Gravitational Separation Research Articles

Fiber-based super-bridging agents enable efficient contaminant removal via settling and screening: Impact on microplastics, textile fibers, and turbidity

The water treatment industry relies heavily on coagulation and flocculation processes. This technology requires large amounts of chemicals and large settling tanks for floc separation. The flocs formed during conventional treatment are small (<100 µm), which limit their removal by gravitational separation. To improve floc separation, fiber-based super-bridging agents have been added to the coagulation/flocculation process. When fibers were used in combination with a coagulant and flocculant, the flocs formed were 10 – 100 times larger, and settling was remarkably improved. The tested super-bridging agents also led to a 50 % reduction in demand for both the coagulant and flocculant. The use of super-bridging agents is an effective technique for reducing turbidity and improving the removal of emerging contaminants in both synthetic and natural surface water. Formation of very large flocs with fibers also allowed the replacement of settling by screening without any effect on removal of monitored contaminants. Fibrous treatment removed up to 78 % of turbidity when using a 5000 µm screen mesh size, compared to only 45 % with conventional treatment (coagulant and flocculant, no fibers). Super-bridging agents also drastically improved microplastic removal. The fibrous treatment removed 80 % of 15 µm polyethylene beads, compared to only 20 % with the conventional treatment. Such low removal indicates potential concerns regarding the effective removal of smaller microplastics in existing water treatment plants.

Facile synthesis and physicochemical characterization of κ-Carrageenan-silver-bentonite based nanocatalytic platform for efficient degradation of anionic azo dyes

Water pollution due to textile industry effluents is a global concern that warrants versatile research solutions for degrading them, and for a sustainable environment. In the present work, by using the imperative role of nanotechnology, a facile one-pot synthesis has been devised to generate κ-carrageenan capped silver nanocatalyst (CSNC), and was immobilized on 2D bentonite (BT) sheets to generate nanocatalytic platform (BTCSNC) for the degradation of anionic azo dyes. The nanocomposite(s) were physicochemically characterized using UV–Vis, DLS, TEM, FESEM, PXRD, ATR-FTIR, TGA, BET and XPS etc., to obtain insights into the nanocomposite composition, structure, stability, morphology and mechanism of interaction. The obtained CNSC are monodispersed, spherical with a size of 4 ± 2 nm, and were stabilized by the functional groups (-OH, COO‾, and SO3‾) of κ-Crg. The broadening of peak corresponding to basal plane (001) of BT montmorillonite in PXRD spectra established its exfoliation upon addition of CSNC. XPS and ATR-FTIR data evidenced the absence of covalent interactions between CSNC and BT. The catalytic efficiency of CSNC and BTCSNC composites were compared for the degradation of methyl orange (MO) and congo red (CR). The reaction followed a pseudo first order kinetics, and immobilization of CSNC on BT resulted in a 3–4 fold enhancement in degradation rates. The rates achieved for the degradation kinetics are: MO degradation within 14 s (Ka 9.86 ± 2.00 min−1), and CR degradation within 120 s (Ka of 1.24 ± 0.13 min−1). Further, a degradation mechanism has been proposed by analyzing the products identified through LC-MS. The reusability studies of the BTCSNC evidenced the complete activity of the nanocatalytic platform for six cycles, and gravitational separation method for catalyst recycling. In a nutshell, the current study provided an environmentally friendly, sizable, and sustainable nano catalytic platform” for the remediation of industrial wastewater contaminated with hazardous azo dyes”.

Unrestricted Horizon Predictive Controller Applied in a Biphasic Oil Separator under Periodic Slug Disturbances

