Study On Electrode Metal Ion Release During Pulsed Electric Field Treatment

Pulsed Electric Field(PEF)treatment is a popular cold sterilization technology,which can be used as an alternative to traditional thermal liquid sterilization.The high voltage pulse is connected to the high voltage electrode,the high voltage pulse electric field is generated in the treatment room and used for microorganisms,and the irreversible perforation and inactivation of microbial cells are caused under the action of the high voltage pulse electric field.However,when the traditional PEF sterilization system is used,adverse electrochemical reactions are inevitable,resulting in toxic metal ions and gaseous bubbles.The effect of high voltage pulsed electric field on the sterilization of saccharomyces cerevisiae and the effect on the release of electrode metal ions were studied.The research work is as follows:(1)Two coaxial PEF processing Chambers with the same geometric structure and processing space were made respectively,and the self-made exponential attenuation wave high-voltage pulse generator was used to conduct sterilization comparison experiments of saccharomyces cerevisiae under different electrical parameters(pulse number N electric field intensity E).(2)The influence of different electrical parameters(pulse number N electric field intensity E and total energy ratio input W_T)on the release of metal ions in stainless steel(type 304)electrode during the process of static coaxial processing chamber PEF was tested.The experimental results are as follows:(1)The sterilization efficiency of both flow and static PEF treatment chambers is positively correlated with the electric field intensity and the number of pulses;However,under the condition of the same pulse number and electric field intensity,the sterilization efficiency of the static intermittent treatment chamber is better than that of the flow continuous treatment chamber.The experimental results showed that the sterilization efficiency of both flow and static PEF treatment chambers was positively correlated with the electric field intensity and the number of pulses.However,under the same treatment conditions,the sterilization efficiency of the static intermittent treatment chamber is better than that of the flow continuous treatment chamber.Through the analysis of energy density in two PEF treatment chambers during the experiment,the results show that in addition to the factor of energy density per unit mass(d E/dm),energy density per unit mass time(d E/dm?dt)is also an important factor affecting the sterilization efficiency of PEF.(2)The output of metal ions is positively correlated with the pulse number,electric field intensity and total energy ratio input.Compared with the number of pulses,the release of metal ions from the electrode is more sensitive to the PEF electric field intensity and the total specific energy input.In summary,according to the above experimental results,PEF treatment technology is an efficient sterilization technology,but in practical application,the influence of processing electrical parameters should be considered.In addition to improving PEF sterilization efficiency by increasing electric field intensity,number of pulses and other parameters,increasing energy density per unit mass per unit time is also an effective way.However,when the electric field intensity and the number of pulses are increased,it is necessary to consider the negative effect of the increasing release of metal ions from the electrode.Therefore,the minimum electric field intensity and the number of pulses needed to ensure the sterilization efficiency should be considered when selecting the electric field intensity and the number of pulses.At the same time,in the optimization process of pulse parameters,it is necessary to consider the release amount of metal ions under the total specific energy input,and choose the minimum total specific energy input while ensuring the inactivation of microorganisms.