Vibratory Ball Mill Research Articles

Fabrication of Mg-Ti by MA-SPS process and its properties

Pure magnesium (Mg) powders together with pure titanium (Ti) powders were mechanically alloyed (MAed) using a vibration ball mill. Stearic acid was used as process control agent (PCA) for the mechanical alloying (MA) process. The MAed powders were consolidated into bulk materials by the spark plasma sintering (SPS). Changes in hardness and solid-state reactions of the MAed powders and the SPS materials have been examined by hardness measurements and an X-ray diffraction (XRD), respectively. The Vickers hardness of the MAed powders increased to 58 HV after MA 8 h. No solid-state reactions were observed in MAed powders. The Vickers hardness of the SPS materials fabricated from MA 8 h Mg-10 mass%Ti powders reached to 76 HV. Formation of TiH2 by solid-state reaction was observed for the SPS materials, but TiH2 did not act as a strengthening phase. The Vickers hardness of the SPS materials improved by increasing sintering temperature, but not improved by increasing the amount of titanium. Mg-Ti system of hardness can be improved by MA-SPS process.

Comparative study on the hydrogen storage performance of as-milled MgRENi rapid quenched alloy catalyzed by metal sulfides

The composites of Mg20Pr1Sm3Y1Ni10 as-quenched alloy and 3 wt.% M (M = CoS, CoS2, MoS2) catalyst were prepared by high-speed vibration ball mill. The effects of metal sulfides on the hydrogenation and dehydrogenation dynamics of alloys were compared. The results show that the as-milled composites contain a large number of amorphous embedded by a small amount of nanocrystals, and there are many point defects. After ball milling, the crystal grain size in the composites containing CoS is relatively larger, followed by CoS2 and MoS2 again. After hydrogenation, the amorphous phase is crystallized to form Mg2NiH4, YH3, Pr8H18.96, Sm3H7, Mg, Co or Mo phases, however, Mg2Ni, YH2, PrH2 and Ni3Y phases appeared after dehydrogenation. The maximum hydrogenation capacity of the composites containing CoS, CoS2 and MoS2 are 3.939, 4.265 and 4.507 wt.%, respectively. The hydrogenation saturation ratio of composite containing MoS2 is higher than that of the composites containing CoS and CoS2. The dehydrogenation activation energy of the composites containing CoS, CoS2 and MoS2 is 107.76, 68.43 and 63.28 kJ.mol−1.H2. On the improvement of hydrogen storage performance of Mg20Pr1Sm3Y1Ni10 alloy, the catalytic effect of MoS2 sulfide is better than that of CoS2 sulfide, and which is better than CoS sulfide.

Ternary and Quaternary Nanocrystalline Cu-Based Sulfides as Perspective Antibacterial Materials Mechanochemically Synthesized in a Scalable Fashion.

Twelve Cu-based ternary (Cu–Me1–S, Me1 = Fe, Sn, or Sb) and quaternary (Cu–Me2–Sn–S, Me2 = Fe, Zn, or V) nanocrystalline sulfides are shown as perspective antibacterial materials here. They were prepared from elemental precursors by a one-step solvent-free mechanochemical synthesis in a 100 g batch using scalable eccentric vibratory ball milling. Most of the products have shown strong antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria. For instance, stannite Cu2FeSnS4 and mohite Cu2SnS3 were the most active against E. coli, whereas kesterite Cu2ZnSnS4 and rhodostannite Cu2FeSn3S8 exhibited the highest antibacterial activity against S. aureus. In general, stannite has shown the best antibacterial properties out of all the studied samples. Five out of twelve products have been prepared using mechanochemical synthesis for the first time in a scalable fashion here. The presented synthetic approach is a promising alternative to traditional syntheses of nanomaterials suitable for biological applications and shows ternary and quaternary sulfides as potential candidates for the next-generation antibacterial agents.

Solvent-Free Synthesis of Core-Functionalised Naphthalene Diimides by Using a Vibratory Ball Mill: Suzuki, Sonogashira and Buchwald-Hartwig Reactions.

