Mechanochemical Activation Research Articles

One-step high efficiency synthesis of zeolite from fly ash by mechanochemical method as a low-cost adsorbent for cadmium removal

The hydrothermal synthesis of zeolite from fly ash is a time-consuming process with a low conversion rate. Mechanochemical activation is commonly employed as a green and moderate pre-treatment process for surface modification purposes. This study proposes a one-step high efficiency synthesis of zeolite from fly ash using the mechanochemical method. The ball milling modification is conducted simultaneously with the zeolite synthesis process, reducing the overall synthesis time to a significant extent (3 h being determined as the optimal synthesis time). The findings reveal that P1 zeolite can be effectively synthesized under the following conditions: a sodium hydroxide concentration of 2 mol L−1, a synthesis temperature of 130 °C and a ball milling frequency of 30 Hz. Moreover, the synthesized zeolite exhibits a maximum Cd2+ adsorption capacity of 130.68 mg/g at pH= 5, following pseudo-second-order kinetics and Langmuir adsorption isotherm. This study not only simplifies the production process and saves energy but also yields zeolite with smaller particle sizes and higher purity. By utilizing the mechanochemical method, the disposal of solid waste can be made environmentally friendly, convenient, and economically beneficial.

A mechanochemical process to capture and separate carbon dioxide from natural gas using boron nitride nanosheets.

Addressing climate change is a critical and pressing matter that requires immediate attention to mitigate its severe repercussions. In order to enhance the capture and separation of carbon dioxide from natural gas and nitrogen gas, it is imperative to develop new capture materials and more efficient storage processes. In this study, we introduce an innovative environmentally friendly storage and separation technique. Through a controlled mechanochemical process, a substantial amount of carbon dioxide (103.6 wt%) was successfully captured within boron nitride. This process also excels at effectively isolating carbon dioxide from a gas mixture containing natural gas (CH4) or nitrogen due to its superior adsorption selectivity for CO2 over the other two gases. The stored carbon dioxide can be released upon heating, and this procedure can be repeated several times (minimum four times), indicating a game changing process in CO2 gas capture and separation technology with the advantages of green, low cost and efficiency.

Sulfur-dissolved high-entropy alloys with ultrawide-bandwidth electromagnetic-wave absorption properties synthesized via a mechanochemical process

Further enhancing the effective absorption bandwidth (EAB) and the harsh-environment stability of high-entropy alloy (HEA) electromagnetic-wave absorbing (EMA) materials is of great practical significance and broad application prospects.

Synthesis of Nickel-Based Medical Alloys via Mechanochemical Processing and Powder Metallurgy Techniques

In this study, medical nickel alloys suitable for dental applications were synthesised by a combination of force chemical synthesis and powder metallurgy. Titanium and base powders were used, processed in a hydrogen atmosphere to obtain sub-micron particle sizes and homogeneously mixed by mechanical alloying techniques to optimise sintering and compaction properties. This method ensures perfect consistency of particle composition and morphology, essential for the subsequent sintering process, which densifies the material to a relative density of 98.96% while maintaining the precise shape and weight specifications required. Manganese, boron and cerium are added in moderate amounts to enhance bond strength with porcelain veneers without sacrificing corrosion resistance or causing discolouration. Boron content is controlled below 0.1 weight percent to reduce brittleness, and silicon is adjusted to maintain mechanical strength. The alloy's coefficient of thermal expansion is optimised and determined by dilatometry techniques to ensure compatibility with porcelain and compliance with industry standards for nickel-based dental alloys. Tested mechanical properties including yield strength, tensile strength and Vickers hardness showed robustness and resistance that surpassed most nickel-based alloys and competed with cobalt-based alternatives. The study concluded that the advanced synthesis technology used to produce the nickelcontaining medical alloy has improved mechanical, thermal and aesthetic properties, making it ideal for the manufacture of dental prostheses that require high precision.

