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采用气相色谱法间接测定了光照下纳米及常规TiO2、ZnO悬浮液中.OH的产生情况.结果表明,光照下常规TiO2及ZnO悬浮液中没有检测到.OH,而纳米TiO2及ZnO悬浮液在日光灯及紫外灯照射下的.OH生成量与时间之间具有较好的线性关系,120h内溶液中.OH含量随纳米颗粒浓度(<200mg.l-1)的升高而逐渐升高;但当纳米颗粒浓度高于200mg.l-1时,.OH含量不再随纳米颗粒浓度升高而增加.本实验中不同光照条件下纳米颗粒悬浮液中.OH产生速率各不相同,其中普通日光灯照射下.OH产生速率最慢、紫外光(254nm)其次、太阳光最快,而避光条件下没有检测到.OH.同时,.OH的产生与纳米颗粒化学组成十分相关,在日光灯照射下纳米TiO2的.OH产生速率为纳米ZnO的2—4倍(200mg.l-1的纳米TiO2、ZnO在日光灯照射下的.OH生成速率分别为0.0239mmol.l-.1h-1、0.010mmo.ll-1.h-1).由于.OH是活性氧簇(ROS)中毒性最强的自由基之一,所以金属纳米氧化物颗粒在不同条件下产生的ROS应作为纳米材料水生态毒理学研究的主要因素之一.
The production of .OH in nanosized TiO2 and ZnO suspensions under indirect illumination was measured by gas chromatography.The results showed that no OH was detected in the conventional TiO2 and ZnO suspensions under illumination, There was a good linear relationship between .OH generation and time under the irradiation of fluorescent lamp and UV lamp. The content of OH in solution increased with the increase of nanoparticle concentration (<200mg.l-1) within 120h; however, When the nanoparticle concentration is higher than 200mg.l-1, the content of OH no longer increases with the increase of nanoparticle concentration.In this experiment, under different light conditions, the production rate of .OH in the nanoparticle suspension varies, Under the irradiation, the production rate of OH is the slowest, the UV light (254nm) is the second, the sunlight is the fastest, while the darkness is not detected. OH. At the same time, .OH is closely related to the chemical composition of nanoparticles, The production rate of nano-TiO2 is 2-4 times that of nano-ZnO (200mg.l-1 nano-TiO2, the OH generation rate of ZnO under fluorescent light irradiation is 0.0239mmol.l-1h-1, 0.010mmo respectively. ll-1.h-1). Since OH is one of the most toxic free radicals in reactive oxygen species (ROS), ROS metal oxide nano-particles produced under different conditions should be used as one of the main factors of nanomaterials ecotoxicological water.