Solvent‐free synthesis by using a vibratory ball mill (VBM) offers the chance to access new chemical reactivity, whilst reducing solvent waste and minimising reaction times. Herein, we report the core functionalisation of N,N’‐bis(2‐ethylhexyl)‐2,6‐dibromo‐1,4,5,8‐naphthalenetetracarboxylic acid (Br2‐NDI) by using Suzuki, Sonogashira and Buchwald–Hartwig coupling reactions. The products of these reactions are important building blocks in many areas of organic electronics including organic light‐emitting diodes (OLEDs), organic field‐effect transistors (OFETs) and organic photovoltaic cells (OPVCs). The reactions proceed in as little as 1 h, use commercially available palladium sources (frequently Pd(OAc)2) and are tolerant to air and atmospheric moisture. Furthermore, the real‐world potential of this green VBM protocol is demonstrated by the double Suzuki coupling of a monobromo(NDI) residue to a bis(thiophene) pinacol ester. The resulting dimeric NDI species has been demonstrated to behave as an electron acceptor in functioning OPVCs.

Utilization of nanosize spent oil shale for water treatment: application of top-down nanonization technology for solid residues.

Since the dawn of nanoscience, producing nanomaterials in a simple, low-cost, and high-yield manner has been a major issue. For the commercial manufacturing of nanomaterials, various bottom-up and top-down methodologies have been established. High-energy dry ball milling is widely used for the production of diverse nanomaterials, nanograins, nanoalloys, and nanocomposites. Physical grinding of inorganic solid waste into nanosize (1-100nm) has improved their industrial applications particularly as water adsorbent. Application of nanosize spent oil shale by top-down methodology as adsorbent for phenol is addressed in the current research. The collected spent oil shale (SiO2 and Al2O3 making 45% of the material) has microstructure with average particle size of 56.6μm. The dry grinding was performed in a vibrating ball mill at various grinding time (5-150min) while keeping the grinding parameters constant including number of balls, ball size, total mass, vibration frequency, and amplitude. Upon grinding, the mean particle diameter of the bulk material was reduced to 191.8 and 85.2nm using 0.5 and 0.1mm grinding balls, respectively. The effect of grinding time on particle size and surface area was investigated; both particle size and surface area were not affected after 60min of grinding. Physical grinding by 0.1mm balls has notably improved surface area and total pore volume by 52% and 62%, respectively. Although nanosize particles (85.2nm) perform better than bulk material for phenol uptake, they underwent serious aggregation at pH > 2 and ionic strength > 1.0mM. Hence, the 191.8-nm size is selected to assess the effect of mechanical grinding on adsorption rate and equilibrium capacity for phenol as a common pollutant. Upon nanonization, adsorption rate of phenol was highly increased from 0.39 to 4.43mgg-1min-1 as analyzed by pseudo-second-order model. Adsorption isotherms were adequately presented by Sips model (prediction error 5.4-7.2%) with a maximum phenol retention capacity of 39.29mg/g after nanonization compared to 10.71mg/g for the raw material. The performance of the nanosize spent oil shale for phenol retention was promising when compared with advanced adsorbents like multiwalled carbon nanotube.

Reduced deactivation of mechanochemically delaminated hierarchical zeolite MCM-22 catalysts during 4-propylphenol cracking

The delamination of MCM-22 using shear forces in a vibratory ball mill, rather than chemical surfactants and sonication, is illustrated. The resulting material has comparable or improved physical properties compared to chemically delaminated MCM-22 without a significant loss of acid sites. The mechanical treatment affected the initial rate of 4-propylphenol cracking to phenol and propylene, a model reaction for lignin-derived aromatics, much less than chemical delamination. It also shows improved deactivation resistance for this reaction known to experience fast deactivation by pore blockage.

Properties of biomass powders resulting from the fine comminution of lignocellulosic feedstocks by three types of ball-mill set-up.