Multi-phase flow, characterised by the presence of both liquid and gas phases, often occurs in riser pipes during oil extraction. These flows can be problematic because they can cause oscillations due to the formation of bubbles within the pipes, which can negatively impact the safety and efficiency of offshore production operations. One solution to this problem is to use a gravitational oil separator, which is designed to dampen these oscillations. The separator is equipped with a control system that uses liquid level and gas pressure sensors to stabilise the flow by adjusting the positions of its valves. This paper presents the use of a specific type of model-based predictive controller to control the level and pressure of a biphasic oil separator, particularly in the presence of slug disturbances. The designs of the separator model and controller are discussed in detail, with a focus on the advantages of using an unrestricted horizon predictive controller, such as its ability to make predictions over a long horizon and its relatively low computational requirements. For the sake of comparison, a linear quadratic regulator is also evaluated. The simulation results demonstrate that the proposed control system is able to effectively regulate the separator’s liquid level and gas pressure within a magnitude range of 10−4 m for the liquid level and 10−3 bar for the internal pressure. Aside from that, the dynamics of the closed-loop system is six times faster than the plant’s for the liquid behaviour and 30 times faster for the pressure, while also presenting sharp attenuation characteristics for the input disturbances of nearly 50 dB for the pressure output and 68 dB for the liquid level.

МЕТОДИКА ОЦЕНИВАНИЯ ПАРАМЕТРОВ ЭЛЕКТРОТЕХНИЧЕСКОГО КОМПЛЕКСА «КАБЕЛЬНАЯ ЛИНИЯ — АСИНХРОННЫЙ ДВИГАТЕЛЬ» НА ОСНОВЕ БАЛАНСА ПОТРЕБЛЯЕМОЙ МОЩНОСТИ

Relevance In the Russian Federation, 82 % of oil is produced using Electric Submersible Pumps (ESP), while only 63 % of wells are equipped with such pumps. Since more than half of the operating wells are equipped with ESP, developing methods to reduce operating costs for these wells is a rational and logical allocation of human, material, and financial resources. One method to increase the profitability of oil production from low- and medium-flow rate wells is to transition a well equipped with ESP from continuous operation to intermittent operation, specifically cyclic operation. Intermittent operation reduces energy consumption by up to 40 % and increases oil production by 3 % due to partial gravitational separation of the produced fluid during accumulation. However, the negative effect of transitioning to intermittent operation is reflected in the reduction of the average runtime before failure due to a decreased ESP hydroprotection resource, accelerated wear of the pump unit thrust bearings, and intermediate radial bearings. The cause of these negative effects is the increased vibration level during intensive startup. One way to address these issues is transitioning from the existing scalar open-loop control system to a vector sensorless control system for the ESP. To implement such a system, it is necessary to obtain information about the vector of the ESP state variables. A promising approach to obtaining information about the ESP state involves creating observers based on explicit mathematical models. To create an observer for the state variables, mathematical models for each component of the studied system must be developed and combined into a unified system. When measuring currents and voltages at the output of the step-up transformer, the studied system will be an electric complex «Cable Line — Induction Motor». To implement this observer, it is necessary to determine the parameters of the equivalent circuit of the studied complex. Based on the above, developing a methodology for identifying the parameters of the equivalent circuit of the electric complex «Cable Line — Induction Motor» when measuring currents and voltages on the surface is a timely and relevant task. Solving this task will create prerequisites for the implementation of a vector control system for the ESP, increasing the reliability of the ESP during intermittent operation, and consequently, increasing the profitability of oil production from low- and medium-flow rate oil wells. Aim of research To develop and experimentally confirm the effectiveness of a methodology for assessing the parameters of the electric complex «Cable Line — Induction Motor» based on the balance of consumed power. Research methods Analysis of literary sources, system analysis, mathematical modeling, experimental research. Results The effectiveness of the methodology for assessing the parameters of the electric complex «Cable Line — Induction Motor» based on the balance of consumed power has been experimentally tested and confirmed.

