Particle Size Distribution Measurements Research Articles

Study on strain stiffening of non-colloidal suspension in oscillating shear by a subsequent steady shear test

Rheological behavior of non-colloidal suspensions in oscillatory shear has been studied experimentally. With increase of strain amplitude, both storage and loss moduli first decrease and then increase at a critical point, which is called strain stiffening. Our experiment results show that suspension with small particles exhibit a larger modulus before the critical strain amplitude, and additional steady shear tests also show similar phenomenon. According to particle size distribution measurement, there is certain amount of small size particles which may have significant Brownian motion, and play a crucial role in shear thinning. Special experiment procedure is designed to investigate strain stiffening, two different tests of oscillating shear are parallel conducted and they are stopped at the strain amplitude corresponding to the critical point and peak point respectively. Both of them are further tested by a subsequent steady shear test (with constant shear rate) to inspect the internal particle structures. Samples with oscillating tests stopped at the critical point and peak point show similar magnitudes of shear viscosity in the steady shear tests. It is conjectured that particles in non-colloidal suspension exist as a metastable structure during strain stiffening, which can maintain a relatively stable configuration in oscillatory shear, but the structure will be broken rapidly in steady shear with the increase of shear rate. As a result of this, the metastable structure only affects the modulus in oscillatory shear, but does not affect the viscosity of steady shear.

Mechanical Activation of Construction and Demolition Waste in Order to Improve Its Pozzolanic Reactivity

The aim of this study was to investigate the construction and demolition waste (CDW) fine size fraction by increasing its reactivity with mechanical activation (MA) in a stirred media mill. Systematic measurements were carried out in order to gain information about its reactivity. Particle size distribution and BET specific surface area measurements were carried out as dispersion properties. The changes in the particle shape and surface were measured by scanning electron microscopy (SEM), and structural alteration was investigated by FTIR spectroscopy and X-ray diffraction (XRD). The effect of MA on the pozzolanic reactivity was measured by lime sorption as well as strength tests. As a result of the research, it was found that reactivity of the construction and demolition waste (CDW) fine size fraction could be controlled by MA in a stirred media mill.

Analyzing ophthalmic suspension particle size distributions using laser diffraction: Placebo background subtraction method

The current study demonstrated that the presence of excipients can interfere with the measurement of particle size distribution (PSD), a critical quality attribute of ophthalmic suspensions, by laser diffraction (LD) and that a placebo background subtraction approach can eliminate the impact of excipients on the PSD measurement. Commercially available loteprednol etabonate and brinzolamide ophthalmic suspensions were used as model suspensions. The impact of excipients in these formulations on the LD measurements was determined using a one-factor-at-a-time experimental design approach, using National Institute of Standards and Technology (NIST) traceable polystyrene particle size standards as references. Among the evaluated excipients, polymers containing polyacrylic acid were found to interfere with the PSD analysis by creating the LD signals correspond to particles ranging from a few micrometers to a hundred micrometers in size. As a result, the measured PSD of active pharmaceutical ingredient (API) particles in the formulation overlapped with or superimposed on the excipient PSD signal, leading to erroneous interpretation of the API particle size. Additionally, dispersion of brinzolamide particles in unsaturated solutions led to rapid dissolution of brinzolamide particles during the measurement, resulting in underestimation of the particle size range. Here, a placebo background subtraction approach was developed to eliminate the interference of the excipients. This newly developed LD method was also evaluated using orthogonal methods, including polarized light microscopy and scanning electron microscopy (SEM). The strategy used in this study to eliminate the interference of excipients may also be useful for other heterogeneous dispersions where excipient interference may be of concern.

Numerical modeling of a batch fluidized-bed gasifier: Interaction of chemical reaction, particle morphology development and hydrodynamics

The present study aims to analyze the interaction of chemical reactions, particle morphology change and hydrodynamics in fluidized-bed gasifiers. The char gasification in a batch fluidized-bed gasifier was modeled. The two-fluid model approach was coupled with an extended version of the uniform conversion model accounting for inert ash fraction. Model assumptions were confirmed via measurement of char density, porosity and particle size distribution at different stages of conversion in a lab-scale fluidized-bed gasifier. The CFD model correctly predicts the effects of particle structure change on chemical reactions, approved by a first of its kind comprehensive validation against unsteady experiments. Based on the validated CFD model, the interaction of hydrodynamics and local particle density variations due to chemical reactions is analyzed, and the effect of the initial bed height is studied.

