Pore Blocking Research Articles

Role of Microfiltration Membrane Morphology on Nanoparticle Purification to Enhance Downstream Purification of Viral Vectors.

In the rapidly advancing realms of gene therapy and biotechnology, the efficient purification of viral vectors is pivotal for ensuring the safety and efficacy of gene therapies. This study focuses on optimizing membrane selection for viral vector purification by evaluating key properties, including porosity, thickness, pore structure, and hydrophilicity. Notably, we employed adeno-associated virus (AAV)-sized nanoparticles (20 nm), 200 nm particles, and bovine serum albumin (BSA) to model viral vector harvesting. Experimental data from constant pressure normal flow filtration (NFF) at 1 and 2 bar using four commercial flat sheet membranes revealed distinct fouling behaviors. Symmetric membranes predominantly showed internal and external pore blockage, while asymmetric membranes formed a cake layer on the surface. Hydrophilicity exhibited a positive correlation with recovery, demonstrating an enhanced recovery with increased hydrophilicity. Membranes with higher porosity and interpore connectivity showcased superior throughput, reduced operating time, and increased recovery. Asymmetric polyether sulfone (PES) membranes emerged as the optimal choice, achieving ∼100% recovery of AAV-sized particles, an ∼44% reduction in model cell debris (200 nm particles), an ∼35% decrease in BSA, and the fastest operating time of all membranes tested. This systematic investigation into fouling behaviors and membrane properties not only informs optimal conditions for viral vector recovery but also lays the groundwork for advancing membrane-based strategies in bioprocessing.

Sol-gel coating containing carbon quantum dots for effective corrosion prevention

This study investigates the impact of carbon quantum dots (CQDs) on the corrosion protection properties of sol-gel coating on AM60B alloy. CQDs were synthesised via microwave technique and characterised using Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and X-ray Diffraction (XRD). Adding 50 ppm CQDs eliminated micrometric cracks in the coating due to chemical bonding with the silica network. Transmission Electron Microscope (TEM) images revealed that CQDs are well dispersed at 50 ppm in the coating. Also, the Atomic Force Microscopy (AFM) confirmed that this concentration reduces the coating's roughness. Electrochemical Impedance Spectroscopy (EIS) in sodium chloride solution revealed a significant reduction in both electrical double- layer and sol-gel layer capacitances after adding 50 ppm CQDs. This indicates reduced penetration of the corrosive electrolyte, attributed to pore blocking and the elimination of micrometric cracks. After 48 h of immersion, the polarisation resistance (Rp) increased from 0.006 to 0.353 MΩ cm2, significantly enhancing the anti-corrosion performance. However, higher concentrations (100 and 200 ppm) of CQDs negatively impacted the corrosion resistance due to the accumulation and micrometric crack formation.

Impacts of ball-milling on ZSM-5 zeolite properties and its catalytic activity in the two-phase glycerol ketalization with acetone

A series of acidic ZSM-5 zeolites were mechanically ball-milled for different periods and further applied as catalysts in the liquid-phase glycerol ketalization with acetone. Structural and textural characterizations showed that the samples had considerable crystallinity and micropore volume loss due to amorphization. On the other hand, due to a comminution effect, the external surface area increased and particle size reduced. TPD and FTIR analyses with probe molecules with different sizes, such as ammonia, pyridine (Py), and 2,6-di-tert-butylpyridine (DTBPy) chemisorbed on the catalyst acid sites, aided in quantifying the various levels of accessibility of chemicals. The treated materials lost acidity due to amorphization or blockage of pores, but the milling enabled higher accessibility of bulkier chemicals to acid sites, as revealed by the chemisorption of Py and DTBPy. A crucial balance of acidity, accessibility, and hydrophobicity was tailored by milling time. The one-hour grounded zeolite had a glycerol conversion 35 % greater than the pristine sample and 67 % greater than the eight-hour milled sample. The results showed that ball milling is a tool to improve the catalytic activity of zeolites with bulky chemicals by fine-tuning the milling time.

