Yalnizca The World and Modern Science
  • Adsorbent Hydroxides

    Filed under News
    Sep 17

    In the manufacture of activated aluminosilicate adsorbent by ion-exchange capacity of natural aluminosilicate framework of substitution of trivalent aluminum cations magnesium and calcium, comprising the activator, as well as filling "vacancies" in the crystal lattice and in the interlayer space of the above cations. As a result of purposeful modification and activation of aluminosilicate materials obtained granular material which, when filtering water through a granular layer forms a slightly alkaline environment and positive electrokinetic potential. A prerequisite for creating an alkaline environment are oxides of calcium and magnesium, formed in the structure of the adsorbent in the manufacturing process. Magnesium oxide and calcium hydroxide formed in water, thus increasing pH due to excess OH-anions. Heavy metal cations, getting in an alkaline environment, react to form insoluble hydroxides in the scheme: Me2 + + 2ON- Me (OH) 2 Me3 + + 3ON- Me (OH) 3 .

    Product solubility of hydroxides of heavy metals is much smaller (tens to hundreds of times) the solubility product of magnesium hydroxide and calcium, so the balance of the chemical interaction is shifted toward formation soluble hydroxides of heavy metals. Addition of the adsorbent in water diffuse exchange cations Mg2 + and Ca2 +, also contributes to the pH of the medium due to the excess of OH-anions, bound in later in the hydroxides heavy metals. Diffusion of the cations Mg2 + and Ca2 + is possible due to weak ties with the lattice cation. Thus, the micelles formed hydroxides of heavy metals with the further enlargement of the aggregates, formation and growth of colloidal structures due to the forces of electrostatic interaction between the positively charged surface of the grains of the adsorbent and negatively charged micelles of hydroxides of heavy metals.

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