Application of artificial bee colony algorithm for particle size distribution measurement of suspended sediment based on focused ultrasonic sensor

A new focused ultrasonic sensor is proposed, based on which the measurement system for particle size distribution measurement of suspended sediment is established. Compared with the traditional ultrasonic sensors, the one used in this paper is equipped with piezoelectric transducer (PZT) on an arc-shaped shell, to concentrate ultrasonic beams on one measurement point. The sensor is used to measure the particle size distribution of suspended sediment. The experiments were carried out on water-sediment mixtures with different particle size distribution. Due to multiple parameters and non-linearity of the ultrasonic attenuation model, the artificial bee colony (ABC) inversion algorithm is used to estimate particle size distribution, thus improving measurement accuracy. The particle sizes obtained by sieving method are seen as reference values. The results indicate that whether the suspended particles are subject to a unimodal distribution, uniform distribution or random distribution, the particle size distribution obtained by ABC inversion algorithm is consistent with the result obtained by the sieve method. The results demonstrate that the method has good utility and accuracy within the low concentration range.

Minimizing the filtration loss of water-based drilling fluid with sustainable basil seed powder

Filtration control is important to ensure safe and high efficient drilling. The aim of the current research is to explore the feasibility of using basil seed powders (BSPs) to reduce filtration loss in water-based drilling fluid. The effect of BSP concentration, thermal aging temperature, inorganic salts (NaCl and CaCl2) on the filtration properties of bentonite/basil suspensions was investigated. The filtration control mechanism of BSP was probed via water absorbency test, zeta potential measurement, particle size distribution measurement, and filter cake morphologies observation by scanning electron microscope. The incorporation of BSPs into the bentonite suspension generated acceptable rheology below 1.0 w/v%. The BSPs exhibited effective filtration control after thermal aging at 120°C, but less efficiency at 150°C. After thermal aging at 120°C, the bentonite suspension containing 1.0 w/v% BSPs could resist NaCl and CaCl2 pollution of 5.0 w/v% and 0.3 w/v% respectively. Besides general filtration control behaviors, the exceptional water retaining capability formed by numerous nanoscale 3D networks in the basil seed gum and considerable insoluble small particles in BSPs might further contribute to the filtration control. The excellent filtration properties bring basil seed a suitable and green candidate for the establishment of high-performance drilling fluids.

Interaction between bovine serum albumin and Solutol® HS 15 micelles: A two-stage and concentration-dependent process

The objective of this study was to investigate the interaction and the time evolution between protein and nanomicelles and to further understand the interaction mechanisms. Solutol® HS 15 (HS 15) and bovine serum albumin (BSA) were selected as the model nanomicelles and model protein, respectively. HS 15 has been used as solubilizer for injection, oral and subcutaneous administration systems. BSA was chosen as the model protein for its high sequence similarity and homology to human serum albumin. The interaction between BSA and HS 15 was studied by particle size distribution and zeta-potential measurement and fluorescence quenching assay. The effects of HS 15 concentration on the interaction between HS 15 nanomicelles and protein were investigated. The interaction mechanisms between BSA and HS 15 was studied by isothermal titration calorimetry and molecular docking. The interaction between HS 15 and BSA was demonstrated to be a two-stage process, with 0–3 h as the first phase and 3–12 h as the second phase. Moreover, the rearranged capsule-shaped HS 15 micelles could be absorbed onto the surface of BSA and the binding mode between HS 15 and BSA was concentration-dependent. Additionally, the interaction mechanisms of HS 15 and BSA include van der Waals forces, hydrophobic forces, and hydrogen bonding. In conclusion, this study provided a detailed study and insights of the interactions between nanomicelles and the serum albumin in vitro, which is of high importance to predict and understand the in vivo fate of such micellar drug delivery systems after intravenous injection in the future study.

Characterization of Ultrafine Particles and VOCs Emitted from a 3D Printer.

