Mechanochemical Treatment Research Articles

In Situ Mechanochemical Treatment of the Fe–Si–PGMs Alloy for Enhanced Platinum Group Metal Recovery: Overcoming Thermodynamic and Kinetic Barriers

In Situ Mechanochemical Treatment of the Fe–Si–PGMs Alloy for Enhanced Platinum Group Metal Recovery: Overcoming Thermodynamic and Kinetic Barriers

Ciprofloxacin (CIP)-polluted water treatment via a facile mechanochemical route: Influencing factors and mechanism insights

Degrading ciprofloxacin (CIP)-polluted water has recently emerged as an urgent environmental issue. This study introduced mechanochemical treatment (MCT) as an innovative and underexplored approach for the degradation of CIP in water. The influence of various additives (CaO, Fe2O3, SiO2, Al, and Fe) on CIP degradation efficiency was investigated. Additionally, six types of composite additives (Fe–CaO, Fe–Fe2O3, Fe–SiO2, Fe–Al, Al–SiO2, and Al–CaO) were explored, with the composite of 20% Fe and 80% SiO2 exhibiting notable performance. The impacts of additive content, pH value, and co-existing ions on CIP degradation efficiency were investigated. Furthermore, the effectiveness of MCT in degrading other medical pollutants (norfloxacin, ofloxacin, and enrofloxacin) was verified. The transformations and changes in the crystal structure, oxidation state, microstructure, and morphology of the Fe–SiO2 composite additive were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques. This study proposed a sigmoid trend kinetic model (the Delogu model) that better elucidates the MCT process. Three plausible degradation pathways were discussed based on intermediate substance identification and pertinent literature. This study not only establishes a pathway for the facile degradation of CIP pollutants through MCT but also contributes to advancements in wastewater treatment methodologies.

Effect of lignin in cellulose nanofibers on biodegradation and seed germination

AbstractPure cellulose nanofibers (CNFs) rapidly degrade in soil, limiting their prospective applications in agriculture. We incorporated lignin into CNFs as an antimicrobial and crosslinking agent to control the biodegradation rate. CNFs with different lignin concentrations were prepared by mechanochemical treatment in the presence of choline chloride-urea deep eutectic solvent. These were characterized using conductometric titration, scanning electron microscopy, and FT-IR. The fibers were applied to soil to determine the effect of lignin on soil respiration and nanocellulose degradation, and were used as a substrate for radish and cress seed germination. Modifying the lignin content of the fibers successfully modulated the biodegradation rate in soil. Fibers containing 35% lignin degraded 5.7% in 14 days, while fibers with 20% lignin degraded 20.8% in 14 days. Nanofiber suspensions showed low chemical inhibition for the germination of radish and cress seeds but higher lignin contents reduced the imbibition rate as a seed coating. This study presents the first use of lignin to control the biodegradation rate of cellulose nanofibers in a one-pot, scalable and sustainable system, allowing the advancement of lignocellulose nanofibers for applications such as seed coatings, mulches, and controlled release fertilizers. Graphical Abstract

Use of Mechanochemical Methodology to Explore the Formation of a New Crystalline Phase in the Curcumin‐Quercetin System

AbstractThis study addressed the formation of co‐crystals from Quercetin and Curcumin by mechanochemical treatment employing ball mill grinding. The binary system was initially studied using molecular complementarity and hydrogen bond propensity analysis structural tools available in Mercury software. This study was performed from CCDC reported structural data for Curcumin and Quercetin dihydrate used as starting reagents. Reaction conditions, such as Quercetin: Curcumin molar ratio, grinding time, and solvent‐assisted variables, were optimised to synthesise a new solid phase from the binary system. The synthesised product was characterised by differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and powder X‐ray diffraction techniques. Finally, to compare the anti‐oxidant capacities from the pure components, eutectic mixtures previously reported and the new crystalline phase was evaluated in vitro using the 1,1‐diphenyl‐2‐pycril‐hydrazylhydrate radical inhibition method. The co‐crystal phase and eutectic mixtures present higher anti‐oxidant activity with values around 5.0 mg/L compared to pure Quercetin (3,444 mg/L) and Curcumin (9,141 mg/L), using only half of the molecules. These results indicate Quercetin molecule is synergically active with the Curcumin molecule in the binary mixtures.

