PHOTOCATALYTIC BEHAVIOR OF GADOLINIACERIA MIXED OXIDES FOR LEAD (II) IONS’ REMOVAL FROM WATER
Keywords:
Cerium oxide, gadolinium oxide, semiconductor, photocatalysis, lead, wastewaterAbstract
The photocatalytic removal of Pb(II) ions from water by Gd2O3-CeO2 mixed oxides was investigated. The heat treatment of the Gd2O3-CeO2 particles affects the removal of Pb(II)ions accompanied with an absorption and a precipitation of Pb(II) ions. A partial dissolution of Gd2O3 was detected for the 2-phase mixture of Gd2O3-CeO2 particles calcined at 1,000°C, which increases the pH-value of the Pb(II) solution and results in a Pb(OH)2precipitation, regardless of the photo-irradiation. The Gd2O3-CeO2 particles calcined at1,400°C form a solid solution Gd2O3-CeO2 (Ce0.9Gd0.1O1.95 or GDC) coexistent with CeO2particles (GDC-CeO2), which decreases the pH of the Pb(II) solution and exhibits a more effective Pb(II) ion removal. A photoelectrode position of PbO2 and a precipitation ofPb(NO3)2 are deposited on the surface of the mixture phase GDC-CeO2 particles. The enhanced photocatalytic activity is supported by a strong photoluminescence signal,suggesting the fast transfer and efficient separation of photogenerated electron-hole pairs due to the formation of an interface between the solid solution GDC and CeO2 particles.
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