Formation Of Agglomerates Research Articles

Mapping self-avoiding walk on obstacle-ridden lattice onto chelation of heavy metal ions: Monte Carlo study

Self-avoiding walk (SAW) represents a linear polymer chain on a large scale, neglecting its chemical details and emphasizing the role of its conformational statistics. The role of the latter is important in the formation of agglomerates and complexes involving polymers and organic or inorganic particles, such as polymer-stabilized colloidal suspensions, microemulsions, or micellar solutions. When such particles can be adsorbed on a polymer of considerably larger dimensions than themselves, this setup may represent the chelation of heavy metal ions by polymeric chelants. We consider the SAW of the length N on a cubic lattice ridden by randomly distributed obstacles of the concentration p interpreted as ions. The SAW monomers can bind to the obstacles with variable binding energy ɛ mimicking the formation of the chelation bond. Pruned-enriched Rosenbluth method (PERM) Monte Carlo (MC) algorithm is applied to simulate system behavior. We focus on several relevant properties related to the chelation efficiency and strength, as functions of the variables set {p,N,ɛ}. The results are interpreted in terms of conformational freedom, excluded volume effects, and loop formation for the SAW, and the tendencies being predicted are in agreement with some experimental data. Published by the American Physical Society 2024

Industrial Zones: A Successful Agglomeration Form in Morocco - Taking the Marrakech Cluster as An Example

This article aims to investigate the experience of clustering policy adopted by Morocco and demonstrate the positive effects of this agglomeration on the development of a given sector. For our study, we chose the case of the Menara Cluster based in the city of Marrakech, specializing in agri - food and cosmetics. Our theoretical study allows us to classify the cluster as an industrial district, upon which we shed light on the success of this policy.

Surface wettability of lignin materials from supercritical water hydrolysis of wood

To meet the demands of the evolving circular economy, there is a growing need for renewable resources as base materials for innovative, easily recyclable products. Lignin, the second most abundant biopolymer, has emerged as a promising source of aromatics and reinforcing agent in polymer composites. For the successful manufacturing of homogeneous composite materials, good bonding between the coexisting phases is essential to prevent the formation of voids and agglomerates. Therefore, understanding the surface properties of these materials is crucial for designing optimal composite compounds. In this study, the wettability of lignin-cellulose composites and lignin samples obtained through supercritical water hydrolysis (SCWH) of birch wood is investigated. The contact angle (CA) technique, specifically the sessile drop method, was employed to assess and compare the wettability of SCWH lignin with commercially available lignin and raw birch wood. The results provide insights into their surface energy, adhesion, and hydrophilic or hydrophobic characteristics under processing conditions. All samples exhibited hydrophilicity, with an initial CA approximately 40 °, except for raw birch wood, which had a higher initial CA of ∼ 64°. Notably, when lignin is accompanied by significant amounts of cellulose, different trends in CA changes over time were observed. The influence of pressure on the CA between water and these polymers was also analyzed, but no significant impact was detected. This research advances the development of lignin-based materials with tailored surface properties for various industrial applications.

Making quality agglomerates using lean iron ores for sustainable iron-making

For sustainable iron making and hassle-free operation of large blast furnaces (BF) and direct reduced iron (DRI) units, a more prepared burden in the form of good quality agglomerates is required. However, the situation is becoming more and more challenging owing to the faster depletion of high-grade iron ore, increased fines generation due to mechanized mining, wide variations in chemistry & mineral characteristics, high content of gangue minerals, and poor liberation characteristics. The growing demand for steel vis-à-vis iron ores has necessitated the utilizationof low-grade iron ores for steel production. The challenges lie in the economic extraction of lean ores and their conversion into quality agglomerates for use in iron making. The utilization of low-grade iron ores has assumed greater significance for the optimal utilization of natural resources and the sustainability of the steel industry. Thebeneficiated concentrate of BHQ iron ore from the Sandur Schist belt is used for the pellets. Green green pellets with 1.21 kg/pellet GCS and drop strength of 12 drop number were producedat an optimum binder of 1.2% and moisture of 9.5%. Induration of green pellets at a firing temperature of 1300 °C has resulted in adequate pellet properties of 237 kg/pellet of CCS, 91.87% TI, 7.41% RDI, and 22.56% porosity. An attempt is made to produce pellets suitable for iron making by optimizing various raw materials and operating parameters.This will reduce dependency on high-grade ores and effectively utilize low-grade iron ore to produce good-qualityiron-making pellets.

