- Thesis topic: Photocatalytic removal of NOx and SOx under Solar Light Using UiO-66-NH2@B/g-C3N4

- Doi: 

- Abstract: 

        In recent years, the continuous rise in international prices of gold and other precious metals, coupled with the rapid advancement of high-tech industries, has significantly elevated the strategic value and demand for rare and precious metals as critical materials in advanced manufacturing processes. This trend has led to increasing global attention and investment in the precious metal refining industry. However, the extraction and metallurgical processes of rare and precious metals are often accompanied by the emission of various air pollutants, including particulate matter (PM), nitrogen oxides (NOx), and sulfur oxides (SOx), which pose potential threats to air quality and environmental health.
This study focuses on the rare and precious metal industry under the Taiwan Resource Recycling Industrial Association, specifically analyzing the emission concentrations of NOx and SOx from their manufacturing processes. Furthermore, it explores synergistic removal technologies for these two types of gaseous pollutants, aiming to propose concrete pollution control strategies that promote both emission reduction performance and environmental regulatory compliance.The objective of this research is to develop and evaluate the removal performance of the composite material UiO-66-NH2 and B/g-C3N4 for gaseous pollutants NOx and SOx. UiO-66-NH2, a metal–organic framework (MOF), exhibits high thermal stability and structural porosity. Due to its functional groups (e.g., –NH2, –NO2, –Br), it can be easily modified to enhance catalytic properties. Under simulated sunlight conditions, experiments using UiO-66-NH2 for NOx removal at an initial concentration of 1 ppm demonstrated a removal efficiency of up to 88%, and an average of 85% was maintained across five reuse cycles.
Graphitic carbon nitride (g-C3N4) is a visible-light-responsive, metal-free semiconductor with a bandgap of ~2.7 eV. Boron doping (B/g-C3N4) enhances its photocatalytic activity. The composite UiO-66-NH2@B/g-C3N4 was tested for simultaneous NOx and SOx removal. At 10 ppm, peak removal rates were 48% for NOx and 35% for SOx; at 50 ppm, they increased to 53% and 40%, respectively. The composite maintained stable NOx removal over three cycles, though SOx removal remained more challenging due to differing chemical properties and reaction mechanisms. Effective co-removal requires both redox and selective adsorption capabilities, highlighting the need for further material development.

Keywords: Sulfur oxides, Nitrogen oxides, Photocatalysis, UiO-66 ,g-C3N4