Coagulation Of Particles Research Articles

Optimization of hydrolysis temperature in liquid phase deposition for TiO2 photocatalysis

TiO2 nanostructure could be produced at below 100 °C by means of liquid phase deposition (LPD), which is a green approach with low cost and low impact on the environment. The improvement of crystallinity is one of the main challenges toward efficient photocatalysis. Herein, we investigated the dependence of synthesis temperature on the crystal structure of TiO2 photocatalysts to provide higher photocatalytic efficiency. Scanning electron microscopy, X-ray diffraction, and Raman spectroscopy analysis confirmed the formation of waxberry-like TiO2 with an anatase phase with a synthetic temperature up to 80 °C. Both reaction temperature and time are found to dictate the crystallinity, structure, and size of the products, which could be attributed to the hydrolysis of a precursor (ammonium hexafluoro titanate), as well as the aggregation and coagulation of primary particles. The product synthesized at 70 °C for 3 h exhibited higher crystallinity, which led to higher photocatalytic efficiency observed based on the decomposition of methylene blue.

Brownian coagulation of like-charged aerosol particles

In this study we explore the role of Brownian coagulation on bidisperse like-charged spherical particles interacting via non-continuum hydrodynamics interactions. It is well established in the existing literature that van der Waals interactions enhance the coagulation rate. However, the role of near-field attractive electrostatic forces on the pair interactions of like-charged aerosols is relatively less explored. We have found that electrostatic interactions enhance the coagulation rate between like-charged Brownian particles while interacting through non-continuum hydrodynamics.

ნახშირის წვრილმარცვლოვანი ფრაქციის გაუწყლოების პროცესის ინტენსიფიკაცია ტყიბულის საბადოს პირობებში

Recently, the world is intensively exploiting renewable energy sources, yet coal still remains the main raw material for the energy, ferrous and non-ferrous metallurgy, chemical industries. The main coalfield currently operating in Georgia is the Tkibuli-Shaori minefield. Coals of Tkibuli minefield belongs to the category of difficultto-enrich minerals due to its complex physico-chemical composition. Due to the complexity of the technological process of enrichment, in the process of dehydration of the commodity product, a large amount (20-25%) of finegrained (-0.5 mm) fraction is formed - the so-called silts. These products, which due to the problem of its dehydration and consequently its separation as a separate product, now represent losses. Intensification of the dehydration process of the fine-grained fraction (1515 + 0 μm) clay product, in addition to reducing losses, allows circulating water to be used in the main enrichment process. Experiments have shown that during the treatment of wastewater in a magnetic field, the sedimentation rate of solid particles in the liquid increases dramatically, which is conditioned by the improvement of the particle coagulation process. Accordingly, the number of fine fraction losses in the runoff is reduced by 60-65%.

The Effect of pH Solution in the Sol–Gel Process on the Structure and Properties of Thin SnO2 Films

The synthesis of surface-active structures is important for creating many applications. The structural formation of SnO2 thin films in the range from 1.4 to 1.53 pH is studied in this work. This process occurs on the surface of the sample in the range of 1.4 to 1.49 and in the volume in the range of 1.51 to 1.53. SnO2 is formed after annealing at 400 ∘C, according to XRD. Doping NH4OH to solution stimulates particle coagulation and gel formation. All of these have an impact on the transparency of samples investigated by spectrophotometric methods. By increasing the pH, the resistance raises at room temperature. The Eg calculation along the fundamental absorption edge shows that it is greater than 3.6 eV’ for SnO2 films. According to the Burstein–Moss effect, a change of the bandgap is related to the increased concentration of the free charge carriers. Elemental analysis has shown that chlorine ions are considered to be additional sources of charge carriers. The value pH = 1.49 is critical since there is a drastic change in the structure of the samples, the decrease in transparency is replaced by its increase, and the energy of activation of impurity levels is changed.

