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Biochar (BC) is often used as an additive in anaerobic digestion (AD) to increase yield and/or to stabilise the process when the manure content is increased. Unfortunately, BC is rarely described in detail in terms of its raw material sources, production processes, and structural, physical and chemical properties to allow correlation with its effects on AD. It is an open question whether microorganisms from AD can penetrate into different biochar pore types, depending on their wood origin. In this paper, we describe the preparation (temperatures, treatment times, yields) and characterisation shrinkage, density, pore sizes, pore size distribution, specific surface area, ash, volatiles, fixed carbon, elemental composition, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), benzene, toluene, ethyl-toluene, xylene (BTEX) and volatile halogenated hydrocarbons (VHH) of BC cubes of Scots pine (Pinus sylvestris) and common beech (Fagus sylvatica) powder made from this BC in addition to commercial charcoal powder. The pore size distribution determined by mercury porosimetry differs from that determined by 3D-reflected light microscopy. After incubating BC cubes in AD, the cubes were mechanically cleaned and cut into two pieces. Microorganisms were detected inside the cubes by fluorescence microscopy. Particle size and wood source determine the influence of BC on AD. [ABSTRACT FROM AUTHOR]

Abstract Using surfactants to extract oil, the anionic surfactant Karamay petroleum sulfonate (KPS), the zwitterionic surfactant octadecyl betaine (BS-18) and the nonionic surfactant coconut oil fatty acid diethanolamide (6501) were selected for adsorption experiments with minerals contained in the conglomerate reservoir with different mineral compositions to study the adsorption law of different types of surfactants. Zeolite and montmorillonite, which have the highest specific surface area and zeta potential among the minerals in the conglomerate reservoir, have the most obvious adsorption effect on surfactants, resulting in a large amount of adsorption of KPS and BS-18. The three types of surfactants were then used to conduct physical simulation oil recovery experiments with conglomerate core samples, and the results showed that 6501 had better overall performance, the best adsorption resistance, and a higher degree of recovery in oil recovery experiments, which provided a basis for the selection of surfactants in the process of chemical drive in conglomerate reservoirs.

Seismic emission is the spontaneous emission of waves in a porous or fractured medium. There is still no explanation for the dependence of these phenomena on the medium parameters and pore structure, as well as for the transition from slow to fast movements. The paper proposes a description of the transition process from statics to dynamics using a model of a structured continuum. The most important parameters of the model are the specific surface area and porosity of the medium. The reason for the emission is that the forces caused by internal stresses are only on average equal to zero over a representative volume, being different at each point of the medium. It is shown that the model of a structured continuum predicts the emission of waves under static load and gives an estimate of the vibration periods. In this case, the characteristic vibration periods depend neither on the characteristic time of destruction of particles, nor on the loading time. [ABSTRACT FROM AUTHOR]

Background. The cinder of industrial molybdenum product (IPM), obtained at JSC Almalyk Mining and Metallurgical Combine, based on a charge with kaolin, is processed by soda leaching in 6-7 stages. Purpose: to study the textural and sorption properties of IPM samples based on kaolin and organic binders. Methodology. Using the calorimetric method of adsorption of water and nitrogen vapors on the surface of the cinder, by constructing adsorption isotherms, using the Langmuir equation, the sorption characteristics of the materials were obtained. Originality. It has been established that the IPM cinder, based on organic binders, is characterized by a porous structure. It is more efficient in processing, compared to kaolin cinder. Findings. The sorption of water vapor and nitrogen on granules of IPM cinder based on kaolin and organic binders was studied. [ABSTRACT FROM AUTHOR]

The detonability of mixtures of solid and liquid explosives (explosive suspensions) has been little studied although they are part of plastisol and paste explosive compositions widely used in practice. This paper presents an experimental study of the critical detonation diameters of suspensions of PETN, RDX, HMX, and FOX-7 of various dispersity (specific surface area 350–7000 cm2/g) in nitromethane. The concentration of crystalline explosives in suspensions was 3–60% (wt.). Suspensions were prepared using a vibrovacuum method. The sedimentation stability and homogeneity of suspensions were ensured by their thickening with a small addition of aerosil (2.0–2.5%). Charges of suspensions were prepared in thin-walled polyethylene terephthalate tubes of various diameter. Thus, the critical detonation diameter of explosive suspensions was determined for practically unconfined charges. The dependences of the critical detonation diameter of suspensions on the volume fraction of solid explosives have the same nearly S-shaped form. The effect of the dispersity of explosives on these dependences was shown. The obtained dependences for suspensions of solid explosives in nitromethane were compared with similar experimental dependences for other explosive systems: solutions of liquid explosives in nitromethane, solutions of solid explosives in nitromethane, binary mixtures of finely dispersed solid explosives, binary mixtures of coarsely and finely dispersed explosives, and compositions containing mixtures of coarsely and finely dispersed explosives and an inert binder. It was found that the dependences for the suspensions are similar to those for binary mixtures of coarsely-dispersed and micron-sized explosives and compositions based on these mixtures (distinct heterogeneous systems). [ABSTRACT FROM AUTHOR]

Particle crushing takes place in a wide range of engineering applications and affects fluid flow through granular materials. This study examines volumetric changes and the evolution of hydraulic conductivity during particle crushing using a combination of high-stress experiments, data compilation from published studies and particle-scale numerical simulations. An asymptotically correct hyperbolic model fits void ratio versus stress data and provides reliable estimates of the yield stress. Alternatively, hydraulic conductivity follows a power law with void ratio and the trend extends into the grain crushing regime. Hydraulic conductivity diminishes rapidly as sand grains start crushing; the reduction in hydraulic conductivity can reach 1-to-4 orders of magnitude depending on mineral composition, particle shape and initial packing density. Crushing involves the progressive detachment of small fragments; these small particles move into the larger pores, increase the drag resistance, clog pore constrictions, and effectively hinder fluid flow after the yield stress. [ABSTRACT FROM AUTHOR]

