Mechanochemical Treatment Research Articles

Highly sustainable polyphenylene sulfide membrane of tailored porous architecture for high-performance lithium-ion battery applications

Mechanically robust and chemically stable polyphenylene sulfide (PPS) membrane of efficient porous architecture as well as high porosity has been prepared from a PPS/SiO2 composite including homogeneous distribution of SiO2 nanoparticles, and its applicability as a separator in lithium-ion battery (LIB) was extensively examined in terms of sustainability of electrochemical behaviors. To improve distribution of SiO2 nanoparticles for the incompatible PPS/SiO2 mixture, prerequisite for the efficient porous architecture, interface modulation by plasma-assisted mechanochemical (MP) treatment has been performed, and the MP-treated PPS/SiO2 composite exhibited perfectly homogeneous distribution of SiO2 nanoparticles, finally resulting in porous PPS membrane including a large number of pores with nearly monodisperse pore diameter after removal of SiO2 phase. Alongside the well-developed porous architecture, the porous PPS membrane also deployed notably improved wetting to electrolyte imparted by the MP-based interface modulation, which gave rise to the complete suppression of disastrous build-up and intrusion of lithium dendrite on a separator as well as the electrochemical performances superior to those of the existing PP separator such as the highly sustainable cyclic charging/discharging behavior. Furthermore, it was notable that the PPS membrane exhibited outstanding mechanical stability especially at high temperature even after a large number of pores were developed inside, which has been generic from the nature of PPS. Conclusively, it could be stated that the porous PPS separator is a promising candidate fulfilling the performance requirements for the high-performance LIB.

Mechanochemical stabilization of heavy metals in fly ash from coal-fired power plants via dry milling and wet milling.

Fly ash from coal-fired power plants has become the world's largest solid waste pollutant. The mechanochemical (MC) method used as a non-thermal method shows good stability to heavy metals in soil and municipal solid waste incineration (MSWI) fly ash. It is first uesd to stabilize the heavy metals in fly ash from coal-fired power plants. In this paper, dry milling and wet milling MC methods were carried out on fly ash from a 300MW supercritical circulating fluidized bed (CFB) boiler. The relative leaching rate (RLR) is defined to indicate the degree of leaching. Experimental results show that after mechanochemical treatment for 10h, the RLRs of Cu, Cr, Pb, Zn, Cd, and Ni by dry milling decrease by 52.10%, 70.16%, 89.80%, 22.97%, 3.15%, and 23.49% respectively, and the RLRs of Cu, Cr, Pb, Zn, Cd and Ni by wet milling decrease by 58.11%, 70.92%, 89.64%, 23.26%, 10.59%, and 30.77% respectively. Compared with dry milling, the fly ash particle size is smaller after wet milling, indicating that the presence of water will weaken the agglomeration of fine particles. A continuous extraction experiment shows that the water-and acid-soluble fraction of the six heavy metals in fly ash can be reduced by dry or wet milling, and the residual fraction can be increased.

Mechanochemical degradation of hexachlorobenzene with a combined additive of SiC and Fe

Mechanochemical treatment (MTC) with SiC as an additive possessed a good performance on the degradation of hexachlorobenzene (HCB). However, this method consumed the additive of SiC and generated a toxic product of CCl4. This work attempted to add another additive, iron powder, to the MCT and explored the performance of the combined additive of SiC + Fe to solve this problem. Result indicated that CCl4 was not produced and SiC was not consumed when Fe was added in proper proportion. Compared with the single additive of SiC, the addition of Fe can further accelerate the degradation of HCB. The reaction pathway was proposed as: HCB can be mostly dechlorinated after a duration of MCT, and only trace-level low chlorobenzenes were generated under the effect of the combined additive. The left benzene skeletons can be broken to produce graphite and amorphous carbon. The shedding Cl radicals preferentially reacted with Fe to form FeCl3, and the reaction between Cl radicals and SiC and its toxic products can be avoided. Free electrons generated from the additive of SiC, fast reaction between Cl and Fe, and sparks in the MCT were considered the potential factors to accelerate the HCB degradation in MCT.