Effect of the medium composition on the extraction of chromium, aluminium and iron hydroxides from wastewater by electroflotation

The process of electroflotation is used for treatment of wastewaters carrying heavy and non-ferrous metals in the form of poorly soluble compounds if the concentrations of contaminants are too high to be handled by adsorption process. The problem of raising the efficiency of electroflotation process is currently of relevance. This paper examines how the composition of the medium, i.e. the nature of the electrolyte, surfactants and hardness salts, can influence the extraction of iron, aluminum and chromium hydroxides from aqueous solutions by electroflotation. It was found that the electrolyte (NaCl, Na2SO4) nature has no significant effect on the process. The hydroxide extraction performance can be impacted by the presence of calcium ions regardless of the electrolyte nature. It happens due to the adsorption of Ca2+ on the hydroxide surface, which makes it more hydrophilic. The degree of dispersed phase extraction can be increased due to the introduction of surfactants: didecyldimethylammonium chloride, sodium dodecyl sulfate and a mixture of primary oxyethylated synthetic alcohols. Sodium dodecyl sulfate, which is an anionic surfactant, proved to deliver the best result. The high process efficiency in terms of dispersed phase extraction is due to the hydrophobization of the particle surface by adsorbed sodium dodecyl sulfate and the stabilization of gas bubbles. The particle sizes of iron and chromium hydroxides vary in the range of 0.04 to 4 microns. At the same time, most of the aluminum hydroxide particles are bigger than 10 microns, which can be attributed to the high polymerization ability of aluminum ions and subsequent particle coagulation. The efficiency of electroflotation extraction of chromium, aluminum and iron hydroxides in the presence of calcium ions using anionic surfactant is at least 90%. Additional filtration is recommended to ensure the treated wastewater is in compliance with applicable standard.

Role of gravity in coagulation of colloidal particles under low-shear environments

Shear rates play a critical role in the coagulation-flocculation-sedimentation processes of colloidal particles. Under high shear environments, it is widely accepted that the median floc size at equilibrium (D) decreases with an increase in shear rates (G). For low shear conditions, however, conflicting D-G relationships were measured in previous laboratory experiments, without a clear explanation of the reasons and a reasonable reproduction of the physical processes. In this study, the direct numerical simulation technique was used to mimic the flocculation of two typical colloidal particles (i.e., latex and silica) with different densities but under similar hydrodynamic conditions. Our results show that the previous different observations at low shear are mainly caused by particle gravity, which influences the particle residence time in a device system. They also confirm previous arguments about limited residence time due to gravitational settling being the reason for the observed peak, in accordance with Winterwerp (1998) [J. Hydraul. Res. Vol 36, pp. 309–326]. This study implies that to better investigate the shear-dominated flocculation of high-density particles such as sediments, settling processes should be addressed unless particles are always in suspension under specific conditions.

Modeling particle-particle binary coagulation rate constants for spherical aerosol particles at high volume fractions using Langevin Dynamics simulations

Effect of volume-fraction and particle-particle hydrodynamic interactions on the coagulation rate of particles are investigated. Particle coagulation is modeled using Langevin Dynamics (LD) based trajectory simulations of N mono-sized spherical particles in a periodic domain. The extended Kirkwood-Risemann approach (J. Fluid Mechanics 855, 535 (2018)) is invoked to compute particle-particle hydrodynamic interactions whose effect is parameterized as a function of the momentum Knudsen number (Kn). The results are summarized as a model for coagulation rate constant (βij) that depends on the diffusive Knudsen number (KnD) used in prior work to parameterize coagulation in the dilute regime (Aerosol Sci. Tech. 45, 1499 (2011)), Kn and particle volume-fraction ηv. In the absence of hydrodynamic interactions, it is observed that the coagulation rate constant in the continuum limit for mass transfer (KnD→0) is significantly enhanced by a factor of ∼80 at ηv∼0.3 due to particle crowding. While considering hydrodynamic interactions for ηv≥0.05, we use a screening distance around each particle that scales inversely with ηv beyond which the contribution of farther neighbors is neglected owing to the rapid decay of hydrodynamic interactions with distance. We also present new LD calculations of βij and elucidate the dependence of the same on Kn1 and the particle radii ratio θr for the coagulation of two particles in the dilute limit ηv→0. It is observed that the reduction of βij becomes significant as Kn1→0: at the lowest momentum Knudsen number considered (Kn1=0.1): βij is reduced by a factor of ∼10 for equally sized particles (θr=0.5). At high KnD,Kn1, the particle size disparity is not significant, and it is seen that βij matches hard sphere predictions, indicating the insignificant contributions by hydrodynamic interactions. A series of animations of 2-particle simulations are presented as part of the Supplemental Information to illustrate the role of hydrodynamic interactions in particle coagulation. Computational results are summarized as regressions for convenient incorporation into particle/droplet growth sectional models.