AFM Analysis of Polymeric Membranes Fouling

This work represents a part of a larger work, aimed at evaluating the fouling behavior of different flat polymeric membranes for low-pressure applications when placed in contact with industrial wastewater (IWW). To design and understand the operation of a membrane process it is essential to know the fouling mechanisms. Commercial PVDF and PS membranes were tested under static conditions. The reduction in membrane flux was calculated, before and after the fouling tests. Parameters such as membrane material, pore size, solids concentration, particle size, pH, temperature, flow rate, and pressure were studied to identify the fouling behavior of the membrane. The strong adhesion of organic molecules on the membrane surface develops a resistance to pore blockage which allows a significant decrease in the flow of clean water. It is important to note that membranes of the same material, PVDF, but with different pore size (0.2 and 0.5 mm), and membranes of different materials, PVDF and PS, but with the same pore size (0.2 mm) were tested to study the trend of surface fouling to predict it and/or design surface modifications of the membranes employed. A morphological analysis of the membranes was carried out to understand the fouling mechanism, the fouling times, and the nature of the block that determines the reduction of flow through the membrane itself. Roughness measurements reveal that roughness goes up to 120 minutes of immersing time in wastewater, but after 4 hours it returns to initial value but with a significant decrease of flux to water. Understanding the relationship between flux decline, morphology, and roughness role is key to preventing fouling and studying a valid method to clean the membrane.

Description of non-ideal effects in composite membranes by a new theoretical approach

In present study, a theoretical model is introduced to calculate the gas permeability of mixed matrix membranes (MMMs) containing porous fillers. This model is based on analogy of gas permeation in MMMs with tensile modulus in composites. The representative parameters of MMM morphologies such as polymer chains tightening around the filler (β<1), unselective channel formation (β>1) and polymer chains penetrating into filler pores (0≤α≤1) which leads to the filler pore blocking are all included in the model. Furthermore, the interphase thickness (t) which is a critical parameter of MMMs participates in calculation equation along with the other parameters. To validate the proposed model, an experimental study with poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend as polymer matrix and zeolite 4A and NH2-MOF-199 as fillers is performed. The obtained gas permeability data of constructed MMMs and some of the literature data are employed to be fitted with the proposed model. The details of the existence morphologies of MMMs can be described by earning the mentioned parameters ranges. Therefore, by this model, by having a measure of t, the gas permeation of MMM can be achieved accompany with details of the related morphologies. All the theoretical investigations are done utilizing one equation which contains all parameters simultaneously.

Lattice Boltzmann study of liquid water flow and freezing in the gas diffusion layer

The flow and freezing process of liquid water in the gas diffusion layer (GDL) is studied using a proposed lattice Boltzmann method that integrates the multi-component pseudo-potential model and the enthalpy-based method. The evolution of liquid water, ice, and temperature distributions inside the GDL during this process is specifically analyzed, and the effect of GDL porous structure, such as porosity and carbon fiber diameter, is discussed. Results indicate that liquid water exhibits a propensity to break through the GDL through the regions characterized by larger pores, subsequently forming a liquid droplet on the GDL surface and beginning to freeze. The freezing process extends from the droplets to the CL side through the liquid pathways within the GDL. In addition, liquid water is more prone to freezing around carbon fibers. Due to the released latent heat during freezing, the temperature at the liquid water/ice interface stabilizes at 273 K. Moreover, it is also demonstrated that a large porosity and coarse carbon fibers both facilitate the flow of liquid water into the GDL where it then freezes, leading to more serious blockage of pores by ice and liquid water.

Spectroscopic analysis and prediction of membrane fouling potential of NOM in the continuous membrane filtration-submersed (CMF[sbnd]S) reactor

The long-term running continuous microfiltration-submersed (CMFS) reactor was built and spectral indicators, organic matter, and fouling potential were monitored. The specific filtration volume decline rates (V0.5 and V0.25) and unified membrane fouling index (UMFI) were characterized as pore blocking, gel layer, and cake layer fouling potential, respectively. Spectral analysis results showed the parameters of both S275–295 (slope of log-transformed absorption coefficient with the range of 275–295 nm) and SR (the ratio of S275–295 and S350–400) were significant correlations with V0.5, V0.25, and UMFI. The humification index (HIX) had stronger correlations with UMFI, proving the humic acids (HA) had more significant impacts on the cake layer. The V0.5 and V0.25 had correlations with the ratio of peak T to peak C (fT/C) because the aromatic proteins (PN) were more involved in the pore blocking. Statistical analysis results showed that V0.5 and V0.25 were mainly contributed by the polysaccharide (PS) and the interactions of PS × PN × HA, while UMFI was mainly contributed by the HA and PS × PN × HA interactions. The multivariate linear regression (MLR), backpropagation neural network (BPNN), and support vector regression (SVR) models were successfully employed to achieve multiple signals fusion and prediction potential, with the SVR model having better accuracy, especially for UMFI.