Mechanochemically Prepared Co3O4-CeO2 Catalysts for Complete Benzene Oxidation

Considerable efforts to reduce the harmful emissions of volatile organic compounds (VOCs) have been directed towards the development of highly active and economically viable catalytic materials for complete hydrocarbon oxidation. The present study is focused on the complete benzene oxidation as a probe reaction for VOCs abatement over Co3O4-CeO2 mixed oxides (20, 30, and 40 wt.% of ceria) synthesized by the more sustainable, in terms of less waste, less energy and less hazard, mechanochemical mixing of cerium hydroxide and cobalt hydroxycarbonate precursors. The catalysts were characterized by BET, powder XRD, H2-TPR, UV resonance Raman spectroscopy, and XPS techniques. The mixed oxides exhibited superior catalytic activity in comparison with Co3O4, thus, confirming the promotional role of ceria. The close interaction between Co3O4 and CeO2 phases, induced by mechanochemical treatment, led to strained Co3O4 and CeO2 surface structures. The most significant surface defectiveness was attained for 70 wt.% Co3O4-30 wt.% CeO2. A trend of the highest surface amount of Co3+, Ce3+ and adsorbed oxygen species was evidenced for the sample with this optimal composition. The catalyst exhibited the best performance and 100% benzene conversion was reached at 200 °C (relatively low temperature for noble metal-free oxide catalysts). The catalytic activity at 200 °C was stable without any products of incomplete benzene oxidation. The results showed promising catalytic properties for effective VOCs elimination over low-cost Co3O4-CeO2 mixed oxides synthesized by simple and eco-friendly mechanochemical mixing.

Disposable hydrogen generators: Magnesium hydride oxidation in aqueous salts solutions

The impact of mechanochemical activation and methods of addition of non-hydrolyzing salts of NaCl, NH4Cl, NH4Br и MgCl2∙(either dry powder or solution) on the reaction rate and yield of hydrogen production upon magnesium hydride oxidation by water was investigated. It was established that addition of halides increases the hydrogen yield from 22% to 99% (of theoretical value) while the rate of hydrogen production has increased from ∼220 to 1700 mL/min g (MgH2). The addition of dry salts during the mechanochemical treatment of the hydride always results in much higher reaction rate compared to the use of the same salt solutions. It was observed that activation by NH4Cl and MgCl2 results in bell-shaped change in the hydrogen release rate. Of all evaluated halide salt activators, the greatest overall yield (∼99%) was achieved in the presence of 0.17 M NaCl solution. The reaction rate at these conditions was rather slow; it took up to 4 h to complete the oxidation. The highest rate of oxidation, when 94% of theoretical yield was achieved in 3 min, was observed in the presence of 0.85 M NH4Br.

Influence of hydrothermal, microwave and mechanochemical treatment of tin phosphate on porous structure and catalytic properties

Influence of hydrothermal, microwave and mechanochemical treatment of tin phosphate on porous structure and catalytic properties

Changes of porosity of hard carbons during mechanical treatment and the relevance for sodium-ion anodes

Lithium-ion batteries have revolutionized battery technology. However, the scarcity of lithium in nature is driving the search for alternatives. For that reason, sodium-ion batteries have attracted increasing attention in recent years. The main obstacle to their development is the anode as, unlike for lithium-ion batteries, graphite cannot be used due to the inability to form stoichiometrically useful intercalation compounds with sodium. A promising candidate for sodium storage is hard carbon - a form of nongraphitisable carbon, that can be synthesized from various precursor materials. Processing of hard carbons is often done by using mechanochemical treatments. Although it is generally accepted and often observed that they can influence the porosity of hard carbons, their effect on battery performance not well understood. Here, the changes in porosity occurring during ball milling are elucidated and related to the properties of hard carbons in sodium storage. Analysis by combined gas physisorption and small-angle X-ray scattering shows that porosity changes during ball milling with a significant increase of the open porosity, unsuitable for reversible sodium storage, and decrease of the closed porosity, suitable for reversible sodium storage. While pristine hard carbon can store 58.5 mAh g−1 in the closed pores, upon 5 h of mechanical treatment in a ball mill it can only store 35.5 mAh g−1. The obtained results are furthermore pointing towards the disputed “intercalation-adsorption” mechanism.