Background: Lignocellulosic biomass has many functionalities that hold huge potential for material, energy or chemistry applications. To support advanced applications, the biomass must be milled into ultrafine powder to increase reactivity. This milling unit operation needs to be fully mastered to deliver high-quality standard end-products. Here we studied the relationship between the characteristics of the starting lignocellulosic plant material and the properties of the resulting ultrafine powder in different ball-mill process routes. Methods: Two lignocellulosic biomasses (pine bark and wheat straw) with contrasted compositional and mechanical properties were milled using three ball-mill set-ups delivering different balances of impact force and attrition force. The resulting powders were analysed for particle characteristics (size, agglomeration extent, shape) and powder flow properties (compressibility, cohesion) using a dynamic powder rheometer. Results: Pine bark is more amenable to a fast particle size reduction than the fibrous wheat straw. The resulting pine bark powders appear less compressible but much more cohesive than the straw powders due to particle shape, density and composition factors. The mill set-up working by attrition as dominant mechanical force (vibratory ball mill) produced a mix of large, elongated particles and higher amounts of fines as it acts mainly by erosion, the resulting powder being more prone to agglomerate due to the abundance of fines. The mill set-up working by impact as dominant mechanical force (rotary ball mill) produced more evenly distributed particle sizes and shapes. The resulting powder is less prone to agglomerate due to a preferential fragmentation mechanism. Conclusions: The attrition-dominant mill yields powders with dispersed particle sizes and shapes and the poorest flow properties, while the impact-dominant mill yields more agglomeration-prone powders. The mill set-up working with impact and attrition as concomitant mechanical forces (stirred ball mill) produces powders with better reactivity and flow properties compared to rotary and vibratory mills.

Mechanochemical effects on the structural properties of wheat starch during vibration ball milling of wheat endosperm

Pure wheat endosperm was fully ground in a vibratory ball mill and structural changes in wheat starch were measured to assess the effect of mechanochemical action during the grinding process. Vibratory ball milling changed the endosperm granule size to ~30 μm (D50). There was a significant increase in damaged starch content, and this was positively correlated with the grinding time. The relative crystallinity of starch decreased by 5% after milling 105 min, and the short-range order decreased. The damaged structure of amylopectin starch decreased with milling time, as detected macroscopically by the peak viscosity and final viscosity of milling samples. Overall, the in vitro digestion results showed that mechanical modification caused irregular defects inside wheat starch crystals, increased the sensitivity of wheat starch to enzymes, enhanced the hydrolysis rate three-fold, and increased the maximum starch hydrolysis by 50%. Mechanochemistry effects was used to analyze the quality changes in wheat milling.

Sustained-Release Drug Delivery Potential of Antibiotic–Montmorillonite Composites Prepared Using Montmorillonite Mined in Gampo, Republic of Korea

AbstractBiocompatible drug-delivery materials are important because they provide controlled release of biologically active agents to enhance the effectiveness of medical treatments. Montmorillonite (Mnt) has been utilized in drug-delivery systems for delayed-release application because it can safely encapsulate drug molecules via intercalation reactions. The objective of the present study was to evaluate the delivery characteristics of the drug ciprofloxacin (CIP) from a composite with Mnt (Mnt-CIP) in which the Mnt was first prepared by acid treatment and vibration ball milling. The surfaces of Mnt were modified by reacting the Mnt suspension in 1.0 M HCl acid and by dispersing the powder with a vibration ball mill, then the CIP drug was added at pH 4 and stirred. The goal was to improve the sustained-release performance of the CIP. This Mnt-CIP drug-release system was characterized by X-ray diffraction, X-ray fluorescence analysis, Fourier-transform infrared spectroscopy, surface area measurement using the Brunauer-Emmett-Teller (BET) method, and ultraviolet spectroscopy. The X-ray diffraction results confirmed the intercalation of CIP into the interlayer space of Mnt. The in vitro release properties of the intercalated CIP were investigated using a simulated phosphate-buffered saline solution (pH 7.4) at 36±0.5°C. The CIP drug exhibited a continued release for 3 h. Moreover, Mnt prepared by HCl acid treatment and dispersion in the vibration ball mill delayed the drug dissolution rate. In summary, the Mnt-CIP composite prepared in this study exhibited slow and sustained release characteristics, indicating that Mnt mined from the Gampo-40 mining area in Gyeongju can be used in various drug-delivery applications.

Solid-State Nuclear Magnetic Resonance as a Tool to Probe the Impact of Mechanical Preprocessing on the Structure and Arrangement of Plant Cell Wall Polymers.