SYNTHESIS, STRUCTURE AND PROPERTIES OF BENTONITE - ACTIVATED CARBON COMPOSITE

The development of adsorption purification technology in industry is divorced from research in the development of new methods for the synthesis and modification of composites, while the efficiency of the adsorbent directly depends on its structural and surface properties. Currently, there is an increasing demand for hydrogel adsorbents used in pharmaceuticals, medicine, and the chemical industry for wastewater treatment. Dash-Salakhlinsky bentonite, a natural clay mineral and activated carbon of the BAU-A brand, was used as an object of study. By intercalation of bentonite with activated carbon, a bentonite-coal composite was obtained. Grinding equipment of medium energy density was used: roller-ring vibrating mill VM-4. Activation time was 15 min. The average particle size of the initial bentonite and bentonite-carbon composite was determined by laser diffraction on a particle size analyzer. During mechanical activation of bentonite, the nature of the distribution of particles indicates the predominant process of aggregation over grinding. The morphology, structure, and textural properties of the composite were studied by the methods of low-temperature nitrogen adsorption-desorption and IR spectroscopy. An increase in the specific surface area and porosity after mechanochemical activation as compared to the calculated values indicates the interaction between the components. IR spectroscopy established the formation of additional functional groups that can act as active centers, which positively affects the adsorption properties. It is shown that the bentonite-charcoal composite has a high sorption activity with respect to the brilliant green dye. The data obtained can be useful in the development of effective sorbents for wastewater treatment from pollution by organic compounds, as well as in medicine and pharmaceuticals.

Mechanical Activation as a Stage of Coal Sample Preparation in the Analysis of Rare Earth Elements Content by Inductively Coupled Plasma Mass Spectrometry

Background: Brown coals are recognized as promising sources of rare earth elements (REEs). Rare earths are present in both the mineral and organic parts of brown coal. Objectives: This study was conducted to investigate the influence of preliminary mechanical activation in the process of sample preparation prior to analyzing the concentrations of rare earth elements in brown coal samples of various origins and compositions Methods: Four coal samples from different deposits in Russia were selected for the study. Samples were treated with mechanical activation, without reagents, or mechanochemical activation, with humic acids added externally as reagents. X-ray phase analysis was carried out with the selected samples. The quantities of rare-earth elements present in the samples were studied by the method of high-sensitivity inductively coupled plasma mass spectrometry (ICP-MS). Results: It was found that the mechanical activation of coal before dissolution in a mixture of nitric and hydrofluoric acids leads to an increase in the determined concentration of rare earth elements. For this study, the expediency of using only nitric acid as an optimal solvent for the elemental analysis of coal samples was shown. The total concentration of all REE after dissolution of nitric acid and mechanochemical activation with humic acid reached 2456 g/t in Vanchin coal, 968 g/t in Azeysky coal, and 24 g/t and 150 g/t in Itatsky and Spetsugli coals, respectively. Conclusion: Mechanical activation and mechanochemical treatment can greatly help to facilitate sample preparation of natural objects, such as coals for elemental analysis, but in some cases, only a change of solvent is sufficient. When developing technology for concentrating rare earth elements from coal involving grinding, it is necessary to take into account the fact that mechanical activation of coal changes its tendency to dissolve, which may affect the results of the analysis and should be taken into account during experiments.

Mineralogical characteristics influence the structure and pozzolanic reactivity of thermally and mechano-chemically activated meta-kaolinites

Mechano-chemical activation enhances early age (<12 hours) pozzolanic reactivity of clays by transforming kaolinite to meta-kaolinite, reducing particle size, and potentially increasing the edge : basal surface area ratio of meta-kaolinite.

CoZr nanocomposites in a ceramic-metal AlOx(OH)y/Al matrix with a different Co/Zr ratio and its potential for syngas processing.

