Abstract:
The reduction of manganese dioxide with ammonium sulphite in the presence of Cu(II), Ni(II) and Co(II) has been studied. It was observed that the catalytic activity is in the order Cu(II)> Co(II)> Ni(II). The activation energies were estimated to be approximately 41, 70 and 74 kJ mol(-1) in the presence of Cu(II), Co(II) and Ni(TI), respectively. The catalytic reduction follows the shrinking core model. The interactive effects of metal ions were studied using 2(3) full factorial design of experiments. The linear coefficients for the three metals were positive whereas Cu(II)-Co(II) showed a negative correlation and Ni(II) did not have any synergistic effect. (C) 1999 Published by Elsevier Science B.V. All rights reserved.