改性废弃皮革对U(Ⅵ)的动态吸附

Dynamic adsorption of U(Ⅵ) by modified leather waste

以改性废弃皮革为吸附剂对U(Ⅵ)进行动态吸附实验,采用直径3 cm、高50 cm的玻璃吸附柱,在填料高度为3、4和5 cm,U(Ⅵ)溶液进水流速为0.85、1.7和2.55 m L·min^(-1),初始U(Ⅵ)浓度为6、12和18 mg·L^(-1)的条件下,考察了各因素对U(Ⅵ)吸附穿透曲线的影响。动态实验表明:柱高的降低、流速的增大和U(Ⅵ)浓度的增加均会使穿透时间提前;动态吸附穿透曲线能很好地符合Thomas模型的条件(R2> 0.95),同时吸附量的预测值与实际测试值较为接近。使用穿透时间(ta)与填料高度(h)的关系式ta=220h-433(R2=0.998),在仅改变流速和初始U(Ⅵ)浓度时,穿透时间预测值与实际测试值相差较小,表明BDST模型能确定固定床的动态吸附周期。

The dynamic adsorption of U（Ⅵ） by modified leather waste was investigated in this study. Effects of various factors on the breakthrough time were studied by a glass adsorption column with a diameter of 3 cm and a height of 50 cm, including column heights（3, 4 and 5 cm）, flow rates（0.85, 1.7 and 2.55 m L·min^（-1）） and initial concentrations（6, 12 and 18 mg·L^（-1））. The results indicated that the breakthrough time would be apparently reduced with increase in the flow rate and initial concentration or with decrease in column height. Thomas model was used to fitted the breakthrough curve, the significant coherence（R2 0.95） exists between the experimental and theoretical results for the amount of adsorption. The relationship between breakthrough time（ta） and packing height（h） was ta = 220 h-433（R2= 0.998）. The results showed that the error between the predicted and experimental values of breakthrough time was small when the flow rate and the initial U（Ⅵ） concentration are only changed. Based on these results, the bed depth service time（BDST） model can be used to predict the breakthrough time with certain flow rate and the initial U（Ⅵ） concentration.