PROPERTIES OF MAGNETIC SILICA GEL FOR ENVIRONMENT MONITORING

摘要

Sol-gel method allows production of effective adsorbent systems from fine SiO_2 powder and magnetite. The protolytic exchange capacity of synthesized gels was studied within the pH range of 4-12. The main characteristics of the synthesized silica gel are: surface - 250-350 m~2/g; density - 0.9 g/cm~3; thermal stability - 900℃; sorbent capacity - 0.8-1.2 mmol-eq/g. Synthesized silica gels have high sorption capacitance in relation to Pb~(2+) and Sr~(2+) ions and provide steep withdrawal of these ions from liquid environments. The isotherms of ion sorption on SiO_2-Fe_3O_4 as sorbent display two steps of sorption. The first step is responsible for the main contribution to capacitance of sorption, the second step provides complete extraction of metal from depletion at the maiden stage of solution. With increase of the content of magnetite in the SiO_2-Fe_3O_4 sorbent, the sorption capacity of metals and depth of their withdrawal increases, indicating prospects to apply the data on such sorbents in geochemical research.