In contrast to the western part of the Lower Silesia, information about the basalt-derived weathering crusts occurring in the Opole region is rather limited. However, in 2018, significant volumes of such regolith (about 20,000 m3) were discovered during development works in the NW part of the Rutki Quarry near Niemodlin. This weathering crust is rich in clay minerals and represents a smectite-kaolinite mixture with some halloysite, the latter being a poorly ordered member of the kaolinite group. The minerals of the smectite group contain in their interlayer spaces bivalent cations (calcium and magnesium), which is the most often case in the nature. The mineral composition of the regolith mass is supplemented by iron-containing phases, i.e. goethite and magnetite, and traces of phosphate mineral - crandallite. A significant amount of clay minerals, particularly those belonging to the smectite group and halloysite, results in high value of the specific surface area (up to 100 m2/g) of the studied crust. Such favorable property of the crust makes it a promising sorptive raw material that can be applied, even in an unprocessed form, for waterproofing. It must be emphasized that the sorption properties of basalt weathering crusts were noticed some centuries ago in the western part of Lower Silesia, where medicine called terra sigillata was produced from them. Moreover, the crust from Rutki was also used in the XIXth century, in a ceramic manufacture located in nearby Tułowice, where the so-called "Silesian black porcelain" was produced. [ABSTRACT FROM AUTHOR]

This study examined the use of clay brick powder (CBP) as a partial substitute for cement in mortar mixes. Five mixes were tested, each differing by the fineness of the CBP, obtained by grinding brick waste for different durations (30, 60, 90, 120 minutes). Several parameters were evaluated; apparent density, porosity, spread, ultrasonic pulse velocity (UPV), flexural and compressive strength, and the pozzolanic activity index. The results indicate that, when the brick powder is ground for 60 minutes, the spread of the mortar exceeds 95% compared to the reference mortar. The addition of CBP appears to increase the water absorption and porosity of the mortars, without significantly influencing their apparent density. Most samples have a UPV close to 4000 m/s, attesting to satisfactory mechanical properties. The use of 20% CBP in replacement of cement leads to a decrease in flexural strength. However, this drop is less when the specific surface area of the CBP is close to that of cement. As for compressive strength, a decrease is also noted with the introduction of CBP, but this decrease can be mitigated by using CBP with a specific surface area similar to that of cement. These factors can significantly influence the pozzolanic activity of the mortar mix. Furthermore, our investigations into environmental and economic analyses show that the use of cement mixes including CBP results in a significant decrease in energy consumption and CO2 emissions. More specifically, the replacement of 20% of cement with CBP of different granulometries has led to promising results. [ABSTRACT FROM AUTHOR]

Nanoparticles of NiLaxFe2−xO4 ferrite spinel incorporated in a SiO2 matrix were synthesized via a sol-gel method, followed by annealing at 200, 500, and 800 °C. The resulting materials were characterized via XRD, AFM, and BET techniques and evaluated for photocatalytic activity. The XRD diffractograms validate the formation of a single-phase cubic spinel structure at all temperatures, without any evidence of secondary peaks. The size of crystallites exhibited a decrease from 37 to 26 nm with the substitution of Fe3+ with La3+ ions. The lattice parameters and crystallite sizes were found to increase with the rise in La3+ content and annealing temperature. Isotherms were employed to calculate the rate constants for the decomposition of malonate precursors to ferrites and the activation energy for each ferrite. All nanocomposites have pores within the mesoporous range, with a narrow dispersion of pore sizes. The impact of La content on sonophotocatalytic activity was evaluated by studying Rhodamine B degradation under visible light irradiation. The results indicate that the introduction of La enhances nanocomposite performance. The prepared Ni-La ferrites may have potential application for water decontamination. [ABSTRACT FROM AUTHOR]

It has been experimentally established that samples of low-layer graphene, synthesized by carbonization of plant materials (lignin, cellulose, and spruce bark) under conditions of self-propagating high-temperature synthesis, are effective sorbents for mycotoxin T-2 under conditions simulating the environment in the gastrointestinal tract of mammals, and are capable of irreversibly sorb at least 94.6% of mycotoxin with a sorption capacity of 1 mg of mycotoxins per 1 g of sorbent. Key words: few-layer graphene, self-propagating high-temperature synthesis, specific surface area, mycotoxin sorption. [ABSTRACT FROM AUTHOR]

The photocatalytic approach is known to be one of the most promising processes for the tertiary treatment of polluted water. The paper presents studies of Zn2SnO4 (ZTO) coatings synthesized by spray pyrolysis of Zn and Sn salt solution with the addition of dispersed Ta2O5 powder. The structural, morphological and optical properties of the coatings were investigated. Despite the simplicity and availability, the spray pyrolysis method provides homogeneous coatings. Introducing 0.001 mol/L of Ta2O5 into the initial salt solution was found to contribute to a significant change in the surface morphology of the synthesized coatings. The effect of the doped Ta2O5 phase on the photocatalytic activity of ZTO for the degradation of methylene blue (MB) has been investigated. An improvement of up to 90% in the degradation of MB has been observed for the Zn2SnO4/Ta2O5 system after five hours of UV irradiation.

In this paper, the porous structure of three types of β-cyclodextrin (β-CD) carbons was synthesized and investigated. The first carbon was obtained from pure β-CD, the second carbon was synthesized from β-CD using the KOH activator, and the third carbon was synthesized from pure β-CD with additional ultrasonic treatment in the non-cavitation mode at the last stage. It was found that the carbon from pure β-CD has a micromesoporous structure with a small specific surface area (~35 m2/g). Activation with KOH causes a significant increase in the specific surface area (~654 m2/g) due to an increase in the content of micropores with an average size of 1,25 nm. The ultrasonic treatment causes mechanical grinding and oxidation of the carbon surface. It has been shown that such treatment increases the mesopore content and significantly changes the mesopore size distribution. It has been established that the oxidation of the β-CD carbon surface after ultrasonic treatment causes an increase in its hydrophilicity of up to 83,1%. The increase in hydrophilicity will allow more efficient use of synthesized carbon and composites based on it in solving the problems of environmental safety in water environments.