Remediation of petroleum-contaminated soil by ball milling and reuse as heavy metal adsorbent

A simple mechanochemical (MC) method is used to treat petroleum-contaminated soil and prepare a heavy metal adsorbent in one step. XRD, Raman, FT-IR, VSM, BET, and XPS were used to characterize the adsorbent. After MC treatment, the dissolved total petroleum hydrocarbons of the adsorbent is less than 1 mg·L−1, and a porous structure and carbonization phenomenon are evident. The specific surface area and cumulative void volume increase, and the adsorption pore size decreases. On the surface of soil, the percentages of iron oxides, carbonates, CO, -C-O-H, -COOH, and π unsaturated bonds increase. The Langmuir model shows that the maximum adsorption capacity of Pb2+, Cu2+, Cd2+, and Zn2+ are 338.58, 51.61, 32.34, and 25.05 mg·g−1, respectively. The pseudo-second-order kinetic model fits the Pb adsorption process, indicating the domination of chemical adsorption. GC-MS shows that petroleum hydrocarbons are completely degraded. The Tessier continuous extraction result shows that heavy metals are bound to carbonate, iron manganese oxide, and organic matter. The MC treatment achieves deep cleanup and resource utilization of petroleum-contaminated soil through the formation of amorphous carbon, carbonates, and iron oxides on the surface of soil particles. The material is magnetic and can be recycled when used in wastewater treatment.

M(II)Al4 Type Layered Double Hydroxides-Preparation Using Mechanochemical Route, Structural Characterization and Catalytic Application.

The synthesis of the copper-poor and aluminum-rich layered double hydroxides (LDHs) of the CuAl4 type was optimized in detail in this work, by applying an intense mechanochemical treatment to activate the gibbsite starting reagent. The phase-pure forms of these LDHs were prepared for the first time; using copper nitrate and perchlorate salts during the syntheses turned out to be the key to avoiding the formation of copper hydroxide sideproducts. Based on the use of the optimized syntheses parameters, the preparation of layered triple and multiple hydroxides was also attempted using Ni(II), Co(II), Zn(II) and even Mg(II) ions. These studies let us identify the relative positions of the incorporating cations in the well-known selectivity series as Ni2+ >> Cu2+ >> Zn2+ > Co2+ >> Mg2+. The solids formed were characterized by using powder X-ray diffractometry, UV–Vis diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. The catalytic potential of the samples was investigated in carbon monoxide oxidation reactions at atmospheric pressure, supported by an in situ diffuse reflectance infrared spectroscopy probe. All solids proved to be active and the combination of the nickel and cobalt incorporation (which resulted in a NiCoAl8 layered triple hydroxide) brought outstanding benefits regarding low-temperature oxidation and increased carbon monoxide conversion values.

Valorization and Mechanical Recycling of Heterogeneous Post-Consumer Polymer Waste through a Mechano-Chemical Process.

In this paper, a sustainable strategy to valorize and recycle heterogeneous polymer-based post-consumer waste is proposed. This strategy is based on a high-energy mechano-chemical treatment and has been applied to a polyolefin-rich fraction, coded as FIL/S, deriving from household plastic waste collection. This processing, performed in a planetary ball mill, allowed us to obtain fine grinding and, consequently, to induce an intimate mixing of the different polymer fractions and contaminants composing the FIL/S, as demonstrated by SEM analysis. As a result, an improvement in the deformability of the treated material was obtained, recording values for elongation at the break which were two and half times higher than the neat FIL/S. Finally, the addition of small amounts of organic peroxide during mechano-chemical treatment was tested, determining a more homogeneous morphology and a further improvement in mechanical parameters.

Simultaneous Methylene Blue Adsorption and pH Neutralization of Contaminated Water by Rice Husk Ash.

In this study, the potential of rice husk ash (RHA) to act as an adsorbent for treating dye-containing wastewater was demonstrated. The RHA used in this study contained 91.7% silica, which was composed of crystalline (cristobalite and tridymite) and amorphous phases. The mechanochemical treatment of RHA led to an increase in its specific surface area from 6.2 to 14.6 m2/g in 15 min and dramatically improved its methylene blue (MB) adsorption ability. Langmuir adsorption isotherms revealed that the maximum adsorption capacity of the treated RHA was 8.59 mg/g, which is 2.45 times higher than that of raw RHA. pH-dependent adsorption studies on the RHA revealed that MB was adsorbed on the deprotonated Q3 silanol through electrostatic interactions. Moreover, the RHA adsorbent showed pH buffering at a pH value of approximately 7; thus, the pH of the solution could be neutralized simultaneously with the adsorptive removal of MB.

Novel Method for Fabricating Visible-Light Phototransistors Based on a Homojunction-Porous IGZO Thin Film Using Mechano-Chemical Treatment.