Numerical Study on the Coagulation and Breakage of Nanoparticles in the Two-Phase Flow around Cylinders.

The Reynolds averaged N-S equation and dynamic equation for nanoparticles are numerically solved in the two-phase flow around cylinders, and the distributions of the concentration M0 and geometric mean diameter dg of particles are given. Some of the results are validated by comparing with previous results. The effects of particle coagulation and breakage and the initial particle concentration m00 and size d0 on the particle distribution are analyzed. The results show that for the flow around a single cylinder, M0 is reduced along the flow direction. Placing a cylinder in a uniform flow will promote particle breakage. For the flow around multiple cylinders, the values of M0 behind the cylinders oscillate along the spanwise direction, and the wake region in the flow direction is shorter than that for the flow around a single cylinder. For the initial monodisperse particles, the values of dg increase along the flow direction and the effect of particle coagulation is larger than that of particle breakage. The values of dg fluctuate along the spanwise direction; the closer to the cylinders, the more frequent the fluctuations of dg values. For the initial polydisperse particles with d0 = 98 nm and geometric standard deviation σ = 1.65, the variations of dg values along the flow and spanwise directions show the same trend as for the initial monodisperse particles, although the differences are that the values of dg are almost the same for the cases with and without considering particle breakage, while the distribution of dg along the spanwise direction is flatter in the case with initial polydisperse particles.

PELATIHAN PRAKTIKUM SEDERHANA BERBASIS KIMIA HIJAU UNTUK GURU-GURU KABUPATEN OGAN ILIR SUMATERA SELATAN

Green chemistry is an alternative solution that can be used by chemistry teachers for safe and environmentally friendly chemistry experiments in schools. This community service aims to provide training to high school/vocational high school chemistry teachers in Ogan Ilir Regency, South Sumatra to carry out simple practical activities based on green chemistry. This service activity consists of 3 main stages, namely the preparation stage, the implementation stage and the evaluation stage. The target audience for this community service activity are 24 high school chemistry teachers from Ogan Ilir, South Sumatra. And furthermore, it is hoped that chemistry teachers who attend training can guide their chemistry teacher colleagues in their place. There are 7 simple green chemistry-based practical procedures collected from this service activity. The simple green chemistry-based practicum procedures are: 1) Redox reactions; 2) Making Binahong Covid-19 Herbal Soap; 3) Factors Affecting Reaction Rate; 4) Colloid-Tofu Making; 5) Colloids - Clumping (Coagulation) of Colloidal Particles; 6) Combustion of carbon compounds (complete and incomplete combustion); 7) Freezing Rubber Sap Using Pineapple Peel Extract. Overall, the target audience has been trained to make simple practical procedures based on green chemistry. This can be seen from the materials and practicum procedures that are in accordance with the basic principles of green chemistry, namely environmentally friendly, reducing environmental pollution, not classified as hazardous materials.

