Alba Janette, Navarro Ricardo, Saucedo Imelda, Vincent Thierry, Guibal Eric
Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, C.P. 36040, Mexico.
Centre des Matériaux des Mines d'Alès, Ecole des mines d'Alès, F-30319 Alès cedex, France.
Materials (Basel). 2017 Jun 9;10(6):634. doi: 10.3390/ma10060634.
The decontamination of dilute industrial effluents is a critical challenge for decreasing the environmental impact of mining and metallurgical activities. As an alternative to conventional processes, new extractant impregnated resins (EIRs) have been synthesized by the immobilization of Cyanex 301 and Cyanex 302 in alginate capsules using two different procedures (matrix-type immobilization vs mononuclear encapsulation). These materials have been tested for Pb(II) sorption from acidic solutions. The Langmuir equation fitted well the sorption isotherms and the maximum sorption capacities vary between 24 and 80 mg·g at pH 1, depending on the type and loading of the extractant in the EIR. Uptake kinetics were controlled by the resistance to intraparticle diffusion; though both the Crank equation (intraparticle diffusion) and pseudo-second order rate equation equally fitted uptake profiles. The amount of extractant immobilized in mononuclear capsules is lower than in matrix-type beads; this leads to lower sorption capacities but slightly better mass transfer properties. The balance between the advantages and drawbacks of the different systems makes more promising matrix-type capsules. The desorption of Pb(II) is possible using 1 M HNO₃ solutions: metal ions were completely desorbed. However, the probable oxidation of the extractants (conversion to oxidized forms more sensitive to pH) reduces the sorption efficiency when they are re-used.
稀释工业废水的净化是降低采矿和冶金活动对环境影响的一项关键挑战。作为传统工艺的替代方法，通过两种不同程序（基质型固定化与单核包封）将Cyanex 301和Cyanex 302固定在藻酸盐胶囊中，合成了新型萃取剂浸渍树脂（EIRs）。已对这些材料从酸性溶液中吸附Pb(II)的性能进行了测试。Langmuir方程能很好地拟合吸附等温线，在pH为1时，最大吸附容量在24至80 mg·g之间变化，这取决于EIR中萃取剂的类型和负载量。吸附动力学受颗粒内扩散阻力控制；尽管Crank方程（颗粒内扩散）和伪二级速率方程都能同样很好地拟合吸附曲线。固定在单核胶囊中的萃取剂数量低于基质型珠粒中的数量；这导致吸附容量较低，但传质性能略好。不同体系优缺点之间的平衡使得基质型胶囊更具前景。使用1 M HNO₃溶液可以实现Pb(II)的解吸：金属离子能完全解吸。然而，萃取剂可能发生的氧化（转化为对pH更敏感的氧化形式）会降低其重复使用时的吸附效率。
