Synergistic photocatalytic oxidation and adsorption of elemental mercury by carbon modified titanium dioxide nanotubes under visible light LED irradiation

• Carbon modified titanium dioxide nanotubes were synthesized via a hydrothermal method.
• The prepared catalysts showed a good removal efficiency of elemental mercury under the irradiation of visible-light LED.
• The activity promotion was attributed to the improved nano-structure and the expanded light adsorption.

In this paper, carbon modified titanium dioxide nanotubes (hereafter denoted as CTNTs) were synthesized via a hydrothermal method, followed by ethanol washing and then heat-treatment steps. The physicochemical properties of CTNTs were investigated by XRD, BET, HR-TEM, TG-FTIR and UV–Vis spectra. The resultant CTNTs were then utilized for the removal of elemental mercury (Hg0) under the irradiation of visible light LED. Experimental results revealed that the CTNTs had a good adsorption capability and photocatalytic oxidation ability for the removal of Hg0, particularly for the catalyst that was calcinated at 300 °C. We proposed that the activity promotion for the CTNTs was mainly attributed to three aspects: the abundant adsorption sites for Hg0, the well sustained nanotubes structure and the expanded light adsorption spectrum of CTNTs. Furthermore, the roles of influence factors such as empty bed retention time, O2 concentration, SO2 concentration and NO concentration, were investigated. The experimental results verified that white light LED lamp was a suitable light source for the application of photocatalytic oxidation process.

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