Mechanochemical Treatment Research Articles

Синтез акрилової кислоти на B–P–V–W–OX/SIO2 каталізаторах, модифікованих механохімічною обробкою

Досліджено вплив механохімічного оброблення каталізаторів на процес альдольної конденсації оцтової кислоти з формальдегідом в акрилову кислоту в газовій фазі. Компоненти активної фази B2O3–P2O5–WO3–V2O5/SiO2 каталізатора впроваджено в структуру носія (силікагель марки КСКГ) під час його механохімічного оброблення у воді або під час механохімічного оброблення вологого гелю SiO2 у процесі приготування силікагелю. Механохімічне оброблення здійснено за 300 об./хв, 500 об./хв, 650 об./хв та 800 об./хв. Каталітичні властивості одержаних каталізаторів досліджено в реакції альдольної конденсації оцтової кислоти з формальдегідом у температурному діапазоні від 573 до 673 К, часі контакту 8 с за еквімолярного співвідношення вихідних реагентів. Встановлено вплив температури реакції та умов механохімічного оброблення каталізатора на параметри процесу конденсації оцтової кислоти з формальдегідом. Кращим із досліджених є каталізатор, підданий механохімічній обробці у воді за 300 об./хв. Оптимальними умовами здійснення процесу є температура 648 К, час контакту 8 с. У зазначених умовах вдалося досягти виходу акрилової кислоти 65,8 % за селективності її утворення 91,3 % та конверсії ОК 72,1 %. Механохімічне оброблення каталізатора є простим та ефективним способом вдосконалення ефективності каталізаторів і дає змогу збільшити вихід АК на 8,8 %. Показано, що метод приготування каталізатора істотно впливає на його порувату структуру.

Amorphous Ni‐Rich Li(Ni1−x−yMnxCoy)O2–Li2SO4 Positive Electrode Materials for Bulk‐Type All‐Oxide Solid‐State Batteries

AbstractAll‐solid‐state batteries attract significant attention owing to their potential to realize an energy storage system with high safety and energy density. In this paper, a mechanochemical synthesis of novel amorphous positive electrode materials of the Ni‐rich LiNi1−x−yMnxCoyO2 (NMC)–Li2SO4 system suitable for oxide‐type all‐solid‐state batteries is reported. Through the mechanochemical treatment with Li2SO4, excellent formabilities of the electrode materials as those of ductile solid electrolytes are obtained. Owing to the deformability of the active material, a good electrode/electrolyte interface is provided simply by pressing at room temperature. In all‐oxide solid‐state cells using 80NMCs·20Li2SO4 (mol%) positive electrode materials, the cell capacity increases with the Ni content in the NMC. The all‐solid‐state cell using the 80NMC811·20Li2SO4 positive electrode active material exhibits a high capacity larger than 250 mAh g−1 in a voltage range of 1.6–4.8 V versus Li at 100 °C. Furthermore, bulk‐type all‐oxide solid‐state batteries (Li4Ti5O12/80NMC532·20Li2SO4 (mol%)) successfully function as secondary batteries with excellent cycle performances.

Influence of mechanochemical treatment on thermal and structural properties of silica\u2013collagen and hydroxyapatite\u2013collagen composites

The paper presents the results of research on a series of composite materials based on hydroxyapatite, silica gel and collagen as biologically active substances. Their preparation was made using mechanical energy in accordance with the principles of “green chemistry”. Mechanochemical treatment was conducted in a planetary mill with different rotations of milling (200 and 400 rpm) and various periods of time (30, 60 and 120 min). Temperature and pressure changes generated during the mechanochemical treatment were recorded. The obtained composites were analyzed using the low-temperature nitrogen adsorption/desorption method and thermal analysis (TG/DTA). Very interesting and promising results were obtained encouraging further research in this area.

Carboxymethylation of Peat by a Mechanochemical Method

The effects of the synthesis time, the amount of alkali, and the amount of alkylating reagent on the concentration of bound carboxymethyl groups and the solubility of the resulting products in aqueous alkaline solutions was studied in the carboxymethylation of peat with sodium monochloroacetate in the presence of sodium hydroxide under mechanochemical treatment conditions.