Refining of the oil from asphaltene-resins and paraffins

THE PURPOSE. To consider the problems of express-control and asphalten-resins and paraffins (ARP) purification of oil from them. Elaborate new methods of oil-well liquid and oil express-contro, especially of ARP. The task is actual, because great amount of ARP lead to ARP – deposits in pipeline, which result to complications in oil-mining, increase of power consumption and wearing of machinery. Elaborate the technology and installation for removing ARP from oil under affect of physical fields. METHODS. When solving this problem, we used the backward/forward method of nuclear (proton) magnetic resonance (PMR) relaxometr, which is noncontact, nondestructive, does not need probe preparense. For ARP removing were used: rotating magnetic, nonuniform alternating electric, centrifugal fields and gravitation separation of emulsion. Was used also physica modeling and MatLab Simulink mathematical modeling.RESULTS. Elaborated the methodics of express-control of ARP and water concentrations, disperse distributions of water solutions of ARP with reagents in emulsions. Were received experimental equations between ARP and water concentrations and times of PMR spin-spin relaxations, which gives the opportunity determine the oil characteristics from NMR-parameters. Theoreticall grounded the technology of the ARP removing from oil, described the forces, affecting on droplets in the rotating magnetic, nonuniform alternating electric, centrifugal fields. Elaborated the structure-functional scheme of installation for purification of oil from ARP, controlled by elaborated relaxometer NMR-NP2. Made the calculation of the rotating magnetic resonance source, its optimization and physical, mathematical modeling of its function in Matlab Simulink program. CONCLUSION. The survey of methodic and instrumental equipment of oilmining deposits showed, that control of studied oil characteristics is carried in laboratories, expensive and long in time, there is no instrumental method of ARP determination and removing. Were received experimental equations for the asphaltene-resins control in the range 0-30% withthe accuracy of »±2 %, for paraffinsin the range 0-30% withaccuracy »± 3 %, droplets distribution in the range 1-20 mm withaccuracy »± 1mm, offered the installation for ARP removing from oil.

Numerical Simulation and Experimental Study of a Multistage Multiphase Separation System

Nowadays, most oilfields have entered the high water cut stage of waterflood development. The importance of oil–water separation technology becomes more obvious. Gravity separation is one of the most commonly used treatment techniques for produced fluid. The gravitational separator has a large processing capacity and a wide application range, but its structure is relatively simple and the separation efficiency gradually falls behind to meet current production needs. The key difficulties to improve the separation efficiency are to analyze the flow field and coalescing components inside the separator. Aiming at these difficulties, this paper reports an innovatively designed series-parallel multistage multiphase separation system (MMSS). A horizontal separator is connected in series with a vertical separator, and the vertical separator consists of five discrete pipes connected in parallel. Different coalescing components are then set inside the vertical separator. The separation effect of the MMSS is studied by numerical simulation and laboratory experiments. The oil phase volume distribution cloud diagrams of coalescing components are analyzed by numerical simulation, including semicircle baffle, spiral track plate, four-hole plate and seven-hole plate. Laboratory experiments show that MMSS has a high separation efficiency, and the water content at the oil outlet is 3.0% less than that of the horizontal separator. By observing the shape of oil droplets at the outlet and measuring the oil cut and water cut at the sampling outlet, the separation effect of four coalescent plates is obtained. According to the statistics, when the volumetric flow at the inlet of the separator is 1.5 m3/h, the average particle size of oil drops in the blank pipe, semicircular baffle, four-hole plate, spiral track and seven-hole plate increases in turn. A continuous oil layer appears at the outlet of the vertical separator in the fully open state. The water content at the oil outlet of the semicircular baffle coalescing component is always at a high level under different flow rates. When the inlet volumetric flow rate is less than 1.6 m3/h, the performance of the spiral track coalescing component is better. With the increase of the inlet volumetric flow rate, the separation efficiency of the spiral track is lower than that of the orifice. The results show that the semicircular coalescing component has the worst performance, the spiral track coalescing component is superior at small volumetric flow rates, and the orifice coalescing component is superior at large volumetric flow rates.

To the Theory of Grain Motion in an Uneven Air Flow in a Vertical Pneumatic Separation Channel with an Annular Cross Section

The possibilities of the action of uneven air flows on the grain material in the separating channels are still not used enough. The reason for this is the insufficient knowledge of the processes of interaction of the components of the grain material with an uneven air flow. The purpose of the research is to increase the efficiency of grain material separation according to aerodynamic properties by purposefully changing the diagram of air velocities in the channel sections using the actions of lateral and aerodynamic forces. The separation efficiency of grain material components was determined by trajectory analysis. The different geometry of the pneumatic separation channel was studied. The study of the distribution of air velocity and air pressure vectors in a vertical annular channel was carried out using the FlowVision software. It has been established that a change in the air velocity diagram can be implemented both by changing the geometric parameters of the channel and by additional distributed air supply through the perforation in the side walls of the pneumatic channel. Based on the analysis of the velocity field, an improved scheme of a pneumatic gravitational separator is proposed for separating grain material into three fractions according to aerodynamic characteristics.

