节球藻毒素的紫外光降解研究

Degradation of nodularin by ultraviolet light( UV)

为优化节球藻毒素(NOD)光解处理的最佳光源及反应条件,利用自制光反应装置研究了NOD在暗反应、可见光、暗反应+TiO_2、可见光+TiO_2及单独紫外光(UVA、UVB、UVC)处理下的去除效果,继而选择UVC作为最佳光源进行后续实验,探讨NOD初始浓度、温度、p H和光强对NOD去除效果的影响及反应动力学.结果表明:暗反应、可见光、可见光+TiO_2的组合、UVA和UVB均对NOD无显著去除作用,最高去除率约为20%;UVC处理可以快速去除水中NOD,其去除过程符合二级动力学.UVC处理时,pH对NOD的去除无显著影响;温度升高,NOD去除率缓慢增大,但组间差异并不显著;初始浓度越大,NOD去除率越低;光强增大,NOD去除率快速升高,但到达一定临界值后保持稳定状态.3种因素对UVC去除NOD的影响程度由大到小分别为:光强>时间>温度.光强318μW·cm^(-2)、p H=7、温度30℃、反应时间4 h为最佳处理条件,此时NOD去除率最高,初始浓度为0.1μg·m L^(-1)的NOD几乎被完全去除,残留浓度低于WHO及我国规定的藻毒素含量限值.研究表明,UVC光解NOD安全高效,是一种非常理想的NOD去除方法.

In order to optimize the light source and reaction conditions of photolysis for removing nodularins（ NOD）,self-made light reaction device was used to study the removal efficiency of nodularin under different light conditions,including dark,visible light,dark with Ti O2,visible light with Ti O2 and ultraviolet light（ UVA,UVB,and UVC）. UVC was chosen as the best light source to test the influence of NOD initial concentration,temperature,p H and light intensity on the removal efficiency of NOD photolysis and the kinetics of photolysis was developed. The results show that the dark condition,visible light with and without TiO_2,UVA and UVB had no obvious effect on NOD removal with the highest rate about 20%. UVC could remove NOD rapidly and the process could be well described by the second order kinetic model. p H had no significant effect on NOD photolysis under UVC illumination.the removal rate of NOD increased slowly with the increase of temperature. Meanwhile,the removal rate decreased with the increase of NOD initial concentration,and increased rapidly with the increase of light intensity but remained stable when light intensity reached to a certain threshold. The effect sequences of three main factors on NOD removal were as follows： light intensity time temperature. After 4 h of treatment with initial NOD concentration of 0.1 μg·m L-1,99.60% of NOD could be removed and the remaining content complied with the algal toxin limit of WHO and China＇s rules with light intensity 318 μW·cm^（-2）,pH 7 and temperature 30 ℃.The results indicate that UVC photolysis can remove NOD safely,efficiently and can be considered as an ideal method to remove NOD.