基于硅基冠醚分离90Sr的辐照性能研究

Effect of Irradiation on Adsorption Property of 90Sr by Porous Silica-based Crown Ether Adsorbent

  • 摘要: 吸附剂的辐射稳定性是评价其在高放废液中实际应用的重要指标。采用旋转蒸发减压法将4′,4′(5″)-二(叔丁基环己基)-18-冠-6(DtBuCH18C6)担载至硅基载体中,合成大孔硅基冠醚吸附剂。研究吸附剂在60Co-γ辐照条件下对Sr的吸附性能及重复利用性能。通过扫描电镜(SEM)、傅里叶红外光谱(FT-IR)和压汞(MIP)对吸附剂进行表征。结果表明:吸附剂粒径为100 μm,分布概率最高为28.12 nm,孔隙率为56.66%。当γ辐照吸收剂量>100 kGy后,吸附剂的FT-IR图谱中观察到羰基的吸收峰,但冠醚特征的C—O—C伸缩振动吸收峰无明显变化。吸附过程符合Langmuir模型,吸附量随着吸收剂量增加而降低。当吸收剂量<100 kGy时,辐照对吸附剂的Sr吸附量的影响<15%,但吸收剂量达到500 kGy后,饱和吸附量仍达到0.16 mmol/g。以去离子水作为洗脱剂经过5次吸附-解吸后,吸附剂效果仍高达88.9%,具有较好的重复利用性。

     

    Abstract: The radiation stability of adsorbent is an important reference for its practical application in high level liquid waste. A silica-based crown ether adsorbent was synthesized by impregnation the 4′,4′(5″)-Di(tert-butylcyclohexano)-18-crown-6(DtBuCH18C6) into the porous silica support. The effect of 60Co-γ irradiation on the adsorption and reuse performance of Sr(Ⅱ) has been investigated. The characterization of adsorbent was examined using SEM, FT-IR, and MIP. The adsorbent possessed spherical and porous particles with a diameter of approximately 100 μm, a distribution frequency peak of pore size around 28.12 nm, and high porosity of 56.7%. At absorbed dose above 100 kGy, the absorption peak of carbonyl groups was observed in FT-IR spectrum while the C—O—C stretching vibration of crown ether without discernible changes. The adsorption process conformed well with Langmuir model and the adsorption capacity was decreased with increasing absorbed dose. The adsorption capacity decreased slightly (<15%) under 100 kGy absorbed dose and remained at 0.16 mmol/g at a dose of 500 kGy. A relatively high adsorption efficiency of 88.9% was obtained after 5 times adsorption/elution cycles, indicating the excellent reusability of crown ether adsorbent.

     

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