We investigated the possibility of synthesizing Co nanoparticles in CoZrnH/AlOx(OH)y/Al ceramic-metal catalysts and controlling the catalytic properties of these nanoparticles in syngas conversion by changing the Co/Zr ratio. The CoZr nanocomposites were obtained from metal powders by mechanochemical activation in a high-energy mill under an argon atmosphere, followed by treatment with hydrogen at high pressure and room temperature. Ceramic-metal catalysts were prepared by mixing the corresponding CoZrnH powder nanocomposite (30 wt%) with powdered aluminum (70 wt%), hydrothermal treatment of the mixture and subsequent calcination. The materials were characterized with a set of physicochemical methods: powder X-ray diffraction, scanning electron microscopy, 59Co internal field nuclear magnetic resonance spectroscopy, and temperature programmed reduction. Catalytic studies were performed in a laboratory fixed-bed flow reactor at 2 MPA and 210-270 °C. It is shown that the activity in syngas conversion to C5+ hydrocarbons and selectivity to methane and C2-C4 hydrocarbons depend on the Co/Zr ratio. Thus, with an increase in the zirconium content in the samples, the interaction of metal cobalt with metal zirconium improves in the process of mechanical activation and subsequent treatment with hydrogen. The destruction of the agglomerates of crystallites of metallic cobalt in the form of β-Co (Cofcc) occurs as well as their transformation to α-Co (Cohcp) particles active in the syngas conversion to C5+ hydrocarbons. This can explain the highest specific yield of C5+ hydrocarbons on a cermet with the lowest Co/Zr ratio.

Mechanically accelerated catalytic hydrogenation: correlating physical state, reaction rate, and interface area

This study thoroughly examines the role of mechanochemistry in organic synthesis by analysing the factors affecting the mechanochemical reduction process of unsaturated and oxidized compounds.

Mechanochemical extraction of edible proteins from moor grass.

Extracting edible nutrient-rich food fractions from unconventional sources, such as grass, could play a pivotal role in ensuring food security, bolstering economic prosperity, combating climate change, and enhancing overall quality of life. Current extraction techniques rely heavily on harsh chemicals, which not only degrade nutrients but can also substantially add to the cost of the process and make downstream separation challenging. In this study, we harnessed a mechanochemical process, liquid-assisted grinding (LAG) with and without Na2CO3, termed sodium carbonate assisted grinding (SAG), to extract the protein fraction from moor grass. These techniques were compared to the conventional alkaline extraction (AE) method. Unlike alkaline extraction, which solubilized over 70% of the material, the mechanochemical approach using Na2CO3 solubilized only 55% of the grass while still extracting the vast majority of the protein in the original grass feedstock. The protein fractions obtained from the SAG process had a similar amino acid profile to the core feedstock but also contained distinct characteristics over the other methods of extraction. FT-IR analysis, for example, identified the presence of an amide III band in the protein fractions obtained from the SAG process, indicating unique structural features that contribute to improved dispersibility, gelation properties, and water-in-water stability. Furthermore, the extracted moor grass protein contained a higher proportion of glutamic acid in comparison to other amino acids in the protein, which indicates a savoury umami (meaty) characteristic to the protein fraction. The protein extracted via SAG also exhibited good heat stability (139-214 °C), rendering them potentially suitable for baking applications. Additionally, coupling Na2CO3 with liquid assisted grinding not only removed the need for organic solvents and conventional heating but also reduced solvent consumption by 83%, compared with the typical alkaline extraction, thus simplifying the downstream processes necessary to produce food fractions. This study demonstrates the potential significance of mechanochemical extraction processes in unlocking nutrients from unconventional resources like grass, to produce the next generation of sustainable food ingredients.

Mechanochemical synthesis of β-cyclodextrin urea derivatives under reactive CO2 atmosphere by Staudinger aza-Wittig reaction

Easily synthesize various ureido β-cyclodextrins with minimal environmental impact using a fast and solvent-free mechanochemical process under carbon dioxide reactive atmosphere.

Effect of calcination temperature induced structural modifications on the photocatalytic efficacy of Fe2O3-ZrO2 nanostructures: mechanochemical synthesis.

