of heat transfer on the secondary side of the evaporator by causing fluid cross mixing. However, there is relatively little research on the properties of transverse non-uniform heat transfer in the secondary side tube bundle of the evaporator under natural circulation conditions with the free liquid surface. Therefore, to conduct comparative experiments and studies between uniform and non-uniform heating, an experimental setup with the natural circulation of the free liquid surface and the ability of transverse non-uniform heating was constructed, considering the characteristics mentioned above for the secondary side of the evaporator. The results indicate that higher proportions of gas-phase distribution are frequently found in the tube bundle on the high-power side, and corresponding positions usually have higher water temperature, heat transfer capacity, and heat transfer coefficient. Besides, four heat transfer correlations that are suitable for pool boiling are estimated, and the results show that the Rohsenow correlation has the best applicability to compute the heat transfer coefficient for uniform heating experiments while performing worse in non-uniform heating experiments. The main reason is the lack of consideration for the factors of fluid cross mixing in traditional correlations.

Heterogeneous MoS2 Nanosheets on Porous TiO2 Nanofibers toward Fast and Reversible Sodium-Ion Storage.

2D layered molybdenum disulfide (MoS2) has garnered considerable attention as an attractive electrode material in sodium-ion batteries (SIBs), but sluggish mass transfer kinetic and capacity fading make it suffer from inferior cycle capability. Herein, hierarchical MoS2 nanosheets decorated porous TiO2 nanofibers (MoS2 NSs@TiO2 NFs) with rich oxygen vacancies are engineered by microemulsion electrospinning method and subsequent hydrothermal/heat treatment. The MoS2 NSs@TiO2 NFs improves ion/electron transport kinetic and long-term cycling performance through distinctive porous structure and heterogeneous component. Consequently, the electrode exhibits excellent long-term Na storage capacity (298.4mAhg-1 at 5Ag-1 over 1100 cycles and 235.6mAhg-1 at 10Ag-1 over 7200 cycles). Employing Na3V2(PO4)3 as cathode, the full cell maintains a desirable capacity of 269.6mAhg-1 over 700 cycles at 1.0Ag-1. The stepwise intercalation-conversion and insertion/extraction endows outstanding Na+ storage performance, which yields valuable insight into the advancement of fast-charging and long-cycle life SIBs anode materials.

Statistical modeling and multi-objective optimization of a flat tubular indirect evaporative cooler for enhanced performance

The flat tubular indirect evaporative cooler complements the conventional round tubular indirect evaporative cooler owing to its superior wetting surface area and enhanced heat transfer capacity. Given the multitude of influencing parameters, achieving a comprehensive analysis and optimization of the flat tubular indirect evaporative cooler demands a significant number of experimental tests or numerical simulations. Consequently, this study seeks to employ statistical techniques for constructing a precise and expeditious performance prediction model for the flat tubular indirect evaporative cooler. Nine pivotal parameters were selected to evaluate their impact on the cooling performance of the flat tubular indirect evaporative cooler. A numerical model was developed and verified experimentally. The response surface method was applied to establish polynomial regression equations for the cooling performance prediction of flat tubular indirect evaporative coolers. In addition, this work proposed a multi-objective optimization strategy for the proposed cooler. By innovatively using weighting factors to assign different weights to response values, multi-objective optimization with preferences was performed for the flat tubular indirect evaporative cooler with different demands to increase the applicability of the proposed cooler. The optimization results showed that when only the optimized wet-bulb efficiency was considered, the wet-bulb efficiency can reach up to 81.1%. When optimizing both the wet-bulb efficiency and the coefficient of performance simultaneously, the coefficient of performance can be up to 58.0, and the wet-bulb efficiency was 64.7%.

Fabrication of a Molybdenum Dioxide/Multi-Walled Carbon Nanotubes Nanocomposite as an Anodic Modification Material for High-Performance Microbial Fuel Cells.

