Abstract:
Nanoporous materials with large surface area and well-ordered pore structure
have been synthesized. Thiol groups were grafted on the materials' surface to make
heavy metal ion pre-concentration media. The adsorption properties ofthe materials were
explored. Mercury, gold and silver can be strongly adsorbed by these materials, even in
the presence of alkaline earth metal ion. Though the materials can adsorb other heavy
metal ions such as lead and copper, they show differential adsorption ability when several
ions are present in solution. The adsorption sequence is: mercury> == silver> copper »
lead and cadmium.
In the second part of this work, the memory effects of mercury, gold, silver and
boron were investigated. The addition of 2% L-cysteine and 1% thiourea eliminates the
problems of the three metal ions completely. The wash-out time for mercury dropped
from more than 20 minutes to 18 seconds, and the wash-out time for gold decreased
from more than 30 minutes to 49 seconds. The memory effect of boron can be reduced by
the use of mannitol.