Effect of Aggregated Lysozyme on Fluorescence Properties of Rose Bengal.

Protein aggregates cause abnormal states and trigger various diseases, including neurodegenerative disorders. This study examined whether the xanthene dye derivative Rose Bengal could track a series of conformational changes in protein aggregates. Using lysozyme as a model protein, aggregated proteins were prepared by heating under acidic conditions. The absorption spectra, steady-state fluorescence spectra, fluorescence quantum yield, fluorescence lifetime, and phosphorescence lifetime of a solution containing Rose Bengal in the presence of aggregated lysozyme were measured to identify their spectroscopic characteristics. The absorption spectrum of Rose Bengal changed significantly during the formation of agglomerates in heated lysozyme. Additionally, the fluorescence intensity decreased during the initial stages of the aggregation process with an increase in heating time, followed by an increase in intensity along with a red-shift of the peak wavelength. The decrease in quantum yield with a fixed fluorescence lifetime supported the formation of a nonfluorescent ground-state complex between Rose Bengal and the aggregated lysozyme. Based on the characteristic changes in absorption and fluorescence properties observed during the aggregation process, Rose Bengal is considered an excellent indicator for the sensitive discernment of aggregated proteins.

Thermoelectric properties of filled InCo4Sb12 skutterudite with embedded ZnO inclusions: Influence on thermal conductivity and stability of electrical properties

Composite thermoelectric materials based on skutterudite represent an interesting subject for the synthesis and study of their thermoelectric properties. The introduction of oxide additives typically reduces the cost of the product and can positively affect the mechanical properties and thermal stability of the material. In this work, a high-performance composite skutterudite (InCo4Sb12) + xwt.% (ZnO) (x = 0, 1, 2.7 and 7.4) was obtained by a combination of induction melting and planetary ball milling. Bulk composites with a density of 90 % were obtained by spark plasma sintering. In contrast to the results reported in previously published works, in this case there was an increase in thermal conductivity, which was associated with the formation of agglomerates of highly thermally conductive oxide phases. The figure of merit zT reaches 1.41 at 700 K for the reference sample InCo4Sb12, and 1.28 for the composite with embedded ZnO inclusions. Despite a 9 % decrease in the zT, the best composite InCo4Sb12/ZnO demonstrates an increase in hardness of 18 % and reduction in the cost of raw materials.

Effect of high-boiling point solvents on inkjet printing of catalyst layers for proton exchange membrane fuel cells

Inkjet printing (IJP) is considered as a promising and flexible method for low cost and drop-on-demand pattern formation in proton exchange membrane (PEM) fuel cells. Although significant advancements have been made in inkjet-printed electrodes, identifying the optimal ink formulations remains challenging due to severe restrictions on the ink properties. Generally, the catalyst layer prepared by IJP using low boiling point solvents (water/alcohol) show reasonable electrochemical performance. However, low boiling point solvents lead to clogging of the printhead nozzle due to fast evaporation of the solvent in the inkjet print head. In this study, high boiling point solvents (propylene glycol (PG) or ethylene glycol (EG)) were used as additives to reduce nozzle clogging and improve printing efficiency. In this context, the relationship between catalyst ink properties, CL microstructure, and electrochemical performance of the MEA is investigated. Results show that printing time is significantly reduced with adding high boiling point solvents in the ink (66.67% reduction of time with 30 wt% PG). However, an increased amount of additive is detrimental in terms of electrochemical performance due to formation of larger agglomerates, lower porosity of the catalyst layer, and reduced ECSA. The results of this work can be used to develop a strategy to adjust the trade-off between printing time and electrochemical performance of electrodes prepared using IJP.