A nanocomposite of multi-walled carbon nanotubes (MWCNTs) decorated with molybdenum dioxide (MoO2) nanoparticles is fabricated through the reduction of phosphomolybdic acid hydrate on functionalized MWCNTs in a hydrogen-argon (10%) atmosphere in a tube furnace. The MoO2/MWCNTs composite is proposed as an anodic modification material for microbial fuel cells (MFCs). MWCNTs have outstanding physical and chemical peculiarities, with functionalized MWCNTs having substantially large electroactive areas. In addition, combined with the exceptional properties of MoO2 nanoparticles, the synergistic advantages of functionalized MWCNTs and MoO2 nanoparticles give a MoO2/MWCNTs anode a large electroactive area, excellent electronic conductivity, enhanced extracellular electron transfer capacity, and improved nutrient transfer capability. Finally, the power harvesting of an MFC with the MoO2/MWCNTs anode is improved, with the MFC showing long-term repeatability of voltage and current density outputs. This exploratory research advances the fundamental application of anodic modification to MFCs, simultaneously providing valuable guidance for the use of carbon-based transition metal oxide nanomaterials in high-performance MFCs.

Experimental study of a low-cost reversible thermal diode for advanced heat manipulation

A low-cost reversible thermal diode was fabricated by a copper tube loop incorporating a valve in the top channel for advanced thermal management. The inner surface of one vertical tube was treated to superhydrophobic, while that of the other vertical tube was modified to superhydrophilic and further loaded with a superhydrophilic copper mesh for water wicking. Furthermore, the valve in the top channel can behave as a switch to control the hot vapor flow between the two vertical tubes. Then, different heat powers from 5 W to 15 W were applied to investigate the rectification effect of the thermal diode under low (30 %), medium (50 %), and high (70 %) filling ratios (FR) of the working fluid. The results showed that its rectification ratio could exceed 2.8 with the help of the control valve at FR = 30 %. Furthermore, the rectification effect could be reversed by the valve without flipping the thermal diode. In reversible working mode, the reversed heat transport could reach twice of the forward heat transport at FR = 50 %. Therefore, owning to the reversible heat transfer capacity, this study can guide the advanced thermal diode design for unstable waste heat recovery, solar energy harvesting, building energy management, etc.

Cu single atoms mediated multiple active site reconfiguration to trigger Dual-pathway nonradical peroxymonosulfate activation process

Developing atomically dispersed metal sites is vital to enhance the activation of peroxymonosulfate (PMS). However, for catalyst systems where single atoms and nanoclusters coexist, how to identify the independent and synergistic effects of atomic sites and investigate the possible coexistence of multiple activation mechanisms still remains a great challenge. Herein, CuSA/CoOx-CeO2 catalysts with Cu single atoms and CoOx nanoclusters were fabricated for PMS activation. The introduction of Cu single atoms led to the reconstruction and diversification of catalytic active sites of CoOx-CeO2. The synergy between CoOx nanoclusters and neighboring Cu single atoms in CuSA/CoOx-CeO2 catalyst led to the 1O2 pathway of PMS activation, while the isolated Cu atom induced the Cu(III) oxidation pathway. The introducing of adjacent Cu single atoms caused the redistribution of the site charges in CoOx nanoclusters, which enhanced the charge transfer and promoted the adsorption and activation behavior of PMS molecules. During the evolution of 1O2, the synergistic effect of Cu single atoms and CoOx nanoclusters increased the stability of the reaction intermediate state (*OO*SO3), reducing the total Gibbs free energy change (ΔG) required for 1O2 formation. Compared with the cooperative site, the isolated Cu-O4 sites exhibited stronger charge transfer capacity to PMS molecules and were more conducive to the activation of the local substrate electronic structure, facilitating the formation and stabilization of Cu(III)–OH metastable intermediates. Overall, this study demonstrated the importance about the construction of multi-site induced multipath coexisting PMS activation system and the accurate identification of active sites.

A comprehensive framework for targeting the disturbance propagation path and debottleneck strategy of chemical process considering the topology and cascading effects

For the chemical processes, multiple fluctuations exist, and elucidating the system's dynamic changes is essential in improving its adaptability. With changes in reactor and separator operating conditions and cascading effects related to the system's topological structure considered, a comprehensive framework is established to target the disturbance propagation path and determine cost-effective debottlenecking strategies. Relations among distillation column parameters and the seasonal change in ambient temperature are deduced considering meteorological data, and the utility demand or column pressure under various conditions can be determined. All independent subsystems of the heat exchanger network and their heat surplus/deficit are identified based on the improved information flow diagram and output difference analysis, and the disturbance propagation path is determined. Correlations are deduced to clarify the heat transfer capacity requirement under fluctuating states, and the bottlenecks and cost-effective debottlenecking strategy without topology modification are identified at different stages. The proposed method is intuitive and efficient and can be applied in chemical processes' enhancement, retrofitting, and fault diagnosis. A benzene alkylation process is studied, with the total annual cost decreased by 3.4 %.