Exploring Ternary and Quaternary Mixtures in the LiBH4‐NaBH4‐KBH4‐Mg(BH4)2‐Ca(BH4)2 System

Binary combinations of borohydrides have been extensivly investigated evidencing the formation of eutectics, bimetallic compounds or solid solutions. In this paper, the investigation has been extended to ternary and quaternary systems in the LiBH4 -NaBH4 -KBH4 -Mg(BH4 )2 -Ca(BH4 )2 system. Possible interactions among borohydrides in equimolar composition has been explored by mechanochemical treatment. The obtained phases were analysed by X-ray diffraction and the thermal behaviour of the mixtures were analysed by HP-DSC and DTA, defining temperature of transitions and decomposition reactions. The release of hydrogen was detected by MS, showing the role of the presence of solid solutions and multi-cation compounds on the hydrogen desorption reactions. The presence of LiBH4 generally promotes the release of H2 at about 200 °C, while KCa(BH4 )3 promotes the release in a single-step reaction at higher temperatures.

Structural, thermal and photocatalytic properties of composite materials SiO2/TiO2/C

In the study the mechanochemical treatment procedure was used to prepare composite materials based on SiO2 with the addition of TiO2 and carbon black as a carbon matter. The investigations were carried out at the three rotational speeds 300, 500 and 700 rpm. Thermal and structural characteristics of the composites were investigated using N2 adsorption, TG/DTG/DTA, SEM and FT-IR/PAS methods. The photocatalytic properties were evaluated by methylene blue degradation (Co = 1 × 10−5 mol L−1) at UV light. The obtained results show that the mechanochemical treatment at different rotational speeds causes intensive changes in the porous structure of the obtained materials. Thermal analysis proved that the obtained materials are characterized by significant thermal stability. The obtained composites have comparable photocatalytic properties with pure TiO2 despite the fact that in the composite only 5% of TiO2 is used.

Ultrasonically-assisted mechanochemical synthesis of zinc aluminate spinel from aluminium-rich layered double hydroxide

An ultrasonically-assisted mechanochemical method was further improved to increase the yield of high-quality ZnAl2-LDH with carbonate interlayer anions. In the LDH formation, the rarely studied temperature, power and pulse character of ultrasound irradiation were investigated to determine the optimal parameters for the synthesis. The as-prepared samples were milled with varying the grinding frequency in order to convert the layered hydroxide structure into ZnAl2O4 spinel. This was the first time that ZnAl2O4 spinel formation was induced mechanochemically. The main method to identify the effects of ultrasonic and mechanochemical treatments was X-ray diffractometry; however, infrared spectroscopy, scanning electron microscopy, and thermal analysis were also applied to follow and compare the mechanochemically induced spinel formation to the more frequently used heat treatment.

Influence of mechanochemical and microwave modification on ion-exchange properties of tin dioxide with respect to uranyl ions

Wet gel and dried xerogel of precipitated tin oxy-hydroxide were subjected to mechanochemical and microwave treatments (MChT and MWT, respectively). The prepared samples were studied using DTA-TG, XRD, FTIR, nitrogen adsorption–desorption. MChT and MWT cause improvement of crystal structure, removal of structural OH-groups and increase mesopores diameter as well as form the meso-macroporous structure. As a result, drastic increase of uranyl-ions sorption for all modified samples is observed. Sorption centers can be divided into three groups: selective cation-exchange, non-selective cation-exchange and anion-exchange.

