Laser Diffraction Particle Size Analyzer Research Articles

Production of sub-micro sized silver particles by chemical reduction method in an environmentally-friendly manner

Silver nitrate in the solution was reduced in the presence of the dispersants by ascorbic acid, and silver particles were generated. The main goal was to examine the influence of different dispersants. The purpose was to improve the production process of the micro-sized silver powder for thick film silver pastes for applications in the photovoltaic sector and the printed electronics. Relatively high concentrations of the reagents were used to achieve a high yield of silver particles. It was a strict request for highly economic production. This paper shows the possibilities for the routes for future large-scale synthesis and potential industrial production. The particles were analyzed by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and laser diffraction particle size analyzer.

Isolation and characterization of nanocellulose crystals via acid hydrolysis from agricultural waste-tea stalk

Nanocellulose crystals (NCCs) were successfully prepared via acid hydrolysis from an abundant agricultural waste (tea stalk) in China. The effective factors for NCC yield were modeled by the response surface methodology (RSM). The RSM determined the reaction conditions (H2SO4 concentration, hydrolysis temperature, and reaction time) that optimized the yield of tea stalk NCCs (TNCCs). Under the optimized operating conditions, the fundamental properties of TNCCs were characterized via transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), laser diffraction particle-size analyzer, and scanning probe microscopy (SPM). Wood NCCs (WNCCs) and microcrystalline NCCs (MNCCs) were simultaneously prepared from common wood and microcrystalline cellulose under the same conditions. The results show that TNCCs not only shows similar physical and chemical properties with WNCCs and MNCCs, but also has better stability. Therefore, this study offers novel routes for high-valued utilization of tea stalk and provides some theoretical guidance for utilizing cellulose obtained from tea stalk.

Particle-Size Analysis of Modern Bottom Sediments by the Laser Diffraction and Sieve Methods

A combination of laser diffraction and wet sieving through a nylon screen with a 0.1-mm mesh has been suggested for the particle-size analysis of silty bottom sediments from estuarine and coastal sea areas. The necessity of individual determination of sand fractions even in case of the technical ability of the device to analyze the content of coarse particles to 2 mm in size is shown. This is related to poor sorting of coastal silts and inadequately represented weighed samples used for the standard laser diffraction particle-size analysis. In addition to sand fractions, the pre-sieving affects the determination of the 0.1–0.01 mm silt fractions, while its impact on the analysis of pelite fractions of less than 0.01 mm is minimal. The effectiveness of the proposed modified method is proved by the closer correlation between the content of pelite fractions and the concentration of metals and organic carbon in bottom sediments.

Field evaluation of spray drift and environmental impact using an agricultural unmanned aerial vehicle (UAV) sprayer

Unmanned Aerial Vehicle (UAV) applications at low-volume using fine and very fine size droplets have been adopted in several commercial spray scenarios allowing water-saving and high-efficiency operation in delivery of pesticides. However, spray drift associated with UAV applications, especially for fine droplets generated from spinning disk nozzles, has not been fully understood, raising environmental and regulatory concerns. The objectives of this study were to compare the drift potential of three different volume median diameter (VMD, or Dv0.5) of 100, 150 and 200 μm from a commercial quadcopter equipped with centrifugal nozzles exposed to different wind speeds under field conditions. Prior to field test, the droplet size of the centrifugal nozzle was measured by a laser-diffraction particle-size analyzer. The results showed that the relationship between rotation speed and Dv0.5 agrees with the negative power function. Field tests found that the deposition at 12 m downwind direction decreased by an order of magnitude compared with the average deposition within the in-swath zone. The deposition of almost all the treatments at 50 m downwind is lower than the detection limits of 0.0002 μL/cm2. Based on the results from this study, the drift distance of this specific very popular UAV model is much less than that of manned aerial applicators. Based on the predicted equation (R2 = 0.83), the detected drift amount increased with increasing wind speed and decreasing Dv0.5. This work provides basic information to quantify the effect of wind speeds and droplet sizes on UAV spray drift potential which supports on-going regulatory guideline development for spray buffer zone and drift risk assessment protocols.