Efficient separation of the plant cell wall polymers during lignocellulose processing has been historically challenging due to insolubility of the polymers and their propensity for recalcitrant reassembly. Methods, such as “lignin first” extraction techniques, have advanced efficient biomass use, but the molecular mechanisms for recalcitrance remain enigmatic. Here, we discuss how solid-state Nuclear Magnetic Resonance (NMR) approaches report on the 3D organization of cellulose, xylan, and lignin in the plant cell wall. Recent results illustrate that the organization of these polymers varies across biomass sources and sample preparation methods, with even minimal physical processing causing significant effects. These structural differences contribute to variable extraction efficiencies for bioproducts after downstream processing. We propose that solid-state NMR methods can be applied to follow biomass processing, providing an understanding of the polymer rearrangements that can lead to poor yields for the desired bioproducts. The utility of the technique is illustrated for mechanical processing using lab-scale vibratory ball milling of Sorghum bicolor.

Few layered graphene wrapped Sn4P3 with high initial coulombic efficiency and cyclic stability for reversible Li+ storage

To enhance the rate capability and cyclic stability, we develop few layered graphene wrapped nanocrystalline/amorphous Sn4P3 (named as Sn4P3@FLG) by ball milling. The high energy output of vibrational ball milling enables tight contact of Sn4P3 with FLG via POC bonding as well as compact structure with a high tap density of 4.5 g cm−3. The constraint of FLG not only enhances kinetics of electron and Li+ transfer, but also relieves the volume variation and particle aggregation of Sn4P3 during the lithiation/delithiation process. Therefore, Sn4P3@FLG exhibits superior rate and cyclic performance when evaluated as anode material for lithium-ion batteries. At 0.1 A g−1, it delivers a high reversible capacity of 1077.6 mA h g−1 with a high coulombic efficiency of 89.0% in the first cycle. Even at 1 A g−1, it still retains 929.6 mA h g−1 after 830 cycles. Furthermore, when matched with commercial LiFePO4 cathode in a full cell, it delivers a reversible capacity of 778.0 mA h g−1, with a coulombic efficiency of 79.4%. Considering the high tap density of 4.5 g cm−3, the volumetric capacity of Sn4P3@FLG can be as high as 3500 A h dm−3. Therefore, Sn4P3@FLG can be a promising anode material for high performance lithium-ion batteries.

Synthesis and characterization of (HfMoTiWZr)C high entropy carbide ceramics

(HfMoTiWZr)C high entropy carbides (HEC) were prepared from the commercial carbide powders of IVB (Hf, Ti, Zr) and VIB (Mo, W) group metals of the periodic table via high energy ball milling (HEBM) and spark plasma sintering (SPS). Metal carbide powders (HfC, TiC, ZrC, Mo2C and WC) were HEBM’d for 3 h in a vibratory ball mill, and then SPS’d at different temperatures (1800, 1900, 2000 and 2100 °C). The HEBM’d powders and SPS’d ceramics were characterized in composition, density and microstructure using an X-ray diffractometer (XRD), a scanning electron microscope/energy dispersive spectrometer (SEM/EDS), a particle size analyzer and a pycnometer. Also, microhardness and sliding wear tests were conducted on the SPS’d ceramics. Based on the performed characterization, a single-phase FCC structure was observed at all sintering temperatures indicating a high entropy carbide ceramic, and they all have high hardness and wear resistance values.

Properties of biomass powders resulting from the fine comminution of lignocellulosic feedstocks by three types of ball-mill set-up

