Fast Water Transport Research Articles

Superhydrophilic and highly elastic monolithic sponge for efficient solar-driven radioactive wastewater treatment under one sun

As an effective way to obtain solar energy and separate the soluble contaminants from water, solar-driven interfacial evaporation is used in desalination, wastewater treatment, electricity generation, and domestic water heating system. Herein, we demonstrate a monolithic sponge with three-dimensional porous structure as the solar-energy evaporator, which is composed of hydrophilic polymer (Konjac Glucomannan, KGM) and solar absorbent (reduced graphene oxide, rGO). Under one sun irradiation, the sponge achieves a rapid evaporation rate (1.60 kg m−2 h−1) and high interfacial water evaporation efficiency (92 %) due to its good absorption, photothermal, thermal insulation, and fast water transport properties. Meanwhile, the concentrations of radioactive elements (strontium, cesium, and uranium) in wastewater dropped from grams to micrograms after purification, even under radiation and acidic conditions. Additionally, the durability and repeatability of the sponge also have been verified. The results showed that solar-driven interfacial evaporation can effectively treat radioactive wastewater and enrich various radionuclides in a more energy-saving manner.

Two-state diffusive mobility of slow and fast transport of water in narrow nanochannels.

Transport of water in narrow nanochannels as a single-file chain is involved in various biological activities and nanofluidic applications. However, although the consistent dipole orientation of the water molecules is intensively studied, its effect upon the transport behavior is still unknown. In this Rapid Communication, we find two states of slow and fast transport coexist in the single-file water in the presence of channel defects that break the collective dipole orientation. A low diffusive mobility is found for the dipole orientation inconsistent configurations while mobility approximately two times higher is found for the consistent ones. The two-state diffusion process relies on the different hydrogen bond connections, which possess overlapped structures, enabling a spontaneous transition. The slow state is insensitive to the increased defect number while the fast state is reduced accordingly. The two states exhibit different lifetime and temperature dependences that demonstrate a possibility for manipulation. Our result implies the possibility of two-state diffusion process of water in nanofluid phenomena due to the common presence of defects in nanochannels.

Root-like polyamide membranes with fast water transport for high-performance nanofiltration

The surface of the nanoparticle-templated membranes formed the root-like structure which could provide more rapid nanochannels for water molecules transport.

Exploring fast water permeation through aquaporin-mimicking membranes.

Using molecular dynamics simulations, herein, we illustrate that a bending structure shows different behaviors for fast water transport through aquaporin-mimicking membranes in multilayer graphene and tubular structures. This suggests that the bending structure enhances water transport through multilayer membranes, indicating the optimum state at θ = 45°. Disruption of the single-file water arrangement inside the membrane can contribute to promoting water transport in this system. However, a bending structure reduces the rate of water transport in tubular systems. Our results exhibit that a straight tubular membrane transfers water molecules faster than its non-straight counterpart. A stabilized form of the single-file water structure was observed in the membrane. Interestingly, we found that the tubular hourglass-shaped membranes possessed a lower free energy than the multilayer membranes with an hourglass shape. This can be attributed to the accommodation of the single-file water configuration in a confined space with hydrophobic characteristics. Accordingly, integrating an hourglass shape pore in a tubular structure in an impermeable membrane provides high water permeability compared with its multilayer counterpart. We also found that the wide variation in the dipole orientation of water molecules and the energy barrier have dominant effects in determining fast water transport through multilayer and tubular membranes, respectively. The contribution of interlayer spacing on fast water transport through multilayer membranes was also studied.

Carbon quantum dots (CQDs) nanofiltration membranes towards efficient biogas slurry valorization

In this article, novel nanofiltration (NF) membranes with highly selective surface and fast water and ion transport channels were fabricated for the valorization of biogas slurry. Unlike conventional thin film composite (TFC) membranes, the novel NF membranes compose hydrophilic carbon quantum dots (CQDs) as the interlayer. The carboxyl groups from CQDs react with the polyethyleneimine (PEI), leading to the lower cross-linking degree in the interfacial polymerization layer of NF membranes. Besides, the presence of the hydrophilic CQDs can create fast water and ion transport channels in the NF membranes. The water permeability of membranes is therefore enhanced significantly from 3.6 to 9.7 LMH·bar−1. The NF membranes were used to concentrate the amino acids from biogas slurry; it achieved rejection rates above 90% towards model amino acids such as lysine, glutamic acid and leucine, due to its highly positive electrical properties, while allowing most of the unwanted salt ions to permeate through. The excellent selectivity between amino acids and salt ions demonstrates the great potential application of the NF membranes in biogas slurry valorization.