Currently, widely available three-dimensional (3D) printers are very popular with the public. Previous research has shown that these printers can emit ultrafine particles (UFPs) and volatile organic compounds (VOCs). Several studies have examined the emissivity of filaments from 3D printing, except glycol modified polyethylene terephthalate (PETG) and styrene free co-polyester (NGEN) filaments. The aim of this study was to evaluate UFP and VOC emissions when printing using a commonly available 3D printer (ORIGINAL PRUSA i3 MK2 printer) using PETG and NGEN. The concentrations of UFPs were determined via measurements of particle number concentration and size distribution. A thermal analysis was carried out to ascertain whether signs of fiber decomposition would occur at printing temperatures. The total amount of VOCs was determined using a photoionization detector, and qualitatively analyzed via gas chromatography-mass spectrometry. The total particle concentrations were 3.88 × 1010 particles for PETG and 6.01 × 109 particles for NGEN. VOCs at very low concentrations were detected in both filaments, namely ethylbenzene, toluene, and xylene. In addition, styrene was identified in PETG. On the basis of our results, we recommend conducting additional measurements, to more accurately quantify personal exposure to both UFPs and VOCs, focusing on longer exposure as it can be a source of potential cancer risk.

Performance comparison of SMPSs with soft X-ray and Kr-85 neutralizers in a humid atmosphere

Scanning mobility particle sizer (SMPS) is widely used for particle number size distribution measurements of submicron particles. In this work, two TSI® SMPSs equipped with a soft X-ray neutralizer and a Kr-85 neutralizer, respectively, were operated in parallel to measure particle number size distributions of ambient air. An independent TSI® ultrafine condensation particle counter (CPC) was used as a reference to measure the total concentration of particles in the ambient air. Our results show that the total particle concentrations measured by the two SMPSs were comparable with each other, while their size-resolved concentration ratios were size-dependent and relative humidity (RH)-dependent. Neutralizer was found to be essential to quickly bring small particles to charge equilibrium in field measurements, as indicated by the comparison of particle number size distributions measured by the Kr-85 SMPS with those inverted from naturally charged particles. The total particle concentrations measured by two SMPSs tend to exceed those by the reference CPC at high RH, hinting that the particle concentrations measured by SMPSs could be overestimated at high RH. This study urges a better understanding of the bipolar charging processes under high RH conditions.

Comparing multifractal characteristics of soil particle size distributions calculated by Mie and Fraunhofer models from laser diffraction measurements

Particle size distribution (PSD) is a basic soil property, closely related to main soil physical and chemical attributes. Soil PSD determined by laser diffraction (LD) may provide additional information to soil texture determined by traditional methods. In turn, LD may be implemented using either Mie or Fraunhofer calculation methods, based on different assumptions. The multifractal approach has been demonstrated to be useful for characterizing the inner structure of soil PSD. We analysed the PSDs of 18 soil horizons sampled on the most characteristic soil types from Argentina with a wide range of textural classes, from clayey to sandy, mainly developed over loess material. Our aims were to assess the multifractality between PSDs computed using either Mie scattering or Fraunhofer diffraction models, and to compare the scaling properties and multifractal behavior of PSDs from soils with contrasting textures. Fraunhofer model provided PSD curves, which were shifted toward coarser particles compared to those obtained with Mie model. Regardless calculation method, all the PSDs studied displayed a well-defined multifractal structure, as shown by singularity, f(α) versus α, and by Rènyi spectra, Dqvs q. Moreover, all singularity spectra were strong asymmetric, right deviating curves, which is consistent with a greater heterogeneity of the low values of volume frequencies for all the PSDs analysed. Soil PSDs computed by Fraunhofer model showed higher asymmetry than those computed by Mie model for 16 out of 18 horizons studied; this suggests that scaling heterogeneity mainly depends on the support length, which is larger for the PSDs computed by Mie. In addition, other features of the PSDs stemming from soil processes such as weathering intensity of loess materials may also influence multifractality. Stronger correlations were found between multifractal parameters from PSDs calculated by the two models for the most positive q moments of singularity and Renyi spectra, i.e. α10, D10, than for those gathered from the central and negative q moments. The entropy dimension, D1, significantly (P<0.05) increased with increasing clay content, in contrast to previous findings; this may be due either to differences in the inner structure of various PSD data sets compared, or to shortcomings of standard PSD measurement and calculation procedures.

Enhanced corrosion protection of reinforcement steel with nanomaterial incorporated fly ash based cementitious coating