Background: Lignocellulosic biomass has many functionalities that hold huge potential for material, energy or chemistry applications. To support advanced applications, the biomass must be milled into ultrafine powder to increase reactivity. This milling unit operation needs to be fully mastered to deliver high-quality standard end-products. Here we studied the relationship between the characteristics of the starting lignocellulosic plant material and the properties of the resulting ultrafine powder in different ball-mill process routes. Methods: Two lignocellulosic biomasses (pine bark and wheat straw) with contrasted compositional and mechanical properties were milled using three ball-mill set-ups delivering different balances of impact force and attrition force. The resulting powders were analysed for particle characteristics (size, agglomeration extent, shape) and powder flow properties (compressibility, cohesion) using a dynamic powder rheometer. Results: Pine bark is more amenable to a fast particle size reduction than the fibrous wheat straw. The resulting pine bark powders appear less compressible but much more cohesive than the straw powders due to particle shape, density and composition factors. The mill set-up working by attrition as dominant mechanical force (vibratory ball mill) produced a mix of large, elongated particles and higher amounts of fines as it acts mainly by erosion, the resulting powder being more prone to agglomerate due to the abundance of fines. The mill set-up working by impact as dominant mechanical force (rotary ball mill) produced more evenly distributed particle sizes and shapes. The resulting powder is less prone to agglomerate due to a preferential fragmentation mechanism. Conclusions: The attrition-dominant mill yields powders with dispersed particle sizes and shapes and the poorest flow properties, while the impact-dominant mill yields more agglomeration-prone powders. The mill set-up working with impact and attrition as concomitant mechanical forces (stirred ball mill) produces powders with better reactivity and flow properties compared to rotary and vibratory mills.

Nanocrystalline Formation and Magnetic Properties in Fe₂O₃-C System by Mechanical Alloying.

The effect of mechanical alloying (MA) on the solid state reaction of hematite and graphite system with a positive reaction heat was investigated using a mixture of elemental Fe₂O₃-C powders. The solid state reduction of hematite to Fe₃O₄ has been obviously observed after 3 hours of MA by a vibrating ball mill. A two-phase mixture of Fe₃O₄ and remaining Fe₂O₃ is obtained after 5 hours of MA. Saturation magnetization gradually increases with MA time due to the formation of Fe₃O4 and then reaches 23 emu/g after 5 hours of MA. In addition, a Fe₃O₄ single phase is obtained by MA after 3 hours and subsequently heat treated up to 700°C. X-ray diffraction result shows that the average grain size of Fe₃O₄ prepared by MA for 5 hours and heat treatment to be in the range of 92 nm. The saturation magnetization of Fe₃O₄ prepared by MA and heat treatment reaches a maximum value of 56 emu/g for 5 hours MA sample. It is also observed that the coercivity of 5 hours MA sample annealed at 700 °C is still high value of 113 Oe, suggesting that the grain growth of magnetite phase during annealing process tends to be suppressed.

Mechanochemically Assisted Synthesis of Hexaazatriphenylenehexacarbonitrile.

1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HAT CN) was synthesized mechanochemically at room temperature. The coupling of hexaketocyclohexane and diaminomaleonitrile was conducted in 10 min by vibratory ball milling. The effects of milling parameters, acids, dehydrating agents, and liquid-assisted grinding were rationalized. With 67%, the yield of this mechanochemical approach exceeds that of state-of-the-art wet-chemical syntheses while being superior with respect to time-, resource-, and energy-efficiency as quantified via green metrics.

Elucidation of the Diels–Alder Reaction Kinetics between Diphenylfulvene and Maleimide by Mechanochemistry and in Solution

The Diels–Alder reaction kinetics between diphenylfulvene and maleimide using mechanochemistry and in liquid state is described. This reaction was carried out in solid state using a modified vibratory ball-mill with temperature control and in solution with toluene as solvent. The effect of temperature, ball mass, material, additives, and aging reaction were studied. We reported for the first time the kinetics of a mechanochemical reaction depending on the ratio ball mass/mass of the reagent. A new kinetic model has been established that corresponds well to our experimental data and allows an estimation of the global activation energy. In solution, the retro Diels–Alder reaction was observed. The reaction was second order for the formation of endo and exo and first order for the retro Diels–Alder reaction. The grinding method shows many advantages compared to solution: shorter reaction time, total reaction, and better selectivity.

Mechanochemical Aza-Vinylogous Povarov Reactions for the Synthesis of Highly Functionalized 1,2,3,4-Tetrahydroquinolines and 1,2,3,4-Tetrahydro-1,5-Naphthyridines.

