Decomposition Of Acetaminophen In Water By A Gas Phase Dielectric Barrier Discharge Plasma Combined With RGO-TiO₂ Nanocomposite

Acetaminophen,also known as paracetamol or APAP,is a medication used to treat pain and fever.It has rapidly become the most commonly used antipyretic analgesics around the world since the first time it was discovered in 1877.However,it was found that APAP can neither be fully metabolized in the body nor completely degraded by municipal sewage plants.Due to this,APAP and their metabolites are continually introduced into aquatic environs and prevalent at low-level concentrations which can lead to bioaccumulation in aquatic organisms and potentially impact human health.In this paper,APAP served as the model pollutant to evaluate the feasibility of pollutant removal by gas phase dielectric barrier discharge plasma combined with the Reduced Graphene Oxide-titanium dioxide(RGO-TiO2)nanocomposite.RGO-TiO2 nanocomposite was prepared using the modified hydrothermal method and characterized by TEM,XPS and BET.The result showed that TiO2 particles were well-dispersed on the supporting flake-like wrinkled RGO sheets,which should be ascribed to the the formation of the Ti-O-C bond during hydrothermal treatment.The influence of some parameters on the degradation of APAP was studied and described in details,such as input power,initial pH value,RGO-TiO2 dosage,mass ratios of RGO-TiO2,stability of RGO-TiO2 in catalytic recirculation.The experimental results indicated that the APAP degradation efficiency was significantly improved to 92%after 18 min of discharge plasma treatment coupling 0.25 g/L RGO-TiO2 5%wt at 18 kV,compared with the plasma alone and plasma combined with P25 TiO2.The degradation mechanism for APAP in this system was studied by the amount of the generated active species(e.g.dissolved ozone concentration and H2O2 concentration)and changes of APAP solution properties(e.g.changes of UV-vis absorption spectra and TOC)during degradation process.It was observed that the addition of RGO-TiO2 reduced the concentration of dissolved ozone and enhanced H2O2 production,which was ascribed to coefficient of substrates coverage on the RGO-TiO2 and photodecomposition effect in combined system.Finally,intermediate products were analyzed by HPLC/MS,and possible transformation pathways were identified with the support of theoretically calculating the frontier electron density of APAP.