气隙式膜蒸馏处理模拟放射性废液

Treatment of Simulated Radioactive Waste Liquid by Air-Gap Membrane Distillation

采用气隙式膜蒸馏对模拟放射性废液的处理进行了工艺实验研究,以膜通量和Cs^(+)、Sr^(2+)、Co^(2+)、UO_(2)^(2+)的截留率为评价指标,对聚四氟乙烯(PTFE)、聚偏氟乙烯(PVDF)和聚丙烯(PP)疏水膜进行了性能比较分析,并重点讨论了料液温度、料液流速、气隙厚度等因素的影响规律。结果表明:料液温度的变化对膜通量的影响最为明显,升高料液温度可以显著提高膜通量,料液温度从60℃升高到90℃,孔径为0.22μm的PTFE膜通量从4.79 kg/(m^(2)·h)提升到了16.24 kg/(m^(2)·h);增大料液流速可在一定范围内快速提高膜通量,但随着流速的增大,膜通量的提高速率减慢;加大气隙厚度会使膜通量下降;在实验考察的条件范围内,改变工艺条件参数对离子的截留率没有明显的影响。在上述三种疏水膜中,孔径为0.22μm的PTFE膜对离子的截留性能最佳,对上述离子的截留率均在99.97%以上,是更适合应用到膜蒸馏处理放射性废液过程的膜材料。

The treatment of simulated radioactive wastewater by air-gap membrane distillation process was conducted.The membrane flux and rejection rates of Cs^(+),Sr^(2+),Co^(2+)and UO_(2)^(2+) were used as indexes to evaluate the performance of PTFE,PVDF and PP hydrophobic membranes.The effects of feed temperature,feed flow rate and air gap thickness on membrane flux and the rejection rates were discussed.The results show that the feed temperature has the most significant effect on the membrane flux.Increasing the feed temperature can significantly increase the membrane flux.The membrane flux of PTFE membrane with a pore size of 0.22μm increases from 4.79 kg/(m^(2)·h)to 16.24 kg/(m^(2)·h),when the feed temperature increases from 60℃to 90℃.Increasing the feed flow rate can notably increase the membrane flux in the lower feed flow rate range.But with the increase of feed flow rate,the increase rate of membrane flux is slowing down.Increasing the air gap thickness decreases the membrane flux.Within the experimental conditions,the process conditions have no obvious effect on the rejection rate.Among the above three hydrophobic membranes,the PTFE membrane with a pore size of 0.22μm has the best rejection performance with the rejection rate above 99.97%.The PTFE membrane with a pore size of 0.22μm is more suitable to be applied to treat radioactive wastewater by the membrane distillation process.