Water contamination due to organic pollutants is a challenging issue around the globe, and several attempts have been made to deal with this issue. Out of which, the semiconductor-based photocatalytic process had gained much attention and proved to be an efficient, easy, and economical process for the removal of organic dyes from aqueous solutions. For this purpose, the iron oxide-zirconium dioxide nanocomposite (Fe2O3-ZrO2 NC) was prepared via a simple mechanochemical process using a mortar and pestle, followed by a calcination process at 300, 600, and 900 °C. Different physicochemical analyses were carried out in order to investigate the successful synthesis of Fe2O3-ZrO2 NC and the effect of temperature on the crystallinity, surface area, pore size, phase composition, sample morphology, and particle/crystallite size. The Fe2O3-ZrO2 NCs were subjected to a photocatalytic test under solar light irradiation against fluorescein dye in an aqueous medium, and the photocatalytic performance was examined under the influence of calcination temperatures, pH, catalyst dose, and initial concentration. The stability of the Fe2O3-ZrO2 NCs was also checked by recycling them for five reuse cycles.

SOFT MECHANOCHEMICAL SYNTHESIS OF CuO/ZnO/AL2O3 CATALYST FOR METHANOL PRODUCTION

In the work, using a set of methods for physicochemical studies, such as X-ray phase, X-ray diffraction, synchronous thermal and energy-dispersion analysis, scanning electron microscopy, low-temperature adsorption-desorption of nitrogen, IR-Fourier spectroscopy, the processes occurring at the stage of mechanochemical activation and further heat treatment of the Cu(NO3)3·3H2O/Zn(NO3)3·2H2O/Al(NO3)3·9H2O/H2C2O4·2H2O were studied. It has been established that at the stage of mechanochemical activation, intensive interaction of copper and zinc nitrates with oxalic acid occurs with the formation of one-water copper oxalate (CuC2O4∙Н2О) and two-water zinc oxalate (ZnC2O4∙2Н2О). The formation of oxalates occurs at the initial moment of activation 0-15 min, which is confirmed by the data of IR spectroscopy, X-ray phase and thermal analysis. The calcination of the samples leads to the formation of the ternary oxide system CuO/ZnO/Al2O3 and the interaction of copper and zinc oxides with the formation of a solid solution. It is shown that with an increase in the MCA time, the size of the coherent scattering regions decreases from 152 Å for the initial sample to 115 Å after 60 min of treatment. In this case, the accumulation of defects in the crystal structure occurs from 0.24 to 0.72%, respectively. The value of the specific surface passes through a maximum and at 30 min of treatment is 67.1 ± 0.3 m2/g. During processing, a mesoporous structure of the catalyst is formed with a total pore volume of 0.132 cm3/g. For the scaling process or the selection of other types of mills, the values of the supplied energy were calculated. It has been established that in order to obtain a catalyst with properties close to industrial analogs of leading foreign manufacturers, it is necessary to carry out treatment with an input energy of 79 kJ/g, and the calcination process should be carried out at a temperature of 350 °C and a duration of 360 min.

Driving the rapid regeneration of LiFePO4 from spent lithium-ion batteries through one-pot mechanochemical activation

Driving the rapid regeneration of LiFePO4 from spent lithium-ion batteries through one-pot mechanochemical activation, thus allowing for better environmental and economic returns.

Solventless mechanochemical synthesis of Sn-based halide perovskite microcrystals with high stability tracked by photoluminescence spectroscopy

Developing solvent-free methods to synthesize lead-free perovskites is of practical importance from the viewpoint of sustainability. In this work, we use a facile mechanochemical approach to synthesize a series of lead-free Sn-based halide perovskite microcrystals (powders) in ambient conditions directly from precursor powders (CsX and SnX2 (X = I, Br, Cl)) without any solvent. Such an approach is energy-saving and avoids the use of toxic solvents. There exists phase evolution during the mechanochemical processing of the precursor powders with CsSn2Br5 to CsSnBr3 in the first hour and finally into the stabilized phase of Cs2SnBr6 after 28 days and with Cs2SnCl4 to CsSnCl3 in the first hour and finally to the stabilized phase of Cs2SnCl6 after 36 days. The stabilized Cs2SnI6 powders emit light centered at 930 nm under the excitation of 785 nm, and the stabilized Cs2SnBr6 powders emit light centered at 682 nm under the excitation of 365 nm. Both the stabilized Cs2SnI6 and Cs2SnBr6 powders exhibit excellent long-term structural and optical stabilities, and the Cs2SnBr6 powders have a better thermal stability than the Cs2SnI6 powders. This work likely offers a green-route synthesis of lead-free halide perovskites towards large-scale manufacturing and industrialization.