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The synthesis of molybdenum powders with a highly developed surface by reducing molybdenum oxides with magnesium vapor in the temperature range of 600–750°C under dynamic vacuum conditions (0.01 kPa) and residual argon pressure of 0.5–10 kPa in a reactor is studied. During the MgMoO4 and CaMoO4 reduction, mesoporous molybdenum powders with a specific surface area of up to 31.8 m2 g–1 are obtained. The average size of the metal crystallites is 16–25 nm. [ABSTRACT FROM AUTHOR]

The photocatalytic approach is known to be one of the most promising processes for the tertiary treatment of polluted water. The paper presents studies of Zn2SnO4 (ZTO) coatings synthesized by spray pyrolysis of Zn and Sn salt solution with the addition of dispersed Ta2O5 powder. The structural, morphological and optical properties of the coatings were investigated. Despite the simplicity and availability, the spray pyrolysis method provides homogeneous coatings. Introducing 0.001 mol/L of Ta2O5 into the initial salt solution was found to contribute to a significant change in the surface morphology of the synthesized coatings. The effect of the doped Ta2O5 phase on the photocatalytic activity of ZTO for the degradation of methylene blue (MB) has been investigated. An improvement of up to 90% in the degradation of MB has been observed for the Zn2SnO4/Ta2O5 system after five hours of UV irradiation. [ABSTRACT FROM AUTHOR]

A fundamentally new vibrational mill design is considered, with polyharmonic vibration of the grinding chamber. Experimental data for the mill are analyzed. Specifically, attention focuses on the speed of the control masses, their positions with respect to the chamber's center of mass, and the content of grinding bodies. The goal of optimization is to maximize the specific surface of the product. The influence of each factor (and their interactions) on the specific surface is established. The corresponding regression equation is derived, and the results are plotted. [ABSTRACT FROM AUTHOR]

The results of analysis of the effect of Raschig ring wall thickness in dumped packings on energy consumptions during column equipment operation with reference to drying tower of sulfuric acid production plant are presented. Regression equations and graphical relationships of specific surface and free volume of dumped Raschig ring packing as well as of hydraulic resistance and energy consumptions during operation of the column equipment with Raschig ring wall thickness are presented. [ABSTRACT FROM AUTHOR]

Given the technological importance of the grinding processes and the energy implications they bring, the present work sought to deepen the physics of these processes, namely: the determination of the energy consumption of the laboratory mill, the determination of the Blaine Specific Surface Area (SSA) and the variation between them. This work aimed to optimize large clinker grinding plants in the cement industry, by measuring in a laboratory mill with a rotating horizontal drum, the energy consumption, and the Blaine specific surface area. For example, clinker grinding in a laboratory ball mill was simulated by a professional simulation program EDEM 2022.0. To carry out the experiments, clinker material from a cement factory in Romania marked Clincher A was used. To carry out the experimental research, the CEPROCIM process was applied, which is based on the grinding of a batch of material in a laboratory mill with a rotating horizontal drum. [ABSTRACT FROM AUTHOR]

Nanoparticles of NiLaxFe2−xO4 ferrite spinel incorporated in a SiO2 matrix were synthesized via a sol-gel method, followed by annealing at 200, 500, and 800 °C. The resulting materials were characterized via XRD, AFM, and BET techniques and evaluated for photocatalytic activity. The XRD diffractograms validate the formation of a single-phase cubic spinel structure at all temperatures, without any evidence of secondary peaks. The size of crystallites exhibited a decrease from 37 to 26 nm with the substitution of Fe3+ with La3+ ions. The lattice parameters and crystallite sizes were found to increase with the rise in La3+ content and annealing temperature. Isotherms were employed to calculate the rate constants for the decomposition of malonate precursors to ferrites and the activation energy for each ferrite. All nanocomposites have pores within the mesoporous range, with a narrow dispersion of pore sizes. The impact of La content on sonophotocatalytic activity was evaluated by studying Rhodamine B degradation under visible light irradiation. The results indicate that the introduction of La enhances nanocomposite performance. The prepared Ni-La ferrites may have potential application for water decontamination.

The study focuses on the two-stage process of the thermal treatment of waste hemp shives aimed at obtaining a carbonaceous adsorbent. In the first stage, pyrolysis was carried out in a retort apparatus, which, at temperatures in the range of 450–850 °C, provided approximately 22.6–29.9% of the solid residue, 31.6–34.0% of the condensate, and 38.5–43.4% of gas with respect to the charge. The organic part of the condensates showed the net calorific value of 30.8–31.3 MJ kg−1, which makes it well suited for energy purposes. In the separated pyrolysis gases, GC-TCD-FID determined only five compounds, namely carbon dioxide, carbon monoxide, hydrogen, methane, and ethane, which together accounted for 98.5–99.8% of the gas volume. The remainder was composed mainly of ethene, propane, and propene. The highest net calorific value (14.7–14.8 MJ m−3) was exhibited by the gas collected in the range of 450–650 °C, which can be advantageously used for energy purposes. Non-activated solid pyrolysis residues had relatively low specific surface areas (BET), with the highest value determined being 294 m2 g−1. Therefore, they were activated by steam in a separate apparatus in the temperature range of 740–900 °C. The activation apparatus operated with a batch reactor of similar design to the pyrolysis retort. The activation increased the specific surface area of the pyrolysis residues up to the maximum of 915 m2 g−1. This study discusses the significant trends in specific surface area and total pore volume caused by a combination of different pyrolysis and activation temperatures. Better results were generally obtained for residues pyrolyzed at lower temperatures and then activated at high temperatures. The structure of the activated products mostly contained pores with a diameter of < 6 nm. Their development was mainly facilitated by the activation temperature of 850 °C, resulting in the relative presence of these pores in the range of 57.9–59.1%. All activated products were also characterized by an increased proportion of 20–80 nm pores, which formed, however, approximately one-third in comparison with the pores < 6 nm. Last but not least, the study also discusses the effect of activation conditions on the process loss of the product. [ABSTRACT FROM AUTHOR]