This work evaluated the performance of a novel nanophase modified fly ash based cement polymer coating over steel reinforcements in a corrosive environment. Five types of coatings were prepared with 100 wt. % Ordinary Portland Cement (CC), OPC replaced with 40 wt. % fly ash (CF), and CF admixed with 2 wt. % nano-CaCO3 (CFC), nano-SiO2 (CFS) and nano-ZrO2 (CFZ). Electrochemical studies were carried out under exposure to chlorides and the long term performance was evaluated by impressed voltage test. The microstructure of the developed coatings and chemical composition of corrosion products were analyzed using SEM, XRD, and LRS. The instantaneous corrosion rates of CFC, CFS, and CFZ coated rebars were found to be notably lower than CF coated rebars. The accelerated studies using impressed voltage test indicated a significantly longer initiation time for cracking in nanomaterials incorporated coatings than the conventional cement polymer coating. The evaluation of electrochemical parameters like open circuit potential, corrosion current, and polarization resistance showed that the addition of nano-ZrO2 significantly enhanced the corrosion performance of cementitious coatings as compared to other nanomaterials owing to its better dispersibility, without aggregation in cementitious product, which was further confirmed from the particle size distribution measurement using dynamic light scattering technique. The XRD patterns and laser Raman spectra results confirm negligible corrosion products on CFZ coated rebars. The visual inspection of rust formation and weight loss measurements of CFZ coated rebars, subjected to salt spray and chemical resistance tests corroborated its long term durability in chloride-rich environment. Our results suggest the important benefits of nanomaterial incorporated fly ash cementitious coating on rebars in corrosion protection.

Hydroxyapatite/titania nanocomposite coating on nickel-free austenitic stainless steel

In this research, a series of biocompatible coatings are applied to nickel-free austenitic stainless steel via the electrophoretic method. Hydroxyapatite (nHA) and titania (nTiO2) nanoparticles are utilized as primary materials, while polycaprolactone (PCL) is employed as a binder for production of the electrolyte suspensions. Optimum concentration of binder is achieved and suspensions with different amounts of nHA-nTiO2 are fabricated and investigated. The suspensions are characterized by particle size distribution, zeta potential, and viscometer measurements. The results show that PCL is protonated via an electrostatic stabilization mechanism absorbed on the nHA-nTiO2 surface, which stabilizes the suspension. Microstructural of coated layers is characterized using x-ray diffraction (XRD), optical microscopy, and scanning electronic microscopy. Mechanical properties of the coating are measured by microhardness, thickness measurements, pin-on-disk sliding, and pull-off adhesion tests. Moreover, the electrochemical behavior of the coated layers is investigated via Tafel polarization tests in simulated body fluid (SBF). It is found that the coated layer containing PCL (2 g/l) has the highest adhesion strength and a smoother surface with minimal or no cracks or pores. Mechanical characterization indicated that the hardness and wear resistance of the coating can improve by increasing the TiO2 concentration, while increased TiO2 enhances the electrochemical behavior of the coating too.

Measuring particle size distribution and mass concentration of nanoplastics and microplastics: addressing some analytical challenges in the sub-micron size range

HypothesisThe implementation of the proposal from the European Chemical Agency (ECHA) to restrict the use of nanoplastics (NP) and microplastics (MP) in consumer products will require reliable methods to perform size and mass-based concentration measurements. Analytical challenges arise at the nanometre to micrometre interface, e.g., 800 nm–10 µm, where techniques applicable at the nanometre scale reach their upper limit of applicability and approaches applicable at the micrometre scale must be pushed to their lower limits of detection. ExperimentsHerein, we compared the performances of nine analytical techniques by measuring the particle size distribution and mass-based concentration of polystyrene mixtures containing both nano and microparticles, with the educational aim to underline applicability and limitations of each technique. FindingsLight scattering-based measurements do not have the resolution to distinguish multiple populations in polydisperse samples. Nanoparticle tracking analysis (NTA), nano-flowcytometry (nFCM) and asymmetric flow field flow fractionation hyphenated with multiangle light scattering (AF4-MALS) cannot measure particles in the micrometre range. Static light scattering (SLS) is not able to accurately detect particles below 200 nm, and similarly to transmission electron microscopy (TEM) and flow cytometry (FCM), is not suitable for accurate mass-based concentration measurements. Alternatives for high-resolution sizing and concentration measurements in the size range between 60 nm and 5 µm are tunable resistive pulse sensing (TRPS) and centrifugal liquid sedimentation (CLS), that can bridge the gap between the nanometre and micrometre range.

