A quantitative approach to mechanochemical processes

Delogu, Francesco; Deidda, Claudio; Mulas, G.; Schiffini, L.; Cocco, G.

doi:10.1023/b:jmsc.0000039194.07422.be

Cited by 78 publications

(57 citation statements)

References 1 publication

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“…Relatively simple exponential functions have been previously derived for multi-component mechanochemical reactions, proving to describe a range of mechanochemical systems [48,53,54]. Typically, if only a single process is dominant, a single function can be employed of the form:…”

Section: Mechanical Treatment Of Caffeine Form Ii-30 Hzmentioning

confidence: 99%

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

2018

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ABSTARCTMechanochemical methodologies, particularly ball milling, have become commonplace in many laboratories. In the present work, we examine the effects of milling ball mass on the polymorphic conversion of anhydrous caffeine. By investigating a single-phase system, the rate-limiting step of particle-particle contact formation is eliminated. It is found that larger milling balls lead to considerably faster conversion rates. Modelling of the transformation rate suggests that a single, time-independent rate constant is insufficient to describe the transformation. Instead, a convolution of at least two rate-determining processes is required to correctly describe the transformation. This suggests that the early stages of the transformation are governed only by the number of particle-ball collisions. As the reaction proceeds, these collisions less frequently involve reactant, and the rate becomes limited by mass transport, or mixing, even in originally single-phase systems, which become multi-phase as the product is formed. Larger milling balls are less hindered by poorly mixed material. This likely results from a combination of higher impact energies and higher surface areas associated with the larger milling balls. Such insight is important for the selective and targeted design of mechanochemical processes.

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Section: Mechanical Treatment Of Caffeine Form Ii-30 Hzmentioning

confidence: 99%

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

2018

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“…The occurrence of collisions inside the reactor was monitored using piezoelectric transducers attached to the external reactor surface, according to the experimental methodology described in detail elsewhere [22,[37][38][39]. Here, it is simply worth remembering that the piezoelectric sensor generates an electric signal every time a ball collides with either the lateral wall of the cylindrical reactor, or the bases.…”

Section: Discussionmentioning

confidence: 99%

Mechanically activated metathesis reaction in NaNH2–MgH2 powder mixtures

et al. 2017

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The present work addresses the kinetics of chemical transformations activated by the mechanical processing of powder by ball milling. In particular, attention focuses on the reaction between NaNH 2 and MgH 2 , specific case studies suitably chosen to throw light on the kinetic features emerging in connection with the exchange of anionic ligands induced by mechanical activation. Experimental findings indicate that the mechanical treatment of NaNH 2 -MgH 2 powder mixtures induces a simple metathetic reaction with formation of NaH and Mg(NH 2 ) 2 phases. Chemical conversion data obtained by X-ray diffraction analysis have been interpreted using a kinetic model incorporating the statistical character of the mechanical processing by ball milling. The apparent rate constant measuring the reaction rate is related to the volume of powder effectively processed during individual collisions, and tentatively connected with the transfer of mechanical energy across the network formed by the points of contact between the powder particles trapped during collisions.

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“…At the ratio of 30, the destruction rate of HCB reached 99.1 %. According to the study of Delogu et al [23], when the mass ratio of ball to reactant reached certain value, the effective impact among mill balls increased. The energy produced by the impact can destruct the structure of HCB.…”

Section: Effect Of the Mass Ratio Of Ball To Reactantmentioning

confidence: 99%

Mechanochemical degradation of hexachlorobenzene using Mg/Al2O3 as additive

Ren

Kang²,

Zhu

2015

J Mater Cycles Waste Manag

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In the present work, we investigate the destruction efficiency of hexachlorobenzene (HCB) by milling with various reagents in a planetary ball mill under different milling conditions. Under the same conditions of mill rotary rate and charge ratio, the mixture of magnesium powder and aluminum oxide (Mg/Al 2 O 3 ) was found best in promoting the destruction of HCB, which can be completed destroyed after 90 min grinding at a charge ratio of 20:1 (reagent/HCB, m/m), a ball mass/reagent mass ration of 30:1 and a mill rotation speed of 550 rpm. The ground samples were characterized and analyzed by X-ray fluorescence, gas chromatography (GC), X-ray diffraction and ion chromatography. The intermediate products, such as pentachlorobenzene, tetrachlorobenzene, trichlorobenzene isomers, dichlorobenzene and monochlorobenzene were detected by GC. Then the main dechlorination path way for HCB was proposed. With a series of verification experiments, the final degradation products of HCB were amorphous carbon and inorganic chlorine. Based on this study, Mg/Al 2 O 3 has the potential to complete the innocuous treatment of chlorinated compounds.

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A quantitative approach to mechanochemical processes

Cited by 78 publications

References 1 publication

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

Mechanically activated metathesis reaction in NaNH2–MgH2 powder mixtures

Mechanochemical degradation of hexachlorobenzene using Mg/Al2O3 as additive

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