Microphysical Interactions Determine the Effectiveness of Solar Radiation Modification via Stratospheric Solid Particle Injection

AbstractRecent studies have suggested that stratospheric aerosol injection (SAI) of solid particles for climate intervention could reduce stratospheric warming compared to injection of . However, interactions of microphysical processes, such as settling and coagulation of solid particles, with stratospheric dynamics have not been considered. Using a global chemistry‐climate model with interactive solid particle microphysics, we show that agglomeration significantly reduces the backscatter efficiency per unit of injected material compared to mono‐disperse particles, partly due to faster settling of the agglomerates, but mainly due to increased forward‐ over backscattering with increasing agglomerate size. Despite these effects, some materials substantially reduce required injection rates as well as perturbation of stratospheric winds, age of air and stratospheric warming compared to injection of , with the most promising results being shown by 150 nm diamond particles. Uncertainties remain as to whether stratospheric dispersion of solid particles is feasible without formation of agglomerates.

Contemporary problems of settlement in the ethnic plain villages of the northwestern regions of Azerbaijan (on the example of the Balakan administrative district)

The geographical position of the region, ethnic composition, acceleration of the process of polarization among rural settlements, and other factors increase the relevance of the research. The subject of the research is the study of rural settlement problems, and the object of the research is the villages and ethnic minorities of the Balakan district. The study aims to reveal the modern problems of the settlement of ethnic minorities and the formation of rural agglomerations, to study the causes of the emptying of some villages, and to prepare a rural development model to prevent the problems. To conduct research, the literature and statistical materials were analyzed, as well as cartographic, comparative analysis, SWOT, and modelling methods were used. Moreover, a field investigation was conducted in the research area. It was revealed that although a majority of the rural population settles in villages with a high demographic potential, villages with a weak demographic potential, due to their higher number, play a major role in the settlement system. Moreover, some villages form rural agglomerations, while some of them lose their population due to socioeconomic challenges. Due to the intense migration processes, some villages have turned into endangered villages (Mazimustu, Goyrujuluk), and even some villages are on the brink of extinction (Bayrambina, Mazimchay, Abjit). Studying the regulation of rural settlement in the region is of practical importance in terms of ensuring the equal development of the region, ensuring the security of the borders, and protecting ethnic minorities. However, there is still a need for serious research in this field.

Microstructural Evaluation of Al-Al2O3 Composites Processed by Stir Casting Technique

The exceptional qualities of aluminum alloys, including their superior thermal properties, high specific strength and low density make them widely employed as industrial materials. By adding a tougher ceramic reinforcement phase to the aluminum matrix phase, aluminum alloy components can perform even better with improved mechanical properties. It has been discovered that the liquid state processing method is the most affordable and straightforward for processing MMCs out of all the existing ways. Primary processing, such as casting composite materials has its own restrictions on agglomerate formation and porosity. A metal matrix composite made of aluminum and aluminum oxide (Al2O3) has been chosen for the current investigation based on the literature review. A composite material including aluminum A356 and different percentages of Al2O3 (3%, 6%, 9%, and 12%) particles of 23�m size is chosen for the study. Using the SEM and EDAX test, the impact of these materials on the microstructural investigations is being investigated and the results indicates that uniform distribution of the reinforcement is difficult to achieve at higher percentages.

Experimental Study of Agglomeration Formation during Co-Combustion of Coal and Palm Kernel Shell in Fluidized Bed

Abstract Co-combustion of biomass and coal in Indonesia power plants are a key element of the path towards achieving net-zero emissions. However, introducing biomass into a coal-boiler furnace may pose operational challenges. Therefore, this study aims to assess the potential of agglomeration when mixing biomass with a fluidized bed boiler. Complementation simulation tests were conducted by combining coal with various fractions of palm kernel shell (PKS) in a furnace capacity of 5kWth maintained at 850°C within an hour. The initial fuel was 100% coal, gradually increasing the biomass mixture by 5%, 10%, 15%, 20%, and 25%. The results indicated that de-fluidization occurred at 25% of the biomass mixture and to prevent agglomeration, the temperature of the bed was kept below 850°C. The agglomeration test of coal and PKS mixtures was successfully performed in a 5kW lab-scale facility, and the result will be useful for predicting agglomeration phenomena in power plants.