A homojunction-structured oxide phototransistor based on a mechano-chemically treated indium-gallium-zinc oxide (IGZO) absorption layer is reported. Through this novel and facile mechano-chemical treatment, mechanical removal of the cellophane adhesive tape induces reactive radicals and organic compounds on the sputtered IGZO film surface. Surface modification, following the mechano-chemical treatment, caused porous sites in the solution-processed IGZO film, which can give rise to a homojunction-porous IGZO (HPI) layer and generate sub-gap states from oxygen-related defects. These intentionally generated sub-gap states played a key role in photoelectron generation under illumination with relatively long-wavelength visible light despite the wide band gap of IGZO (>3.0 eV). Compared with conventional IGZO phototransistors, our HPI phototransistor displayed outstanding optoelectronic characteristics and sensitivity; we measured a threshold voltage (Vth) shift from 3.64 to -6.27 V and an on/off current ratio shift from 4.21 × 1010 to 4.92 × 102 under illumination with a 532 nm green light of 10 mW/mm2 intensity and calculated a photosensitivity of 1.16 × 108. The remarkable optoelectronic characteristics and high optical transparency suggest optical sensor applications.

Enhanced strength and microstructure of dredged clay sediment-fly ash geopolymer by mechanochemical activation

A low reactivity dredged high plasticity clay rich in quartz and alumina was obtained from an intercoastal waterway in southeast Texas and mechanochemically treated with fly ash and sodium silicate and used to manufacture a geopolymer mortar. The treated dredged clay and fly ash precursor was activated with a liquid sodium hydroxide solution. Ten different mixes were considered to study the effects of mechanochemical treatment, mixing procedure, and fly ash replacement dosage. The compressive strength, the reactivity during thermal curing, degree of polymerization, and microstructure and morphology were investigated using isothermal calorimetry, Fourier-transform infrared spectroscopy, nano-indentation, and optical and scanning electron microscopy. Co-grinding fly ash, sodium silicate, and dredge clay enhances the bulk reactivity and dispersion of the blended precursor which enhances the connectivity of the geopolymer, intensifies the polymerized structure, increases compressive strength, and lowers the matrix pore size surface area despite increased water demand and some physical interferences from the dredge clay sediment. The efficacy of the mechanochemical treatment will largely depend on the quantity and reactivity of the fly ash present in the geopolymer. The inert dredge high plasticity clay sediment serves as an effective filling agent in geopolymer systems up to 50% replacement. However, the mechanochemical treatment of a blended fly ash-dredge clay system is most effective in increasing compressive strength (by ~ 30 MPa) when the inert dredge clay sediment is less than or equal to 25% of the total precursor mass.

Oxygen Reduction/Evolution Activity of a Mechanochemically Synthesized Multilayer Graphene

Multilayer graphenes were synthesized by a mechanochemical treatment of commercial graphite powder and studied as an air electrode for metal-air batteries. The mechanochemical treatment of the commercial graphite powder was performed for 2h using a planetary ball mill apparatus with large stainless steel balls (10 mm diameter) that did not require the aid of solvents. As a result, multilayer graphenes were successfully obtained when the rotational speed of the planetary ball mill was 500 rpm or more. Raman spectroscopy revealed that the resulting multilayer graphenes contains many defects, while electrochemical measurements revealed that this multilayer graphene has high stability against anodic corrosion. Moreover, a higher bifunctional ORR/OER activity was observed for this material than other bifunctional ORR/OER materials, such as LaNiO3 and multilayer graphene synthesized by a modified Hummer’s method. This excellent electrochemical performance implies that the mechanochemically synthesized multilayer graphenes with high stability and high bifunctional ORR/OER activity obtained in this study can be an excellent alternative to carbon black, which is conventionally used for air electrode materials.

Energetic Compositions by Mechanochemical Treatment of Metal Powders: 3. Influence of Activated and Modified Aluminum Particles on Combustion of Thermite SiO2–Al Mixtures

Energetic Compositions by Mechanochemical Treatment of Metal Powders: 3. Influence of Activated and Modified Aluminum Particles on Combustion of Thermite SiO2–Al Mixtures

‘Horror Vacui’ in the Oxygen Sublattice of Lithium Niobate Made Affordable by Cationic Flexibility

The present review is intended for a broader audience interested in the resolution of the several decades-long controversy on the possible role of oxygen-vacancy defects in LiNbO3. Confronting ideas of a selected series of papers from classical experiments to brand new large-scale calculations, a unified interpretation of the defect generation and annealing mechanisms governing processes during thermo- and mechanochemical treatments and irradiations of various types is presented. The dominant role of as-grown and freshly generated Nb antisite defects as traps for small polarons and bipolarons is demonstrated, while mobile lithium vacancies, also acting as hole traps, are shown to provide flexible charge compensation needed for stability. The close relationship between LiNbO3 and the Li battery materials LiNb3O8 and Li3NbO4 is pointed out. The oxygen sublattice of the bulk plays a much more passive role, whereas oxygen loss and Li2O segregation take place in external or internal surface layers of a few nanometers.