Charge-Discharge Mechanism of All-Solid-State Batteries Using Li2RuO3-Li2so4 Positive Electrode Active Materials

All-solid-state batteries have attracted great attention because of their high safety owing to the use of non-flammable inorganic solid electrolytes. Solid electrolytes with an extremely high ionic conductivity have already been discovered, and therefore the discovery of new and efficient electrode materials is key for the construction of high energy density all-solid-state batteries. In the electrode layers for conventional all-solid-state batteries, mixtures composed of active material, solid electrolyte and carbon conductive additive powders are often applied to secure lithium ionic and electronic conduction pathways. Moreover, most of all-solid-state batteries reported so far comprise a thin electrode layer with a small amount of active materials and a thick electrolyte layer as the separator. Therefore, the energy density of all-solid-state batteries at the present stage is considerably lower than that of typical lithium ion batteries. To enhance the energy density of all-solid-state batteries, high capacity electrode materials should be developed and the active material content should be increased in the composite electrode layers. With consideration to the demands and features described above, we have successfully developed a novel Li2Ru0.8S0.2O3.2 (80Li2RuO3·20Li2SO4 in mol%) positive electrode material for all-solid-state batteries. Mechanochemical treatment with Li2SO4 imparts ionic conductivity and favourable ductility to the Li2RuO3 active material. Because of the favourable formability and high electronic and ionic conductivities, we achieved the fabrication of all-solid-state cells, where the positive electrode layer was composed of the active material without any conductive additives. The all-solid-state cell using a monolithic Li2Ru0.8S0.2O3.2 positive electrode functioned as a secondary battery showing a high reversible capacity of about 270 mAh g-1. In this study, the detail charge-discharge mechanism of the Li2Ru0.8S0.2O3.2 positive electrode was investigated by XRD, TEM, XPS, and XAFS measurements.

The concentration of melanin in powder materials obtained from white-rot fungi by the mechanochemical method

The effect of mechanochemical treatment of solid mixtures of white-rot fungi as chaga, ganoderma, tinder with alkalines powders on concentrations of biologically active substance melanin was studied. The rise of alkalinity of mechanochemical reagent in the range “sodium bicarbonate – carbonate – hydroxide” leads to the increase in yield of water soluble substances and melanin among them. The use of 5% solid sodium hydroxide changes the yield of water soluble substances from tinder from 4 to 24%.

A green and effective room-temperature recycling process of LiFePO4 cathode materials for lithium-ion batteries

Nowadays LiFePO4 cathode develops rapidly for its advantages of long life span, low cost and non-toxicity, especially in electrical vehicle markets. Because of its stable olivine structure, LiFePO4 is difficult to be recycled by the conventional hydrometallurgical processes as for LiCoO2 or LiNixCoyMnzO2. Pyrometallurgical processes consume much energy and release toxic gases. Herein, an effective room-temperature process based on the mechanochemical treatment is proposed to extract metals from LiFePO4. Spent LiFePO4 is co-grinded with low-cost citric acid agent in a ball mill. After grinding, the mixture is dissolved in deionized water and filtrated. With addition of H2O2, the extraction efficiency of Li reaches as high as 99.35%. Conversely, Fe is hardly extracted with a low extraction efficiency of only 3.86%, indicating a selective recovery of valuable Li element. In addition, when H2O is used instead of H2O2, the mechanochemical reaction changes and the extraction efficiencies of Li and Fe at optimal conditions reach 97.82% and 95.62%, respectively. The Fe impurity is removed as Fe(OH)3 precipitation by adding NaOH, and Li is recycled as Li2CO3 after reaction with saturated Na2CO3 at 95 °C. This simple and easily-operated process has little negative impact on the environment and has great potential in industrial applications.

Effect of mechanochemical treatment on phase composition and properties of Mn-containing cordierite materials

Mn-containing cordierites 2MnO·2Al2O3·5SiO2 were prepared by mechanochemical method from kaolinic clay, alumina and MnO2 after calcination at 1100°C. Phase composition of prepared samples, their texture properties and catalytic activity in ammonia oxidation reaction were found to depend on the activation time. The mechanochemical treatment of raw materials for 90-180s gave well-crystallized cordierite ceramic characterized by the surface enrichment with Mn cations and high catalytic activity in ammonia oxidation reaction. The increase activation time to 270-360s led to the possible interaction of MnO2 with Al-containing components during the mechanochemical treatment to form Mn-Al-spinel which is less selective.