Simultaneous Roadside and Urban Background Measurements of Submicron Aerosol Number Concentration and Size Distribution (in the Range 20–800 nm), along with Chemical Composition in Strasbourg, France

The adverse health impact of particles and ultrafine particles (UFP) is proven, highlighting the need of measuring the particle number concentration (PNC) dominated by UFP. So far, PNC had never been measured in the Strasbourg urban area (France). The present study on particle size distribution and PNC measurements by an UFP-3031 analyzer was conducted during winter 2019 on a background and a roadside multi-instrumented sites (Black Carbon, chemical speciation, particulate matter 10 μm or less in diameter—PM10 mass). This paper shows significantly higher particle number concentrations of particles below 100 nm at the traffic site compared to the background site. The presence of a road axis thus mainly influences UFP, contrary to larger particles whose levels are more homogeneous over the agglomeration. During the measurement period, the nature of the particles (particle size contribution and chemical composition) was different between periods of high PM10 mass concentrations and periods of high PNC. High PM10 mass concentrations were associated with a high contribution of particles larger than 100 nm but they did not show specific chemical signature. On the other hand, during the periods with high PNC, the chemical composition was modified with an increase of the primary carbonaceous fraction compared to the periods with low PNC, but there was then no clear change in size distribution. Overall, this study illustrates that PM10 mass concentrations were barely representative of UFP and PNC variations, confirming that the monitoring of the latter metrics is necessary to better evaluate the particles toxicity, knowing that this toxicity also depends on the particle’s chemical composition.

Online Measurement of the Size Distribution of Pneumatically Conveyed Particles Through Acoustic Emission Detection and Triboelectric Sensing

In a thermal power plant, online measurement of the size distribution of pneumatically conveyed pulverized fuel is essential for the improvement of combustion efficiency and the reduction of pollutant emissions. In this article, an innovative instrumentation system based on acoustic emission (AE) detection and triboelectric sensing is proposed for the on-line continuous measurement of particle size distribution. With a waveguide protruding into the flow, the AE signal is generated from the impacts of particles with the waveguide. The peak voltage of the AE signal is related to the particle size and impact velocity. For the first time, two triboelectric sensor arrays each with three arc-shaped electrodes near to the waveguide are used to measure the impact velocity. Meanwhile, a novel particle sizing algorithm with Gaussian prediction is proposed to reduce the effect of overlapping impacts and environmental noise on the peak distribution. With the known impact velocity measured from the triboelectric sensor arrays and the modified peak distribution, the measurement of particle size distribution is achieved. Experimental tests were conducted on a gas–solids two-phase flow rig to assess the performance of the developed measurement system. Silica sands in three size ranges of 116–750, 61–395, and 10– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$246~\mu \text{m}$ </tex-math></inline-formula> , respectively, were used as test particles. The experimental results demonstrate that Spearman’s rank correlation coefficients between the measured and reference size distributions for all test particles are all greater than 0.8, while the discrepancy for each particle size segment is within ±4.8%.

Isolation and characterization of hydroxyapatite powder from the scale of freshwater fish Labeo rohita using green technology

The objective of the present work was to isolate and characterize hydroxyapatite (HAP) from Labeo rohita scale using green technology. The method used only 0.6% KOH solution for isolation, which did not generate any spent liquid for disposal to the environment. Investigation through thermogravimetric analysis, X-ray diffraction study, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and particle size distribution measurement was carried out for characterization of HAP. The powder after isolation from scale contained &lt; 7% organic matter and could be converted to thermally stable perfectly crystalline pure HAP without any organic impurity by exposition to 1000 °C for only 1 h. The heated HAP powder had a Ca:P ratio of 1.52 and indicated the grains to be in submicron size but remaining in soft agglomerated condition with 50% of the mass passing through ≈ 167 µm.

Viscoelasticity of non-colloidal hydrogel particle suspensions at the liquid-solid transition.

Suspensions of soft particles transition from a viscous fluid to a soft material upon increases in phase volume. The criteria defining the transition to this jammed state are difficult to define due to the porous and deformable nature of soft particles. Here, we characterise the rheology of aqueous suspensions of industrially relevant non-colloidal, polydisperse, frictional agarose microgels and evaluate shear and viscoelastic behaviour across a range of phase volumes from the dilute regime to the highly concentrated regime. In order to model the viscoelastic response of suspensions without free fitting parameters, the random close packing volume fraction (φrcp) and the particle modulus are determined, respectively, from particle size distribution measurements and direct measurements of reduced elastic modulus of individual particles (Erp) using Atomic Force Microscopy. It is found that at φrcp, previously shown to correspond to divergence of the viscosity, also corresponds to the suspension transition from a viscous to viscoelastic fluid. However, the transition to a jammed solid-like state (φj) occurs at phase volumes exceeding this value (i.e. φj > φrcp). The suspension modulus and its sudden growth at φj are well-predicted by the Evans and Lips model that incorporates the Erp of the hydrogel particles. This rheological behaviour showing a dual transition is reminiscent of two families of systems: (i) colloidal suspensions and (ii) frictional-adhesive non-colloidal suspensions. However, it does not strictly follow either case. We propose that the width of the transition region is dictated by frictional contact, particle size distribution and particle modulus, and plan to further probe this in future work.