Pressure filtration properties of sludge generated in the electrochemical treatment of mining waters

In this study, batch electrocoagulation (EC) experiments were performed with synthetic mining water in various conditions in a laboratory-scale 1L reactor. The process was scaled up and the selected results were verified with both synthetic and real mining water in a 70 L reactor. The generated solids were characterized by XRD, SEM, and a laser diffraction particle size analyzer. After preconcentration by settling and decantation, the EC solids were separated by constant pressure filtration at 2–6 bar. In order to improve the separation, various filter aids were used in body-feed and precoat modes. The results show that the overall removal efficiency was the highest with consumable electrode pairs such as Fe/Fe, Al/Al and Fe/Al, and the highest treatment efficiency was achieved with Fe/Al electrodes where 100/100% of the nitrate and 96/87% of the sulfate were removed in small/large-scale experiments. Depending on the dissolved electrode material, different solid species were formed: crystalline primary particles with a minor degree of agglomeration were observed in Fe/Fe slurry, whereas aluminium-containing solids (Al/Al and Fe/Al) were mainly amorphous agglomerates. High values of average specific cake resistances (αav = 2·1012 - 4·1013), average porosities (>90%) and moisture contents (>68 wt%) of filter cakes were obtained for all filtered samples. The highest values of the above-mentioned cake characteristics were observed for aluminium-based solids, which might be explained by its highly amorphous structure. The application of filter aids improved the filterability of the sludges by reducing the average specific cake resistance by as much as 95–96% in the body-feed mode and by 84% in the precoat mode.

Synthesis and characterization of polyaniline nanomaterials with different molar ratio of monomer


 
 
 Formation of polymer nanomaterials are achieved by the process of polymerization and there was an availability of different methods such as chemical oxidative polymerization,electro chemical polymerization, In-situ oxidative polymerization and emulsion polymerization etc., Many monomers combine to form polymers under certain conditions by chemical reactions between the monomers. The chemical oxidative polymerization was most commonly used method to synthesize PANI and the synthesis process involved various molar ratio of aniline (0.1M, 0.2M, 0.3M) in which APS was used as an oxidant with dopant of HCl. This study revealed that the properties changed based on their initial conditions. The prepared aromatic polyaniline was characterized by FT-IR, UV-VIS,Particle size analyzer techniques and anti-bacterial activity of the sample was analyzed.FT-IR spectroscopy gives deep view of many functional groups that were present in a system by measuring vibrational frequencies of chemical bonds involved. UV-VIS was a good tool to identify, characterize and to study the optical properties of nanomaterials.In particle size analyzer, the size of a particle was measured using the instrument laser diffraction particle size analyzer (SALD-2300). The synthesized polyaniline had the tendency to resist the growth of both gram positive and gram negative bacteria. These organic conducting polymers were sometimes called “smart polymers” and have varies application in medical, OLED, solar cell, batteries and sensor etc.,
 
 

Effects of high hydrostatic pressure on swelling behavior of rice starch

In this study, we aimed to reveal the effects of high hydrostatic pressure (HHP) on the swelling behavior of starch. We investigated the changes in starch granule size, specific surface area and porosity, and swelling factors of HHP- (HHGS) and heat-gelatinized rice starch (HGS) at a similar degree of gelatinization (DG) by using scanning electron microscope, a laser diffraction particle size analyzer, low-temperature N adsorption/desorption and ultraviolet spectrophotometer. Results showed that the average diameter of HHGS increased from 6 μm to 572 μm, and that of HGS increased to 877 μm. The adsorption-desorption isotherms of HHGS and HGS in terms of shape were the type IV profile. Pore structure loosened and enlarged from mesopore to macropore. The specific surface area of HHGS decreased from 1.165 m2/g to 0.138 m2/g, and that of HGS decreased to 0.260 m2/g. Swelling of HHGS was not instantaneous. HHP gelatinization possesses simultaneous compression and swelling.