The adsorption properties of an ASD-4 aluminum powder and the powder modified with copper formate in different concentrations of 1, 2, 3, and 5 wt % were studied using the low-temperature adsorption of nitrogen at 78 K. The structural properties as morphology and phase composition of the interaction products were studied; the specific surface area and porosity were evaluated. It was shown that the adsorption characteristics of the powders modified with 1 and 2 wt % copper formate remained almost unchanged, which is of interest for creating a protective layer on the surface of the aluminum particles without significantly changing its structure-forming properties. The introduction of the modifier at a concentration of 3 and 5 wt % significantly affected the adsorption characteristics of the interaction products. For example, the specific surface of the ASD-4 + 3% Cu powder amounted to 12 m2/g, while that of the ASD-4 + 5% Cu achieved 19 m2/g, whereas the specific surface of the initial ASD-4 powder was only 0.7728 m2/g. [ABSTRACT FROM AUTHOR]

This study presents an analysis of a set of iron oxides nanoparticles (NPs) (γ-Fe2O3, α-FeOOH, δ-FeOOH, 5Fe2O3·9H2O, and Fe3O4) as potential candidates for ferroptosis therapy in terms of a phase state, magnetic characteristics, and the release of Fe2+/Fe3+ as ROS mediators. Due to the values of saturation magnetization for Fe3O4 (31.6 emu/g) and γ-Fe2O3 (33.8 emu/g), as well as the surface area of these particles (130 and 123 m2/g), it is possible to consider them as promising magnetically controlled carriers that can function with various ligands. The evaluation of the release of Fe2+/Fe3+ ions as catalysts for the Fenton reaction showed that the concentration of the released ions increases within first 3 h after suspension and decreases within 24 h, which probably indicates desorption and adsorption of ions from/onto the surface of nanoparticles regardless their nature. The concentration of ions released by all nanoparticles, except α-FeOOH-Fe2+, reached 9.1 mg/L for Fe3+ to 1.7 mg/L for Fe2+, which makes them preferable for controlling the catalysis of the Fenton reaction. In contrast, a high concentration of iron ions to 90 mg/L for Fe3+ and 316 mg/L for Fe2+ released from compound α-FeOOH-Fe2+ allows us to utilize this oxide as an aid therapy agent. Results obtained on iron oxide nanoparticles will provide data for the most prospective candidates that are used in ferroptosis-inducing systems. [ABSTRACT FROM AUTHOR]

Most electric motors of the grain mills used in the Sub-Saharan African towns and villages operate without a motor control unit and out of their rate conditions. This leads to a considerable energy loss and the granularity of the obtained cereal flour is not standard due to the variation of motor speed. In this paper, the influence of the rotational speed of a hammer grinder on the milling energy indices is studied for a small scale production of the corn flour. So, an adjustable speed drive is used in the range of 40 to 60 Hz with a step of 5 Hz, either for a scalar control or for a vector control. The grinding energy and milling energy indices, as well as equivalent diameter, specific surface of the corn powders, and the milling efficiency among other parameters are assessed. Thus, it is shown that above 45 Hz, the motor control improves the granularity of corn powders. Grinding under vector control of current allows to maximize specific surface of the corn powder and thus provides a corn powder with more fine particles than the two other control techniques. However, it is rather the vector control of voltage that allows having the lowest grinding energy. Compare to grinding without motor control, grinding under control of the motor allows saving grinding energy of the order of 51 to 72% and of 46 to 60% respectively with the vector controls of voltage and of current, and of 14 to 60% with the scalar control. [ABSTRACT FROM AUTHOR]

An acceptable viscosity and an easy penetrability of cement - limestone filler grout in the granular matrix of self compacting concrete are an important factors that affecting both its rheological and its hardened properties. This experimental and theoretical work consists to study the effect of limestone filler fineness on the rheological behavior of cement - limestone filler grout. In the first part, five different grouts were prepared by varying the Blaine Specific Surface (BSS) of the limestone filler, 3060, 4750, 6320, 7680 and 9440 cm2/g, respectively. A large number of properties relating to the rheology and the stability are carried out on the five grouts such as grain dispersion, density, volume concentration of solid, dynamic viscosity and Marsh funnel flow. The second part consists to develop a theoretical model to predict the different rheological properties of the grout as function of limestone filler BSS. The results show that the rheological properties of cement-limestone filler grout such as the dispersion percentage, the intergranular distance and the flow time are strongly affected by the limestone fillers fineness. In addition, the experimental and the predicted results present a good agreement.