Self-assembled core-shell polydopamine@MXene with synergistic solar absorption capability for highly efficient solar-to-vapor generation

As a renewable and environment-friendly technology for seawater desalination and wastewater purification, solar energy triggered steam generation is attractive to address the long-standing global water scarcity issues. However, practical utilization of solar energy for steam generation is severely restricted by the complex synthesis, low energy conversion efficiency, insufficient solar spectrum absorption and water extraction capability of state-of-the-art technologies. Here, for the first time, we report a facile strategy to realize hydrogen bond induced self-assembly of a polydopamine (PDA)@MXene microsphere photothermal layer for synergistically achieving wide-spectrum and highly efficient solar absorption capability (≈ 96% in a wide solar spectrum range of 250–1,500 nm wavelength). Moreover, such a system renders fast water transport and vapor escaping due to the intrinsically hydrophilic nature of both MXene and PDA, as well as the interspacing between core-shell microspheres. The solar-to-vapor conversion efficiencies under the solar illumination of 1 sun and 4 sun are as high as 85.2% and 93.6%, respectively. Besides, the PDA@MXene photothermal layer renders the system durable mechanical properties, allowing producing clean water from seawater with the salt rejection rate beyond 99%. Furthermore, stable light absorption performance can be achieved and well maintained due to the formation of ternary TiO2/C/MXene complex caused by oxidative degradation of MXene. Therefore, this work proposes an attractive MXene-assisted strategy for fabricating high performance photothermal composites for advanced solar-driven seawater desalination applications.

Biomass Carbon Materials for Efficient Solar Steam Generation Prepared from Carbonized Enteromorpha Prolifera

Solar steam generation is a promising technique using solar energy to obtain fresh water from seawater, industrial waste water, or sewage. In the current work, a green‐tide waste, enteromorpha prolifera (EP), is used as raw material to prepare efficient absorbers and light‐to‐heat converters for solar steam generation. The EP waste is treated by a one‐step carbonization process to produce carbonaceous EP foam that exhibits strong absorption in a wide spectrum from ultraviolet to near‐infrared regions. The carbonaceous EP foam shows a solar steam generation efficiency of 89% under 5‐sun irradiation. The hydrophilic surface characteristics, highly porous structure, and long‐range continuous channels of the carbonaceous EP foam enable fast water transport and sufficient water supply for solar evaporation. Fresh water recovered from seawater and dye wastewater completely meets with the standards of drinking water. The strategy can not only reduce the cost of solar steam generation materials but also enable large‐scale application.

Atomic insight into water and ion transport in 2D interlayer nanochannels of graphene oxide membranes: Implication for desalination

Currently, graphene oxide (GO) membrane is becoming a new-generation material for desalination application with high water permeability and ion rejection rate. The unusual 2D interlayer nanostructure in GO membrane provides a reliable and precise molecular sieving function for fast water transport and ion rejection. However, the studies on molecular mechanisms for water and ion transport in the 2D interlayer nanochannels of GO membrane are far from adequate, and the trade-off between selectivity and permeability is another problem significantly restraining the further development of GO membrane for desalination. In this work, molecular dynamics simulations were conducted to investigate the atomic mechanism of water and ion transport in 2D nanochannels of GO membrane, and the influences of interlayer space and nanostructure on water and ion transport were also revealed. We find that there are strong electrostatic, vdW and hydrogen bond interactions between water/ion and the oxygen-containing groups in GO nanosheets, which largely impedes their transport. The hydration interaction also plays an important role in ion adsorption in the 2D nanochannels. The fast water and ion transport in GO membrane mainly occurs in the non-oxidized region of neighboring GO nanosheets. By combing the influences of interlayer space and nanostructure on water and ion transport, a new design principle for high-efficient GO desalination membrane is proposed. The findings in this work expand our understanding of water and ion transport in GO membrane and may also greatly promote the development of desalination membrane prepared by other 2D materials.

