Mechanism of photocatalytic degradation of humic acid by carbon dots composite materials
Humic acids contain complex molecular structures and abundant active groups,which can cause environmental safety hazards through ion exchange or complexation.To solve the problem that humic acid is difficult to effectively and ultimately remove,carbon dots composite material(CDs/P25)photocatalytic technology was used to achieve efficient degradation.The effects of hydrothermal synthesis conditions and humic acid concentration on the degradation of humic acid in composites were studied by simulated solar photocatalytic experiments.The experimental results showed that when the carbon dot loading was 0.2 mol·L-1,pH was 6,hydrothermal synthesis temperature was 160 ℃,and hydrothermal synthesis time was 4 hours,the composite material had better photocatalytic activity.The infrared spectroscopy results showed that carbon dots have been loaded onto the surface of TiO2.The photoelectrochemical test results indicated that decorating carbon dots can enhance the separation ability of photogenerated carriers in TiO2 and accelerate the transfer of electron-hole pairs.Moreover,the photocatalytic activity of CDs/P25 was compared under different humic acid concentrations.The results showed that 97％humic acid was removed under 4 hours of visible light irradiation,with 0.5 g·L-1 of CDs/P25 dosage and an initial humic acid concentration of 100 mg·L-1.The main active species in the CDs/P25 photocatalytic reaction system are·OH,·O2-,and 1O2.Humic acids were degraded mostly by opening-ring reactions and chemical bond-breaking reactions.The analysis of LC-MS revealed that CDs/P25 faster degraded humic acids to small molecule substances(i.e.,caprolactam)compared to the TiO2.This study can help develop new and efficient photocatalytic systems for humic acids,facilitating applications in environmental pollution control.
carbon dotsphotocatalysishumic acidtitanium dioxideactive oxygen species
万方数据
维普