Вплив механохімічної активації композиційного цементу на міцність будівельного розчину

The article discusses issues related to the use of technology for the production of mortar mixtures and mortars based on high-speed mixers, the operation of which causes mechanochemical activation of the binder. The rotary counterflow mill used in the work acts as an activator of the surface zone of both Portland cement grains and quartz sand grains and, thus, contributes to the intensification of the processes of structure formation of cement paste and mortar based on it. Based on the fact that one of the promising ways to reduce the cost of cement activation is to reduce the energy intensity of the dispersion process itself, the use of relatively low-energy rotary mills can be considered as an effective way to increase the activity of the binder. After the joint activation of Portland cement and unground quartz sand (the amount of which was adjusted from 0 to 50 % of the cement mass; activation period - 300 seconds), samples were made from equal-viscosity cement paste. It was experimentally established that the maximum strength of cement stone at 28 days of age was achieved when using composite cement with a 20 % content of activated sand. To determine the influence of the studied factors, such as the consumption of mechanically activated composite binder, the concentration of superplasticizer C-3 (0...1,5 %) and the consumption of microsilica (0...10 %) on the strength of the mortar in 2 and 28-day old, a 3-factor experiment was conducted. It was established that in the studied hardening period, the content of mechanically activated composite cement has the greatest influence on the compressive strength for the studied mortar compositions (from 1:3 to 1:1). The next most important influence on the strength of the mortar is the consumption of superplasticizer C-3. The increase in compressive strength of a mortar from the introduction of microsilica into its composition does not exceed 10-15 %. The combined effect of mechanical activation of the binder and the use of the C-3 additive ensures an increase in the strength of the mortar (mortar composition 1:1) at 28 days of age from 43,5 MPa (non-activated binder; no C-3 additive) to 63 MPa, that is, almost by 45 %. For a mortar of similar age with a lower consumption of composite cement (mortar composition 1:3), mechanical activation of the binder in the presence of 1,5 % C-3 additive ensures an increase in the compressive strength of the mortar from 21 MPa (non-mechanically activated binder; C-3 = 0 %) to 39 MPa.

Multimechanophore Polymers for Mechanically Triggered Small Molecule Release with Ultrahigh Payload Capacity.

Polymers that release small molecules in response to mechanical force are promising for a variety of applications including drug delivery, catalysis, and sensing. While a number of mechanophores have been developed for the release of covalently bound payloads, existing strategies are either limited in cargo scope or, in the case of more general mechanophore designs, are restricted to the release of one or two cargo molecules per polymer chain. Herein, we introduce a nonscissile mechanophore based on a masked 2-furylcarbinol derivative that enables the preparation of multimechanophore polymers with ultrahigh payload capacity. We demonstrate that polymers prepared via ring-opening metathesis polymerization are capable of releasing hundreds of small-molecule payloads per polymer chain upon ultrasound-induced mechanochemical activation. This nonscissile masked 2-furylcarbinol mechanophore overcomes a major challenge in cargo loading capacity associated with previous 2-furylcarbinol mechanophore designs, enabling applications that benefit from much higher concentrations of delivered cargo.

Granulation of nanocomposites based on glauconite and urea: binding materials and characterization of activated mineral fertilisers