The Key Role of Water Activity for the Operating Behavior and Dynamics of Oxygen Depolarized Cathodes

AbstractAdvanced chlor‐alkali electrolysis with oxygen depolarized cathodes (ODC) requires 30 % less electrical energy than conventional hydrogen‐evolution‐based technology. Herein, we confirm that the activities of hydroxide and water govern the ODC performance and its dynamics. Experimental characterization of ODC under varying mass transfer conditions on the liquid side reveals large differences in the polarization curves as well as in potential step responses of the electrodes. Under convective transport in the liquid electrolyte, the ODC is not limited by mass transfer in its current density atj>3.9 kA m−2, whereas transport limitations are already reached atj≈1.3 kA m−2with a stagnant electrolyte. Since gas phase conditions do not differ significantly between the measurements, these results are in contrast the common assumption that oxygen supply determines ODC performance. A dynamic model reveals the strong influence of the electrolyte mass transfer conditions on oxygen availability and thus performance. Dynamic responses of the current density to step‐wise potential changes are dominated by the mass transport of water and hydroxide ions, which is by orders of magnitude faster with convective electrolyte flow. Without convective liquid electrolyte transport, a high accumulation of hydroxide ions significantly lowers the oxygen solubility. Thus, a fast mass transport of water and hydroxide is essential for high ODC performance and needs to be ensured for technical applications. The predicted accumulation of ions is furthermore validated experimentally by means of scanning electrochemical microscopy. We also show how the outlined processes can explain the distinctively different potential step responses with and without electrolyte convection.

Zwitterionic electrospun PVDF fibrous membranes with a well-controlled hydration for diabetic wound recovery

This works describes the formation of nanofibers made of poly(vinylidene fluoride) (PVDF) and a zwitterionic copolymer prepared from the reaction of 3-iodopropionic acid with a polymer of polystyrene and poly(4-vinylpyridine), zP(S-r-4VP). After presenting the copolymer, we move onto the characterization of nanofibers. It is proven that zP(S-r-4VP) is well distributed, from mapping FT-IR images, and that its concentration at the surface gradually increases with the initial copolymer content in solution. The PVDF/zP(S-r-4VP) nanofibers hydration capacity is enhanced, compared to virgin PVDF, leading to improved resistance to fibrinogen (75% reduction), Pseudomonas aeruginosa (>90% reduction), Staphylococcus aureus (>80% reduction) and Escherischia coli (>95% reduction), cells from whole blood (>95% reduction), but also L929 cells (85% reduction). Besides, steam sterilization does not negatively impact the antibiofouling properties of the membranes. Given their highly porous nature, ability to remain hydrated, antibiofouling property, nonsticky property and improved hemocompatibility, these nanofibers were applied onto diabetic wounds (type 2), leading to faster wound recovery than commercial DuoDerm™ bandage (14 days vs. 17 days), while histological analysis unveiled a complete remodeling of the skin tissue. Faster water transport though the zwitterionic nanofibrous membrane than through the commercial dressing suggests faster removal of exudates away from the wound bed, which is necessary in the case of highly exuding wounds.

Bola-amphiphile-imidazole embedded GO membrane with enhanced solvent dehydration properties

Inspired by fast and selective water transport in natural Aquaporin (AQP), imidazole-quartet water channels (IQWC) constructed by imidazole-ureido (IU) molecular scaffolds, are excellent candidates to design membranes with fast and selective water transport properties. In this work, a water binding IU bola-amphiphile-imidazole compound was embedded with the hydrophilic and laminated graphene oxide (GO) to prepare IU-GO membrane. H NMR, TG, XRD, SEM, AFM and FTIR were conducted to characterize physicochemical properties of IU and IU-GO membrane. It was demonstrated that IU could well interact with GO to generate a robust membrane structure. The resulting IU-GO membranes were applied for pervaporation dehydration of n-butanol-water. The total flux and the separation factor of the optimized IU-GO membrane were 3506 g·m-2·h-1 and 4454 respectively when the membrane was measured at 343 K with butanol content of 80 wt%. Furthermore, the membrane exhibited good stability and separation performance during 120 h continuous operation test, showing great potential in application of solvent dehydration.

