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Journal of thermal analysis

, Volume 30, Issue 3, pp 603–609 | Cite as

Thermal analysis, X-ray diffraction and infrared spectroscopic study of synthetic brochantite

  • S. V. S. Prasad
  • V. Sitakara Rao
Article

Abstract

Pure brochantite was prepared at 60° from 0.5M copper(II) sulphate and sodium hydroxide solutions at pH 8.0. The decomposition products arising when it was heated at different temperatures were identified using X-ray diffraction analysis and infrared spectroscopy. Dolerophanite, CuO.CuSO4, which is invariably reported to be formed during the thermal decomposition of brochantite (of both synthetic and mineral origins), was not formed at any stage of the decomposition in the present case. The sequence of decomposition is
$$\begin{gathered} CuSO_4 .3Cu(OH)_2 .xH_2 O\xrightarrow{{80 - 170^ \circ }}CuSO_4 .3Cu(OH)_2 + xH_2 O \hfill \\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,CuSO_4 .3Cu(OH)_2 \xrightarrow{{250 - 400^ \circ }}CuSO_4 .2Cu(OH)_2 + CuO + H_2 O \hfill \\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,CuSO_4 .2Cu(OH)_2 \xrightarrow{{610 - 700^ \circ }}3CuO + 2H_2 O + SO_2 + {\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}O_2 \, \hfill \\ \end{gathered} $$

The higher pH conditions adopted here for the precipitation are probably responsible for the above mechanism of decomposition.

Keywords

Thermal Analysis Thermal Decomposition Infrared Spectroscopy Decomposition Product Spectroscopic Study 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Zusammenfassung

Reines Bronchantit wurde bei 60° und pH 8 aus Lösungen von Kupfer(II)-sulfat (0.5 M) und Natriumhydroxid hergestellt. Die beim Erhitzen auf verschiedene Temperaturen entstehenden Zersetzungsprodukte wurden röntgendiffraktometrisch und infrarotspektroskopisch identifiziert. Dolerophanit, CuO.CuSO4, das bei der thermischen Zersetzung von sowohl synthetischem als auch natürlich vorkommendem Bronchantit gebildet werden soll, konnte nicht als Produkt einer der Zersetzungsstufen nachgewiesen werden. Die Reihenfolge der Zersetzung ist:
$$\begin{gathered} CuSO_4 .3Cu(OH)_2 .xH_2 O\xrightarrow{{80 - 170^ \circ }}CuSO_4 .3Cu(OH)_2 + xH_2 O \hfill \\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,CuSO_4 .3Cu(OH)_2 \xrightarrow{{250 - 400^ \circ }}CuSO_4 .2Cu(OH)_2 + CuO + H_2 O \hfill \\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,CuSO_4 .2Cu(OH)_2 \xrightarrow{{610 - 700^ \circ }}3CuO + 2H_2 O + SO_2 + {\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}O_2 \, \hfill \\ \end{gathered} $$

Резюме

Чистый брокантит был получен при 60° из 0,5 молярных растворов с ульфата двухвалентной меди и гидроокиси натрия пр и pH=8. Продукты разложения, образующиеся при нагревании его при ра зличных температура х, были идентифицированы ре нтгенофазовым анализом и ИК спектро скопией. Долерофанит, CuO.CuSO4, являющийся устойчив ым соединением и должен был бы образо вываться при термиче ском разложении как синте тического, так и минерального брокан тита, в настоящем случ ае не образовывался на все х стадиах разложения. Последовательность разложения броканти та может быть представлена следую щими уравнениями реакций:
$$\begin{gathered} CuSO_4 .3Cu(OH)_2 .xH_2 O\xrightarrow{{80 - 170^ \circ }}CuSO_4 .3Cu(OH)_2 + xH_2 O \hfill \\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,CuSO_4 .3Cu(OH)_2 \xrightarrow{{250 - 400^ \circ }}CuSO_4 .2Cu(OH)_2 + CuO + H_2 O \hfill \\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,CuSO_4 .2Cu(OH)_2 \xrightarrow{{610 - 700^ \circ }}3CuO + 2H_2 O + SO_2 + 1/2O_2 \, \hfill \\ \end{gathered} $$

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Copyright information

© Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest 1985

Authors and Affiliations

  • S. V. S. Prasad
    • 1
  • V. Sitakara Rao
    • 1
  1. 1.Department of ChemistryIndian Institute of TechnologyKharagpurIndia

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