Relevance. Development of controlled release fertilisers and their granulation is at the forefront of agriculture and environment. With growing world population and increasing food demand, agriculture faces the challenge of efficient resource management and increased crop yields. In this environmentally friendly and easy to obtain and use fertilisers become a key element for sustainable development of agribusinesses. Aim. To study the complete cycle of creation of granular fertilisers based on new materials, including aggregation of mineral particles with different binding solutions and mechanochemical activation of initial mixtures of glauconite and urea. Potassium-containing clay mineral – glauconite of Karinskiy deposit (Russia) was used as a "container" material. Urea containing up to 46 wt % of nitrogen was used as an additive (nutrient) component for fertilisers. The following parameters were stable during mechanochemical preparation: mineral/urea ratio and abrasion type. Solutions with different nitrogen concentrations were used as binders during granulation. The methodology for investigating the characteristics of the resulting nanocomposites included particle size analysis, X-ray diffraction analysis, scanning electron microscopy, and FTIR spectrometer. Results. The advantages of different granulation options for mechanochemically activated composites were investigated. The authors have produced f full cycle of controlled-release granular fertiliser. The average nitrogen content in glauconite particles reaches 5.5 wt %. The granule size depends on the content of urea gel concentrate in the binder. The maximum strength and proportionality of granules are achieved, when using a binder consisting of 100% urea gel concentrate. Determination of the optimal content of gel concentrate in the binder used in granulation plays a key role in obtaining strong fertiliser granules.

Improving the pozzolanic reactivity of clay, marl and obsidian through mechanochemical or thermal activation

This research investigated the physicochemical properties and pozzolanic reactivity of mechanochemically and thermally treated clay, marl, and obsidian as supplementary cementitious materials (SCMs). The results suggest that the mechanochemical treatment of clay and marl resulted in delamination, dehydroxylation, and amorphisation of the mineral components (including calcite); while for obsidian, the main effect was particle size reduction. Among all samples prepared, the mechanochemically treated obsidian exhibited the best performance as a SCM and achieved marginally higher strength performance at 20% cement replacement compared with the CEM I cement mortar (with on SCM). The thermally activated clay and marl exhibited highest pozzolanic reactivity than the mechanochemically treated counterparts owning to the formation of free lime from calcination of calcite. However, the mechanochemically treated clay and marl were still able to achieve over 80% of the strength activity index and performed much better than the untreated materials. These results indicate that mechanochemical treatment can effectively improve the pozzolanic reactivity of clay minerals that contain calcite up to 68% without directly emitting process CO2 to the environment (calcination of carbonates), which can be an alternative activation route to the high-temperature calcination-treatment method.

АКТИВАЦІЯ ЦЕМЕНТУ І ЇЇ ВПЛИВ НА СТРУКТУРОУТВОРЕННЯ ЦЕМЕНТОВМІЩУЮЧИХ КОМПОЗИЦІЙ

The article discusses issues related to the mechanochemical activation of the cement binder in a specially designed rotary counterflow mill. The given brief description of the design of a counterflow mill gives a general idea of the principle of its operation as an activator of the surface zone of a mineral binder. Typically, a positive characteristic of mineral binders is their rapid increase in strength. Therefore, scientific research related to the development of technology aimed at intensifying the processes of structure formation of cement paste and stone based on it is relevant. The use of this technology makes it possible to significantly increase the specific surface area of cement during its activation, reduce the setting time, increase the amount of chemically bound water and intensify the exothermic heating of hardening cement stone. The presented experimental data made it possible to optimize the activation period of the binder, which ranged from 60 to 600 seconds. It has been established that the optimal time from the point of view of the energy intensity of the process is the activation period of the binder for 300 seconds. During this activation period, there is an increase in the specific surface area of cement by an average of 8...10%, acceleration of setting time by 50...60 minutes, an increase in the amount of chemically bound water at 28 days of age from 13 to 16.3%, an increase in the maximum temperature of exothermic heating cement stone from 53.8 to 64.0 °C. A further increase in the activation period (up to 600 seconds) has little effect on the change in the listed properties. The effect of mechanochemical activation is significantly reflected in the compressive strength of cement stone. It has been established that activation of cement for 300 seconds causes an increase in the compressive strength of cement stone from 48 to 57 MPa, that is, by almost 20%. The effect of mechanochemical activation of cement is enhanced by the introduction of quartz sand into its composition. It has been experimentally established that the activation of cement with the addition of 20% quartz sand increases the strength of the filled cement stone by almost 30% relative to the strength of the stone using unadded cement that is not subject to mechanical activation.