| Summary: | A study on the separation of Au(III) ion in the Au/Ag/Cu system with
mercapto-silica hybrid column has been carried out. Mercapto silica hybrid
(MSH) was synthesized via sol-gel process of sodium silicate solution produced
from destruction of rice husk ash. It was formed by adding 3M HCl in a mixture
of sodium silicate and 3-(trimethoxisylil)-1-propantiol (TMSP) until the pH of
7,0. Characterization was done with Fourier Transform Infrared Spectroscopy
(FTIR) and X-ray Diffractometer (XRD). Separation of metal ion was carried out
in solid phase extraction column system by adsorbing Au, Cu, and Ag ions and
followed by desorption with thiourea in HCl solution. Solution of Au, Ag, and Cu
10 mL with the concentration of 10 ppm adsorbed on the column containing 0,5 g
of MSH with three repetition. Elution using solution of thiourea in HCl was
carried out three times with the volume of 10 mL each. The amount of metal ions
that adsorbed and desorbed from the MSH were calculated based on the difference
of concentration using Atomic Absorption Spectroscopy (AAS) before and after
processes.
The result of characterization with FTIR showed that the synthesis of
MSH was successful. It was indicated with the presence of characteristic
functional groups, such as: methylene (-CH2-), thiol (-SH), silanol (Si-OH) and
siloxane (Si-O-Si). MSH has an amorphous structure in accordance to XRD data.
Adsorption result showed that all three metal ions were adsorbed completely in
the MSH column. Au(III) ion was eluted 84.61% using 1M thiourea in 0.5 M HCl
and 96% using eluent 1M thiourea in 1M HCl. In the sequencing elution, Au(III),
Ag(I) and Cu(II) ions can be eluted 96.67%, 79.31% and 45,71% respectively.
Moreover, the repetition of the use of adsorbent for separation of Au(III), the
hybrid still can adsorb Au(III) more than 96% in Au/Ag/Cu system. After being
reused three times for adsorption and desorption, the performance of the MSH
column does not change.
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