Self-propagating high-temperature synthesis of AlN–TiC powder composition using sodium azide and C2F4 fluoroplastic

Producing powder compositions using conventional processing technology can lead to the formation of large agglomerates and, therefore, makes it difficult to obtain a uniform microstructure. The production of composites by self-propagating high-temperature synthesis can reduce costs and the number of technological stages, as well as lead to obtaining composites that are more homogeneous. Synthesis by the combustion of mixtures of powder reagents of sodium azide (NaN3), fluoroplastic (C2F4), aluminum and titanium with different ratios of reagents in a nitrogen gas atmosphere at a pressure of 4MPa was used for the production of a highly dispersed powder ceramic AlN–TiC composition. Thermodynamic calculations have confirmed the possibility of synthesis of AlN–TiC compositions of different formulations in combustion mode. The dependences of temperature and combustion rate on the composition of the initial mixtures of reagents were experimentally determined for all stoichiometric reaction equations. The study have shown that the experimentally found dependences of combustion parameters on the ratio of the initial components correspond to the theoretical results of thermodynamic calculations. The formulation of the synthesized composition differs from the theoretical composition by a lower content of target phases and the formation of Al2O3, Na3AlF6 and TiO2 side phases. The powder composition consists of aluminum nitride fibers with a diameter of 100–250nm and ultradisperse particles of predominantly equiaxed and lamellar shapes with a particle size of 200–600nm. As the combustion temperature increases to produce the largest amount of titanium carbide phase, the particle size increases to the micron level.

THE EXPERIENCE OF AGGLOMERATION DEVELOPMENT IN CHINA AND KAZAKHSTAN

This article examines the experience of agglomeration development in China and Kazakhstan. It reviews the history of formation and approaches to defining the concept of urban agglomeration, including the definition of urban agglomeration by Chinese scholars. Forecasts are presented for metropolitan areas around the world and in China. In the practice of agglomeration development in China today, five urbanization belts and nineteen major urban agglomerations are outlined. The transfer of "non-capital functions" from the Chinese capital to Hebei Province is transforming Xiong'an into a center of innovation. The set of special measures used by the Chinese authorities to stimulate the development of megalopolises and agglomerations is considered. Characteristics of the functioning of China's urban agglomerations are presented, as well as their advantages and disadvantages. The experience of agglomeration development in Kazakhstan at the legislative level is studied, and attention is paid to the introduction of a new model of agglomeration management in the country, which gives regional administrations basic, additional powers and responsibilities for agglomeration development. The imbalances around the major cities and the main factors contributing to these imbalances are considered. The need for the formation and development of agglomerations as points of economic growth of the country and their effective positioning according to the level and specialization of their development is substantiated. Based on the analysis of the development of agglomeration processes in Kazakhstan, the advantages and disadvantages of urban agglomerations are presented. Suggestions are made on the directions of their further development.

Impact of delayed compaction on the geoengineering properties of stabilised pond ash

ABSTRACT The impact of delayed compaction on the geoengineering properties of pond ash (PA) treated with geopolymer, Portland cement, and hydrated lime is presented in this paper. The gradation, compacted dry density (CDD), unconfined compressive strength (UCS), California bearing ratio (CBR), hydraulic conductivity, and compressibility index of PA treated with 3%, 9%, and 15% additive contents were evaluated at 0, 3, 6, 12, 24, 48, and 72 h delay periods. The mineralogical and morphological changes in the stabilised material were assessed using X-ray diffraction and scanning electron microscope analysis. The results show an enhancement in the particle size of PA with delay time due to the development of cementitious products and agglomeration of particles. Delay in compaction causes a reduction in dry density and strength properties, whereas hydraulic conductivity and compressibility index increase with delay time. The formation of cementitious products and agglomeration during delay periods leads to improper compaction and deteriorates the mechanical performance. The formations of both sodium-based geopolymer compounds and calcium-based hydration products contribute to the superior geoengineering properties of geopolymer-stabilised PA compared to cement and lime-stabilised PA, which have Ca-based hydration products alone. The developed mathematical models predict the engineering properties of stabilised PA with higher R-square values (>0.90). Based on this study, it is concluded that the geopolymer is more effective as a stabiliser than lime and cement.

