| Chlorophenol wastewater is a typical kind of refractory and toxic organic wastewater.Recently,the main focus has been put on the treatment of chlorophenol wastewater.Advanced oxidation technology is a common used method for the treatment of refractory and toxic industrial wastewater.Among them,liquid discharge plasma treatment technology has attracted much attention due to the unique advantages,such as high efficiency,clean process,environment-friendly,less chemical reagents and easy to realize automation.However,during the process of liquid-phase discharge,the reactor would have salinity gradually due to electrode discharge and accumulates in the reaction solution,on the other hand,the wastewater has a high salinity,which seriously affects the high-voltage discharge process of the electrode and processing efficiency.Recent years,plenty of research has focused on the development of new liquid-phase pulsed discharge reactors that are resistant to salinity interference.In this paper,the traditional high-efficiency needle-plate(net)reactor has been investigated.Firstly,the salt accumulation law of the electric needle in the liquid phase pulse discharge has been studied by changing the installation mode of the needle electrode and the aeration tube.The influence of the wastewater's salinity on the discharge plasma and 4-chlorophenol degradation efficiency was carried out systematically.The phenomenon and mechanism laid a solid experimental foundation for the development of new type high-efficiency salt resistance needle plate(net)reactor.On the other hand,based on the optimized electrode,the impact of the electrode number in the unit area of the reactor and distribution on the plasma properties of the discharge and the degradation effect of 4-chlorophenol are discussed systematically,which provides a new field of vision for the study of the structural optimization of the reactor.The experimental results demonstrated that:(1)Flat-needle liquid-phase discharge reactor is the most appropriate system for the remove of 4-chlorophenol.The removal rate of 4-chlorophenol can reach 86.2% when the reaction time is 40 min.(2)Electric needle lower than the installation of the aeration tube would lead to the accumulation of salt.It can effectively reduce the accumulation of salinity during high pressure discharge of the liquid phase when the electric needle higher than that.Additionally,the discharge rate is moderate when the electric needle located near the nozzle.(3)The mounting position of the electro-acupuncture plays a critical role in determine the liquid-phase high pressure discharge corona morphology and the characteristics of the plasma active species.There are significant differences between the electro-acupuncture anti-salt resistance ability based on the different mounting modes.We found that the concave needle possess the highest resistance to salinity.(4)For a needle-plate(net)reactor with a certain cross-sectional area,the number of electro-acupuncture needles or the electro-acupuncture needles distribution form has a significant effect on the processing efficiency and energy utilization efficiency of the reactor.It is attributed to the mass transfer and reaction characteristics of phase-pulsed discharge plasma gas-liquid system are mainly determined by the size and distribution of plasma bubbles.The rupture and polymerization of plasma microbubble groups during the transportation process are also very important for the reaction system.(5)For a specific needle-plate(net)reactor,the treatment effect can be further improved by optimizing the operating conditions,such as discharge voltage,discharge pulse frequency and reasonable intake air amount. |
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