A semi dynamic in vitro digestion study of milk protein concentrate dispersions structured with different polysaccharides

Hydrocolloids are often added as functional ingredients in foods, to better design the structure of the matrix and ensure food quality and optimal sensory properties. However, much less is known about their influence on the physical and chemical changes during gastric digestion. In this study, semi-continuous in vitro gastric digestion was applied on a model food system, prepared with milk protein concentrate (MPC) (3% w/v) and 1% alginate, pectin, guar gum, as well as a 1:1 mixture of alginate and pectin. The dynamics during simulated gastric digestion were observed by measuring particle size distributions, structuring at various length scales, as well as by evaluating differences in protein breakdown. Immediately after contact with the simulated gastric fluids, all samples showed extensive aggregation and formation of different structures. MPC control dispersions (no polysaccharide) and MPC containing alginate formed large inhomogeneous aggregates. The lack of structural homogeneity affected the simulated gastric emptying: there were marked differences in the type of aggregates present at various times of emptying depending on the hydrocolloid present in the mixture. MPC containing pectin or guar gum formed macroscopically homogeneous dispersion, with rather small protein aggregates showing a large population of particles between 60 and 100 ​μm of diameter, with marked differences in microstructure. Pectin created large coacervates, while guar microscopic phase separated systems. These dispersions showed a higher extent of protein digestion, due to the larger surface area created for enzyme activity compared to the macroscopically phase separated matrices. In all cases, there was a large undigested fraction at the end point of 140 ​min. SDS PAGE demonstrated differences in the casein peptides distribution depending on the type of polysaccharide present during simulated gastric emptying. This in spite of similarities in cumulative protein emptied. It was concluded that in this semi-continuous in vitro gastric digestion model, structuring with polysaccharides has a significant impact on gastric emptying and protein digestion kinetics.

A novel binary pipette splitting sediment subsampling method for improving reproducibility in laser-diffraction particle-size analysis

Laser-diffraction analysis has been established as one of the standard methods for particle-size distribution (PSD) measurement. However, the uncertainty when analyzing naturally heterogeneous sediment is poorly constrained for the lack of control on one of its largest error sources simply originating from subsampling. Here, we introduce a novel subsampling method, binary pipette splitting (BPS), and verify its precision by using sediment samples from ten flood-layer deposits that have formed in the wake of Hurricane Florence (2018). The BPS approach avoids extracting from only a fixed part of the suspended fluid but considers all the suspended sediment, resulting in the generation of twin subsamples. The median coefficient of variation (COV) for D10, D50, and D90 of subsamples obtained using BPS is 4%, 3%, and 2%, respectively. These values are significantly smaller than the corresponding values of 18%, 15%, and 13% obtained using the conventional pipette subsampling method. Therefore, the new BPS method represents a significant improvement in producing statistically identical subsamples for laser-diffraction particle-size analysis. •The binary pipette splitting (BPS) subsampling method dramatically improves the reproducibility of subsampling wet sediment.

Aerosol Filtration Testing of Fabrics for Development of Reusable Face Masks

The ongoing outbreak of coronavirus disease of 2019 (COVID-19), triggered by the rapid community spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has brought forward the need for speedy testing and manufacturing of respiratory face masks for global use. Overwhelmed by the fast-growing demand for disposable face masks, many governments have recommended the use of, and elaborated design criteria for, reusable face masks that are meant to slow down the transmission of SARS-CoV-2 in the general population. Using aerosol particle size spectrometers, we performed particle size distribution measurements and calculated the fractional aerosol particle size-selective filtration efficiencies of over 300 fabrics and fabric-assemblies, including chiffon, cotton, synthetics, and various promising layered combinations. We suggest, and experimentally verify, a simple way for estimating the aerosol filtration efficiency of layered fabrics. The analysis herein investigates the relationship between the breathability and filtration properties of fabrics, assemblies of fabrics, and commercial reusable masks from various regions around the globe. In addition, we demonstrate how a hydrophobic coating can provide a statistically significant increase in the fabrics’ filtration efficiency. The insights of this work are crucial to developing non-woven, high-filtration-performance, reusable face masks that can be worn for extended periods of time. © The Author(s).