等离子体产物溶液中扩散与大肠杆菌杀灭

Plasma Reactive Species Diffusion and the Inactivation of Bacteria

大气压低温等离子体对微生物的杀灭主要通过紫外线、高能粒子刻蚀、强反应活性物质等效应实现。当利用等离子体杀灭水溶液中微生物时,由于液体的阻隔,紫外线与离子刻蚀的作用非常微弱,杀灭作用主要依靠水溶液中的活性物质。该研究利用介质阻挡放电等离子体处理水溶液中的大肠杆菌,通过菌落稀释计数法比较等离子体对不同深度细菌的杀灭效果,并使用pH指示剂可视化研究长寿命酸性物质扩散过程,探究长短寿命活性粒子对杀灭效果的不同影响。实验结果发现,即使将等离子体作用从1 min延长到10 min,等离子体也只能即时杀灭水溶液表层的大肠杆菌,且杀灭效果与长寿命活性物质的扩散深度无关;而溶液深层大肠杆菌的杀灭需要在等离子体处理后静置溶液一段时间,也能抑制甚至杀灭溶液中的大肠杆菌。短寿命活性物质对细菌有强烈快速的杀灭作用,但其在溶液中的寿命和扩散距离都很短,杀灭作用的有效距离有限;长寿命活性粒子虽然能作用于更大水体,但需要较长作用时间,无法做到即时迅速的杀灭。该研究对低温等离子体在不同场合的消毒运用提供了实验基础和设计参考。

The killing of microorganisms by atmospheric pressure low-temperature plasma is mainly achieved by the effects of ultraviolet light(UV), high-energy particle etching, and strong reactive active substances. When using plasma to kill microorganisms in aqueous solutions, the effects of UV and ion etching are feeble due to the liquid barrier, and the killing effect is mainly dependent on the reactive substances in the aqueous solution. In our study, medium-blocking discharge plasma was used to treat E. coli in aqueous solution, and the killing effect of plasma on bacteria at different depths were compared by colony dilution counting. To investigate the different effects of long and short-lived active particles on the killing effect, pH indicator was used to visualize the diffusion process of long-lived acidic substances. The experimental results show that even if the plasma action was extended from 1 min to 10 min, the plasma could only kill E. coli in the surface layer of the aqueous solution instantly, and the killing effect is independent of the diffusion depth of the long-lived active material. Furthermore, the killing of E. coli in the deep layer of the solution requires a period of standing solution after plasma treatment, which can also inhibit or even kill E. coli in solution. Short-lived active substances have a rapid and robust killing effect on bacteria, but their lifetimes and diffusion distances in solution are short, and the effective distance of the killing effect is limited. Long-lived active particles can act on larger water bodies, but they require a longer action time and cannot achieve immediate and rapid killing. This study provides an experimental basis and design reference for the use of low-temperature plasma for disinfection in different settings.