Aqueous TiO{sub 2} photocatalysts of metal-EDTA complexes
- Univ. of New Mexico, Albuquerque, NM (United States)
- Sandia National Labs., Albuquerque, NM (United States)
This report summarizes a subset of work aimed at determining the viability of titania photocatalysis for the treatment of metal-organic complexes. The organic complexing agent EDTA and the metals Ni(II) and Pb(II) were selected for the study. For the Pb-EDTA system, the purpose was to examine the behavior of the complex in the presence of illuminated photocatalyst in aqueous solution and whether lead could be removed under these conditions. The goal of the Ni-EDTA study was to determine if the EDTA could be oxidized to liberate the Ni(II) into solution, making it amenable for other treatments. Photocatalytic reactions were carried out in batch mode in a glass pot reactor with two photocatalysts: Degussa P-25 titanium dioxide and Aldrich titanium dioxide with 0.5 wt% loadings of Au and Pt metals on the TiO{sub 2} surface. Analysis of the aqueous samples included ion chromatography, atomic absorption, total organic carbon, and pH measurement. The photocatalytic treatment of Ni-EDTA using the Aldrich TiO{sub 2} catalyst resulted in no adsorption of the complex in the induction period and no disappearance of the Ni during the photoreaction. A pH adjustment and filtering of the treated solution removed only 10% of the Ni; it is therefore concluded that most of the Ni is still strongly complexed by EDTA oxidation products. Analysis of the Pb-EDTA reaction with the P-25 catalyst showed rapid removal of the complex. The atomic absorption analysis for total Pb shows that removal of the Pb occurs, but it seem to lag the removal of the complex, suggesting that some adsorption of the complex prior to reaction occurs. Both the Ni-EDTA and Pb-EDTA reactions were performed under identical conditions in the absence of photocatalyst to determine if the above behavior could be attributed to ultraviolet photochemistry only. No reduction of either metal complex or any removal of metal was detected. Therefore, illuminated photocatalyst is required to achieve the above results.
- OSTI ID:
- 210241
- Report Number(s):
- CONF-9509139--; CNN: Contract RFQ AN-2964
- Country of Publication:
- United States
- Language:
- English
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