为了研究老化引起的浸渍活性炭性能、结构上的变化,对在现场应用老化后的浸渍活性炭,开展了其关键物理性能、微观结构等变化特征的实验分析。结果表明:对于老化后除碘效率不合格的浸渍活性炭,其物理性能项中粒度、强度变化并不显著,仍可满足标准要求;但其pH已从9.6显著下降至7左右,与除碘效率、CCl4吸附率的下降趋势一致;扫描电镜和N2吸附测试表明,老化后的浸渍活性炭微观孔结构变化显著,孔道堵塞、边棱磨损严重,比表面积减小、孔径增大。这些物理性能的变化是造成浸渍活性炭老化失效的重要原因之一。
In order to study the changes in properties and structure of impregnated activated carbon(AC) caused by aging,the change characteristics of key physical properties and microstructure of the impregnated AC aged in-place application were analyzed experimentally.It was found that the efficiency of aged impregnated AC adsorbing radioactive methyl iodide was not up to eligibility criteria,however,the physical properties in particle size and strength of theAC did not change significantly,which still met the standard.But its pH value decreased significantly from 9.6 to about 7,which was consistent with the declining trend of iodine removal efficiency and CCl4 adsorption rate.SEM and N2 adsorption tests showed that the pore structure of the AC after aging changed significantly,with channel blockage,edge severe abraded,surface area decreased and pore width increased.These changes in physical properties were one of the important reasons for the aging failure of impregnated AC.
[1] 核工业标准化研究所.NB/T20039.11—2011核空气和气体处理规范 通风、空调与空气净化第11部分:碘吸附器(Ⅰ型)[S].北京:原子能出版社,2011:2-8.
[2] Emma A,Diana B,Mark R S F.Affinity of charcoals for different forms of radioactive organic iodine[J].Nuclear Engineering and Design,2018,328:228-240.
[3] Wilhelm J.Development and application of filters for air cleaning in nuclear power plants[J].Nuclear Engineering and Design,1987,103(1):139-147.
[4] Zhou J,Hao S,Gao L,et al.Study on adsorption performance of coal based activated carbon to radioactive iodine and stable iodine[J].Annals of Nuclear Energy,2014,72:237-241.
[5] Sachin U N,Kai C,Vivek U,et al.Capture of harmful radioactive contaminants from off-gas stream using porous solid sorbents for clean environment-a review[J].Chemical Engineering Journal,2016,306:369-381.
[6] 王坤俊,王龙江,韩丽红,等.核空气净化用浸渍活性炭的中毒老化效应及影响因素分析[J].化工新型材料,2018,46(9):190-194.
[7] Deuber H,Gerlach K.Investigations on the aging of activated carbons in the exhaust air of a pressurized water[J].Reactor Nucl Techn,1985(70):161-169.
[8] Jungsook C W,Chris J M,Miyoko T R.Methyl iodide trapping efficiency of aged charcoal samples from bruce-a emergency filtered air discharge systems[J].Nuclear Technology,1999,125(1):28-39.
[9] González-García C M,González J F,Román S.Removal efficiency of radioactive methyl iodide on TEDA-impregnated activated carbons[J].Fuel Processing Technology,2011(92):247-252.
[10] Kevin W W.Phase I aging assessment of nuclear air-treatment system high efficiency particulate air and adsorbers[J].Nuclear Engineering and Design,1996(163):315-322.
[11] González-García C M,Roman S.Surface free energy analysis of adsorbents used for radioiodine adsorption[J].Applied Surface Science,2013(282):714-717.
[12] So J Y,Cho H R.Thermal characteristics of spent activated carbon generated from air cleaning units in korean nuclear power plants[J].Nuclear Engineering and Technology,2017,49(4):873-880.
[13] 核工业标准化研究所.EJ/T 20056—2014核级活性炭去除甲基碘性能试验方法[S].北京:原子能出版社,2014:2-10.
[14] American Society for Testing and Materials.ASTM D 3803—1998 standard test method for nuclear-grade activated carbon[S].Philadelphia,PA:ASTM International,1998.
[15] American Society for Testing and Materials.ASTM D 3467—2004 standard test method for carbon tetrachloride activity of activated carbon[S].Philadelphia,PA:ASTM International,2004.
[16] American Society for Testing and Materials.ASTM D 2862—2010 standard test method for particle size distribution of granular activated carbon[S].Philadelphia,PA:ASTM International,2010.
[17] American Society for Testing and Materials.ASTM D 3802—1999 standard test method for ball-pan hardness of activated carbon[S].Philadelphia,PA:ASTM International,1999.
[18] American Society for Testing and Materials.ASTM D 3466—2006 standard test method for ignition temperature of granular activated carbon[S].Philadelphia,PA:ASTM International,2006.
[19] American Society for Testing and Materials.ASTM D3838—2011 standard test method for pH of activated carbon[S].Philadelphia,PA:ASTM International,2011.
[20] Han X S,Pei Q L,Zhao Q Z,et al.Capture and reversible storage of volatile iodine by porous carbon with high capacity[J].Journal of Materials Science,2015,50(22):7326-7332.