Facile method of raising the LTP content in Mn-Bi alloys by using sequential separation techniques for Bi and Mn

Mn-Bi alloys, especially the Low Temperature Phase belonging to the P63/mmc crystallographic space group are an attractive alternative for replacing the rare-earth permanent magnets especially at elevated temperatures. The encountered issues during the fabrication are driven by phase segregation effects and inhomogeneities that are difficult to control or eliminate, thus leading to low experimental reproducibility and uncorrelated results for structural and magnetic properties. To overcome these issues, we propose an innovative method to increase the content of LTP by integrating an intermediary separation process during the manufacturing of Mn-Bi melt-spun ribbons. The method consists of two steps: one for Bi excess removal and the second for Mn excess removal. Bi excess removal is achieved by using a system of quartz tubes arrays though gravitational separation. This method is suitable for obtaining Mn-Bi ribbons with high content LTP, as the removal of Mn excess from the alloy occurs during the ribbons formation through the melt spinning technique. As the method employs the removal of the excess unalloyed metals, the global weight yield is in range of 53–64 wt%, but it can be increased by recovering the metallic elements and reprocess them. After a proper thermal treatment of the as quenched Mn-Bi melt-spun ribbons, over 99.0 wt% is represented by the LTP crystallographic phase characterized by saturation magnetization (MS) values of 70.6 emu/g.

Efficiency of an Inverted-Shroud Gravitational Gas Separator: Effect of the Liquid Viscosity and Inclination

Summary Gas-liquid separation is a typical process in many applications. For instance, gas separation is critical for the proper operation of electrical submergible pumps in the oil and gas industry as the pumps’ performance and lifetime are severely reduced when working with high gas/oil ratios. Gas-liquid separators are installed in oil production wells to reduce the void fraction at the pump inlet. The inverted-shroud gravitational separator stands out due to its efficiencies higher than 97%. This separator performs the gas separation process in two stages. The first is a segregation process related to inversion from liquid to gas continuous flow, whereas the second stage is related to gas entrainment associated with kinetic-energy dissipation process. The latter is more complex to model in the vertical than in the inclined separator’s position. Previous studies revealed that the liquid flow rate and separator’s inclination are relevant parameters for the gas separation efficiency (GSE). However, studies regarding the effect of the liquid viscosity on GSE are scanty. We evaluate the influence of the liquid viscosity and separator’s inclination on the GSE of an inverted-shroud separator (IS-separator) with water-air and oil-air mixtures. Efficiency maps for each inclination and empirical correlations to predict the GSE in the vertical inclination are proposed. New experimental data collected for several liquid flow rates and separator inclinations are offered in this study as a starting point to develop universal GSE maps. Different gas separation phenomena are observed depending on the flow pattern at the inner annular channel (IAC) of the separator and its inclination. The experiments conducted with the water-air mixture indicated turbulent flow, while the oil-air mixture revealed laminar flow for both inclined and vertical positions. The results suggest that the greater the liquid viscosity, the higher the GSE. The efficiency maps indicate that it is possible to reach total gas separation (TGS) for many experimental conditions. In practice, our approach proposes an alternative technology where the variables that influence the production well’s dynamic fluid level are actively controlled. Therefore, the IS-separator can operate under operational field conditions similar to those tested on a laboratory scale. This fact makes the IS-separator a promising tool for industrial applications.

Enhanced Iron Recovery from Ultrafine Iron Ore Tailing Through Combined Gravitational and Magnetic Separation Process

Enhanced Iron Recovery from Ultrafine Iron Ore Tailing Through Combined Gravitational and Magnetic Separation Process

Estimation of Radioecological State at the Objects of the Former Novotroitsk Mining Department, Baley (Zabaykalsky Region)

The results of dosimetric measurements which were carried out on the territory of the former Novotroitsk mining department quarry (Baley, Zabaykalsky region) are obtained. The map of radioactive contamination of the quarry territory is presented. A number of objects on the explored area where the gamma ray dose ambient equivalent is exceeds the maximum permissible level of 0.60 mSv/h were identified. The specific effective activity and chemical composition of a soil sample taken at one of the contaminated sites were determined. It is detected that the main source of radioactivity is 232Th nuclide, which is part of the mineral monazite. The possibility of effective concentration of thorium-containing minerals by gravitational separation was shown. The main factor of the spread of radioactive contamination is water erosion of soils from the walls of the quarry.