Development of a hydrocyclone for ultra-low flow rates

In this study, a hydrocyclone was designed and manufactured to achieve an inlet flow rate of 1 L/min in the experiment, which was conducted using soda lime bead with a specific gravity of 2.5. Numerical analysis was performed with FLUENT, utilizing the Reynolds stress turbulence and volume of fluid multiphase flow analysis models. Errors in the experimental and numerical analysis were confirmed to be 5.13%, 1.70%, and 2.79% for the inlet pressure, flow rate at the underflow outlet, and total separation efficiency, respectively. To determine the separation efficiency, a laser diffraction particle size analyzer was used to confirm the distribution of particles; the error in each particle size, caused by a reduction in particle size during the experiment, was found to be about 5%. Results from the numerical analysis were consistent with the experimental ones. It was confirmed that the performance of the hydrocyclone could be accurately predicted using numerical analysis. Using the verified value interpreting model, the performance of the hydrocyclone was compared with inlet flow rates of 0.6–1.2 L/min. Additionally, hydrocyclones achieving 1 L/min inlet flow rate with inlet velocities of 1 and 3 m/s were designed for predicting the performance of hydrocyclones in various sizes.

Submicron-Sized Nb-Doped Lithium Garnet for High Ionic Conductivity Solid Electrolyte and Performance of Quasi-Solid-State Lithium Battery.

The garnet Li7La3Zr2O12 (LLZO) has been widely investigated because of its high conductivity, wide electrochemical window, and chemical stability with regards to lithium metal. However, the usual preparation process of LLZO requires high-temperature sintering for a long time and a lot of mother powder to compensate for lithium evaporation. In this study submicron Li6.6La3Zr1.6Nb0.4O12 (LLZNO) powder―which has a stable cubic phase and high sintering activity―was prepared using the conventional solid-state reaction and the attrition milling process, and Li stoichiometric LLZNO ceramics were obtained by sintering this powder―which is difficult to control under high sintering temperatures and when sintered for a long time―at a relatively low temperature or for a short amount of time. The particle-size distribution, phase structure, microstructure, distribution of elements, total ionic conductivity, relative density, and activation energy of the submicron LLZNO powder and the LLZNO ceramics were tested and analyzed using laser diffraction particle-size analyzer (LD), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Electrochemical Impedance Spectroscopy (EIS), and the Archimedean method. The total ionic conductivity of samples sintered at 1200 °C for 30 min was 5.09 × 10−4 S·cm−1, the activation energy was 0.311 eV, and the relative density was 87.3%. When the samples were sintered at 1150 °C for 60 min the total ionic conductivity was 3.49 × 10−4 S·cm−1, the activation energy was 0.316 eV, and the relative density was 90.4%. At the same time, quasi-solid-state batteries were assembled with LiMn2O4 as the positive electrode and submicron LLZNO powder as the solid-state electrolyte. After 50 cycles, the discharge specific capacity was 105.5 mAh/g and the columbic efficiency was above 95%.

Flavonoids from Epimedium pubescens: extraction and mechanism, antioxidant capacity and effects on CAT and GSH-Px of Drosophila melanogaster.

