Alfaro-Cuevas-Villanueva Ruth, Hidalgo-Vázquez Aura Roxana, Cortés Penagos Consuelo de Jesús, Cortés-Martínez Raúl
Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, CP 58060, Edif. B1., CU, Morelia, MICH, Mexico.
Facultad de Químico Farmacobiología, Universidad Michoacana de San Nicolás de Hidalgo, Tzintzuntzan 173 Col. Matamoros, CP 58240, Morelia, MICH, Mexico.
ScientificWorldJournal. 2014 Jan 27;2014:647512. doi: 10.1155/2014/647512. eCollection 2014.
The sorption of cadmium (Cd) and lead (Pb) by calcium alginate beads (CAB) from aqueous solutions in batch systems was investigated. The kinetic and thermodynamic parameters, as well as the sorption capacities of CAB in each system at different temperatures, were evaluated. The rate of sorption for both metals was rapid in the first 10 minutes and reached a maximum in 50 minutes. Sorption kinetic data were fitted to Lagergren, pseudo-second-order and Elovich models and it was found that the second-order kinetic model describes these data for the two metals; comparing kinetic parameters for Cd and Pb sorption a higher kinetic rate (K2) for Pb was observed, indicating that the interaction between lead cations and alginate beads was faster than for cadmium. Similarly, isotherm data were fitted to different models reported in literature and it was found that the Langmuir-Freundlich (L-F) and Dubinin-Radushkevich (D-R) models describe the isotherms in all cases. CAB sorption capacity for cadmium was 27.4 mg/g and 150.4 mg/g for lead, at 25 °C. Sorption capacities of Cd and Pb increase as temperature rises. According to the thermodynamic parameters, the cadmium and lead adsorption process was spontaneous and endothermic. It was also found that pH has an important effect on the adsorption of these metals by CAB, as more were removed at pH values between 6 and 7.
研究了在间歇系统中，海藻酸钙珠（CAB）对水溶液中镉（Cd）和铅（Pb）的吸附情况。评估了不同温度下各系统中CAB的动力学和热力学参数以及吸附容量。两种金属的吸附速率在前10分钟内很快，并在50分钟时达到最大值。吸附动力学数据拟合到 Lagergren、准二级和Elovich模型，发现二级动力学模型能描述这两种金属的数据；比较Cd和Pb吸附的动力学参数，观察到Pb的动力学速率（K2）更高，这表明铅阳离子与海藻酸钙珠之间的相互作用比镉更快。同样，等温线数据拟合到文献中报道的不同模型，发现Langmuir-Freundlich（L-F）和Dubinin-Radushkevich（D-R）模型在所有情况下都能描述等温线。在25℃时，CAB对镉的吸附容量为27.4mg/g，对铅的吸附容量为150.4mg/g。Cd和Pb的吸附容量随温度升高而增加。根据热力学参数，镉和铅的吸附过程是自发的且吸热的。还发现pH值对CAB对这些金属的吸附有重要影响，在pH值为6至7时，更多的金属被去除。