Computer simulation application for substantiation of industrial wastewater treatment technology

The wastewater treatment of the mining industrial enterprises is implemented using mechanical, chemical, biological and physic-chemical methods. The mechanical treatment is used to prepare wastewater for biological, physicochemical and other methods of the deep treatment. In recent years, the field of the physicochemical treatment methods application has been expanding, and their share among other methods has increased. The Mining Institute of the Kola Science Centre of the RAS has been developed a technology of the industrial wastewater treatment based on the synergetic effect of the pollution concentrating in a multiphase medium with formed surface properties of the phases, tested at the mining enterprises of the Kola MMC (Lovozero GOK LLC and Kovdor GOK) and including coagulation, sorption and flotation in activated water dispersion of air. To substantially reduce the cost, duration and complexity of the process of the developing wastewater treatment methods at mining enterprises, an approach based on the use of the mathematical and computer simulation methods, the development of the virtual laboratory benches that fully reproduce the technological processes and devices used. The mathematical simulation of the fine particles coagulation and aggregation in the process of the industrial wastewater treatment from dissolved impurities was carried out. The simulation made it possible to reveal the kinetics of the adsorption process of the contaminants components by the surface of the formed iron hydroxide colloidal particles, which determines the size and lifetime of the floccules. A virtual laboratory stand was created to study the water treatment processes based on the ANSYS Fluent software. This stand simulates the operation of the Outotec radial thickener with a diameter of 30 meters, which made it possible to develop recommendations for the technological regimes optimization for the greater particle aggregation efficiency. The possibility of the application in the technology the column flotation machine – an analogue of the flotation machine of the Canadian Process Technologies Inc. CETCO, was considered.The authors appreciate participation of Junior Researcher A. S. Kitaeva A. S. in the work on the article’s material.

Online colloidal particle monitoring for controlled coagulation pretreatment to lower microfiltration membrane fouling at a potable water reuse facility

Fouling of microfiltration (MF)) membranes during water/wastewater treatment is predominantly caused by colloidal particles (size <1 µm) in the feed water. Until recently no online technology was available to directly measure the occurrence of colloidal particles in these waters. This study evaluated the viability of a novel online light scattering technology (Nanoparticle Tracking Analysis) to continuously monitor colloidal particles in the membrane feed water (a secondary-treated wastewater) for targeted removal by injecting coagulant at a dosage proportional to the measured concentration of colloidal particles. A diurnal variation was observed in the colloidal particle concentration in the feed water with the lowest concentration occurring at approximately 6 am and the highest concentration occurring after mid-day. The peak colloidal particle concentrations were 4 to 6 times higher than the lowest concentrations measured on the same day. Bench-scale studies were performed to develop a relationship between colloidal particle concentration and the optimum coagulant dosage required for their removal. Subsequently, a pilot-scale study was performed using two MF pilot units operated in parallel, one receiving targeted coagulant dosing and the other with no coagulant dosing, to demonstrate the effectiveness of targeted coagulant dosing in preventing membrane fouling. The pilot unit that received targeted coagulant dose experienced only 4 to 20% of the transmembrane pressure increase of the increase experienced by the pilot unit that received no coagulant. Evaluation of fouling resistance indicated that targeted coagulation improved flux by predominantly lowering the irreversible fouling. The filtrate water quality measured by colloidal particle concentration, chemical oxygen demand (COD), and turbidity were very similar for the two pilot units. This suggests that although the efficiency of particle and organic materials removal does not change with coagulant addition, the particles filtered by the membrane in the control unit contributed to membrane irreversible fouling, while in the coagulant-treated unit, the coagulated colloidal particles were removed away from the membrane into the backwash stream during the frequent backwash/air scour procedures.

Organic Matter, Agricultural Use, and Dispersion of Ferralsols for Grain Size Analysis

ABSTRACT Ferralsols are a class of highly weathered, oxidic and often acidic and low fertility soils ubiquitous of the tropical environments. Ferralsols can present anomalous behavior when dispersion is performed for grain size analysis using settling methods. This study evaluates the effect of total dispersion and dispersed solution stability of two Ferralsols from Brazil, under cultivated areas and native savannah vegetation with or without organic matter removal using hydrogen peroxide (H2O2), on percent clay, silt, and sand estimation. Samples of a Rhodic Ferralsol and an Orthic Ferralsol were dispersed using a reciprocating shaker for 16 h at 120 rpm in sodium hydroxide (NaOH) solutions. Results show that chemical modifications associated with agriculture alter the dispersion behavior of the two Ferralsols. Removal of organic matter in cultivated areas caused coagulation of fine particles. For native vegetation sites, removal of organic matter increased soil dispersion increasing clay content and decreasing sand content. NaOH was not an effective dispersant agent in all conditions and thus there is a need for investigating better chemical compounds or combinations of thereof for the dispersion of Ferralsols. Standardization of grain size analysis of Ferralsols is needed for comparisons between different studies and laboratories to be possible.

