Effect of preparation method on the structure and photocatalytic performance of BiOI and $Bi_5O_7I$ for Hg0 removal

Özet

This paper presents a study on the effect of preparation method on the structure and photocatalytic activities of BiOI and $Bi_5O_7I$ photocatalysts for elemental mercury ($Hg^0$ ) removal in a wet bubbling reactor. Two visible-lightdriven BiOI photocatalysts (BiOI-HAc and BiOI-EG) via either glacial acetic acid (HAc) coprecipitation or ethylene glycol (EG) hydrothermal synthesis as well as their derivative samples ($Bi_5O_7I$-HAc and $Bi_5O_7I$-EG) were synthesized, respectively. The photocatalysts were characterized by $N_2$ adsorption-desorption analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS), photoelectrochemical measurement and electron spin resonance (ESR) techniques. The results showed that $Bi_5O_7I$-HAc and BiOI-EG exhibited superior $Hg^0$ removal performances in comparison with BiOI-HAc and $Bi_5O_7I$I-EG, and $Bi_5O_7I$-HAc photocatalyst possessed much better activity on $SO_2$ resistance and wider reaction temperature scope than BiOI-EG. The enhancement in $Hg^0$ removal efficiency can be attributed to the appearance of plenty of adsorbed oxygen, efficient photoinduced carrier separations and their special band gap structures. The photoexcited % $O_2$ − and h+ played key roles in the process of Hg0 removal.