Liao Xuepin, Lu Zhongbi, Du Xiao, Liu Xin, Shi Bi
The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, P R China.
Environ Sci Technol. 2004 Jan 1;38(1):324-8. doi: 10.1021/es034369a.
Tannins, which are rich in ortho-hydroxyl groups, have a high affinity for UO2(2+). In this paper, Myrica rubra tannin was immobilized on collagen fiber by an aldehydic cross-linking reaction to prepare a novel adsorbent for uranium (UO2(2+)) recovery from wastewater. The adsorption equilibrium, the adsorption kinetics, and the effects of temperature and pH on the adsorption equilibrium were investigated in detail. It was found that the Myrica rubra tannin immobilized on collagen fiber exhibits an excellent adsorption capacity for UO2(2+). The adsorption capacity at 293 K and pH 5.0 was as high as 1.19 mmol UO2(2+)/g (283.3 mgU/g) when the initial concentration of UO2(2+) in solution was 7.5 mmol/L. The adsorption isotherms could be described by the Freundlich equation, and the increase of temperature promoted the adsorption to UO2(2+) . The adsorption kinetics data were fitted very well by the pseudosecond-order rate model, and the equilibrium adsorption capacity calculated by the pseudo-second-order rate model was almost the same as that determined by the actual measurement with the error < or = 4%. The pH has a significant effect on the adsorption process. According to our experiments, the suitable pH scope should be 5-8.
富含邻羟基的单宁对UO2(2+)具有高亲和力。本文通过醛交联反应将杨梅单宁固定在胶原纤维上，制备了一种用于从废水中回收铀（UO2(2+)）的新型吸附剂。详细研究了吸附平衡、吸附动力学以及温度和pH对吸附平衡的影响。结果发现，固定在胶原纤维上的杨梅单宁对UO2(2+)表现出优异的吸附能力。当溶液中UO2(2+)的初始浓度为7.5 mmol/L时，在293 K和pH 5.0条件下的吸附容量高达1.19 mmol UO2(2+)/g（283.3 mgU/g）。吸附等温线可用Freundlich方程描述，温度升高促进了对UO2(2+)的吸附。吸附动力学数据用准二级速率模型拟合得很好，由准二级速率模型计算得到的平衡吸附容量与实际测量值几乎相同，误差≤4%。pH对吸附过程有显著影响。根据我们的实验，合适的pH范围应为5-8。
