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Synthesis and characterization of Cu7S4 (anilite) obtained from copper:thiosulfate system

C. M. SIMONESCU1,* , O. CARP2, L. PATRON2, C. CAPATINA3

Affiliation

  1. Department of Inorganic Technology and Environmental Protection, Faculty of Applied Chemistry and Materials Science, University “Politehnica” of Bucharest, Polizu Street, No. 1-7, RO-011061, Bucharest
  2. Institute of Physical and Chemical “Ilie Murgulescu”, Splaiul Independentei Street, No.202, Bucharest, Romania
  3. Department of Environmental Engineering, University “Constantin Brancusi”, Genova Street, No. 3, RO-210152, Targu-Jiu, Romania

Abstract

The system Cu(CH3COO)2·H2O and Na2S2O3·5H2O in a molar ratio 1:1, in 50 mL H2O at room temperature (25 oC) was used to obtain the thiosulfate complex compound ({Na[Cu(S2O3)]}n). After the thiosulfate compound separation, the obtained filtrate was submitted to hydrolytic decomposition at 80oC and pH==11-11.5.The non-stoichiometric copper sulfide Cu7S4 nanocrystallites obtained by hydrolytic decomposition of filtrate were characterized by chemical elemental analysis, X-ray powder diffraction, scanning electron microscopy and IR spectroscopy. The average diameter of the obtained particles varied between 80-110 nm. Their thermal stability in air, studied by nonisothermal techniques together with IR spectroscopy in order to identify phases from different thermal decomposition stages was also investigated. It was established that Cu7S4 is converted to Cu1.8S which is stable in a relatively large temperature range 103-240oC. Furthermore, a five-stepped oxidation to 0.42CuSO4 0.52CuO·CuSO4 occurs. At temperatures higher than 635ºC the formed oxysulfates decompose to CuO. Comparative with the thermal stability of CuS [1] the oxidation process of lower sulfur content sulfides to oxysulfates starts with ~70ºC lower..

Keywords

Anilite, Synthesis, Physico-chemical characterization, Thermal oxidation.

Submitted at: April 25, 2008
Accepted at: Oct. 7, 2008

Citation

C. M. SIMONESCU, O. CARP, L. PATRON, C. CAPATINA, Synthesis and characterization of Cu7S4 (anilite) obtained from copper:thiosulfate system, Journal of Optoelectronics and Advanced Materials Vol. 10, Iss. 10, pp. 2700-2702 (2008)