Development of Water Vapor Transport Resistance Protocol and Analysis

W. L. Gore and Associates, Inc. (Gore) supports the lowest $/kW fuel-cell systems through development of thin, reinforced membranes, ca. 10 µm or less. Thin membranes decrease cost by reducing material content and facilitate higher performance through increased proton conductance and faster water transport. However, it has been postulated that an interfacial water transport resistance, significantly different than the bulk resistance, will dominate for thin membranes. For example, in a previous study, the interfacial effect accounted for half of the total transport resistance for a 10 µm membrane at 30% RH1. Understanding water transport through the membrane is necessary for system-level models to design optimal operation strategies. Gore implemented a protocol and analysis method for characterizing water transport properties of cation exchange membranes. Water flux is driven across the membrane by a chemical-potential gradient at different water activity levels. The water balance is tracked by monitoring the dew point at cell inlet and outlet and closes within 10%. Fick’s law is used to normalize flux data by the activity gradient across cell and inverted to calculate a total transport resistance. Cell hardware with 5 cm2 active area and straight-channel flow field configuration was used. Further details will be discussed in this presentation. Using this method, the bulk permeability of extrusion cast Nafion 11x films is 0.16 µmol/cm/s at 30% relative humidity (RH) and 95 °C, which is in agreement with literature at similar conditions1. An Evaluating the Measurement Process (EMP) study was used to quantify the amount of variation arising from measurement device and operator. With a sample size of 4, the protocol is able to detect a difference in total water transport resistance greater than 0.3 m2-s/mol. The protocol was used to study a series of 700 EW cast film thicknesses from 7 – 70 µm to separate individual contributions to the total water transport resistance, RTotal = RGas + RBulk + RInterfacial. The gas-phase transport resistance, RGas, was separated using hydrogen and nitrogen carrier gasses. The bulk water transport resistance, RBulk, is equal to thickness divided by bulk permeability. Figure 1a shows bulk permeability increases with higher water content, as expected due to the percolating network of water conducting channels2. Typically, any residual resistance is attributed to an interfacial effect, which has been rationalized by the orientation of the hydrophobic backbone toward surface2. In this study, the interfacial resistance is indistinguishable from zero. The equivalent thickness of membrane interface is shown in Figure 1b as a function of RH. ACKNOWLEDGMENTS The authors gratefully acknowledge the contribution of the Electrochemical Products team of W. L. Gore and Associates, Inc. REFERENCES Kienitz, B., Yamada, H., Nonoyama, N. & Weber, A. Z. Interfacial Water Transport Effects in Proton-Exchange Membranes. J. Fuel Cell Sci. Technol. 8, 011013-1-011013-7 (2011).Kusoglu, A. & Weber, A. Z. New Insights into Perfluorinated Sulfonic-Acid Ionomers. Chem. Rev. 117, 987–1104 (2017). Figure 1

Aquaporin and aquaglyceroporin genes have different expression levels in the digestive tract and Malpighian tubules of honey bee nurses and foragers (Apis mellifera)

The major intrinsic protein (MIP) is vital to a fast water transport through cellular membranes. Many studies about the insect MIP family, such as aquaporins and aquaglyceroporins, have been published so far, but research on honey bee (Apis mellifera) aquaporins is still poor. Five putative MIPs have been identified for the honey bee. We investigated the expression of one aquaporin and two aquaglyceroporins in the digestive tract and Malpighian tubules of nurses and foragers of A. mellifera. Honey bees were collected and dissected for mRNA extraction followed by cDNA synthesis. qPCR was performed with primers for Am_Eglp 1, Am_PRIP and Am_Eglp 2, and the reference gene RpL32. The expression profile varied depending on the evaluated organ and honey bee task. The crop of nurse bees showed higher transcript quantities for the three tested genes. In the midgut of nurse workers, Am_PRIP and Am_Eglp 2 were highly expressed, while Am_Eglp 1 had similar expression level comparing nurses and foragers. In the ileum and rectum, the tested MIPs are highly expressed in forager workers. In Malpighian tubules, Am_Eglp 1 was higher expressed in nurses, whereas Am_PRIP and Am_Eglp 2 had similar quantities in nurse and foragers. Our findings provide new data for future studies on the role of aquaporin and aquaglyceroporin in the digestion and osmoregulation of A. mellifera.

Combined Inhibitory Effects of Citrinin, Ochratoxin-A, and T-2 Toxin on Aquaporin-2.

