The Study On The Degradation Of PFOA Wastewater With Photo Catalysis By The Low-temperature Plasma

With the improvement of living standards, persistent organic pollutants (POPs) has become the focus of attention. Perfluorooctanoic acid (PFOA) is a kind of perfluorinated compounds, and also a kind of persistent organic pollutants, with high pollution, refractory etc.. Recently, studies on degradation of PFOA are not perfect, further studies are needed.This paper uses low temperature plasma generated by barrier discharge degradation to degrade simulated wastewater of perfluorooctanoic acid. Low temperature plasma is one of the advanced oxidation technology with ozone oxidation, high-energy electron radiation and UV photolysis, in the medium barrier discharge process can produce a large number of hydroxyl radicals and other active particles that can effectively degrade various organic pollutants. This technology has the characteristics of low internal consumption, short degradation time and high degradation efficiency. It has broad application prospects.The TiO2 thin films were prepared on honeycomb ceramics by sol-gel method, and the results were characterized by XRD. The experiment of different discharge voltage, initial concentration, initial conductivity, initial pH value were compared and studied, and added Cl’and Fe2+ions, powdered TiO2, hydrogen peroxide and n-butanol to the perfluorooctanoic acid solution. Experimental results show that the discharge voltage of 75 V, perfluorooctanoic acid solution initial concentration of 100 mg/L, initial pH value of 3.63, initial conductivity of 80us/cm conditions, with the degradation time of 160min, the degradation rate was 75.08%; adding n-butanol, chloride ion or increase perfluorooctanoic acid solution of initial conductivity, pH value lead to decreased the rate of degradation of perfluorooctanoic acid solution, adding the right amount of Fe2+and H2O2 promoted the degradation of perfluorooctanoic acid solution, when the concentration of Fe2+and H2O2 is too high will inhibit solution degradation. Add titanium dioxide powder on the degradation has certain promotion effect, but the degradation efficiency is slightly lower than using TiO2 films.The experiments of perfluorooctanoic acid solution in the degradation process of pH value, conductivity, TOC and hydroxyl radical were determined. The experimental results show that the solution produced during low-temperature plasma degradation of perfluorooctanoic acid solution lead to the pH and TOC decreased, the conductivity and hydroxyl radical increased.Finally, the experiment detected perfluorooctanoic acid’s intermediate product in the degradation process and the final product by mass spectrometry scanning method, analyzes the structure of degradation products and pushed a possible degradation process.This experiment provides a new idea for the degradation of perfluorooctanoic acid wastewater.