THE RESEARCH OF MECHANISM OF AMMONIA ABSORBTION BY THERMOCHEMICALLY MODIFIED NANOPOROUS SILICA SORBANTS
The research has been conducted to study the adsorbing properties of termochemically modified silica gels of various porosity, affectied by ammonia. The chemical treatment of sorbents was carried out with the use of 0,1 M copper sulfate solution. The time of impregnation by activating solution is estimated on the basis of photocolorimetric investigation. Besides, the saturation of sorbents by the studied solution was executed in the ultrasonic field. The adsorbtion was exploried by a gravimetric method, that is, keeping sorbents in the ammonia medium (the volume concentration is 5 - 400 mg/m3). It is proved that the finely porous silica gel possesses the best adsorbtion properties in the conditions given. On the basis of desorbtion process study, carried out by infrared spectroscopy, the ammonia sorbtion mechanism is presented, which is defermined by the types of interaction between the sorbent and the sorbate. The greatest sorbtion ability of finely porous silica gel is conditioned by physical adsorbtion and formation of ammonia molecules hydrogen links with structure groups (silanol and vicinal) the silica gel surface. The macroporous silica gel demonstrates the chemical adsorbtion component, associated with copper amino-complexes formation.
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