Mass fractal dimension from 2D microscopy images via an aggregation model with variable compactness.

Microscopy-image analysis provides precious information on size and structure of colloidal aggregates and agglomerates. The structure of colloids is often characterized using the mass fractal dimension , which is different from the two-dimensional (2D) fractal dimension that can be computed from microscopy images. In this work, we propose to use a recent morphological aggregation model to find a relationship between 2D image fractal dimension and 3D mass fractal dimension of aggregates and agglomerates. Our case study is represented by scanning transmission electron microscopy images of boehmite colloidal suspensions. The behaviour of the computed at different acid and base concentration shows a fair agreement with the results of small angle x-ray scattering and with the literature, enabling to use the versus relationship to study the impact of the composition of the colloidal suspension on the density of colloidal aggregates andagglomerates.

Freeze-gelcasting of aqueous alumina powder suspension using natural rubber latex

A new and non-toxic aqueous alumina gelcasting system using natural rubber (NR) latex as a gel former has been studied. A gel of reasonable strength is achieved by freezing concentrated alumina-NR latex co-dispersions in a mould followed by mould removal and aging in acetone. Gelation is achieved by coagulation of latex particles due to the breakdown of the protein layer on their surface during ice crystal growth. The minimum concentration of rubber required to percolate and form a soft and stable gel is 8 wt % of alumina. Aging of the frozen body in acetone for solvent exchange results in strengthening of the alumina-rubber gel network by further coagulation leading to reasonably high strength (∼60 kPa). The frozen body passes through a semi-fluid state during aging in acetone which enables the gel to reorganize and fill the space created by melting of ice crystals and thereby preventing the occurrence of pores in the green ceramics. The exchange of water in the gelled body with acetone enables easy and faster gel drying at room temperature. The diametrical compressive strength of the green body increases from 0.35 to 2.14 MPa during annealing at 200 °C due to the cross-linking of rubber. The cross-linked rubber in the green body undergoes near-steady state burnout without creating any crack. Debinding followed by sintering of the gelcast bodies at 1550 °C produce ceramics of ∼96% density. The sintered ceramics show a dense microstructure with an average grain size of 1.3 μm. The gelcasting using the NR latex is capable of producing complex near-net-shapes.

The influence of cooling rate on condensation of iron, aluminum, and uranium oxide nanoparticles

Fundamental observations of particle size distributions are needed to develop models that predict the fate and transport of radioactive materials in the atmosphere following a nuclear incident. The extent of material transport is influenced by the time scales of particle formation processes (e.g., condensation, coagulation). In this study, we investigated the influence of cooling time scales on size distributions of uranium, aluminum, and iron oxide particles that are synthesized separately under identical run conditions inside the controlled environment of an argon plasma flow reactor. Two distinct temperature distributions are imposed along the flow reactor by varying the argon flow rate downstream of the plasma torch. The vaporized reactants of uranium, aluminum, and iron are cooled from about 5000 K to 1000 K before they are collected on silicon wafers for ex situ scanning electron microscope analysis. The microscope images show that the sizes of the largest aluminum and iron oxide particles heavily depend on the cooling time scales, whereas significant size variation with cooling rate is not observed for uranium oxide particles. In addition, the size distribution of aluminum oxide particles exhibits the broadest range among all three metal oxides studied. We performed simulations of particle size distributions using a kinetic model that couples gas phase oxidation chemistry with particle formation processes, including nucleation, condensation, and coagulation. The model results demonstrate the strong sensitivity of particle size distribution to different cooling histories (i.e., temperature vs residence time) along the flow reactor. The kinetic model also helps identify directions for future research to improve the predictions.

