Browsing by Author "Tunc, M"

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    Dissolution Mechanism of Ulexite in H2so4 Solution
    (Elsevier Science Bv, 1999) Tunc, M; Kocakerim, MM; Yapici, S; Bayrakçeken, S
    This work comprises an investigation of the dissolution mechanism of ulexite in H2SO4 solution and the effect of SO42- ions and acid concentration on the dissolution process, using H2SO4, HCL + H2SO4 and H2SO4 + Na2SO4 solutions. From the experimental observations, it can be suggested that the overall dissolution reaction can be written as Na2O . 2CaO . 5B(2)O(3) . 16H(2)O((s)) + 3H(2)SO(4(aq) )--> 2Na((aq))(+) + 2CaSO(4) + + 10H(3)BO(3(aq)) + SO4(aq)(2-) + 4H(2)O((1) )or Na2O . 2CaO . 5B(2)O(3) . 16H(2)O((s)) + 3H(2)SO(4(aq) )--> 2Na(aq)+ + 2CaSO4 . 2H2O(s) + 10H3BO3(aq) + SO4(aq)2- depending upon the experimental conditions. It was observed that, increasing H3O+ acid concentration increased the dissolution rate, but increasing SO42- concentration reduced dissolution rate due to the precipitation of a solid film of CaSO4 and/or CaSO4 . 2H(2)O, determined by X-ray and SEM measurement. (C) 1999 Elsevier Science B.V, All rights reserved.
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    Article
    Dissolution of Thermally Dehydrated Ulexite in Sulfuric Acid Solution
    (Amer Chemical Soc, 1997) Kunkul, A; Tunc, M; Yapici, S; Ersahan, H; Kocakerim, MM
    The present study concerns a work on the investigation of the effect of the dehydration temperature on the dissolution process of a boron mineral, ulexite, in sulfuric acid solution. In the experiments, the dehydration temperature and dissolution temperature were chosen as the parameters. First, the dehydration of ulexite was performed isothermally in an oven, and DTA and X-ray analysis were carried out to observe the structural changes in the mineral. The effect of the dehydration temperature on the dissolution rate of ulexite in sulfuric acid solutions was then investigated, using a batch reactor made of glass. The kinetic parameters of the dissolution process, frequency factor and activation energy, were evaluated using dissolution data.