O sintezi 3-cijano-6-hidroksi-4-metil-2-piridona na sobnoj temperaturi

Milling of cyanoacetamide and acetoacetic ester as reactants, in the presence of KOH as the catalyst and ethanol as a viscous control agent (VCA) was performed in a planetary ball mill with the goal of investigating the effect of mechanochemical treatment for the synthesis of 3-cyano-6hydroxy-4-methyl-2-pyridone at room temperature. The mechanochemical synthesis was performed under various milling parameters, i.e. milling time up to 4 h, number and size of balls, angular velocity as well as molar ratio of reactants and the amount of catalyst. The obtained product was characterized by m.p., UV, IR and NMR data. It was fond that the dominant process parameter is the milling time while others are of less importance. The highest isolated yield after milling was up to 56%. The combination of milling and aging increase yield over 60%.

In English

There are many methods for synthesis of tin dioxide SnO 2 , namely sol-gel, precipitation. However, these methods do not allow to regulate the physical-chemical properties in wide limits in the synthesis stage. The most commonly obtained samples are predominantly microporous as a rule. On the other hand, the meso-macroporous structure is required for the effective use of tin dioxide in sorption processes. The mechanochemical and microwave treatments can be used for eliminating mentioned above disadvantages. Therefore, the purpose of this work was to study the influence of the mechanochemical and microwave treatments on the physical-chemical and sorption properties of SnO 2 prepared by heterogeneous precipitation. SnO 2 gels and xerogels have been obtained by heterogeneous precipitation. The mechanochemical treatment was carried out in air and water at 300 rpm for 0.5 h in the form of dried xerogel as well as wet gel using a planetary ball mill Pulverisette-7. Initial wet gel was subjected to microwave treatment for 1 h using a high-pressure reactor «NANO 2000». We used XRD and DTA-TG analysis, FTIR spectroscopy, adsorption-desorption of nitrogen for characterization of initial and modified samples. The initial sample corresponds to the composition tin oxohydroxide with gross formula Sn 3 O 4 (OH) 4 . For the modified samples a partial removal of the structural OH groups occurs. The initial sample is characterized by high values of specific surface area and high content of micropores. The specific surface area, total volume of pores, mesoporous size are increased as a result of the mechanochemical and microwave treatments. Formation of the secondary porosity that presented by meso- and macropores is peculiarity of xerogel milling in water. The cation exchange capacity under the most optimal conditions for the sorption of U(VI) ions (pH = 5–6, no background, cationic forms of uranium) for the initial sample was 0.82 mEq/g UO 2 2+ . The mechanochemical and microwave treatments result in drastic increase in sorption capacity of tin oxohydroxide in relation to U(VI) ions. The greatest effect was observed for sample milled in the form of wet gel, the sorption capacity А of which increases almost in three times while distribution coefficient K d increases almost 70 times. In case of sorption on the background of 0.1 M NaHCO 3 (pH 8, model of block water of the Chernobyl Nuclear Power Plant), the sorption capacity of sample after mechanochemical treatment of gel increases by 43 % compared to initial sample from 0.31 to 0.43 mEq/g UO 2 2+ . Thus, modified samples can remove both cationic and anionic forms of U(VI) ions in the solution. At the same time, for sorption of Cs(I) and Sr(II) ions, it has been found, that in both cases the mechanochemical and microwave treatments negatively affect to their removal in comparison with initial sample.

Characterization of Multimodal Silicas Using TG/DTG/DTA, Q-TG, and DSC Methods

The formation of hierarchical, multimodal porosity materials with controlled shape and size of pores is the essential challenge in materials science. Properties of silica materials depend largely on different features: crystal structure, dispersity, surface composition, and porosity as well as the method of preparation and possible modification. In this paper, multimodal silicas obtained using different additives are presented. A-50 and A-380 aerosils and wide-porous SiO2 milled at 300 rpm were used as the additives in the sol stage at 20 °C, the sol–gel stage followed by hydrothermal modification (HTT) at 200 °C, or in the mechanochemical treatment (MChT) process. The characterizations were made by application of N2 adsorption/desorption, SEM imaging, quasi-isothermal thermogravimetry (Q-TG), dynamic thermogravimetry/derivative thermogravimetry/differential thermal analysis (TG/DTG/DTA), and cryoporometry differential scanning calorimetry (DSC) methods. Results showed that such a one-step preparation method is convenient and makes it possible to obtain multimodal silicas of differentiated porous structures and surface chemistry.