The aim of the work is to compare the main thermal physical and physical-mechanical properties of finely dispersed fibrous particles from various materials. The authors conducted experimental studies of the definition of the geometric sizes of fine-divided particles and their influence on the structure and properties of multilayer heat-insulation materials, Hydrophysical, mechanical and thermophysical properties of short-fiber waste of the textile industry are determined. The results of the work allow to determine the main quantitative and qualitative indicators of fibrous masses consisting of fine-divided particles affecting the properties of multilayer heat-insulation materials. The use of ultra-thin and fine-tested fibers in finished products allows to give the latest unique consumer properties and to expand their scope. Работа посвящена определению теплотехнических свойств мелкодисперсных волокнистых масс из различного сырьевого состава (КНОП стригальный; флок специальный; ковровые обрези из пряжи аппаратной полушерстяной) и тепло- изоляционных материалов, полученных методом аэродинамического флокирования с их использованием. Авторами проведен анализ свойств теплоизоляционных материалов, волокнистой массы, состоящей из коротковолокнистых отходов текстильной промышленности, выполнены исследования основных эксплуатационных требований, предъявляемых к подобным материалам: геометрических размеров, параметров состояния, гидрофизических, механических и теплофизических свойств коротковолокнистых отходов. При проведении испытаний использовались стандартные методы, определяемые СТБ и ГОСТ, действующими на территории Республики Беларусь. В результате проведенных исследований установлено: – наибольшей насыпной плотностью во всем диапазоне изменения давления прессования обладает волокнистая масса флока; – для мелкодисперсных частиц флока через 24 часа гигроскопичность составляет 1,51 %, сорбционное увлажнение 5,26 %, для кнопа коврового гигроскопичность составляет 6,31 %, сорбционное увлажнение 21,95 %; – образцы на основе флока выдерживает более высокую нагрузку по сравнению с другими вариантами наполнителей; – экспериментально подтверждена возможность получения образцов теплоизоляционных материалов с коэффициентом теплопроводности 0,0314 Вт/(м•К); – доказано, что для повышения свойств теплоизоляционных материалов особое внимание следует обращать на использование наполнителей из материалов, характеризующихся низ- кой теплопроводностью, гигроскопичностью, высокой огнетермостойкостью, что требует определенной методики их измерения. Результаты работы позволяют оперативно определить основные теплофизические и физико-механические свойства коротковолокнистых масс, влияющие на характеристики многослойных теплоизоляционных материалов, текстильных композиционных материалов.

The present work was aimed at evaluating the roles of zinc chloride impregnation states on specific surface and dielectric properties in microwave-assisted activated carbon preparation. Activated carbons were synthesized using castor shell at dry impregnation ratios of 1 and 2 (material-to-activator), and in suspensions of distilled water and zinc chloride, at power intensity of 800 W and irradiation time of 5 min. The activated carbons exhibit an improvement in dielectric properties and specific surface with increasing impregnation ratio. Palm kernel shell was employed for comparison to verify the effect of power intensity. At 800 W, the magnitudes of surface area are 1684 m2/g and 1150 m2/g for castor shell- and palm kernel shell-based activated carbons, respectively. A high specific surface brings about a greater methylene blue adsorption for possible applications in wastewater treatment. [ABSTRACT FROM AUTHOR]

The fractal structure of porous carbon materials (PCMs) obtained by hydrothermal carbonization of plant raw materials in the temperature range of 600 ÷ 1100 °С is investigated using the low-temperature porometry method. It is set that materials with a developed microporous structure and a surface fractal dimension of 2.58 are formed at carbonization temperatures of 600 ÷ 800 °C. At higher carbonization temperatures, the value of the fractal dimension of the surface decreases to 2.17, which indicates the formation of an almost smooth surface due to the intensive removal of carbon atoms from the surface layers of the material particles, a decrease in the number of micropores with their transition to mesopores, the combination of small carbon clusters in larger and the formation of microparticles of non-porous carbon material. [ABSTRACT FROM AUTHOR]

This paper aims to extend the investigation of producing highly reactive additive material in ultrafine size, with a particle diameter of less than 5µm through mechanical activation using a planetary ball mill. In light of the mechanical activation process, most studies were done to test materials such as metakaolin and fly ash. However, studies on the mechanical activation effect via planetary ball mill to conventional RHA or treated RHA are limited. In this research, raw rice husk (RH) was treated using a low heated concentration of acid, i.e., 0.01 - 0.1M hydrochloric acid (HCl). Then, the treated RH was combusted at 600 - 800°C. Finally, the treated RHA was ground using a planetary ball mill for 15 - 60 minutes. As a result, it was also observed that a burning temperature of 600°C, treated at four hours and ground at 300rpm for 15 minutes, had the finest size of ultrafine treated RHA (UFTRHA) with an average particle size value (D50) of 4.012µm. Furthermore, the largest specific surface area (SSA) value was obtained at 222.9125 m²/g with a similar treatment condition. Concerning the UFTRHA morphology, particle agglomeration was observed for samples with a grinding duration of more than 15 minutes. Therefore, grinding parameters involved in the process are proven to affect the physical and morphological attributes of UFTRHA produced. Particle size reduction and significant SSA value of UFTRHA are vital for effective pozzolanic reaction and hence promote a greater material performance as a superior additive in concrete application. [ABSTRACT FROM AUTHOR]

The structural, morphological and magnetic properties of MFe2O4 (M = Co, Ni, Zn, Cu, Mn) type ferrites produced by thermal decomposition at 700 and 1000 °C were studied. The thermal analysis revealed that the ferrites are formed at up to 350 °C. After heat treatment at 1000 °C, single-phase ferrite nanoparticles were attained, while after heat treatment at 700 °C, the CoFe2O4 was accompanied by Co3O4 and the MnFe2O4 by α-Fe2O3. The particle size of the spherical shape in the nanoscale region was confirmed by transmission electron microscopy. The specific surface area below 0.5 m2/g suggested a non–porous structure with particle agglomeration that limits nitrogen absorption. By heat treatment at 1000 °C, superparamagnetic CoFe2O4 nanoparticles and paramagnetic NiFe2O4, MnFe2O4, CuFe2O4 and ZnFe2O4 nanoparticles were obtained. [ABSTRACT FROM AUTHOR]