Enhanced degradation of tetracycline with zinc-based adenine-derived P, N co-doped carbon via peroxydisulfate activation

In this study, a P, N co-doped carbon with excellent adsorption and peroxydisulfate (PDS) catalytic activity based on zinc-based adenine complex (Zn-Ade) derived has been designed and fabricated via a facile two-step pyrolysis strategy. Under the optimized conditions, the synthesized phosphorus and nitrogen co-doped carbon (PNC-4, 4 is the mass ratio of KH2PO4 to pristine nitrogen-doped carbon) has a high graphitic N and pyrrolic N and exhibited excellent catalytic activity in PDS activation. A small amount of PNC-4 (0.05 g/L) could remove about 92.44 % of TC within 80 min when the initial tetracycline (TC) concentration was 20 mg/L (PDS = 0.1 g/L; initial pH = 5.71), which could be attributed to the accelerated electron transfer and large adsorption capacity of PNC-4. The adsorption of TC on PNC-4 was chemisorption and the maximum theoretical capacity of adsorption (qmax) was 500.577 mg/g. The results of reactive oxygen species (ROS) capture experiments and electrochemical characterization confirmed that TC was oxidized mainly through electron transfer mechanism. Furthermore, the reaction rate constant (k) was significantly positively correlated with the graphitic N and pyrrolic N contents and weakly positively correlated with the defects, respectively. These findings demonstrated that graphitic N and pyrrolic N enhanced PDS activation and oxidized TC via the electron transfer pathway. Finally, the results of toxicity assessment showed that the toxicity of the intermediates were significantly reduced after TC degradation. This study not only propelled the mechanistic understanding of the collaborative contribution of active sites to PDS activation, but also offered a new strategy for the design of bifunctional carbon materials for adsorption and catalysis.

Investigation and evaluation of heat transfer enhancement for PEMFC under high current density based on a multiphase and non-isothermal electrochemical model

Heat management plays a vital role in the efficient and stable operation of proton exchange membrane fuel cells (PEMFCs), especially at high current densities, which is directly related to the cooling flow field (CFF). In this paper, a non-isothermal electrochemical model coupled with CFF of PEMFC is developed, and the effects of CFF structures on the water and heat transfer performance enhancement of PEMFC at high current densities are studied. In addition, an Evaluation Criteria is expected to be applied to evaluate the heat transfer capacity of CFFs. The results indicate that high temperatures effectively alleviate PEMFC concentration polarization. Due to the twists and turns design within the channel, the heat transfer capability of the Wave CFF performs well, Nusselt number and field synergy angle values respectively 35.7 % higher and 3.34 % lower than those of Parallel CFF. Additionally, the heat transfer performance factor is used to evaluate the heat transfer capability of different cooling flow field structures. The performance factor of the Wave CFF reaches 1.44 at a coolant temperature difference of 1 K.

Three-dimensional zwitterionic hydrogel-based evaporators with simultaneous ultrahigh evaporation rates and anti-fouling performance

Zwitterionic hydrogels (ZHs) are commonly adopted as evaporators to address the issues of low evaporation rate and poor salt resistance in solar-driven interfacial desalination due to their unique anti-polyelectrolyte (AP) effect. However, the inherent limitations of ZHs, including low water transfer rates compared to their evaporation rates and poor mechanical properties, have restricted their applications to two-dimensional (2D) evaporator configurations. Herein, we proposed a unique design of three-dimensional (3D) composite solar evaporators based on ZHs and polyvinyl alcohol (PVA) sponge to improve the water transfer capacity and mechanical properties of ZHs, and thus achieve ultrahigh evaporation rates and excellent anti-fouling performance. The porous structure and super hydrophilicity of PVA sponge endowed the prepared 5-cm-high ZH-based solar evaporators (ZHSE) with water transfer rates significantly faster than those without PVA sponge. In addition, the elastic PVA sponge component enhanced the mechanical properties of ZHSE, allowing it to easily fabricate 3D structures to obtain higher evaporation rates. Moreover, PVA sponge barely weakened the AP effect of poly(sulfobetaine methacrylate) (PSBMA) hydrogels in the ZHSE. Consequently, the evaporation rate of ZHSE reached 4.66 kg m-2 h-1 at 3.5 wt%, one of the highest among previous reports, attributed to the contributions from the 3D structural design of the evaporator and AP effect of ZHs. Meanwhile, ZHSE showed outstanding anti-fouling properties and excellent shape stability, working in 20 wt% brine ten hours a day for ten consecutive days without noticeable salt deposition and volume shrinkage. This work provides a new route to design high-performance hydrogel-based evaporators with high water transfer rates.