Enhancing fine particle separation by hybrid-electrostatic-turbulence coagulation: An experimental and numerical investigation

The electrostatic precipitator(ESP) has low efficiency in removing sub-micron particles. Coagulation technology, as a fine particle pretreatment technology, uses an external effect to agglomerate and grow fine particles, increase the average particle size, and make it easier to remove by subsequent dust removal equipment. However, the coagulation efficiency of a single coagulation technology is limited. Aiming at the particle charging mechanism and coagulation mechanism in the electric/turbulent composite coagulation process of fine particles, this paper uses a combination of numerical simulation and experiment to study the effects of different structural parameters, discharge parameters and flue gas parameters on corona discharge and particle charge. On this basis, the coagulation characteristics of charged particles in the turbulent flow field are studied. The results show that, when the Angle between the tip of the arista electrode is 90°, the corona discharge effect is the best. With the increase of supply voltage and temperature, the charge of particles increases. When the applied positive voltage is 29 kV and negative voltage is −35 kV, the total coagulation coalescence efficiency of fine particles reaches the maximum. The coagulation efficiency increases with the increase of temperature, but decreases with the increase of inlet flow rate.

Influence of H2O and SO3 on fine particles coagulation for sintering flue gas after desulfurization in an alternating electric field.

Electric coagulation of fine particles has been studied in the simulated sintering flue gas after semi-dry desulfurization to quantify the influence of H2O and SO3. The electric coagulation platform has a DC charging zone and an AC coagulation zone. Fine particles were divided into different diameter intervals to deeply explore the impact of H2O and SO3, including less than 0.15μm (PM0.15), 0.15-0.5μm (PM0.15-0.5) and 0.5-1μm (PM0.5-1). The particle charge, mass fractions of fine particles, and the mean diameter are measured and compared under water and SO3 atmosphere. The experiments showed that the increasing AC voltage helps particles larger than 0.5μm to coagulate but has little effect on the rest particles without H2O or SO3. Both H2O and SO3 enhance the PM1.0 AC coagulation. When flue gas relative humidity went up from 20 to 80%, the charge per particle maximally increased by 120%, as well as the mass fraction of PM0.5-1, PM0.15-0.5, and PM0.15 decreased by 83.2%, 64.5%, and 66.6%, respectively. When the SO3 concentration rose up from 0ppm to 12.3ppm, the charge per particle maximally increased by 100%, as well as the mass fractions of PM0.5-1, PM0.15-0.5, and PM0.15 decreased by 54.5%, 28.6%, and 33.3%, respectively. The impact of water and sulfuric mist on the particle intervals was sequenced as: PM0.5-1 > PM0.15 > PM0.15-0.5. The influence on PM1.0 AC coagulation was sequenced as H2O > sulfuric mist > AC voltage. Through data regression, H2O had approximate linear correlation with the particle mass fractions while the impact of sulfuric mist was non-linear. The interparticle forces were calculated to analyze the dominant force of particle AC coagulation with water: liquid bridge force > Coulomb force > > van der Waals force. The liquid bridge force indicated that liquid film was form on the surface of fine particles when water or sulfuric mist was added into the system which was the main reason enhancing the AC coagulation.

Acceleration effect of sodium halide on zeolite crystallization: ZSM-12 as a case study