Nitrogen adsorption onto the ASD-4 aluminum and modified ASD-4-2% Mn powders was measured experimentally at 78 K. The results of a study of adsorption–structural features of interactions of ultradispersive aluminum with manganese formiate, including morphology and phase composition of reaction products, were presented; the specific surface area and porosity of the powders were calculated. The peculiarities of the adsorption isotherms observed for the studied samples before and after modification were discussed with regard to their matching to a certain type according to the recommendations of the International Union of Pure and Applied Chemistry, as well as to a certain type of porosity, which was necessary to understand the scope of their further application. The adsorption isotherm observed for the modified powder corresponds to a type specific for mesoporous solids. It was shown that both the structure of the adsorbent and its aggregate state determined the shape and type of adsorption isotherm. The introduction of the modifier increased the adsorption capacity of the aluminum powder. The specific surface of the modified powder increased up to 20 m2/g, whereas before modification the specific surface of the ASD-4 powder was 0.7 m2/g. [ABSTRACT FROM AUTHOR]

Nano-scale crystal defects extremely affect the security and reliability of the explosive charges of weapons. In order to understand the evolution of nano-scale defects of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane (CL-20) explosive crystals under thermal treatments, the specific surface, volume fraction and size distribution of the nano-scale defects were studied by using Wide Angle X-ray Scattering (WAXS) and Small Angle X-ray Scattering (SAXS) during the temperature range from 30 °C to 200 °C. The results showed that the number and size of the pores in CL-20 powder did not change significantly during the heating process before phase transformation (30–160 °C). At 170 °C, CL-20 began to convert from ε- to γ- phase, and the specific surface and volume fraction of the nano-scale defects increased significantly. Further investigation of the pore size distribution showed that the number of pores with a small size (radius 9–21 nm) changed particularly significantly, resulting from the cracking of the CL-20 crystal powder during phase transition. At 200 °C, the phase transition was completed and γ-CL-20 was created, and the small-sized pores gradually grew into medium-sized (radius 21–52 nm) pores over time when the temperature was fixed at 200 °C. [ABSTRACT FROM AUTHOR]

The specific surface of coal particles is determined for 370 samples of Kuznetsk Basin coal with a wide range of metamorphic development. Low-temperature adsorption on a Sorbi N.4.1 instrument is employed, at liquid nitrogen temperature and various partial pressures. The specific surface is calculated by the Brunauer–Emmett–Teller (BET) method. In comparison with coal of poor and high metamorphic development, the specific surface is 0.23–3.90 m2/g higher for Zh, KZh, and K coal with vitrinite reflection coefficient 0.93–1.39% and yield of volatiles 20–36%. [ABSTRACT FROM AUTHOR]

Introduction. An important performance characteristic of many building materials is one related to water. Therefore, hydrophobization of the surface of the material is an important task, which at the current level is solved by applying special means. It has been found that it is possible to impart water repellent properties to the surface by using polydisperse mineral materials capable of forming a rough surface. Fine powder from polymineral sand is proposed to be used as a hydrophobisate. The revealed functional relationship between the specific surface and the value of the average particle diameter of the powders, having a linear character, allows assessing their morphological structure and predicting the powder's ability to form a rough layer that enhances the water repellent properties of the surface. Methods and Materials. Four deposits of polymineral construction sands are selected as raw materials. The samples were washed and dried. Then their size modulus and true density were determined. To obtain finely dispersed powders, the raw material was ground by dry dispersion. Particle dimensional characteristics were determined by photon-correlation spectroscopy. The visual characteristic of the shape and size of the particles is determined on a laser analyzer. The specific surface area of highly dispersed rock systems was determined by gas sorption, according to BET theory. Measurement of the edge stationary wetting angle was carried out by applying a drop of distilled water to the powder surface. Results and Discussion. The dimensional characteristics of the obtained fractions showed that with a milling time (30 min) for the sands of all deposits, the average particle size (d) is 360±45 nm. At the same time, the sands of the Kenitsy and Nekhtskoye deposits have the highest values of specific surface area (Ssp). The functional relationship between the Ssp of the powders tested and 1/d was determined. The resulting linear dependencies were characterized by mathematical expressions of the form Ssp = (a/d)+b, a where reflects the rate of change in the specific surface value as the average particle diameter of the samples changes; b – is the regression line shift associated with the asymmetric shape of the particles and the non-uniformity (roughness) of the surface. It has been found that as the value of b increases, the degree of inhomogeneity of the surface formed by these particles also increases. Determination of the edge wetting angle of the surface of the powders under study showed that as the grinding time increased, the wetting angle (surface hydrophobicity) increased. So, for the surface of the fine powder of the Nekhtskoye deposit, the wetting edge angle reaches a value (114о) close in magnitude to superhydrophobicity (120о). Conclusion. The experiments showed the validity of the proposed working hypothesis related to the possible assessment of surface hydrophobicity by the experimentally determined dependence of Ssp = f (1/d). This technique can be used to select mineral powders whose fine systems are capable of hydrophobizing (if necessary hydrophilizing) the surface of the material.

The saturated hydraulic conductivity of soils is a critical concept employed in basic calculation in the geotechnical engineering field. The Kozeny–Carman equation, as a well-known relationship between hydraulic conductivity and the properties of soils, is considered to apply to sands but not to clays. To solve this problem, a new formula was established based on Hagen–Poiseuille's law. To explain the influence on the seepage channel surface caused by the interaction of soil particles and partially viscous fluid, the surface area ratio was introduced. A modified framework for determining the hydraulic radius was also proposed. Next, the relationship between the effective void ratio and the total void ratio was established for deriving the correlation of hydraulic conductivity and total void ratio. The improved equation was validated using abundant experimental results from clays, silts, and sands. According to the results, the accuracies of the proposed model with two fitted multipliers for clays, silts, and sands are 94.6, 96.6, and 100%, respectively, but with only one fitted parameter, the accuracies are 97.1, 91.5, and 100%, respectively. The proposed model can be considered to have a satisfactory capability to predict hydraulic conductivity for a wide variety of soils, ranging from clays to sands. HIGHLIGHTS An improved model of the soil particle-water system was proposed.; The surface area ratio δ is introduced.; We establish an improved method for estimating the effective void ratio.; The relationship between LL and As for clay was established.; The correlation between the parameters C and the specific surface area of soils was established.;