Alkylation of Phenol with Methanol over ZSM‐5 Zeolite

AbstractThe catalytic performance of different molecular sieves in the alkylation of phenol with methanol to produce p‐cresol was evaluated, and the acidity and structure of the catalysts were characterized using N2 adsorption–desorption and Fourier transform infrared spectroscopy techniques. It was shown that the catalytic activity of molecular sieves was closely related to their acidic site number, specific surface area, and pore structure. Since Zeolite ZSM‐5 (Zeolites Socony Mobil No. 5) has a relatively small amount of strong acid as well as a small pore size, it is favorable for the diffusion of p‐cresol out of the pores. Therefore, focusing on ZSM‐5, the effects of operating conditions such as weight hourly space velocity (WHSV), phenol/methanol (P/M) ratio, and reaction temperature on the catalytic performance were investigated. The results showed that increasing the WHSV, P/M ratio, and reaction temperature improved the selectivity to cresol. In addition, X‐ray diffraction and Thermal Gravity/Differential Thermal Gravity characterization methods were also carried out for ZSM‐5, and it was found that the deactivation of ZSM‐5 was due to coke deposition and pore blockage on the active site and that the selectivity to cresol could be restored by regenerating the catalyst and covering the strong acid site, which resulted in the reduction of the strong acid site to increase the selectivity of the product.

Sustainable metal-organic framework based paper sheet as wallpaper for passive indoor moisture control

Passive indoor moisture control is a meaningful way to reduce HVAC operation and improve building energy efficiency. Metal-organic frameworks (MOFs) have been considered one of the most promising sorbent materials for passive indoor moisture control. However, the powder form of MOF is challenging to use in the built environment. Typical shaping methods like pellets, beads, and coating can lead to problems like partial pore blocking, insufficient mechanical stability, amorphization, and low material utilization. Here, we report a new sustainable MOF paper sheet comprising 25% cellulosic fibers and 75% MOF MIL-100(Fe) powder. The porous polymer matrix provides good support and fixation for MOF particles, so it’s more applicable in the built environment. The crystalline and pore structure characteristics of the MOF in the membrane are well preserved. Hydro characteristic test results show that MIL-100(Fe) paper sheet has high water vapor uptake, S-shape isotherm, mild regeneration condition, and high MBV. Then, a numerical model was developed to calculate the relation between a material’s MBV and its thickness. MIL-100(Fe) paper sheet with the most efficient thickness was applied as wallpaper in a building energy simulation model. The simulation result shows that the MIL-100(Fe) paper sheet is promising for passive indoor moisture control. It can remove about 45%-55% of the latent cooling load in most European climate types.

Investigating effective strategies for sustainable operation of a submerged anaerobic membrane bioreactor (SAnMBR) coupled with ceramic ultrafiltration membrane

This study presents a mechanistic approach to explore the key operational parameters governing the flux performance of an SAnMBR system coupled with a ceramic flat-sheet ultrafiltration membrane. Experiments were conducted at mixed liquor suspended solid (MLSS) concentrations of 12, 18, and 24 g/L using biogas sparging, backwashing, and a combination of both to investigate the most effective fouling mitigation strategy by exploring the fouling mechanism at a critical flux regime. To validate the experimental findings, a mathematical model was used to simulate the time-based variation of membrane effective pore radius (m), decrease in membrane porosity (%), thickness of cake layer (m), and membrane resistance (1/m). The study found that at a low biomass concentration, there was a sharp decline in the membrane pore radius leading to an increase in membrane resistance in the absence of any fouling mitigation strategies. However, by implementing these strategies individually and in combination, they maintained a higher pore radius and controlled the increase in membrane resistance even at high biomass concentrations. It was observed that biogas sparging outperformed the conventional backwashing strategy and the SAnMBR system exhibited superior performance attaining higher flux rates for prolonged duration. The advanced spectroscopic analysis confirmed the presence of a higher concentration of polysaccharides responsible for cake layer biofouling, and significant pore blocking due to inorganic foulants at high biomass concentrations. This suggests that the SAnMBR system must be operated at optimised biomass levels below the critical flux for sustained operation. Additionally, the key operational parameters identified using the mathematical model provide a precise assessment of SAnMBR performance, to improve its design efficiency for field applications.