Influence of nanodiamond on compressive and dry-sliding wear behaviors of Al2O3–Al interpenetrating-phase composites

In this research, the effects of nanodiamond (ND) addition at different loadings on the compressive and wear properties of the interpenetrating phases hybrid aluminum/alumina (Al/Al2O3) composite were investigated. The samples were fabricated in a two-step process. First, the Al2O3-ND preforms were fabricated via the replica method. Second, the squeeze casting route was employed to infiltrate the molten pure Al. The ceramic preforms were made by immersing a polyurethane foam with 17 ppi pores in a slurry containing α-Al2O3 powder (1 μm), ND particles (0–10 vol%), and natural egg white. After sintering at 1500 °C for 4 h, the preheated preforms were infiltrated with molten Al. The microstructural evaluations of the preforms and composites revealed a proper distribution of the ND particles in the preform, as well as the formation of the ND agglomerates at higher volume percentages. Also, the hardness of the samples enhanced with an increase in the ND loading, reaching a maximum of 263.8 Vickers for the 10 vol% ND-loaded composite. The compressive strength of the samples enhanced up to 3 vol% ND addition and then decreased due to the agglomeration. The wear test results indicated that the best behavior was related to the 3 vol% ND-loaded composite. Embedding the 3 vol% ND decreased the weight rate and friction coefficient of the interpenetrating phases hybrid Al/Al2O3 composite by 16 % (from 8.2396×10−3 to 6.9269×10−3 mm3/m) and 12 % (0.8165 to 0.7238), respectively. The study of the worn surfaces of the samples after wear testing revealed that the dominant wear mechanisms were abrasive and adhesive for the higher and lower volume fractions of the ND, respectively.

Influencing the powder particle transport in high-speed laser melt injection

Using high-speed laser melt injection (HSLMI), it is possible to generate wear-resistant metal matrix composite (MMC) surfaces on tools with great productivity. Since high laser intensities are required for reaching high process speeds, strong interactions can occur between powder particles and the laser beam. In order to reduce the interaction time and gain a better understanding of the role of particle transport in the HSLMI process, trajectories of spherical fused tungsten carbide (SFTC) particles were analyzed using high-speed imaging. The trajectories were divided into a path outside the laser beam and a path inside the laser beam. The identified interaction mechanisms were particle deformations, the formation of agglomerates, and particle disintegration. The volume flow rate of the feeding gas was found to have a decisive influence on the travel time of the particles, whereas the powder feed rate and the working distance of the powder nozzle only had a minor influence. Consequently, an increased volume flow rate led to a significant reduction of interactions between SFTC particles and the laser beam.

Study on the elimination characteristics of smoke particles with different materials using electric agglomeration technology

ABSTRACT Fire smoke, consisting of solid particles and liquid droplets, poses risks of asphyxiation, poisoning, making it a significant contributor to fire-related fatalities and environmental pollution. The exploration of effective smoke control methods represents a vital approach to reducing the threat of fire smoke to public health and safety. This study aims to determine the characteristics of elimination for the fire smoke generated from burning four typical materials, thereby validating the universality of electric agglomeration smoke elimination technology. The results indicate that the elimination efficiency of electric agglomeration varies with the material type of the smoke. The rate of change in smoke transmittance from fast to slow is: polyvinyl chloride (PVC), polystyrene (PS), wood, and styrene butadiene rubber (SBR), respectively. With an external potential of 4 kV, PVC smoke reaches the safe threshold after 12.1 s, while SBR smoke achieves it in just 4.9 s. Analysis of the microscopic morphology of agglomerates with scanning electron microscopy (SEM) reveals that particle size distribution is an important factor affecting electric agglomeration elimination. This is because larger initial particles carry a greater charge, enabling the formation of larger agglomerates for more efficient removal. This study provides theoretical guidance for the practical application of electric agglomeration in eliminating smoke particles.

Impact of Silver Incorporation and Flash-Lamp-Annealing on the Photocatalytic Response of Sputtered ZnO Films.

Thin films of silver-doped zinc oxide (SZO) were deposited at room temperature using a DC reactive magnetron co-sputtering technique using two independent Zn and Ag targets. The crystallographic structure, chemical composition and surface morphology of SZO films with different silver concentrations were correlated with the photocatalytic (PC) properties. The crystallization of the SZO films was made using millisecond range flash-lamp-annealing (FLA) treatments. FLA induces significant structural ordering of the wurtzite structure and an in-depth redistribution of silver, resulting in the formation of silver agglomerates. The wurtzite ZnO structure is observed for silver contents below 10 at.% where Ag is partially incorporated into the oxide matrix, inducing a decrease in the optical band-gap. Regardless of the silver content, all the as-grown SZO films do not exhibit any significant PC activity. The best PC response is achieved for samples with a relatively low Ag content (2-5 at.%) after FLA treatment. The enhanced PC activity of SZO upon FLA can be attributed to structural ordering and the effective band-gap narrowing through the combination of silver doping and the plasmonic effect caused by the formation of Ag clusters.

