Degradation of acetaminophen by UVA/LED/TiO2 process

Photocatalytic process that uses traditional low pressure mercury lamp and TiO2 as catalyst has attracted numerous attentions recently for the degradation of organic pollutants in water environment. However, there are several important drawbacks to this mercury lamp such as high energy cost and the production of toxic mercury waste. Compared to traditional mercury lamp, the newly emerging UVA/LED is more efficient in converting electricity into light. It has longer lifetime and no toxic waste generation problem exists. Therefore, the purpose of this research was to study the ability of high power ultraviolet A light-emitting diode (UVA/LED) as a light source in the degradation of organic pollutants. The optimal operational conditions were also determined. In this study, a new device equipped with high-energy 365 nm UVA/LED using TiO2-P25 as the catalyst was developed and evaluated for photolytic/photocatalytic oxidation of acetaminophen (Ace). The results showed that the chosen UVA/LED alone degraded negligible amount of Ace, while in the presence of TiO2, the concentration of Ace decreased substantially. In most experiments of this study, Ace could be degraded to non-detectable level within 20 min. The degradation rate was found to be related to the dosage of TiO2, initial Ace concentration and light intensity. Based on the experimental data, the following kinetic equation was achieved by kinetic modeling: rs=-2.4168×I0.5732×[Ace]1+0.1523×[Ace]0, which was also in agreement with the Langmuir–Hinshelwood (L–H) law.

► We examined UVA/LED as light source for degradation of acetaminophen with P25 as catalyst.
► The reaction rate increased with increasing of P25 dosage and light intensity.
► The reaction rates decreased with increasing of initial acetaminophen concentration.
► The kinetic reaction rate follows this equation: rs=-2.4168×I0.5732×[Ace]1+0.1523×[Ace]0.