Room temperature Mössbauer characterization of ferrite with spinel structure

Cobalt ferrite (CoFe2O4) nanoparticle were obtained by different synthesis methods: coprecipitation (CO), ultrasonically assisted coprecipitation (US-CO), coprecipitation followed by mechanochemical treatment (MC-CO), microemulsion (ME) and microwave assisted hydrothermal synthesis (MW-HT). The structure and cation distribution are investigated by XRD diffraction analysis and Raman spectroscopy. The parameters such as chemical shift, quadruple splitting and hyperfine field and site occupancy of Fe3+ were determined by M?ssbauer spectroscopy. The 57Fe-M?ssbauer spectr? of the CoFe2O4 ? w?r? measured at room temperature in ? 12 mm s-1 Doppler velocity range. The 57Fe-M?ssbauer spectr? of the CoFe2O4 samples w?r? fitted with the extended Voigt-based fitting method.

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.

Green mechanochemical Li foil surface reconstruction toward long-life Li–metal pouch cells

A green mechanochemical surface treatment strategy endows practical Li metal pouch cells with excellent electrochemical performance, achieving high energy density, stable cycle performance and high security.

The role of mechanochemical treatment of carbon nanotubes in promoting glycerol etherification

Carbon nanotubes (CNTs) were functionalized and compared, for the first time applying various mechanochemical methods to endow their surfaces with strongly acidic features. The as-prepared samples were used as catalysts in glycerol etherification.

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.

Polymorphism in S(+)Clopidogrel-Picrate: Insights from X-ray Diffraction, Vibrational Spectroscopy, Thermal Analysis, and Quantum Chemistry

The crystal structures of two pseudopolymorphic forms of S(+)clopidogrel–picrate are reported. Form 1 crystallizes in the monoclinic space group P21 with an ionic couple S(+)ClopH+·Pic− and a molecule of solvent ethanol in the asymmetric unit, while Form 2 crystallizes in the monoclinic space group C2 with two ionic couples in the asymmetric unit. The configurations and conformations of the ionic couples, held together by ionized +N-H···O hydrogen bonds, are nearly identical in the structures. The self-assembly properties are compared with reported clopidogrel salts, including those used in pharmaceutical formulations. The hydrogen bonds are discussed in reference to the general corresponding behavior of the N-bases picrates and the properties of the acid-base coformers. The preparations of the pseudopolymorphs were optimized toward two different methods: solvent evaporation and mechanochemical treatment. Reproducibility to generate the single crystalline phases was confirmed by thermal and vibrational spectroscopic properties. Periodic third-order density-functional tight binding (DFTB3) calculations predict rather small energy difference between the two pure phases of polymorphs 1 and 2. However, the included solvent molecules in Form 1 decrease the lattice energy for ~10.5 kcal mol−1, which leads to a lower ΔElatt. lattice energy in comparison to Form 2 (by ~7.3 kcal mol−1). All predicted trends are in line with the experimentally observed formation of Form 1 instead of its simulated non-solvated Form 1.

TECHNOLOGICAL ASPECTS OF OBTAINING OF FOOD ADDITIVE FROM BUCKWHEAT HUSK

The paper shows technological aspects of obtaining of biologically active food additive from buckwheat hull. Husk is the main secondary raw material resource emerged during buckwheat processing. Its yield varies from 20 to 22%. Despite several studies, it is not used in subsequent processing for food and other purposes. At the same time, buckwheat husk is a source of polyphenolic compounds, which are presented by flavonoids (2.2 mg/g), and dietary fibers (45.6%). As a result of the experimental studies, it was found that it is advisable to process buckwheat husk into powder using mechanochemical treatment. The parameters of processing were determined during research. It is also advisable to add sodium bicarbonate in the amount of 5% from the powder during mechanochemical treatment. This amount allows to achieve maximum yield of melanin pigment (14.3%) and maximum improvement in the antioxidant activity of the finished product (3.5 times). It has been established that mechanochemical treatment of buckwheat husk coarse powder changes the availability of its ingredients. Mass fraction of soluble substances increases in 2.2 times. The yield of biologically active substances also increases in 3.6 times for flavonoids and in 1.9 times for melanin. This is what determines the increase of nutritional value of finished product. The obtained fine powder is recommended to be used as an additive in producing of new types of food products, including public catering production.

Magnesium Hydrogen-generating Materials and a Hydrogen Generation Setup

The reaction of composites consisting of MgH2 and a graphene-like or nickel–graphene material with water or citric acid solutions of various concentrations was studied. The composites were prepared by mechanochemical treatment in a hydrogen atmosphere. The reaction of an aqueous citric acid solution with the composites is fast: 98% hydrogen yield is reached at the MgH2 : citric acid molar ratio of 1 : 1. A setup for preparing compressed hydrogen from the composites was developed. It can be used in autonomous mobile installations for hydrogen generation under high pressure, followed by filling balloons.