Development of Low-Temperature Block Type Facility for Sea Water Desalination

This work is devoted to the fresh water deficit analysis. The importance of the research concerning water treatment is emphasized. A comparative analysis of water demineralization traditional methods is given and prospects for low-temperature desalination methods are shown. The increase in the world interest to the research of the block freezing innovative technologies was established, the priority in which belongs to the authors of this work. The aim of the work is to improve the block freezing devices during their transferring to a continuous operation mode. Achievement of this aim lies in a proposed universal design of the apparatus, in which the processes of crystallization, separation and melting of ice are sequentially implemented. A module for a continuous seawater desalination facility was developed. The energy and operational advantages of the proposed method were described. The system modeling of this equipment was carried out. The target function of the modeling determined the key parameters of the process of the ice block gravitational separation — energy and salinity. It was proposed to correct the traditional calculation principles for the outflow in channels by the “capillary drag” coefficient, which takes into account the relief surface of the ice capillaries. A technique for the engineering calculation of ice block salinity during separation was offered. The most significant result of the work lied in the fact of possibility to transfer the block freezing facilities to the continuous mode of sea water desalination with guaranteed salinity indicators. The significance of the work was that an energy-efficient freezing facility with ice recycling for the sea water demineralization in the flow was created.

Freezing-assisted nano-sweeping of short oligonucleotides using spherical nucleic acids: A fluorometric platform for quantification of microRNAs

MicroRNAs (miRNAs) have been identified as biomarkers for early cancer screening and diagnosis. As a result, the development of simple methods for quantifying these small RNA species is of great interest. This study describes a new biosensing platform termed nano-sweeping for quantitative detection of miRNA-30a. The sweeping process is driven by a combination of gold nanoparticle-core spherical nucleic acid (AuNP-core SNA) hybridization and gravitational separation. Two modified oligonucleotides, i.e., a capture DNA strand for attachment to the surface of AuNPs and a fluorescent reporter strand for fluorescence signal detection, were designed to be semi-complementary to the miRNA-30a. MiRNA-30a is hybridized with the two semi-complementary oligonucleotides using freezing-assisted hybridization, yielding a three-segment sandwich-type duplex. A centrifugation step causes the nanoparticles to settle, allowing the fluorescent reporter strands involved in sandwich hybridization to coprecipitate with the nanoparticles and be removed from the solution. The decrease in fluorescence intensity of the supernatant is proportional to the miRNA-30a concentration. Calibration curves were constructed using data from both traditional fluorometry and smartphone-based fluorescence imaging. The obtained quantification limit for miRNA-30a was 0.22 and 0.42 ng/µL for fluorometric and smartphone-based calibration models, respectively and a linear response established for the range of 0–3.55 ng/µL. Unlike fluorescence resonance energy transfer (FRET)-based methods, this approach is fluorophore independent, allowing for attachment of any fluorescent dye on the reporter oligonucleotide strand.