Aquaporins form a large family of transmembrane protein channel that facilitates selective and fast water transport across the cell membrane. The inhibition of aquaporin channels leads to many water-related diseases such as nephrogenic diabetes insipidus, edema, cardiac arrest, and stroke. Herein, we report the molecular mechanism of mycotoxins (citrinin, ochratoxin-A, and T-2 mycotoxin) inhibition of aquaporin-2 (AQP2) and arginine vasopressin receptor 2. Molecular docking, molecular dynamics simulations, quantum chemical calculations, residue conservation-coupling analysis, sequence alignment, and in vivo studies were utilized to explore the binding interactions between the mycotoxins and aquaporin-2. Theoretical studies revealed that the electrostatic interactions induced by the toxins pulled the key residues (187Arg, 48Phe, 172His, and 181Cys) inward, hence reduced the pore diameter and water permeation. The permeability coefficient of the channel was reduced from native ((3.32 ± 0.75) × 10-14 cm3/s) to toxin-treated AQP2 ((1.08 ± 0.03) × 10-14 cm3/s). The hydrogen bonds interruption and formation of more hydrogen bonds with toxins also led to the reduced number of water permeation. Further, in vivo studies showed renal damages and altered level of aquaporin expression in mycotoxin-treated Mus musculus. Furthermore, the multiple sequence alignments among the model organism along with evolutionary coupling analysis provided the information about the interdependences of the residues in the channel.

Thermal-driven flow inside graphene channels for water desalination

A novel concept of membrane process in a thermal-driven system is proposed for water desalination. By means of molecular dynamics simulations, we show fast water transport through graphene galleries at a temperature gradient. Water molecules are driven to migrate through nanometer-wide graphene channels from cold reservoir to hot reservoir by the effect of thermal creep flow. Reducing the interlayer spacing to 6.5 Å, an abrupt escalation occurs in water permeation between angstrom-distance graphene slabs. A change from disordered bulklike water to quasi-square structure has been found under this extremely confined condition. This leads to a transition to subcontinuum transport. Water molecules perform collective diffusion behaviors inside graphene channels. The special transport processes with structure change convert thermal energy into motion without dissipation, resulting in unexpectedly high water permeability. The thermal-driven system reaches maximum flowrate at temperature variance of 80 K, corresponding to the quantity at pressure difference up to 105 bar in commercial reverse osmosis processes and 230 bar in pressure-driven slip flow. Our results also reveal the movement of saline ions influenced by thermophoretic effect, which complements the geometry limitation at greater layer spacing, enhancing the blockage of ions. This finding aims to provide an innovational idea of developing a high-efficiency desalination technology able to utilize various forms of energy.

The roles of metal-organic frameworks in modulating water permeability of graphene oxide-based carbon membranes

Graphene oxide (GO) can be processed into carbon membranes with unique water permeability and molecular selectivity. Metal-organic frameworks (MOFs) have been proposed as filler materials to enhance water permeability of laminar GO-based carbon membranes. However, it remains unclear how the enhancement arises. Herein, we combined experimental and molecular simulation studies to provide critical insights into the water transport behaviors of GO/MOF composite membranes. The water permeability enhancement was found to be directly correlated to the increase in the average interlayer spacing between GO nanosheets. The simulation results indicate a slower water transport through nanochannels in MOFs than in nanochannels formed by GO nanosheets. A small amount of MOF particles only serves as a blockage in laminar GO membranes, suppressing their water permeability. In contrast, a large amount of MOF particles increases the interlayer spacing between GO nanosheets and creates very fast water transport stretches. Besides, some large gaps are formed between non-smooth MOF particles and GO nanosheets, adding supplementary water channels to deliver higher water permeability. We envision a shift in future research direction to exploit the selective adsorption capacity of MOFs other than leveraging them as fast water transport channels to realize their potential water treatment applications.

Influence of hexagonal boron nitride nanosheets as the additives on the characteristics and performance of PVDF for air gap membrane distillation

In this study, composite membranes were fabricated through embedment of hexagonal boron nitride (h-BN) in the polyvinylidene fluoride (PVDF). Exfoliated h-BN nanosheets were characterized by transmission electron microscope (TEM). Then, different concentrations of h-BN were incorporated into PVDF to explore their impacts on the membrane performance. Various analyses comprising Fourier transform-infrared spectroscopy (FT-IR), energy dispersive X-ray (EDS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were applied to identify the membrane characteristics. The composite membrane properties including thermal and mechanical stability, liquid entry pressure (LEP), hydrophobicity, flux, and salt rejection were also investigated. Results showed that PVDF/h-BN membranes compared with PVDF had higher roughness, hydrophobicity, flux, and salt rejection. Applying operating temperature at 80 °C, M2 (contained 0.5 wt% h-BN) as the best membrane indicated flux of 7.1 kg/m2·h (43% increase compared to PVDF) and 99% salt rejection during 60 h continuous desalination process. These improvements in desalination performance were due to increase in pore size, porosity, and van-der-waals interactions between water and h-BN atoms that facilitated fast transport of water through membrane. Moreover, polar nature of BN bonds in h-BN induced high affinity with water that contributed to the selective separation of water through passing from the h-BN nanochannels.