BackgroundEpimedium is a famous medicinal plant in China, Southeast Asian and some other regions. Flavonoids are regarded as its supremely important active constituents used in phytomedicines and/or functional foods. It is of theoretical and applied significance to optimize the procedure for extraction of flavonoids with high bioactivity from Epimedium, to unveil extraction mechanism, to identify chemical composition of flavonoids, to analyze free radical-scavenging ability of flavonoids, and to investigate their effects on the model organism Drosophila melanogaster.MethodsBox-Behnken design was applied to optimization of extraction procedure. Laser diffraction particle size analysis was used to clarify extraction mechanism. Chemical composition of flavonoids was analyzed using high-performance liquid chromatography. Antiradical capacities of flavonoids were determined by chemical-based assay. Then, effects of flavonoids on catalase (CAT) and glutathione peroxidase (GSH-Px) in D. melanogaster were investigated for the first time.ResultsThe optimal condition for ultrasonic extraction of antioxidant flavonoids from Epimedium pubescens was achieved and extraction mechanism was discussed. Epimedium flavonoids contained icariin, epimedin A, epimedin B and epimedin C. Epimedium flavonoids exhibited the ability to scavenge ABTS+ and DPPH⋅ radicals with EC50 values of 55.8 and 52.1 µg/ml, respectively. Moreover, Epimedium flavonoids were able to increase activities of CAT and GSH-Px in D. melanogaster. For females, oral administration of flavonoids improved CAT and GSH-Px activities by 13.58% and 5.18%, respectively. For males, oral administration of flavonoids increased CAT and GSH-Px activities by 13.90% and 5.65%, respectively.ConclusionFlavonoids ultrasonically extracted from E. pubescens considerably affected antioxidant defense system in D. melanogaster. Flavonoids of E. pubescens showed great potential for becoming a natural antioxidant because of their antiradical ability and effects on CAT and GSH-Px of the model organism.

Influence of flow on phosphorus-dynamics and particle size in agricultural drainage ditch sediments.

Particle size is one factor affecting phosphorus (P) dynamics in soils and sediments. This study investigated how flow facilitated by hydraulic pumps and aquatic vegetation species water lettuce (Pistia stratiotes) and water hyacinth (Eichhornia crassipes) affected particle size and P-dynamics in organic sediments in agricultural drainage ditches. Sediments with finer particle size (>0.002 mm) were hypothesized to contain greater total P (TP) and less labile P than sediments with coarser particle size. Particle size was determined using a LS 13 320 Laser Diffraction Particle Size Analyzer. Sediments were tested for pH, TP, and organic matter. Fractions of P were determined using a sequential fractionation experiment and 31P Nuclear Magnetic Resonance (NMR) Spectroscopy. Larger average particle size and lower average total P concentrations were found in the inflows of the field ditches compared to the outflows. Presence of flow and aquatic vegetation did not have a significant impact on particle size, TP, or labile P fractions. Median (p = 0.10) particle size was not significantly correlated to TP. Overall, there was an average trend of coarser particle size and lower P concentrations in the inflow compared to the outflow. The presence of inorganic limerock could have affected results due to increased P adsorption capacity and larger average particle size compared to the organic fraction of the sediment.

Parametric analysis of the spray drying process for the production of starch molecular inclusion complexes with fatty acids

Series of experimental runs were carried out using a pilot scale spray drying unit to produce starch molecular inclusion complexes with fatty acids. Native normal maize and tapioca starch suspensions with added myristic or palmitic acid were employed at various concentrations and feed rates whereas the spray drier was operated at various drying air inlet temperatures. The products were examined using X-ray diffraction analysis, scanning electron microscopy, Confocal laser scanning microscopy, differential scanning calorimetry, Laser diffraction particle size analysis. Experimental data analysis of process parameters was carried out to determine the main variables which affect the performance of the spray drying process. The critical factors were found to be the material feed flow rate in relation to the temperature difference existing in the spray drying chamber between the inlet temperature and the outlet temperature of the drying air. The results revealed that all spray dried products had the same morphological characteristics regardless the type of starch or fatty acid employed and desirable functional properties e.g., low tapped density, uniformity in size, low crystallinity and hollow porous structure. It is concluded that, spray drying is an appropriate technique for the industrial production of starch molecular inclusion complexes in powder form.