Mechanochemical Degradation of Biopolymers.

Mechanochemical treatment of various organic molecules is an emerging technology of green processes in biofuel, fine chemicals, or food production. Many biopolymers are involved in isolating, derivating, or modifying molecules of natural origin. Mechanochemistry provides a powerful tool to achieve these goals, but the unintentional modification of biopolymers by mechanochemical manipulation is not always obvious or even detectable. Although modeling molecular changes caused by mechanical stresses in cavitation and grinding processes is feasible in small model compounds, simulation of extrusion processes primarily relies on phenomenological approaches that allow only tool- and material-specific conclusions. The development of analytical and computational techniques allows for the inline and real-time control of parameters in various mechanochemical processes. Using artificial intelligence to analyze process parameters and product characteristics can significantly improve production optimization. We aim to review the processes and consequences of possible chemical, physicochemical, and structural changes.

Enhanced Degradation of Decabromodiphenyl Ether via Synergetic Assisted Mechanochemical Process with Lithium Cobalt Oxide and Iron

The removal of decabromodiphenyl ether (BDE 209), as a typical persistent organic pollutant (POP), is of worldwide concern. Mechanochemical (MC) processes are promising methods to degrade environmental pollutants, most of which use a single grinding reagent. The performance of MC processes with co-milling agents still needs to be further verified. In this study, an efficient MC treatment with combined utilization of lithium cobalt oxide (LiCoO2) and iron (Fe) as co-milling reagents for BDE 209 degradation was investigated. The synchronous action of LiCoO2 and Fe with a LiCoO2/Fe/Br molar ratio of 1.5:1.67:1 and a ball-to-powder ratio of 100:1 led to almost thorough-paced abatement and debromination of BDE 209 within 180 min using a ball milling rotation speed of 600 rpm. The reduction in particle sizes and the destruction of crystal structure in mixture powders with the increase in milling time induced the enhanced degradation of BDE 209, as characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The X-ray photoelectron spectroscopy (XPS) characterization showed that the valence state of Co was converted from Co(III) to Co(II), and Fe(0) was changed to Fe(III) when treated with an MC process. This indicated that the reductive debromination of BDE 209 by Fe and the following oxidative degradation of debrominated products by LiCoO2 were integrated in a concerted way. It proved the removal of BDE 209 via an MC treatment. The full breakage of C-Br and C-O bonds in BDE 209 was confirmed by Fourier transform-infrared spectrometry (FT-IR) spectra, and a possible abatement pathway was also proposed based on the identified intermediate products using gas chromatography–mass spectrometry (GC-MS). These obtained results indicated that a combination of LiCoO2 and Fe as co-milling reagents is promising in the MC treatment of toxic halogenated pollutants like BDE 209.

ОСОБЕННОСТИ УПЛОТНЯЕМОСТИ И КОНСОЛИДАЦИИ ЗАГОТОВОК ИЗ МЕХАНОСИНТЕЗИРОВАННОГО ПОРОШКА МОЛИБДАТА ДИСПРОЗИЯ

Dysprosium molybdate powder was prepared by the mechanochemical method from a stoichiometric mixture of molybdenum oxide and dysprosium oxide. The XRF, TEM and SEM methods showed that during mechanochemical treatment for 30 minutes, due to mechanochemical reactions between the initial powders, a fine powder of the Dy2MoO6 compound containing up to 8% Dy2(MoO4)3 was formed. The technological properties (fluidity, compactibility) of the mechanosynthesized dysprosium molybdenum powder, as well as its microstructure after sintering, have been investigated.

The Effect of High-Energy Ball Milling of Montmorillonite for Adsorptive Removal of Cesium, Strontium, and Uranium Ions from Aqueous Solution

Clay minerals are widely used to treat groundwater and surface water containing radionuclides. In our study, the method of mechanochemical activation for increasing the sorption capacity of the natural clay mineral montmorillonite was used. By adjusting the grinding time, the increasing sorption parameters of mechanochemically activated montmorillonite were determined. X-ray diffraction method, scanning electron microscopy, and the determination of the specific surface by low-temperature adsorption–desorption of nitrogen to characterize the natural and mechanochemical-activated montmorillonites were used. It was established that the maximal sorption of uranium, strontium, and cesium is found for montmorillonite after mechanochemical treatment for 2 h. It is shown that the filling of the surface of montmorillonite with ions of different natures occurs in various ways during different times of mechanochemical treatment. The appropriateness of the Langmuir and Freundlich models for the sorption parameters of uranium, strontium, and cesium ions on montmorillonite after its mechanochemical activation was established. The effect of natural organic substances—humic acids—on the efficiency of water purification from uranium on mechanoactivated montmorillonite was studied. The obtained sorbents can be effectively used for the removal of trace amounts of radionuclides of different chemical natures (uranium, cesium, and strontium) from polluted surface and ground waters.