The aza-vinylogous Povarov reaction between aromatic amines, α-ketoaldehydes or α-formylesters and α,β-unsaturated dimethylhydrazones was carried out in a sequential three-component fashion under mechanochemical conditions. Following extensive optimization work, the reaction was performed on a vibratory ball mill operating at 20 Hz and using zirconium oxide balls and milling jar, and afforded 1,2,3,4-tetrahydroquinolines and 1,2,3,4-tetrahydro- 1,5-naphthyridines functionalized at C-2, C-4 and also at C-6, in the latter case. This protocol generally afforded the target compounds in good to excellent yields and diastereoselectivities. A comparison of representative examples with the results obtained under conventional conditions revealed that the mechanochemical protocol affords faster Povarov reactions in comparable yields using a solvent-less environment.

Effective removal of arsenate from wastewater using aluminium enriched ferric oxide-hydroxide recovered from authentic acid mine drainage

This study explored an eco-friendly approach for the synthesis of novel aluminium enriched ferric oxide-hydroxide (Fe/AlO(OH)) from authentic acid mine drainage (AMD). The synthesized Fe/AlO(OH) was subsequently tested for arsenate removal capabilities. Fe/AlO(OH) was synthesized from bona fide AMD via selective precipitation, thermal activation, and vibratory ball milling. One-factor-at-a-time (OFAAT) method was used to optimize operational parameters, which include adsorbent dosage, concentration, pH, agitation time, and temperature. Optimized conditions were observed to be 150 ppm of As(V), Solid: Liquid ratio – 1 g: 250 mL, contact time of 60 min, and ambient temperature and pH. Limited temperature and pH effects on adsorption were observed. Equilibrium data fits using Langmuir-, Freundlich-, Two surface Langmuir-, Dubinin-Radushkevich-, and Dubinin-Astokov isotherm models showed highly favorable adsorption conditions, the highest known maximum adsorption capacity for As(V) of 102–129 mg g−1, and coupled physisorption/diffusion limited adsorption. Thermodynamic analysis showed positive Gibbs free energy (ΔG°), negative enthalpy change (ΔH°), and positive entropy change (ΔS°) – likely a result of an inner sphere complexation of the As(V) with the Fe/Al surface. Considering the obtained results, valorization of AMD for the synthesis of Fe/AlO(OH) was viable and effective. This initiative could potentially minimize the footprints of AMD and arsenic pollution.

Characterization and leaching of mechanically activated zinc residue

Zinc extraction from zinc-containing residual (ZCR) was examined with the leach of sulfuric acid of original materials and the materials milled in two different mill systems. For this purpose, vibrating ball mill (VBM) and ring mill (RM) were used. In chemical analysis of ZCR, it was determined that it contains a significant amount of zinc, lead, iron and silver and consisted of mostly CaSO4.2H2O, PbO, SiO2, Fe2O3, ZnFe2O4, Al2FeO4 and PbSO4 mineral phases. It was determined in XRD analysis of samples milled at both mills that peak intensity dramatically decreased when compared to original sample.According to comparative characterization analyses of the milled samples, it was determined that through the increasing grinding time, the particles became agglomerated and an increase in grain size occurred. This situation was also supported by N2-BET and SEM analyses.While zinc extraction value of the sample milled for 1 min, which was obtained at 0.5 M H2SO4 at leach temperature of 25 °C, at the solid–liquid rate of 100:1 and during the leach time of 30 min, was 90% and 60% for, respectively, VBM and RM, zinc of 54% was determined to be extracted in the leach of the original sample, under the same conditions.

Solid-phase synthesis of platinum group metal β-diketonates

The mechanical activation (vibration ball milling) of solid starting reactants (mixtures of platinum group metal chlorides with sodium or potassium β-diketonates) followed by heating results in the formation of the corresponding platinum group metal β-diketonates. Simple (PdCl2, PtCl2), complex (K2PtCl6), and hydrated metal chlorides (RuCl3·xH2O, RhCl3·xH2O) can be used in the reaction. The considered method is quite general and enables to obtain various platinum group metal β-diketonates with a conversion of up to ~ 85% directly from their chlorides by using the same process, varying only the duration of milling, milled mixture heating temperature and the product isolation method (sublimation or extraction).