Enhanced Fenton performance of wet-mechanochemically synthesized FeS2/Biochar: The multiple synergistic effect derived from mutual element doping

FeS2-biochar composites have been considered as promising heterogeneous Fenton materials for pollutants removal. However, the chemical synthesis of element-doped FeS2-biochar composite with superior performance and the comprehensive investigation for its underlying multiple synergistic mechanism remain a difficult endeavor. Herein, a novel FeS2/Biochar nanocomposite with mutual element doping was firstly synthesized by facile wet-mechanochemical method using iron, sulfur and bamboo-biochar for efficient organic pollutant (sulfamonomethoxine, SMM) removal. Experiment and DFT calculation results revealed that multiple synergistic effect between FeS2 and biochar derived from newly formed Fe-C and C-S-C bonds induced the abundant reactive oxygen species (ROS) and excellent electron transfer capacity. Fe-C sites facilitated the H2O2 adsorption and populated O-O bond in H2O2 for its barrierless dissociation into •OH via forming bridging C-Fe-O-O-Fe bond. Oxygen vacancy, C-S-C and Fe-C bonds, persistent free radicals (PFRs) accelerated the generation and transformation of ROS, which resulted in dominating free radical (•OH, •O2–, •SO4-) and auxiliary non-radical (1O2) pathway. Meanwhile, Fe3+/Fe2+ redox-cycle was expedited by electron donor/shuttle (S22-, BC, •O2–, C-S-C and Fe-C bonds). All these specialties contributed to the superior performance of FeS2/Biochar Fenton system for SMM removal at wide pH range (3–11) with negligible Fe release. Completely SMM (50 mg/L) removal was achieved within 20 min for 8 successive reuses. This work emphasized the concept of building mutual element doping on molecular level in enhancing FeS2-Biochar synergy towards efficient environmental remediation.

Diffusion-driven fed-batch fermentation in perforated ring flasks

PurposeSimultaneous membrane-based feeding and monitoring of the oxygen transfer rate shall be introduced to the newly established perforated ring flask, which consists of a cylindrical glass flask with an additional perforated inner glass ring, for rapid bioprocess development.Methods A 3D-printed adapter was constructed to enable monitoring of the oxygen transfer rate in the perforated ring flasks. Escherichia coli experiments in batch were performed to validate the adapter. Fed-batch experiments with different diffusion rates and feed solutions were performed.ResultsThe adapter and the performed experiments allowed a direct comparison of the perforated ring flasks with Erlenmeyer flasks. In batch cultivations, maximum oxygen transfer capacities of 80 mmol L−1 h−1 were reached with perforated ring flasks, corresponding to a 3.5 times higher capacity than in Erlenmeyer flasks. Fed-batch experiments with a feed reservoir concentration of 500 g glucose L−1 were successfully conducted. Based on the oxygen transfer rate, an ammonium limitation could be observed. By adding 40 g ammonium sulfate L−1 to the feed reservoir, the limitation could be prevented.Conclusion The membrane-based feeding, an online monitoring technique, and the perforated ring flask were successfully combined and offer a new and promising tool for screening and process development in biotechnology.

Preparation and Analysis of New Hybrid PAEK Nano-Composites Containing MWCNT, Inorganic and Organic Nano-Particles

In modern era light weight material with complex shape and high material properties is required for advanced applications at room temperature. In this concern, the experimental study analysis to observe the effect of different nanofiller material like GO, MWCNT, NH2 and COOH modified MWCNT as organic nanofiller and WS2 and MoS2 as inorganic nanofiller reinforced in pure PAEK. This experimental study focuses on incorporation of organic and inorganic nanofillers separately and combine as hybrid nanofiller nanocomposite. On preparation of PAEK nano-composite and hybrid nanocomposite the comparative study of mechanical properties like tensile, flexural and impact is carried out. The nano-composites were prepared by melt compounding method. Scanning Electron Microscopy confirm the homogenous dispersion and alignment of nanofilers. The hybrid nano-composites show highest tensile strength as compared to the organic and in-organic nanofiller nanocomposite. As the percentage of MWCNT increases from 0.2 to 1 wt% , the properties of nano-composites decreases due agglomeration tendency of MWCNT that results in low load transfer capacity of nanocomposite, therefore agglomeration tendency of MWCNT required to be controlled for preparation of nano-composite and this is achieved by reinforcing Hybrid nanofillers to pure PAEK matrix. However, organic filler shows 75 MPa to 83 MPa tensile properties and which is lower compared to in-organic and hybrid filler due agglomeration tendency of organic nanofiller confirmed by SEM analysis.

