低温等离子体净化谷物表面污染物的应用基础研究

Taking advantage of the different electricity, kinetic energy, life-spans and penetration of plasma actives species (electrons, ions, free radicals and ultraviolet light) to make them effectively separated at a special plasma field. Based on this, the plasma chemical reaction mechanism model is established, which respectively predicts the characteristics of actives species on conveying, diffusing. The purification experiments on grains (wheat, maize) surface contaminants (pesticides, microorganisms and mycotoxins) by specific plasma are studied in the plasma-grains surface field to indicate the interaction of decontamination dose effect, plasma purification and grains quality changes and the time-dependent effect of residual free radicals. According to modern testing techniques, the purifying effects and contributing share of each active species in the plasma are determined. Combined with the classical theory of organic chemistry and cell structure theory, the degradation mechanism of pesticides and toxins and the micro-mechanism of microbial inactivation are revealed. Based on the plasma purification kinetics, the dynamic mathematical model of plasma-purifying grains is established to analyze the purification mechanisms of grains surface pollutants..The application of non-thermal plasma on food security engineering in this project will develop a safe, simple, efficient, non-selective and non-toxic new technology of grains purification and preservation and provide theoretical basis and accumulate basic data for the further research.

依据等离子体活性物种（电子、离子、自由基、紫外光）电性、动能、寿命、穿透性特征，使其在特定等离子体场中实现有效分离，建立等离子体化学反应机理模型，预测各活性基团的扩散分布态势；通过特定等离子体对谷物（小麦、玉米）表面污染物（农药、微生物、真菌毒素）净化实验，在等离子体-谷物表面场中研究净化剂量效应；探讨等离子体净化与谷物品质变化的交互影响及残存自由基的经时后效；采用现代测试技术，确定等离子体中各活性物种的净化作用和贡献份额；结合经典有机化学反应理论和细胞结构理论，揭示农药、毒素的降解历程及微生物灭活的微观机制；通过等离子体净化动力学研究，建立等离子体净化谷物的动力学数学模型，剖析等离子体作用下谷物表面污染物净化机理。.本项目将低温等离子体化学科学应用于粮食安全安全领域，为开发安全、简便、高效、无选择性、无残留毒性的粮食净化保鲜新技术提供理论依据和积累基础数据。

寻求一种安全、简便、无损粮食品质、能在短时、多环境下实现广谱净化的新方法已成为提高粮食安全和人类健康的迫切需要。本项目提出低温等离子体技术，以玉米、小麦为研究对象，对其表面常见农残、微生物及真菌毒素的去除进行了深入探讨。 .项目自行设计“双区式”低温等离子体谷物净化装置，建立了活性物种的浓度分布函数，定量分析了等离子体场中电子•离子、自由基的输送•扩散、衰减分布特征，并验证了其可靠性。对Ar和Air放电进行了电学及光学特性诊断，Ar更易被激发和电离，放电效果更好。项目设计了一种实用化低温等离子体谷物净化设备，日处理量可达500kg。等离子体-谷物表面场中净化效应研究表明，直流电源最佳参数为放电电压20kV，放电时间60s，载气流量1L/min，上升沿50ns，下降沿50ns，脉冲宽度2000ns，电源频率1200Hz时，农药降解率可达毒死蜱-玉米91.5%(Ar), 86.5% (Air)、甲萘威-玉米73.4%(Ar), 65.1% (Air)、百菌清-小麦72.70% (Ar), 67.76%(Air)。交流电源最佳参数为电源电压Ar/Air-150/180V，放电时间60s，载气流量1L/min，占空比100%，放电间隙玉米/小麦-8/6mm时，农药降解率可达毒死蜱-玉米92.56%(Ar), 85.90% (Air)、百菌清-小麦74.12%(Ar), 70.44%(Air)、氯氰菊酯-玉米77.77 %(Ar) , 75.48%(Air)、氯氰菊酯-小麦87.90%(Ar) , 83.96%(Air)。降解效果均为Ar > Air。镰刀菌属（赤霉素）在距放电区0~40cm内的灭活率分别为99.96% (0cm)、99.96% (20cm)和99.95% (40cm)，并建立了“双区式”氩等离子体场中微生物灭活的动力学模型。当农残与微生物同时存在时会抑制微生物灭活效果，农残浓度越高，灭活率越低。将等离子体场活性物种浓度分布与农药FTIR、GC-MS和微生物各生理指标相关联，揭示了农残降解及微生物灭活机理。在Ar/Air的直/交流等离子场中，测定玉米/小麦表面性质及营养成分，得到净化过程中谷物品质的变化，确认了等离子体粮食净化技术的可行性。.本研究为等离子体技术在粮食安全领域的创新应用积累了基础数据，为后续申请国家级相关科研项目及产业化打下了良好的基础。