Titanate-grafted carbon black-facilitated MPLs for advanced proton exchange membrane fuel cells

This study introduces a novel hydrophobic modification for microporous layers (MPLs) in proton exchange membrane fuel cells (PEMFCs), utilizing a chemical grafting method with Titanate coupling agent NDZ-201 on carbon black. This method overcomes the drawbacks of traditional MPLs that use polytetrafluoroethylene (PTFE) and require high-temperature post-processing, which can lead to pore blockage. The treated carbon black exhibits outstanding hydrophobic properties, enhancing both water and gas flow through the cell, thereby significantly boosting its electrochemical capabilities. With an ideal carbon loading of 2 mg cm⁻² for MPL, the cell delivers an impressive peak power density of 1045.8 mW cm⁻². The treatment also increases the contact angle of the carbon black from 65° to 156°, achieving superhydrophobicity through covalent bonding with NDZ-201. This fluorine-free, covalent grafting approach presents a new method for the development of MPLs for PEMFCs, facilitating performance improvement and sustainability. The study highlights the significance of the intricate interplay among various factors, including chemical grafting for hydrophobicity, carbon loading and open pores, affecting fuel cell performance.

Study on efficiency and mechanism of ultrasonic controlling membrane fouling in ceramic membrane bioreactors.

In recent years, ceramic membranes have been increasingly used in membrane bioreactors (MBRs). However, membrane fouling was still the core issue restricting the large-scale engineering application of ceramic MBRs. As a novel and alternative technology, ultrasonic could be used to control membrane fouling. This research focused on the efficiency and mechanism of ultrasonic controlling membrane fouling in ceramic MBRs. The results showed that ultrasonic reduced the sludge concentration in MBR, and the average particle size of sludge was always in a high range. The sludge activity of the system was stable at 6-9 (mg O2·(g MLSS·h)-1), indicating that ultrasonic did not destroy the activity of microorganisms in the system. The extracellular polymer substance (EPS) of the ultrasonic group was slightly higher than that of the control group, while the soluble microbial product (SMP) content was relatively stable. The ceramic membrane of the ultrasonic group has a partial retention effect on the organic components. The application of ultrasonic slowed down the decrease of the hydrophilicity of the ceramic membrane. The main pollutants on the membrane surface exist in the form of aromatic and heteroaromatic rings, alkynes, and so forth. Ultrasonic removes the amide substances from the membrane surface. Membrane fouling resistance is mainly due to membrane pore blockage, accounting for 75.53%. PRACTITIONER POINTS: Enrich the research on the mechanism of ultrasonic technology in membrane fouling control. The MBR can still operate normally with ultrasonic applied. The time for the ceramic membrane to reach the fouling end point is 2.4 times that without ultrasonic. The main cause of membrane fouling was pore blocking, accounting for 75.53%.

La0·8Mn0·2FeO3 impregnated ceramic membrane for membrane fouling elimination via peroxymonosulfate activation

To endow SiC ceramic membranes a catalytic self-cleaning capability, a pore-functionalized SiC ceramic membrane with impregnated a perovskite-type catalyst La0·8Mn0·2FeO3 was fabricated by a urea-assisted one-step combustion method. Diffraction of X-ray (XRD), canning electronic microscopy (SEM) with an energy dispersion X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were employed to investigate the effects of the impregnating of La0·8Mn0·2FeO3 on SiC membrane pore-structure (La0·8Mn0·2FeO3-CM). The catalytic self-cleaning performance of the as-prepared membranes was assessed through peroxymonosulfate (PMS) activation under a cross-flow filtration mode. Results indicate that La0·8Mn0·2FeO3 has been successfully impregnated into the macropores of SiC membranes without pore blocking, and 92.4 % of the flux recovery rate (FRR) was achieved when the PMS concentration was 70 mM and catalytic flushing time was 45 min. Therefore, the La0·8Mn0·2FeO3 impregnated SiC membrane exhibited excellent catalytic self-cleaning property, which can effectively avoid the environmental pollution and the deterioration of membrane materials caused by chemical cleaning for membrane fouling. In addition, the radical quenching experiment and electron spin resonance (EPR) tests were conducted in the catalytic self-cleaning process, and the results suggested that the hydroxyl radical (⋅OH) and sulfate radical (SO4•‾) are simultaneously captured and ⋅OH is the dominant active species. This study embarks on a novel and environmental friendly membrane cleaning approach for irreversible fouling eliminates in diverse membrane separation applications.