Methods of recycling of lithium power sources

Today, there are technologies for recycling lithium power sources, but they are not yet satisfactory and cost-effective. The purpose of the study - based on the analysis of scientific and technical publications to formulate a general description of modern technologies for recycling lithium power sources. The second purpose is to present the results of the authors' research on the improvement of lithium battery recycling technologies. Based on the analysis of scientific and technical publications, a general description of modern technologies for processing lithium power sources is given. Processing is carried out according to the following scheme. First, they organize the discharge of power sources and their pre-treatment to separate the active substances. Pre-treatment is carried out by mechanical grinding, or ultrasound, or calcination or solvents. Mechanical crushing is performed in blade crushers. Machining is the most common method of separating lithium batteries. However, it has disadvantages: loud noise, emissions of dust and harmful gases. Calcination takes place at temperatures up to 500 ° C to remove carbon and organic material. Disadvantages of the method: calcination requires expensive equipment, is energy-intensive and can emit toxic gases. Solvent pre-treatment uses solutions and solvents to separate the active materials from Al, Cu foil in the battery. This method removes the addition of binder material, which increased the contact of the foil with the active materials. Disadvantages: this method requires the use of hot organic solvents of about 100˚C, which increases the cost and creates hazardous waste into the environment. More promising is the method of processing batteries in ultrasonic cavitation. The pre-treated material is subjected to magnetic or gravitational separation, removing substances containing metals. Then Li, Co, Ni, Mn are removed by pyrometallurgy, or hydrometallurgy, or electrochemical extraction. The obtained metals are suitable for secondary use in lithium power sources. The analysis of the considered technologies of processing of lithium power sources indicates that an important way to increase the efficiency of recycling is to improve the quality of pre-treatment of products that have exhausted the resource, which allows to effectively remove active materials with the lowest energy costs and environmental risks. The authors have developed a schematic diagram of the technology of pre-treatment of lithium batteries based on acoustic or hydrodynamic cavitation, as well as improved the method of magnetic separation of metals.

A new mathematical model of continuous gravitational separation with coalescence of liquid-liquid emulsions

A model for a continuous gravitational separation process of a liquid-liquid dispersion is presented, which is formulated as a population balance equation (PBE) that describes the coalescence and the hindered polydisperse sedimentation of droplets. This is important because this separation process is critical in the operation of many industries as discussed later. This study is based on previous findings by Garcia and Betancourt (2019) where a formulation for a batch process was presented. This analysis shows the improvements and differences between the model presented in this study and the formulation by Garcia and Betancourt (2019). The modeling framework comes from the Kynch’s theory that has been employed to model solid particle sedimentation processes; however, in this case the principles are applied to an organic phase-aqueous phase liquid mixture. For the numerical solution of the model, the PBE is discretized in terms of droplet volume. Since the population balance model is subject to mass loss due to droplet coalescence, we propose a formula to compute the source term of the largest droplet class. Model validation used experimental data from literature for a continuous process. Numerical results explored the variation of parameters such as feed flowrate, feed oil volume fraction and the standard deviation of the initial and feed droplet volumes.

Influence of halite particles on the stability and physical properties of inverse olefin emulsions

The study of synthetic drilling fluids, consisting of inverse emulsions, became essential to the routine of the oil industry in Brazil, due to the discovery of the pre-salt carbonate reservoirs. This work aimed to analyze the incorporation of halite in the physical properties and stability of inverse olefin emulsions, which composes synthetic drilling fluids formulation. Therefore, halite was characterized in relation to its wettability, chemical and mineralogical composition. The properties of the emulsions added with halite, in the contents of 5, 10 and 15% by volume, were monitored by microscopic images, rheological tests and gravitational separation, performed before and after dynamic aging of the emulsion. The results showed that the presence of the halite particles promotes an increase in the consistency index, interfering in the viscous nature of the emulsion. In addition, dynamic aging provide changes in the flow behavior of the emulsified system, once there are increases in the behavior index, proportional to the halite content, bringing it closer to Newtonian behavior. It is also noticed that, under these conditions, the addition of this mineral intensifies the separation of the continuous phase of the emulsion, together with the emulsifying agents, especially for the contents of 10 and 15%.

Gravitational separation of 137Cs contaminated soil in Fukushima environment: Density dependence of 137Cs activity and application to volume reduction

Behavior of radiocesium in Fukushima after its deposition is mainly controlled by mobility of soil components, of which the density is one of the parameters governing the mobility; however, little information is available on the density of soil components associated with radiocesium in environment. Furthermore, the reduction of the volume of radiocesium-contaminated soil in the interim storage is highly demanded. In this study, we developed a gravitational separation method using a sodium polytungstate (SPT) solution combined with size fractionation to understand the relation between 137Cs activity and the density of surface soil components and evaluate the feasibility of the method for the volume reduction of the contaminated soil. In all soil samples examined, 137Cs concentration of the small size (<0.063 mm) and high-density (2.4–2.8 g cm−3) fraction was the highest among the separated fractions, whereas most of the radiocesium-rich micro-particles were distributed in the small size (<0.063 mm) and low density (<2.4 g cm−3) fraction. Although ultrasonication improved the size separation efficiency, a single-step gravitational separation method using an SPT solution with a density of 2.4 g cm−3 without size separation and ultrasonication revealed that the 137Cs concentration on 50°C-dry weight basis in the dense (>2.4 g cm−3) fraction was 25.6–82.7% lower than that of the bulk sample for all soil samples. In particular, for the samples with a bulk 137Cs concentration of 29.6 Bq g−1 50°C-dry weight, the 137Cs concentration in the fraction was below the safety treatment requirement (i.e., 8 Bq g−1). Therefore, single-step gravitational separation may be used for the volume reduction of contaminated soils.

