| Autor: |
Holmes, Andrew B., Ngan, Aldrich, Giesinger, Kayleanna, Gu, Frank |
| Zdroj: |
Environmental Science: Water Research & Technology; 2023, Vol. 9 Issue: 4 p1069-1079, 11p |
| Abstrakt: |
In this paper, we investigate the tunability of Se reduction products (Se0(s)vs.H2Se(g)) during the photocatalytic reduction of selenate over TiO2, using formic acid as an electron hole scavenger, in synthetic mine-impacted brines (SMIB). Photocatalytic reduction can effectively remove Se from SMIB to <2 μg L−1from an initial Se concentration of >3300 μg L−1in under 10 × 1019photons cm−2. An increase in solution temperature led to a marked increase in selenate removal kinetics and an increase in selectivity towards H2Se(g), while increasing the concentration of formic acid led to an increase in selenate removal kinetics and a decrease in the selectivity towards H2Se(g). A bivariate response surface analysis was used to elucidate the mechanism behind the production of >99% gaseous H2Se or >85% solid Se0, under varying reaction conditions. Finally, a two-pronged electron transfer model is proposed to explain the selectivity towards Se0(s)vs.H2Se(g)under varying conditions: (i) Se0(s)is produced through direct reduction of selenate by TiO2conduction band electrons and (ii) H2Se gas is produced through electrons transferred into Se0, followed by an autocatalytic reduction of Se0to H2Se or through a direct reduction by CO2−. |
| Databáze: |
Supplemental Index |
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