Evaluation of Microstructure due to Addition of Carbon in Ni–Cr–Mo Steel Mechanically Through Surface Mechanochemical Case Carburizing Treatment (SMCT)

Mechanochemical reaction of Fe–C is achieved in Ni–Cr–Mo steel during surface mechanochemical case carburizing treatment (SMCT) at room temperature. Gradient nano-carbide layers are formed in the surface and near surface up to few microns. The Ni–Cr–Mo steel was treated for 15, 30, 45 and 60 min, respectively, to find out the alteration in microstructure. The surface and cross-sectional microstructures were investigated by Olympus optical microscope (Japan), 6390-A scanning electron microscope and JEOL F-2100 transmission electron microscope (TEM). It is observed that mechanical alloying of carbon in iron lattice is achieved and surface carbon concentration increased from 0.17 to 0.8 wt% with 1 hour of SMCT operation time. The mechanochemical reaction between Fe and C produces Fe3C (cementite) in the surface and undersurface up to 500–800 microns along with nano-particulate on the surface and near surface in 1-hour operation time. It is observed that the carbide cell blocks (CB) and geometrically necessary boundaries (GNB) are produced due to severe plastic deformation created by SMCT operation.

Structural changes in calcium silicate hydrate gel and resulting improvement in phosphate species removal properties after mechanochemical treatment.

The discharge of phosphate species into aqueous environments is a key issue for eutrophication prevention. In this study, we investigate a mechanochemical treatment of calcium silicate hydrate (C-S-H) gel with different organic solvents with the aim of changing its structure and improving its phosphate species removal properties. The treatment leads to a collapse of the gel structure, resulting in the formation of defective structures in the silicate anion chains. The C-S-H gel sample milled with acetone exhibits better phosphate species recovery characteristics than does the unmilled C-S-H gel sample or the C-S-H gel sample milled with 1-propanol. Ultraviolet irradiation during phosphate recovery using the C-S-H gel sample milled with acetone further enhances the recovery properties.

Mechanochemically modified hydrazine reduction method for the synthesis of nickel nanoparticles and their catalytic activities in the Suzuki–Miyaura cross-coupling reaction

The commonly used hydrazine reduction method for the synthesis of Ni nanoparticles was integrated with the mechanochemical treatment of the nickel hydroxide precursors to modify the structural and catalytic attributes of the as-prepared metallic nickel materials. The precursors and the nanoparticles were studied by X-ray diffractometry, infrared spectroscopy, and dynamic light scattering as well as scanning electron microscopy. The changes in catalytic activities were followed in the Suzuki–Miyaura cross-coupling reaction between iodobenzene and phenylboronic acid and correlated with structural changes resulting from mechanochemical pretreatment.

Mechanochemical-Assisted Extraction of Active Alkaloids from Plant with Solid Acids

In this work, a novel mechanochemical-assisted extraction (MCAE) coupled with the ultra-high performance liquid chromatography (UHPLC) method was developed to extract two alkaloids with solid acids from Stephania tetrandra S. Moore. To further understand the influence of extraction parameters on the MCAE process, the response surface methodology was applied for systematic investigation. The results showed that the highest yield of alkaloids was obtained within 15 min of the total extraction time under the optimal conditions: oxalic acid (20 wt %), grinding plant materials for 5 min, and the liquid/solid ratio of 20 mL/g. Mechanochemical treatment resulted in the destruction of cell walls and increased the total contact surface area due to the smooth surface changing to an open porous structure. Accordingly, the developed extraction method showed advantages of being more ecofriendly, faster, and more efficient than conventional extraction methods. Meanwhile, the extractant was analyzed by UHPLC. The obtain...

Dramatic Simplification of Lignin Heteronuclear Single Quantum Coherence Spectra from Ring-and-Puck Milling Followed by Oxidation

Conversion of biomass into usable fuels and chemicals, especially under very low-cost processing, remains a major challenge. Mechanochemical treatment of lignin can greatly improve the yield of mon...