Melamine Network as a Solution for Significant Enhancement of the Mechanical, Adsorptive, and Surface Properties in a Novel Carbon Nanomaterial-Silica Aerogel Composite.

Silica aerogels exhibit exceptional characteristics such as mesoporosity, light weight, high surface area, and pore volume. Nevertheless, their utilization in industrial settings remains constrained due to their brittleness, moisture sensitivity, and costly synthesis procedure. Several studies have proved that adding nanofillers, such as carbon nanotubes (CNT) or graphene nanoplatelets (GNP), can improve the mechanical strength of the aerogels. The incorporation of nanofillers is often accompanied by agglomeration and pore blockage, which, in turn, deteriorates the surface area, pore volume, and low density. Including flexible melamine foam (MF) as a scaffold for the silica aerogel and nanofiller composite can prevent the restacking of the nanofillers through π-π interaction, hence maintaining the incredible properties of aerogels and improving their mechanical properties. CNT, GNP, and the polymeric silica precursor, polyvinyltrimethoxysilane (PVTMS), were added to a MF, at varying concentrations, to fabricate the MF-aerogel nanocomposites. Surfactant and sonication were utilized to ensure a homogeneous dispersion of the nanofillers in the system. The presence of MF prevented the agglomeration of nanofillers, resulting in lower density and relatively higher surface properties (SBET up to 929 m2·g-1 and pore volume up to 4.34 cc·g-1). Moreover, the MF-supported samples could endure 80% strain without breakage and showed an outstanding compressive strength of up to ∼20 MPa. These aerogel nanocomposites also demonstrated an excellent volatile organic compound (∼2680 mg·g-1) and cationic dye adsorption (∼10 mg·g-1).

Manganese dioxide-coated biocarbon for integrated adsorption-photocatalytic degradation of formaldehyde in indoor conditions

Formaldehyde is a common indoor air pollutant with hazardous effects on human health. This study investigated the efficiency of biocarbon (BC) functionalized with variable contents of MnO2 for formaldehyde removal in ambient conditions via integrated adsorption-photocatalytic degradation technology. The sample with the highest formaldehyde removal potential was used to prepare a functional coating made of acrylic binder mixed with 20 wt% of the particles and applied on beech (Fagus sylvatica L) substrate. SEM images showed that MnO2 was deposited around and inside the pores of the BC. EDX spectra indicated the presence of Mn peaks and increased content of oxygen in the doped BC compared to pure BC, which indicated the successful formation of MnO2. Raman spectra revealed that the disorder in the BC's structure increased with increasing MnO2 loadings. FTIR spectra of BC–MnO2 samples displayed additional peaks compared to the BC spectrum, which were attributed to MnO vibrations. Moreover, the deposition of increased MnO2 loadings decreased the porosity of the BC due to pores blockage. The BC sample containing 8 % Mn exhibited the highest formaldehyde removal efficiency in 8 h, which was 91 %. A synergetic effect between BC and MnO2 was observed. The formaldehyde removal efficiency and capacity of the coating reached 43 % and 6.1 mg/m2, respectively, suggesting that the developed coating can be potentially used to improve air quality in the built environment.

