The organic compounds of p-nitrophenol(PNP) solution was treated by the active species generated in a stirred reactor by an atmospheric pressure plasma jet(APPJ).The emission intensities of hydroxyl(OH),oxygen(O),nitric oxide(NO),hydrogen(H) and molecular(N2) were measured by optical emission spectroscopy(OES).The relations between the flow rates of the PNP solution and degradation,the degradation effects and initial pH value of the solution were also investigated.Experimental results show that there exist intense emissions of O(777.1 nm),N_2(337.1 nm),OH(306-310 nm) and NO band(200-290 nm) in the region of plasma.Given the treatment time and gas flow rate,the degradation increased as a function of discharge energy and solution flow rate,respectively.The solution flow rate for the most efficient degradation ranged from 1.414 m/s to 1.702 m/s,and contributed very little when it exceeded 2.199 m/s.This indicates the existence of diffusion-controlled reactions at a low solution flow rate and activationcontrolled reactions at a high solution flow rate.Moreover,increasing or decreasing the initial pH value of neutral PNP solution(pH=5.95) could improve the degradation efficiency.Treated by APPJ,the PNP solutions with different initial pH values of 5.95,7.47 and 2.78 turned more acidic in the end,while the neutral solution had the lowest degradation efficiency.This work clearly demonstrates the close coupling of active species,photolysis of ultraviolet,the organic solution flow rate and the initial pH value,and thus is helpful in the study of the mechanism and application of plasma in wastewater treatment.
By utilization of different excitation power sources,linear plasma sources can be differentiated into DC,RF,VHF,microwave and dual frequency types.Through installing several linear plasma sources in parallel or adopting the so-called roll-to-roll(air-to-air) process,scale uniform linear plasma sources were realized and successfully applied to the deposition of large area uniform dielectric thin films.Furthermore,the magnetic field system can effectively reduce the recombination losses on the wall of the vacuum chamber and enhance the plasma density.Linear plasma sources with approximately one square meter deposition area with the plasma density of 1011cm-3have been developed,some of which have been used for the deposition of dielectric layers and large area plasma etching.