Nucleate pool boiling enhancement by ultrafast water permeation in graphene-nanostructure

Nucleate boiling efficiency can be significantly enhanced using the nanostructured graphene surface. The wettability of the graphene nanoplatelets (GNPs) coated surface is tunable using thermal curing process. The uncured GNPs surface is hydrophobic in nature while the cured GNPs surface manifests a hydrophilic characteristic and the latter performs better than the former in the nucleate boiling regime. Ultimately the ultrafast water permeation property of the cured GNPs enhances the efficiency of nucleate pool boiling, leading to a maximum enhancement of 151% in the boiling heat transfer coefficient and 154% in the vapor mass flow rate. The boiling performance of the uncured GNPs surface is also enhanced despite its hydrophobicity. Hence, the enhancement in boiling is not solely attributed to the surface wettability. The enhancement is attributed to the fascinating ultrafast water permeation property of graphene on top of its nanoporous structure. The unimpeded fast water transport within the nanochannel-network of GNPs facilitates the fast absorption of latent heat of vaporization by the water molecules, leading to a substantial increase in the nucleation, growth and departure of vapor bubbles. We propose a new explanation on the role of graphene coating on nucleate pool boiling enhancement. This study provides important insights into the effects of ultrafast water permeation property of graphene on the nucleate boiling heat transfer.

Highways for water molecules: Interplay between nanostructure and water vapor transport in block copolymer membranes

Water vapor removal is a crucial process for several industries (e.g., air conditioning systems, flue gas dehydration, compressed air drying etc.). An effective dehumidification has the potential to drastically reduce the energy consumption and the overall cost of a process stream. Membranes with high water permeance and selectivity are promising candidates to achieve an energy-efficient water removal. We propose self-assembled membranes with interconnected and ordered hydrophilic domains that act as extremely fast water transport highways (water channels). We used a commercial amphiphilic pentablock copolymer (Nexar™), which has the ability to form long-range, self-ordering nanoscale morphologies with rigid end-blocks and a flexible molecular network where polar and non-polar solvents regulated the final morphologies of the membranes. Our results demonstrate how well-defined periodic morphology allow for molecular level control in effective removal of water vapor. The membranes with ordered hydrophilic nanochannels present a 6-fold improvement in water vapor permeability and a 14-fold increase in water vapor/N2 selectivity compared to Nexar™ membranes with disordered domains.Molecular dynamics stimulations are carried out on the self-assembly behavior of block copolymer solution in different solvents. In addition, sorption and desorption kinetics studies for Nexar™ films were correlated to the different morphologies imaged by transmission electron, atomic force and environmental scanning electron microscopy.

Particle Leaching Rates from a Loamy Soil Are Controlled by the Mineral Fines Content and the Degree of Preferential Flow.

The mobilization and transport of colloid particles in soils can have negative agronomic and environmental effects. This work investigates the controls of particle release and transport from undisturbed soil columns sampled from an agricultural, loamy field with clay and silt contents of 0.05 to 0.14 and 0.07 to 0.16 kg kg, respectively. Forty-five soil columns (20 × 20 cm) were collected from the field and exposed to a constant irrigation of 10 mm h for 8 h. The accumulated mass of particles in the outflow from each column was highly correlated ( = 0.88) with the volumetric mass of fines (MF). The MF is defined as the sum of clay and fine silt (<20 μm) multiplied by the soil bulk density and divided by the particle density of the mineral fines. Thereby, MF represents both the particle source available for mobilization and leaching and an indicator of soil structure. The particle release process showed two linear particle release rates. Although the two particle release rates were distinctly different, both were strongly correlated with MF. The difference between the two rates was related to the degree of preferential flow characterized by the 5% arrival time of an applied tracer pulse. Soil columns with a longer 5% arrival time (less preferential flow) showed a distinct difference between the two rates, whereas soil columns with a short 5% arrival time and fast water transport showed resemblance between the two particle release rates. Thus, the combined effects of particle source, type, and pathways (via soil structure and compaction) need consideration to understand and predict particle transport dynamics through intact topsoil.