Adsorption of Soluble Silica on Magnesium Hydroxide

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Other Title
  • 水酸化マグネシウムによる溶存シリカの吸着
  • 水酸化マグネシウムと溶存シリカとの反応　Ｉ　　水酸化マグネシウムによる溶存シリカの吸着

Description

The kinetics of adsorption of soluble silica on magnesium hydroxide surface was studied. Magnesium hydroxide powder (0.5g) was suspended in a silica solution of 200 cm3 at 30∼80°C. The rate of adsorption was determined by measuring the decrease of silica concentration in the solution as a function of tin. A parabolic law was observed as C=k.t1/2 where C is the amount of adsorbed silica and t is the reaction time. The value of the rate constant k for a commercial magnesium hydroxide in a solution of 114 ppm of the initial silica concentration was 0.15 mmol.g-1.hr-1/2 at 30°C. The value of k depended on the kinds of magnesium hydroxide, the initial silica concentration, and the reaction temperature. The apparent activation energy of about 5 kcal/mol was caluculated from the temperature dependence of the rate constant, and it was independent of the kinds of magnesium hydroxide. The rate of adsorp- tion was increased by the increase in pH of the solution. The presence of Al3+ ions in the solution strongly promoted the rate of adsorption. The adsorption was a chemisorption, and the IR spectrum of silica adsorbed on magnesium hydroxide suggested the formation of the-Mg-O-Si-bond.

Journal

  • NIPPON KAGAKU KAISHI

    NIPPON KAGAKU KAISHI 1978 (4), 555-560, 1978-04-10

    The Chemical Society of Japan

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