The present study aims at an integration of both petrographic and petrophysical data of 45 sandstone samples collected from Araba Formation (Lower Paleozoic) for reservoir characterization. The studied Araba Formation is classified into three types of facies: (i) quartz arenite, (ii) sublithic quartz arenite, and (iii) calcareous quartz arenite. The mineralogical composition of the studied sandstone samples includes mainly quartz and detrital clays, some pyrite, and iron oxides as cement. The petrographic investigation of the studied Araba Formation reveals various diagenetic processes including compaction and pressure solution, cementation with iron oxides, carbonates, or clays. The porosity values for investigated samples range from 14.5 to 27.8% and permeability values from 2.4 mD to 8.4 D, the surface area per unit pore volume (Spor) from 0.011 to 17 µm−1, the formation factor from 6 to 13, and the dimensionless volumetric magnetic susceptibility from 13 10−6 to 126 10−6. The samples of facies (i) and (ii) are characterized by higher values of porosity and permeability. The samples of facies (iii) indicate increasing permeability with rising porosity. The relationship between permeability and formation factor reflects the effect of porosity changes. The specific surface Spor shows an inverse relationship to permeability. The petrophysical investigations provide relationships between permeability and other reservoir parameters such as porosity, formation factor, specific surface, and longitudinal and transverse relaxation time resulting from nuclear magnetic resonance (NMR) relaxometry. The permeability prediction model based on NMR data proves to be applicable for samples from facies (i) and (ii), whereas the predictive quality is considerably lower for facies (iii). [ABSTRACT FROM AUTHOR]

The textural characteristics of carbon sorbents produced by heating G (gas) coal in the presence of potassium hydroxide (KOH/coal = 0.5 g/g) are studied. In chemical activation with alkali, sorbents with developed specific surface and specific pore volume are obtained; the contribution of micropores is 69–82%. The ash content of the coal has the main influence on the textural characteristics of the sorbents. The specific surface and pore volume of the sorbents are greatest for coal with <10% ash. [ABSTRACT FROM AUTHOR]

The specific surface and porosity of bituminous coal (rank Zh) are studied. The textural characteristics of Kuznetsk Basin coal are determined by various methods: for example, the specific surface by the Brunauer–Emmett–Teller (BET) method; the micropore volume by the comparative t-plot method; and the mesopore volume by the Barrett–Joyner–Halenda method from the low-temperature (77 K) absorption–desorption isotherms obtained by means of a Micromeritics ASAP 2020 instrument. The specific surface is small, and mesopore structure predominates for all the coal samples. Analysis of the pore structure of Kuznetsk Basin coal reveals their macro- and microstructure and provides information regarding their adsorption properties. [ABSTRACT FROM AUTHOR]

Based on the globular model with the use of the values of porosity and particle size, a method is presented for calculating the structure parameters of porous monofractional powder composite materials for filters. A formula for determining the average (hydraulic) radius of the capillaries of permeable materials has been obtained, which is more accurate than the Kozeny formula. The results of calculating the average radius of capillaries and of the permeability of porous powder materials by the proposed dependences are presented, which are in better agreement with experimental data than calculations by the Kozeny formula. [ABSTRACT FROM AUTHOR]

A study is performed of the effect the means of activation of bentonite-like clays (acidic, alkaline, combined) have on the adsorption characteristics of Fe3+ ions under static conditions. The mechanism of the acidic and alkaline activation of montmorillonite is identified and found to depend on the concentration of the activating agent. Solutions of sulfuric acid and lithium hydroxide are used as activating agents. It is shown that during combined treatment of enriched clay which includes activation with sulfuric acid and lithium hydroxide, its sorption capacity grows by 2.0–9.4 times, in relation to Fe3+ ions. [ABSTRACT FROM AUTHOR]

An acceptable viscosity and an easy penetrability of cement - limestone filler grout in the granular matrix of self compacting concrete are an important factors that affecting both its rheological and its hardened properties. This experimental and theoretical work consists to study the effect of limestone filler fineness on the rheological behavior of cement - limestone filler grout. In the first part, five different grouts were prepared by varying the Blaine Specific Surface (BSS) of the limestone filler, 3060, 4750, 6320, 7680 and 9440 cm2/g, respectively. A large number of properties relating to the rheology and the stability are carried out on the five grouts such as grain dispersion, density, volume concentration of solid, dynamic viscosity and Marsh funnel flow. The second part consists to develop a theoretical model to predict the different rheological properties of the grout as function of limestone filler BSS. The results show that the rheological properties of cement-limestone filler grout such as the dispersion percentage, the intergranular distance and the flow time are strongly affected by the limestone fillers fineness. In addition, the experimental and the predicted results present a good agreement. [ABSTRACT FROM AUTHOR]

In this study, coprecipitation has been used to prepare alumina nanoparticles. In order to do that first, the effect of aluminium salt and precipitating agent on the specific surface of alumina was studied. Then under an optimized condition, the effect of reaction temperature on phase changes and its specific surface were studied. Generally in order to prepare different phases of alumina nanoparticles, crystalline boehmite was prepared by heating the gelatinous white precipitate which first formed when precipitating agent was added to acid solutions of aluminium salt and finally, by dehydration of crystalline boehmite, nanoparticles of alumina were obtained with different phases. Different physical and chemical tests such as X-ray diffraction (XRD), X-ray fluorescence (XRF), specific surface area measurement (BET), scanning electron microscope (SEM), transmission electron microscope (TEM) and thermogravimetric analysis (TGA) were performed on prepared alumina nanoparticles. The results show that using aluminium nitrate salt and ammonia as precipitating agent yields alumina with the best specific surface area (211 m2/g). Also alumina which is manufactured by using ammonia and aluminium chloride with 58 m2/g has lowest amount of specific surface area. In addition, it was found that after calcinations at 550 °C, gamma-alumina phases appear. While with increasing reaction temperature to 1400 °C, the alpha-alumina phase was produced.

