Mechanochemistry

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Mechanochemistry refers to a sub-area of physical chemistry that deals with the chemical behavior of substances under mechanical influence. An older definition comes from Wilhelm Ostwald (1919): "Mechanochemistry is the study of the relationship between mechanical forms of energy and chemical energy."

An important branch of mechanochemistry is tribochemistry ( Greek tribein = to rub), which deals with the change in the chemical behavior of solids through mechanical action on their interfaces . Related disciplines are tribology , tribophysics , surface chemistry and surface physics .

Matthew Carey Lea (1882) is considered to be the founder of mechanochemistry .

Mechanisms

Mechanical / physical forces lead to structural changes in the surface: surface enlargements, reduction in particle sizes, the creation of fresh surfaces, material abrasion and, in some cases, phase changes . At the microscopic level, there are highly excited lattice vibrations that would not occur thermally. This enables exotic chemical reactions as well as the emission of photons , electrons and lattice components .

Molecular Nanotechnology

In 1998, Wilson Ho from Cornell University succeeded in assembling individual iron monocarbonyl (FeCO) and iron dicarbonyl molecules (Fe (CO) 2 ) from iron atoms (Fe) and carbon monoxide (CO) using a scanning tunneling microscope .

Applications

In the engineering sciences, the mechanisms of mechanochemistry are collectively referred to as mechanical activation . The high mechanical energy density from the normal and frictional impact of the grinding media in the grinding chamber of vibratory mills , for example, improves the dissolving behavior of the sulphidic raw materials to be ground in such a way that the use of vibratory grinding in the processing of hard-to-dissolve ores becomes technically interesting. Eberhard Gock and his research team at the TU Berlin and later the TU Clausthal systematically dealt with the use of mechanical activation by increasing the efficiency of vibrating mills and the like. a. for the substitution of pyrometallurgical processes by hydrometallurgical processes. Another application example is the grinding of zinc oxide ash: The special feature of the grinding of zinc oxide ash is that the grist can have a temperature of up to 100 ° C. Zinc oxide is used as a trace nutrient in the animal feed industry. With the eccentric vibratory mill developed in the 1990s, the water solubility can be increased from 54% with conventional grinding to more than 75% through mechanical activation.

literature

  • Cleopatra Vasiliu-Oprea, Florin Dan: Macromolecular Mechanochemistry. Cambridge International Science Publishing, 2007, ISBN 978-1-904602-54-5 .
  • Zory Vlad Todres: Organic Mechanochemistry and Its Practical Applications. CRC Press, 2006, ISBN 0-8493-4078-0 .
  • Stephan Kipp, Vladimir Šepelák, Klaus Dieter Becker: Mechanochemistry. Chemistry with the hammer. In: Chemistry in Our Time . 39, No. 6, 2005, pp. 384-392, doi: 10.1002 / ciuz.200500355 .
  • Peter-Adolf Thiessen, Klaus Meyer and Gerhard Heinicke: Basics of Tribochemistry , Akademie Verlag, Berlin (GDR), 1967

Individual evidence

  1. ↑ An Application of Mechanochemistry: Charles Day: Creating and Characterizing Individual Molecular Bonds with a Scanning Tunneling Microscope. In: Physics Today On The Web. Retrieved May 14, 2010 .
  2. ↑ Eberhard Gock, Karl-Eugen Kurrer : Increasing the efficiency of the vibratory milling process with the eccentric vibratory mill . In: Aufbereung-Technik 39 (1998), No. 3, pp. 103-111 (here: p. 111).
  3. ^ Karl-Eugen Kurrer: On the internal kinematics and kinetics of vibratory tube mills , progress reports VDI, series 3: Process engineering No. 124, VDI-Verlag Düsseldorf 1986, p. 44ff., ISBN 3-18-142403-X
  4. ↑ Eberhard Gock: Influence on the dissolving behavior of sulfidic raw materials. through solid-state reactions during vibratory grinding , habilitation thesis TU Berlin 1977, p. 31
  5. ^ Eberhard Gock, Karl-Eugen Kurrer: Eccentric vibratory mills - theory and practice . In: Powder Technology 105 (1999), pp. 302–310 (here: p. 308f)