Analysis of geothermal heat recovery from abandoned coal mine water for clean heating and cooling: A case from Shandong, China

Exploiting heat from abandoned mine water using heat pumps is attracting increasing attention worldwide. China has a large number of abandoned coal mines, but there are few applications of geothermal heat recovery from mine water. Here, we report a new case from Shandong, North China. Based on actual geological and underground space structures, numerical analysis is performed to study the flow and heat transfer in the complex connection network among roadways. For given temperature differences on the source side, the underground heat transfer is greatly influenced by flow rates in roadways. Under the acceptable performances and long-term stability of heat pumps, the maximum heat transfer capacity of roadways reaches 697.3 kW at the flow rate of 100 m3/h, with the power per unit length of 151.3 W/m, indicating a promising heat recovery potential. When switching between the extraction and injection well, both fluid directions and the distribution of flow rates in roadways change obviously, thereby affecting the underground heat transfer. Besides dominant flow paths, there exist weak flow paths, which can be identified by numerical analysis, and necessary blocking can be applied to optimize the flow and heat transfer. Excessively long horizontal straight roadways for heat exchange should be avoided.

Design of Soft/Hard Interface with High Adhesion Energy and Low Interfacial Thermal Resistance via Regulation of Interfacial Hydrogen Bonding Interaction.

Adhesion ability and interfacial thermal transfer capacity at soft/hard interfaces are of critical importance to a wide variety of applications, ranging from electronic packaging and soft electronics to batteries. However, these two properties are difficult to obtain simultaneously due to their conflicting nature at soft/hard interfaces. Herein, we report a polyurethane/silicon interface with both high adhesion energy (13535 J m-2) and low thermal interfacial resistance (0.89 × 10-6 m2 K W-1) by regulating hydrogen interactions at the interface. This is achieved by introducing a soybean-oil-based epoxy cross-linker, which can destroy the hydrogen bonds in polyurethane networks and meanwhile can promote the formation of hydrogen bonds at the polyurethane/silicon interface. This study provides a comprehensive understanding of enhancing adhesion energy and reducing interfacial thermal resistance at soft/hard interfaces, which offers a promising perspective to tailor interfacial properties in various material systems.

Differential responses of the electron transfer capacities of soil humic acid and fulvic acid to long-term wastewater irrigation

Wastewater irrigation is used to supplement agricultural irrigation because of its benefits and freshwater resource scarcity. However, whether wastewater irrigation for many years affects the electron transfer capacity (ETC) of natural organic matter in soil remains unclear, and organic matter could influence the decomposition and mineralization of substances with redox characteristics in soil through electron transfer, ultimately affecting the soil environment. The composition of soil humic substances (HS) is highly complex, and the effects of soil humic acid (HA) and fulvic acid (FA) on ETC is poorly understood. In this study, we separately evaluated the responses of the electron-accepting capacity (EAC) and electron-donating capacity (EDC) of soil HA and FA in agricultural fields to various durations of wastewater irrigation. Results showed that the EAC of HA and FA increased significantly with increasing the duration of wastewater irrigation. When wastewater irrigation lasted for 56 years, the EAC of HA showed a higher increment (590 %) than that of FA (223 %). The EDC of soil HA and FA, conversely, decreased compared to the control, with the highest reduction of 35.6 % for HA and 65.9 % for FA. Specifically, the EDC of HA gradually decreased starting from 29 years of wastewater irrigation, whereas the decrease in the EDC of FA exhibited no clear pattern in relation to the duration of wastewater irrigation. Increased soil organic matter and total nitrogen content under long-term wastewater irrigation led to an increase in sucrase and phosphatase activities, along with an increase in EAC and a decrease in EDC of HS. This suggests that soil enzyme activities may ultimately lead to changes in ETC. The results of this research provide practical insights into the redox system in soil and its driving role in soil organic matter transformation and nutrient cycling under wastewater irrigation.