A review of the engineered treatment of red mud: Construction materials, metal recovery, and soilization revegetation

Red mud, known as bauxite residue, is an alkaline solid waste generated during alumina production. Globally, the stockpile of red mud is about 3 billion tons and is increasing at a rate of 150 million tons per year. The global production of red mud is mainly distributed in China (28.2 %), Oceania region (22.4 %), South America (14.6 %), Europe (12.9 %), and North America (8.8 %). The increasing stockpile of red mud has posed a huge challenge to safe disposal while restricting the development of the alumina industry. The comprehensive utilization of red mud still needs green, efficient, and massive consumption methods. This work gives a review of the engineered treatment of red mud, including the characteristics and threats, as well as the engineered application through construction materials, metal recovery, and soilization revegetation. For red mud with a high content of metals, resource recovery of valuable metals and rare earth elements is a preferred choice, meeting the circular economy concept. Recovery of valuable metals from red mud can be achieved by magnetic separation, hydrometallurgy, and bioleaching. Hydrometallurgy is promising for recovering valuable metals such as Fe, Al, V, Ti, and rare earth elements, and the recovery is up to 99 %. Construction materials such as cement, geopolymers, and ceramics is an efficient alternative for the massive consumption of red mud, and the high-performance concrete with the compressive strength (129.5 MPa) can be obtained. This strategy is limited by the low price of construction materials, the lowered quality by alkaline components, and potential threats of toxic elements in red mud. Soilization of red mud with ecological restoration is promising for the sustainable management of red mud dam. To accelerate the process of red mud soilization, amendments such as gypsum, organic matter, and microorganisms can be added to neutralize red mud (lowering pH from 10 to 12 to near 7), promote the formation of agglomerates, and provide nutrients, promote the conversion of red mud into soil-like substrate. The phytoremediation of red mud can be realized after effective regulation, finally realizing vegetation establishment of red mud. This work provides technological and practical guidance for the engineered disposal of red mud.

Influence of annealing on the physicochemical properties of 2L ferrihydrite synthesized by radiation-chemical method from iron (III) nitrate

In this study, ferrihydrite (Fhy) nanoparticles (NPles) synthesized by the radiation chemical method (RCM) from an iron nitrate alcohol solution were annealed in air at temperatures ranging from 100 to 1200 ºC. The effects of annealing temperature on the phase transformation and basic physicochemical properties of the annealed Fhy nanopowders (NPs) were investigated. Fhy NPles annealed at 400 ºC and above can be converted to hematite NPles. The X-ray diffraction (XRD) pattern of the RCM-synthesized product corresponded to two-line (2 L) Fhy NPles, with no additional peaks, confirming their chemical purity. Up to 200 ºC, no significant phase transformation of Fhy NPles was observed; at 300 ºC, Fhy transformed into maghemite, which further transformed into hematite at 400 ºC. TEM/HRTEM analysis showed the formation of mesoporous agglomerates consisting of amorphous-crystalline NPles approximately 2 nm in size in the Fhy S95 sample annealed at 95 ºC. Selected area electron diffraction (SAED) images indicated the presence of two crystalline phases in sample S95: FeO and zero-valence Fe. The specific surface area (SSA) of mesoporous Fhy NPles varied non-monotonically between 100 and 500 ºC, peaking at 53.2 m2/g at 300 ºC. X-ray photoelectron spectroscopy (XPS) analysis revealed a minor nitrogen impurity, likely from the initial iron nitrate precursor, and a significant amount of adsorbed carbon on the developed porous surface of Fhy NPles. The phase composition of annealed Fhy samples correlated with their photoluminescent (PL) spectra. In samples S400 and S500 containing hematite, a small ferromagnetic contribution emerged, disrupting the linear magnetization-field dependence observed in samples S0-S200. Thus, the properties of 2 L Fhy nanoparticles produced by the radiation chemical method can be modified through thermal annealing while maintaining their potential biomedical applications as nanocontainers for drug delivery and contrast agents.