CO2 adsorption and storage over FAU-zeolites for environmental remediation: Understanding the role of oxygen vacancy and promotor loading

The CO2 level is rising in the atmosphere and has reached well above 400 ppm. Thus, there is growing concern about increasing CO2 levels in the atmosphere as it is a greenhouse gas, constituting 20–25 % of total greenhouse gas emissions. CO2 is quite a resilient molecule and is a by-product of any combustion-driven process. The CO2 conversion is a non-spontaneous process due to its strong stability. The IEA and IPCC constantly mandate laws to monitor and regulate CO2 emissions in the atmosphere. One efficient way is to scrub off CO2 coming out of the exhaust. Several technologies have been developed around this concept, like adsorption and absorption. In this work, we have used zeolite for CO2 adsorption. Four different zeolites with a Si/Al ratio of one, which possess varied pore diameters of 3 Å, 4 Å, 5 Å and 10 Å are tested for CO2 adsorption. The zeolite with the pore diameter of 5 Å exhibited the best performance, which adsorbed 0.3 mmol/g (13.203 mg/g) of CO2. The adsorption capacity of zeolites is further enhanced by creating oxygen vacant sites and loading sodium (Na) promotor. The creation of oxygen vacancy ∼11 % for MZE600 sample raises the CO2 adsorption by 1.6 times compared to the ZE. Various concentrations of Na promotor are loaded on zeolite namely 5,10,15,20,25,35 %. About 11.97 mmol/g (527 mg/g) of CO2 adsorption was observed for 25 % loading of Na promotor on zeolite (M25NaZE). With the sequential increase in promotor loading (up to 25 %), CO2 adsorption increases. Further increase in loading reduces the CO2 adsorption, attributed to blockage of pores on sorbent and plausible agglomeration of the promotor. The M25NaZE sample is stable for a minimum of 10 regeneration cycles and exhibits linear response to variation in CO2 concentration from 2.5 % to 16 % and feed flow rate of 50–500 mL/min.

A novel algorithm for asphaltene precipitation modeling in shale reservoirs with the consideration of capillary pressure during the CCUS processes

Tight and shale reservoirs have markedly expanded their role in global oil and gas production. However, the overall recovery from these reservoirs is suboptimal, leaving much of the shale oil unrecovered. CO2 flooding is a promising enhanced oil recovery (EOR) technique that can improve oil extraction and simultaneously facilitate carbon capture, utilization, and storage (CCUS). However, this method presents challenges, notably the precipitation and deposition of asphaltene, which risks plugging the nanoporous structure characteristic of shale reservoirs. Given that the nanopore sizes in these reservoirs align closely with asphaltene particle dimensions, the risk of pore and throat blockages during gas injection is pronounced. Although various asphaltene precipitation models have been proposed, there is still a lack of robust algorithms accounting for the substantial influence of capillary pressure on asphaltene precipitation in these nanopores. In this study, a novel three-phase vapor–liquid-asphaltene equilibrium calculation algorithm coupled with capillary effect is developed. The algorithm is first validated by comparing with the experimental data of the Px phase diagram and asphaltene precipitation amount. The validated algorithm is then used to conduct example calculations to demonstrate the robustness of the new algorithm and to examine the impact of capillarity on the three-phase vapor–liquid-solid (VLS) equilibria. Computation results show that capillary pressures in nanopores substantially modify the three-phase VLS equilibria, causing shifts in saturation pressure and influencing asphaltene precipitation. Generally, asphaltene precipitation in nanopores occurs at a lower pressure and gas injection concentration. The smaller pore sizes intensify these effects, but the impact diminishes as pressure increases. Additionally, the gas composition also greatly affects asphaltene precipitation. The results reveal that this new algorithm is robust across different conditions, offering an innovative approach that reliably predicts asphaltene precipitation considering the effect of capillary pressures, paving the way for improved EOR and CCUS in shale reservoirs.

Selective furfural hydrodeoxygenation over Cu-Fe catalysts with In-Situ Cu@Fe3O4 formation