Potential hotspots of persistent organic pollutants in alluvial sediments of the meandering Wurm River, Germany

Fluvial sediments can act as archives for lipophilic pollutants. However, their distribution within the highly dynamic regime of the river corridor is scarcely investigated. Herein, a novel approach combining geochemical investigations of sediment bodies in the river corridor of the Wurm River (catchment < 400 km2) and aerial photograph evaluation provide information about the history of river course change and the distribution of pollution by selected persistent organic compounds (POPs) and selected heavy metals. The study is based on nine sediment cores and a total number of 45 subsamples. The sediment samples were analyzed for trace element inventory (X-ray fluorescence), grain size composition (laser diffraction particle size analyzer), and organic compounds (chromatography-mass spectrometry). On the basis of quantitative data of persistent organic substances as well as three heavy metals (Cu, Pb, and Zn) and morphological changes from 1953 until 2016 of the area of investigation provided by eight aerial photographs, analyzed sediments were assigned to different decades, and lateral migration rates as well as deposition rates were calculated. High morphodynamics within the river corridor limits the explanatory power of single approaches (for example, geochronology and radiometric dating). However, a combination enables further insight into floodplains such as the pollution history, spatial pollutant dispersal, hotspot localization, meander migration rates (0.2–0.5 m year−1), sedimentation rates (0.5–5.2 cm year−1) and estimation of hotspot remobilization. Quantitative data for the analyzed heavy metals (Cu, Pb, and Zn) show a decreasing trend for locations with younger sediment bodies, whereas quantitative data for the synthetic organic pollutants reflect the corresponding history of emissions with increasing concentrations until a climax followed by decreasing concentrations due to restrictions regarding their application. Results reveal hotspot areas for POPs and their degree of remobilization. This study demonstrates that by knowing the history of emissions of a lipophilic substance, potential hotspots can be localized solely based on a sufficient number of aerial photographs documenting the river channel migration and sediment body formation in the corresponding period of time.

Application of Density Functional Theory computation (DFT) and Process Capability Study for performance evaluation of Orthophosphate removal process using Polyaniline@Hematite-titaniferous sand composite (PANI@HTS) as a substrate

A new approach is adopted in this study to eliminate orthophosphates in the aqueous medium. It is about synthesizing a composite from a conductive polymer (Polyaniline) and a sandy material (Hematite-titaniferous sand). The synthesized composite (PANI@HTS) and its components were characterized with (XRD) X-ray diffraction, (XRF) X-ray fluorescence, (SEM) scanning electron microscopy coupled with (EDS) energy dispersive X-ray spectroscopy, (FTIR) Fourier-transform infrared spectroscopy and laser diffraction particle size analysis. The phenomenon of adsorption of orthophosphates on PANI@HTS has found to be dependent on several factors, such as adsorbent dose, pH, contact time and pollutant concentration. From the study of adsorption kinetics and the effect of pollutant concentration, the Langmuir model and the pseudo second order model were the most suited for explaining adsorption phenomena with a highest correlation (R2 > 0.98). The adsorbed amount that was found in this study reaches 16.15 mg/g. The adsorption mechanism of orthophosphate ions onto PANI@HTS composite was computationally investigated using Density Functional Theory (DFT). The adsorbate-adsorbent interfacial interactions are assumed to be physisorption in nature due to the low values of binding energy and electronic charge transfer. This DFT simulation result is in good adequacy with the experiment. The capability study of the present process has shown that our method is capable, satisfactory and can be applied on a large scale.