Applying an equivalent free settling ratio to enhance ferro-magnetic and para-magnetic particles’ separation efficiency using the influence of a magnetic field aligned with gravity

ABSTRACT Settling behaviour of particles in aqueous mediums depends on the resultant force acting on them. This force normally is the resultant of gravity, buoyancy and drag forces. Therefore, the settling velocity of coarse and light particles is very close to that of fine but dense particles. This fact is the major cause of poor beneficiation of fine valuable minerals in gravitational separation devices like spirals. So, implementing of an external force such as magnetic force may well improve the beneficiation of such particles. Theoretical analysis of terminal settling velocity (TSV) of particles shows that a magnetic field aligned with gravity can increase TSV of minerals with magnetic properties which in turn results in higher free settling ratios between magnetic and non-magnetic particles. In this regard, an innovative laboratory device was designed, fabricated and used to better understand the simultaneous effects of gravity and a magnetic force aligned with it.

O1/W/O2 nanoemulsions and emulsions based on extra virgin olive oil produced by ultrasound-assisted homogenization process: Characterization of structure, physical and encapsulation efficiency

Oil-in-water-in-oil (O1/W/O2) emulsions and nanoemulsions based on extra virgin olive oil were produced combining high-speed and ultrasonic homogenizer. Droplet size distribution, encapsulation efficiency, kinetic stability, and their structure were studied as a function of homogenization time, dispersed volume fraction, emulsifier type, and composition of the inner O1/W nanoemulsion. The ultrasonic-assisted homogenization was beneficial for the formation of O1/W/O2 nanoemulsion, as the intensity of the ultrasound did not destroy the double structure. The inner O1/W nanoemulsion with the lowest droplet size, surface tension, and viscosity resulted in double nanoemulsion with the minimum droplet size (432 ± 5 nm). Increasing the dispersed volume fraction resulted in higher particle size, gravitational separation, and high oiling off values. The DSC thermograms showed samples with the low droplet size presented also low encapsulation yield. The microscopic analysis demonstrated that all O1/W/O2 samples showed similar structures with distinctly visible phases and spherical aqueous droplets with a broad distribution.

Approaches for Extracting Nanofibrillated Cellulose from Oat Bran and Its Emulsion Capacity and Stability.

The pretreatment process is an essential step for nanofibrillated cellulose production as it enhances size reduction efficiency, reduces production cost, and decreases energy consumption. In this study, nanofibrillated cellulose (NFC) was prepared using various pretreatment processes, either chemical (i.e., acid, basic, and bleach) or hydrothermal (i.e., microwave and autoclave), followed by disintegration using high pressure homogenization from oat bran fibers. The obtained NFC were used as an emulsifier to prepare 10% oil-in-water emulsions. The emulsion containing chemically pretreated NFC exhibited the smallest oil droplet diameter (d32) at 3.76 μm, while those containing NFC using other pretreatments exhibited d32 values > 5 μm. The colors of the emulsions were mainly influenced by oil droplet size rather than the color of the fiber itself. Both NFC suspensions and NFC emulsions showed a storage modulus (G′) higher than the loss modulus (G″) without crossing over, indicating gel-like behavior. For emulsion stability, microwave pretreatment effectively minimized gravitational separation, and the creaming indices of all NFC-emulsions were lower than 6% for the entire storage period. In conclusion, chemical pretreatment was an effective method for nanofiber extraction with good emulsion capacity. However, the microwave with bleaching pretreatment was an alternative method for extracting nanofibers and needs further study to improve the efficiency.