Single-step Synthesis of Highly Porous Nitrogen-doped Carbon by Solid–gas Mechanochemical Treatment as an Oxygen Reduction Electrocatalyst

Single-step Synthesis of Highly Porous Nitrogen-doped Carbon by Solid–gas Mechanochemical Treatment as an Oxygen Reduction Electrocatalyst

Influence of multi-stage processing and mechano-chemical treatments on the hydration and microstructure properties of recycled aggregate concrete

On account of the shortage of naturally occurring coarse aggregate, recycled aggregate (RA) made from crushed concrete debris is now used in the construction industry. With this rise in the utilisation of recycled aggregate in the construction sector, there has been extensive research into ways to improve its quality. The significant fraction of mortar remains that are left on the RA surface is the primary factor that affects its quality. Concrete made from RA loses strength and mechanical performance due to the attached mortar's increased porosity and water absorption values and the frailer transition region between the new mortar and aggregates. In order to minimise the old cement fractions and increase the quality, this paper studies the effect of concrete incorporating multi-stage processed RA from demolished concrete waste, followed by treatment with mechanical abrasion and sodium silicate immersion. The recycled aggregates were produced through multi-stage jaw crushing, followed by utilising natural aggregate, recycled aggregate, and recycled aggregate obtained after mechanical abrasion, followed by sodium silicate treatment for concrete mix design at various substitution percentages as coarse aggregates. The experimental investigation further progresses with the evaluation of mechanical and durability properties of concrete mixes, which is additionally followed by microstructural studies such as scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Thermogravimetry-differential thermal analysis (TG-DTA). The outcomes demonstrate that two-stage treatment, such as mechanical abrasion followed by sodium silicate immersion, yields superior-quality RA. Recycled aggregate concrete (RAC) made with these treated aggregates illustrated an increase in workability and density with respect to an untreated RAC mix. Furthermore, comparable strengths in compression, flexure, and tension are found in treated RAC mixes, particularly at 35% replacement levels, with respect to concrete mixes comprised of natural aggregates. A similar trend is detected in the chloride penetration tests and water sorptivity tests. In addition, the microstructural investigation confirmed the formation of additional calcium silicate hydrate for treated RAC mixes, particularly for the 35% substituted RA mix. On the basis of the results, it is suggested that multi-stage jaw crushing followed by treatment through mechanical abrasion and sodium silicate can potentially enhance the mechanical, microstructural, and durability performance of RAC.

Solid-Phase Reactions of Humic Acids with Sodium Percarbonate as a Way to Study Processes Occurring on the Mechanochemical Oxidation of Brown Coal

The reactions of humic acids in a pure form and in the composition of coal with sodium percarbonate occurring on solid-phase mechanochemical treatment were compared. Analysis for CHNO, IR spectroscopy, and potentiometric titration were used to study changes in the composition of humic acids mechanochemicallytreated after isolation from brown coal. The sorption properties in relation to heavy metal ions (Zn2+, Cu2+, and Cd2+) and their changes as a result of the treatment were studied. The results were correlated with data similar to those for humic acids in coal that underwent mechanochemical treatment. It was demonstrated that, at present, an increase in the yield of humic acids and the concentrations of phenolic and carboxyl groups in brown coal as a result of treatment with sodium percarbonate can be explained by the oxidation of fractions other than humic acids in the organic matter of brown coal.

Highly porous carbons prepared via water-assisted mechanochemical treatment of cellulose-based materials followed by carbonization and mild activation

A facile and eco-friendly mechanochemical treatment of cellulose-based materials, followed by carbonization and mild activation, was employed to obtain highly porous carbons. Potassium citrate (C6H5K3O7) was used as a mild chemical activator and an endotemplate. To prevent any potential alteration of the pore characteristics of the resulting carbons, a simple washing with DI water was performed. As a result, the chemically activated carbon with a large volume of ultramicropores (0.37 cm3/g) showed a high CO2 adsorption capacity of 4.2 mmol/g at 25 °C and a pressure of 1 bar. This paper presents a mechanochemical processing of cellulose-based materials, which can be utilized for advancing the preparation of carbon materials with high surface areas and enhanced porosity.