In this work, the sodium halide, e.g., NaBr, NaCl, or NaF, was added into the synthesis system of ZSM-12 zeolite. The addition of sodium halide accelerated the crystallization of ZSM-12 zeolite, and the acceleration effect of different sodium halide increased in the order of NaBr < NaCl < NaF. To understand the acceleration mechanism of sodium halide, the crystallization process of ZSM-12 zeolite synthesized with and without sodium halide was studied comparatively by using XRD, SEM, TEM, TG and FTIR characterizations. Experimental results revealed that the accelerated crystallization of ZSM-12 zeolite arose from the combined effects of sodium cation and halide anion. The sodium cation induced the coagulation of colloidal particles of initial sol and avoided the formation of gel, resulting in the improved mass transfer. The halide anion promoted the combination of tetraethylammonium cation (as structure-directing agent) with the solid phase. A ZSM-12 zeolite with abundant mesopores was finally obtained from the synthesis system containing sodium halide. The Pt/ZSM-12 catalyst using the mesoporous zeolite as the support exhibited excellent activity and isomerization selectivity in the hydroisomerization of n -dodecane. • The addition of sodium halide significantly accelerated the crystallization of ZSM-12 zeolite. • Both sodium cations and halide anions contributed to the accelerated crystallization. • The mesoporous ZSM-12 zeolites were obtained from the synthesis system containing sodium halide. • The Pt/mesoporous ZSM-12 catalyst exhibits excellent hydroisomerization performance.

STUDYING THE EFFECT OF MAGNETICALLY TREATED SALT WATER ON SOME CHEMICAL AND PHYSICAL CHARACTERISTICS OF THE SANDY, SANDY CALCAREOUS, AND CLAY SOIL

The main purpose of this laboratory study is to indicate the variation in some characteristics of the sandy, sandy calcareous, and clay soil under the effect of the magnetically treated tab and/or salt water. Salt water (SW, 2000-ppm) was prepared by dissolving the sodium chloride (NaCl) salt in tap water TW (2 g L-1). Tab water and/or SW were magnetically treated by passage through a permanent electromagnetic field of 14٫000 G (1.4 Tesla) strength for 10 min, and then allowed to percolate through a soil column continuously for 2 h. Some characteristics of the studied soil samples were estimated after the infiltrate of the magnetically (M) and non-magnetically (NM) treated TW and/or SW. The MSW has decreased the hydraulic conductivity (HC, m day-1) by 41.1, 12.8, and 51.4% compared to NMSW for sandy, sandy calcareous, and clay soil, respectively. Magnetic induction may affect the coagulation of the fine particles to form larger aggregates. For clay soil, MTW decreased the sum of fine particles by 40.5%, while the MSW decreased it by 28.75%, which may be a dispersing effect of NaCl soluble salt. The Zeta potential ζ values were slightly shifted by SW and MSW. The calculated electrophoretic mobility (U) of the colloidal particles has increased under the effect of the SW by 15.6%, 28.6%, and 58.1% for the sandy, sandy calcareous, and clay soil, respectively. Magnetized water may affect the soil properties positively and/or negatively depending on the soil class and the application conditions.

Quantitative assessment of coagulation of atmospheric particles onto airborne birch pollen grains

The coagulation of airborne particles on the surface of allergenic pollen grains is poorly described in the literature. However, particles deposited on the surface of pollen grains could have an effect on allergy and its symptoms. Observations of pollen surface alterations reported in the literature are either qualitative or are tainted by sampling artifacts that overestimate surface particulate pollution. Birch pollen grains (BPGs) were sampled in the atmosphere during pollination to quantitatively assess the extent of particulate deposition on allergenic pollen surfaces. Airborne PGs were collected with a cascade impactor ensuring no sampling artifact unlike pollen samplers usually used in this type of study. Counting, sizing and elemental analysis of particles adhering on pollen surfaces were performed by SEM/EDX. 68% of PGs did not carry any particle on their visible surface while the remaining 32% had between 1 and 16 particles on their surface. On average, polluted BPGs carried 2 ± 1 particles, representing an average surface coverage of 0.95%. We hypothesized that the main coagulation process was particle deposition by gravitational settling. Collision velocity calculations indicate that coagulation due to gravitational settling is prevalent under typical pollination atmospheric conditions. However, the effects of electric charges carried by pollen are largely unknown and may significantly alter coagulation rates. The presence of particle-polluted allergenic pollens appears to be common in the urban atmosphere, even under low air pollution conditions. The impact of chemical pollution of BPGs due to the presence of particulate matter (including soot particles) remains relatively unknown, both on the allergy and on the reproductive capacity of the trees.