Preparation of Sulfur-impregnated Carbonaceous Adsorbent Using Mechanochemical Treatment

Preparation of Sulfur-impregnated Carbonaceous Adsorbent Using Mechanochemical Treatment

PREPARATION OF FLUORIDE ADSORBENT FROM ZIRCON SAND USING MECHANOCHEMICAL TREATMENT, AND ITS APPLICATION FOR FLUORIDE REMOVAL

Removal of low-concentration fluoride in natural water is an important issue all over the world. Japan is a volcanic country with many hot springs, and the removal of low-concentration fluoride from hot spring drainage is desired. In this study, we attempted to prepare a novel adsorbent with high selective removal ability of fluoride from zircon sand using mechanochemical treatment, and applied it for removing fluoride from hot spring water. Mechanochemical treatment of zircon sand was carried out using a planetary ball mill, and fluoride removal of the product was examined using fluoride aqueous solution and hot spring water. The hot spring water is collected from one of the hot spring in Japan, and a typical sulfuric acid hot spring water pH 2 including high contents of SO42-(12000 mg L-1) and Cl- (5000 mg L-1) with 11 - 15 mg L-1 of fluoride ion. Regardless of ball sizes, with increasing the mechanochemical treatment time to 10 min, the removal ability of the product for fluoride increases, and then be almost constant. With decreasing pH of the solution to 2, the adsorption amount increases, and then be almost constant. With increasing the temperature of the solution, the adsorption amount decreases, while the rate of adsorption increases and the amount increases. The adsorption isotherm at pH 2 follows much better Langmuir model than Freundlich model, and the calculated maximum adsorption amount is 0.11 mmol g-1. Fluoride can be adsorbed selectively from hot spring water below Japanese effluent standard for fluoride (8.0 mg L-1).

Histopathological analysis of incompetent great saphenous veins after mechanochemical ablation treatment - An ex-vivo experiment.

The endovascular technique of mechanochemical ablation (MOCA) has become popular in treating patients with saphenous reflux. We reported the histopathological findings in human ex-vivo incompetent great saphenous veins following treatment with saline, polidocanol, mechanical ablation and MOCA using ClariVein device. Twenty-four vein GSV specimens were obtained via traditional surgery and treated with four methods: Group A: 0.9% normal saline (NS); Group B: 3% polidocanol; Group C: mechanical ablation + 0.9% NS; Group D: mechanical ablation + 3% polidocanol (MOCA). Hematoxylin and eosin (HE), Masson's trichrome and immunohistochemical staining were performed on each specimen and integrated optical densities were measured with vWF and a-SMA stains and statistically evaluated. vWF staining was used to assess endothelial damage and a a-SMA staining was used to assess media injury. HE and Masson's trichrome staining of Groups C and D revealed severe damage to the endothelium and media compared to Groups A and B. The statistical result of vWF staining showed the damage of endothelium was significantly increased by Group D compared to Groups A, B and C. The statistical result of a-SMA staining showed the damage of media was significantly increased by Groups C and D compared to Groups A and B. The mechanism of MOCA was caused by both endothelium damage and media tearing. The damage of endothelium was significantly increased by MOCA when compared with mechanical ablation alone.

МЕХАНОХИМИЧЕСКАЯ И УЛЬТРАЗВУКОВАЯ ОБРАБОТКА – УПРАВЛЯЕМЫЙ СПОСОБ ФОРМИРОВАНИЯ СТРУКТУРЫ И СВОЙСТВ НАНОКОМПОЗИЦИОННЫХ ГЕЛЕВЫХ СИСТЕМ

In this work, the preparation of colloidal systems with microcrystalline cellulose as a gelling agent and silica powder as a filler was considered. By mechanochemical and ultrasonic treatment of a filler made of silicon dioxide and a colloidal base, varying the constituent ingredients, one can purposefully influence the structure of the system and regulate the properties of the resulting compositions. It is shown that the introduction of a filler made of highly dispersed silicon dioxide into a gel system based on cellulose, modified by ultrasonic treatment (UST) with acid additives, provides both acceleration of the gelation process and stabilization of the state of the obtained colloidal composition. As a result of UST, a nanostructured colloidal homogeneous system is formed.