This study investigates Cu-Fe mixed oxide catalysts with varying Cu/Fe molar ratios (0.5 to 2) synthesized via a sol–gel method for vapor-phase FFR HDO. The catalysts were characterized using XRD, H2-TPR, NH3-TPD, N2 physisorption, FESEM and XPS to gain sights into their properties. The characterizations unveiled the critical role of Cu/Fe molar ratio in influencing the properties and performance of the catalysts in FFR HDO. Fe promoted the dispersion of CuO, especially at a Cu/Fe ratio of 1, revealing synergistic Cu-Fe interactions. Increasing Cu/Fe ratio enhanced the reducibility of Fe but diminished that of Cu. Extensive investigations were conducted to assess the impact of key parameters, including Cu/Fe ratio, temperature, contact time, reduction temperature and H2/FFR molar ratio. The Cu-Fe mixed oxide catalyst with Cu/Fe = 1 proved to the optimal catalyst, exhibiting > 99 % FFR conversion and 90 % 2-MeF selectivity at H2/FFR = 15, 230 °C, and 0.5 gFFR h−1 gcatalyst-1. The extended evaluation of catalytic activity demonstrated sustained high performance, with stable conversion and 2-MeF selectivity values of > 99 % and 90 % over a period of 12 h. Even after 24 h on stream, the conversion remained above 90 %. Subsequent regeneration study showed partial recovery of the activity, with the catalyst maintaining conversion and selectivity consistently at about 85 % and 86 %, respectively for 10 h. Catalyst deactivation was a result of the site and/or pore blockage caused by the adsorption of FFR and FAL as well as the formation of oligomeric compounds on the catalyst’s surface.

Eliminating adverse effects of fouling layer using composite membranes with dense surface layers for sustainable membrane distillation of high-strength wastewater

This study explored composite membranes (CMs) with dense and water-permeable surface layers for the deep-concentration of high-strength wastewater using membrane distillation (MD). Compared to conventional microporous MD membranes, coating a dense PVA surface layer avoided the detrimental effects of landfill leachate (LFL) foulants (e.g., membrane pore blockage and deformation) during MD concentration. The hydrophilicity and water/salt separation capability of surface layers enhanced the dispersion of water diffusion on membrane surfaces and altered the solute distribution on membrane cross-sections, resulting in inorganic crystallization mitigation and transforming the fouling layer structure to a more porous and water-permeable state. This ensured the membrane efficiency was little affected by membrane fouling even as LFL was highly concentrated (water flux decline: PVDF ∼49 % vs. CM ∼14 % as concentration factor increased to 20). The resistance of foulant intrusion and in-pore deposition, which easily occurred on microporous membranes, and the decrease in membrane-foulant interactions by the surface layer endowed the CM with a high foulant-release capability (clean efficiency: ∼97 %). The surface layer also exhibited an ammonia/water sieving effect which enhanced volatile ammonia rejection (∼1.6 times). This work provides insight into the construction of high-sustainable MD membranes for high-strength wastewater treatment, promoting the practical implementation of MD.

Study on the Temperature and Water Distribution of Hot Air in Red Loam Based on Soil Continuous Cropping Obstacles

In recent years, the problematic circumstances of the constant cropping problem in facility crops have become increasingly serious. Compared to chemical disinfection, soil steam disinfestation offers the benefits of environmental protection and being pollution-free, which can effectively reduce the problem of constant cropping in crops. However, during the steam disinfection procedure, a large quantity of liquid water is formed due to the condensation of high-temperature steam, which causes soil pore blockage, seriously affecting the mass and heat transfer efficacy of steam and, thus, affecting the disinfection efficiency. Therefore, to solve this problem, this paper proposes the use of hot air dehumidification to remove excess water from soil pores and achieve the goal of dredging the pores. However, further exploration is needed on how to efficiently remove excess water from different pore structures through hot air applications. Therefore, this paper first used CFD simulation technology to simulate and analyze the hot air flow field, mass, and heat transfer in soil aggregates of different sizes (&lt;2 mm to &gt;8 mm). Then, based on the soil hot air heating experimental platform, research was conducted on the mass and heat transfer mechanism of hot air under diverse soil pore conditions. The results show that as the soil particle size increases from &lt;2 mm to &gt;8 mm, the number of soil macropores also increases, which makes the soil prone to the formation of macropore thermal currents, and the efficiency of hot air heating for dehumidification first increases and then decreases. Among them, the 4–6 mm treatment has the best dehumidification effect through hot air heating, with a deep soil temperature of up to 90 °C and a water content reduction of 6%. The 4–6 mm treatment has a high-temperature heating and dehumidification area of 15–20 cm deep. The above results lay the theoretical foundations for the parameters of hot air heating and dehumidification operations, as well as the placement of the hot air pipe. This paper aims to combine hot air dehumidification technology, for the removal of excess water from soil, and dredging soil pores, ultimately achieving the goal of improving soil steam disinfection efficiency.