STUDY OF GRANULATION PROCESS OF ILMENITE CONCENTRATE BY PELLETING METHOD

The use of highly dispersed ilmenite ore in the titanium concentrate enrichment technology is accompanied by high dustiness at the stage of titanium charge preparation, which inevitably leads to technological losses and adversely affects the working conditions of the staff. In connection with this, the aim of the present work was to study the process of granulating ilmenite concentrate from the Malyshevsky deposit by pelletization. The size and morphology of ilmenite concentrate particles were determined using a high-resolution electron scanning microscope and a laser diffraction particle size analyzer. The granulation process was carried out in a drum granulator thermostated by assessing the effect of temperature, rotation speed granulator, process duration and a binder flow rate on particle size distribution and static strength formed granules of the title product. During the investigations it was established that the maximum yield of granules fraction of 1.0 - 5.0 mm was obtained using an aqueous solution of molasses molasses volume ratio: water = 5:1. The use as undiluted molasses binder leads to a strong increase in ductility formed mass and negatively affects the possibility of producing a granular product. It was shown that with increasing concentration of binder in the composition of the starting mixture the average yield and static strength of granules fraction of 1.0 - 5.0 mm increases, due to the uniform distribution of the solution between the ilmenite concentrate particles. At the same time when the amount of binder in the composition of the starting raw materials over 9.5% the formation of relatively large lumps is observed, which size is more than 5.0 mm. It has been experimentally proved that with increasing duration pelletization yield pellets of ilmenite concentrate fraction of 1.0 - 5.0 mm increases, passing through a maximum at 300 s.

Selection of a Viable Upgradation Strategy Through Physico-chemical and Mineralogical Approach: A Case Study of Low Grade Barsua Iron Ore Fines

Detailed characterization study is the pioneer step for any mineral beneficiation scheme. A series of mineralogical and peterographic studies coupled with (Brunauer–Emmett–Teller) surface area, (atomic force microscopy), (laser diffraction particle size analyser), FTIR (Fourier transform infrared spectroscopy), contact angle measurement, zeta potential were carried out, and the findings about the mineralogical and physico-chemical nature of the sample have been described. This paper provides a guide on the proper selection of beneficiation route for iron ore with complex mineral assemblage (Hematite–Goethite–Laterite–Quartz–Kaolinite–Gibbsite). The beneficiation method, especially froth flotation process, potential after a thorough characterization is suggested analysed and the successful upgradation by froth flotation route is envisaged. Flotation results indicated that it is possible to achieve high grade iron concentrate along with lower silica, and alumina content providing a specific reagent regime/system for specific mineral assemblages.

The application of multi-particulate microcapsule containing probiotic bacteria and inulin nanoparticles in enhancing the probiotic survivability in yoghurt

The potential application for the multiparticulate synbiotic microcapsule in yoghurt production was presented in the current study. Initially, three different formulae were fabricated to investigate the mechanism of action. This was followed by characterization the size of both of the nanoparticles and the final multiparticulate microcapsule. The yoghurt was then formed and the formulae were added and subjected to 4 weeks storage period. The viability of Bifidobacterium mixed cultures was monitored weekly. The results showed the viability of Bifidobacterium cultures was enhanced when double coated microcapsule was applied compared to the free one. The enhancement was further boosted when inulin was incorporated in either free form or in the form of nanoparticles. Scanning electron microscope image showed the final multiparticulate microcapsule has size of 700 μm while the laser diffraction particle size analyzer revealed the nanoparticles size is 118.1±4 nm. It was concluded that both of the double coat layer covering the multiparticulate microcapsule and the entrapped inulin, significantly enhanced the survivability of the encapsulated Bifidobacterium cultures in yoghurt during the shelf period.

Identifying the soil structure of the piedmont-plains by the fractal dimension of particle size