This study investigates factors affecting the Blaine number, including type, shape, and size distribution of the grains, d80 effect, and retention time of materials in the mill. Samples were taken from different locations in production lines of the Golgohar and Chadormalu plants in Iran. For iron minerals, Davis tube tests were performed in four stages to assess the functionality of the magnetic separator to ensure matching conditions between the plant and laboratory. The Blaine air permeability system was used to analyze the Blain number. Results indicated that the samples with the same d80 but different grain size distributions had different Blaine numbers. More specifically, increasing the percentage of grains finer than 45 microns resulted in higher Blaine numbers. Moreover, in the Golgohar Hematite and desulfurization plant, the grain size distribution was relatively fixed, and minor variations in the percentages of grains finer than 45 microns led to a change in the Blaine number, and this was consistent between different days. During the concentrate production processes, higher grades of iron concentrate and lower grades of non-iron minerals were associated with lower Blaine numbers, which could be explained by the removal of iron-free minerals finer than 45 microns, including clay. Moreover, a 1% reduction in the clay minerals led to a 400-unit reduction in the Blaine number. Several samples of hematite concentrate and clay minerals with the same grain size distribution were analyzed to investigate the influence of density and the shape of grains on the Blaine number of magnetite concentrate. Here, compared to magnetite and hematite with irregular shapes, plate-shaped clay minerals showed higher Blaine numbers. Moreover, when the feed of the magnetic separator was grinded, the reduction in the grain size increased the Blaine number. In the Chadormalu plant, a retention time of 4.5 minutes in the mill was associated with the highest Blaine number as well as the least recovery of phosphorous minerals.

The study focuses on the two-stage process of the thermal treatment of waste hemp shives aimed at obtaining a carbonaceous adsorbent. In the first stage, pyrolysis was carried out in a retort apparatus, which, at temperatures in the range of 450–850 °C, provided approximately 22.6–29.9% of the solid residue, 31.6–34.0% of the condensate, and 38.5–43.4% of gas with respect to the charge. The organic part of the condensates showed the net calorific value of 30.8–31.3 MJ kg−1, which makes it well suited for energy purposes. In the separated pyrolysis gases, GC-TCD-FID determined only five compounds, namely carbon dioxide, carbon monoxide, hydrogen, methane, and ethane, which together accounted for 98.5–99.8% of the gas volume. The remainder was composed mainly of ethene, propane, and propene. The highest net calorific value (14.7–14.8 MJ m−3) was exhibited by the gas collected in the range of 450–650 °C, which can be advantageously used for energy purposes. Non-activated solid pyrolysis residues had relatively low specific surface areas (BET), with the highest value determined being 294 m2 g−1. Therefore, they were activated by steam in a separate apparatus in the temperature range of 740–900 °C. The activation apparatus operated with a batch reactor of similar design to the pyrolysis retort. The activation increased the specific surface area of the pyrolysis residues up to the maximum of 915 m2 g−1. This study discusses the significant trends in specific surface area and total pore volume caused by a combination of different pyrolysis and activation temperatures. Better results were generally obtained for residues pyrolyzed at lower temperatures and then activated at high temperatures. The structure of the activated products mostly contained pores with a diameter of < 6 nm. Their development was mainly facilitated by the activation temperature of 850 °C, resulting in the relative presence of these pores in the range of 57.9–59.1%. All activated products were also characterized by an increased proportion of 20–80 nm pores, which formed, however, approximately one-third in comparison with the pores < 6 nm. Last but not least, the study also discusses the effect of activation conditions on the process loss of the product.

This study presents an analysis of a set of iron oxides nanoparticles (NPs) (γ-Fe2O3, α-FeOOH, δ-FeOOH, 5Fe2O3·9H2O, and Fe3O4) as potential candidates for ferroptosis therapy in terms of a phase state, magnetic characteristics, and the release of Fe2+/Fe3+ as ROS mediators. Due to the values of saturation magnetization for Fe3O4 (31.6 emu/g) and γ-Fe2O3 (33.8 emu/g), as well as the surface area of these particles (130 and 123 m2/g), it is possible to consider them as promising magnetically controlled carriers that can function with various ligands. The evaluation of the release of Fe2+/Fe3+ ions as catalysts for the Fenton reaction showed that the concentration of the released ions increases within first 3 h after suspension and decreases within 24 h, which probably indicates desorption and adsorption of ions from/onto the surface of nanoparticles regardless their nature. The concentration of ions released by all nanoparticles, except α-FeOOH-Fe2+, reached 9.1 mg/L for Fe3+ to 1.7 mg/L for Fe2+, which makes them preferable for controlling the catalysis of the Fenton reaction. In contrast, a high concentration of iron ions to 90 mg/L for Fe3+ and 316 mg/L for Fe2+ released from compound α-FeOOH-Fe2+ allows us to utilize this oxide as an aid therapy agent. Results obtained on iron oxide nanoparticles will provide data for the most prospective candidates that are used in ferroptosis-inducing systems.

Existing methods of determining the specific surface of special coke (rexil) produced by thermal oxidative coking of long-flame Shubarkol coal are reviewed. The specific surface of the specific surface is determined by those methods. The relation between the heating rate of the initial coal and the specific surface of the special coke is established experimentally. On that basis, a method of determining the specific surface of fine-pore special coke obtained by fast thermal oxidative coking is selected. [ABSTRACT FROM AUTHOR]