Soil structure fundamentally determines the hydrodynamic characteristics of the saturated–unsaturated zone, solute transport characteristics, and thermodynamic properties of the soil. Additionally, it regulates the process of transfer and conversion of matter and energy in the saturated–unsaturated zone. However, the quantification of soil structure is difficult because it depends on a combination of factors including soil particle sizes and types and spatial distribution of pores. In this study, the structural characteristics of the vadose zone are examined based on self-similarity in the soil and the fractal theory of non-linear science. This approach describes the soil particle sizes and spatial distribution of pores in the interior layers of the soil. The study area stretches across 165 km of the piedmont–plains of the Taihang Mountains. The particle sizes and volume percentages of particle sizes in 57 soil samples were measured using the Mastersizer 2000 laser diffraction particle size analyser (Malvern Instruments, U.K.). This information is then combined with the volume-based fractal dimension (D), calculated using the fractal theory, of the various samples. The results obtained indicate that: (i) the fractal theory can be used to effectively identify the characteristics of three-dimensional structural changes within the soil profiles. The average soil particle size decreases from the piedmont of the Taihang Mountains towards the plains. Similarly, the volume percentage of particle size and the maximum volume percentage of a single particle size decreases. Moreover, the D values show an overall declining trend; (ii) the D values of the soils of the piedmont–plains of the Taihang Mountains show significant spatial variations in the range of 1.037–1.925. Although there is no correlation between the D value and soil particle size, the D value is very sensitive to the soil structure uniformity. The higher the uniformity, the greater is the D value; and (iii) D values cannot be used as the sole basis for determining the soil hydraulic properties. The D values and soil hydraulic properties are correlated only for a particular range of soil particle sizes.

Effect of sintering temperature and time on composition, densification and electrical properties of InGaZnO4 ceramics

This paper studied the influence of sintering temperature on composition, density and electrical properties of InGaZnO4 ceramics synthesized by conventional solid-state reaction technique. Firstly, IGZO powders were prepared by mechanical ball milling of micron-scale In2O3, Ga2O3 and ZnO mixed powder and the effects of milling time, ball to powder weight ratio (BPR) and dispersant on the properties of mixed powders were investigated by XRD, SEM and laser diffraction particle size analyzer. Secondly, the green compacts formed by mixed powders were sintered at different temperatures (1100, 1200, 1300, 1400 °C) and time (0, 1, 3, 6 h), then the sintering behavior and electrical properties of the compacts were analyzed. The results showed that when the BPR was 10:1 and 2 wt % polyammonium acrylate was used as dispersant, the powder owed the best compression performance and the relative density of the green compact reached 67.14%. Owing to the decomposition of In2O3, obvious loss of mass phenomenon occurred during sintering process. When the compact was hold at 1400 °C for 150 min, the density of compact reached as high as 99.5%. The lowest resistivity of the compact reached 6.07 × 10−3 Ω cm when the compact was kept at 1400 °C for 3 h.

Rare earth elements in fine fraction (

Present studies facilitated testing the hypothesis that sediment fraction <20 μm contains different amounts of REEs. The potentially bioavailable rare earth elements (REEs) were determined in the following fractions of the surface sediments of the Vistula River: <5 μm, 5–10 μm, 10–20 μm, and total <20 μm. The attempt was made to fractionate the sediment by self-adjustable split-flow transport-thin fractionation channel operating in the full depletion mode (SPLITT-FFD-SA), which is a new concept and so far unused method for such purposes. All three fractions were separated in the expected particle size ranges. The collected fractions were analyzed with the laser diffraction particle size analyzer and the inductively coupled plasma – mass spectrometer (ICP-MS) to determine the size and the elemental composition. ∑REEs in the Vistula sediments declined from 123.41, through 112.59 to 95.22 mg kg−1 in fractions: 10–20 μm, 5–10 μm, <5 μm, respectively. Eleven, out of sixteen REEs, showed statistically significant declining trend in REEs content, with decreasing particle sizes of sediment fractions. Particularly exceptional was Er, whose content in <5 μm fraction was by 12–20% higher than in larger size fractions. Rare earth elements of the Vistula sediments are considerably enriched in the light rare earth elements (LREEs) relative to the heavy rare earth elements (HREEs), with the LREEs/HREEs ratio declining from 4.01 (10–20 μm) to 3.599 (<5 μm). The sequence of mass weighted REEs content in <20 μm size fraction was as follows: Ce > La > Nd > Y > Sc > Pr > Sm > Gd > Dy > Er > Yb > Eu > Tb > Ho > Tm > Lu.