L-Cysteine functionalized NH2-MIL-53(Al) for Pb2+ and Ni2+ removal from aqueous solution

Abstract

The hazardous effects of Pb2+ and Ni2+ exposure on human health and environment have become a serious problem. As a new class of porous materials, Metal-organic framework has its unique advantages, so it has great adsorption potential for heavy metals. In the present study, to remove Pb2+ and Ni2+ from aqueous solutions, an original material NH2-MIL-53(Al) was directly graft with l-cysteine to obtain the modified MOFs material l-Cysteine–NH2–MIL-53(Al). The adsorption capacity of l-Cysteine–NH2–MIL-53(Al) had a five-fold elevation than the original material. Further results showed that the l-Cysteine–NH2–MIL-53(Al) exhibited an excellent adsorption property even under the weakly acidic conditions. The adsorption process of Pb2+ and Ni2+ by l-Cysteine–NH2–MIL-53(Al) accorded with the pseudo-secondary kinetic and the Langmuir adsorption model. The maximum adsorption capacity obtained by Langmuir fitting was 12.11 ​mg ​g−1 (Ni2+) and 38.01 ​mg ​g−1 ​(Pb2+) respectively. At the same time, the experiment showed that the material has good reuse effect. In addition, the adsorption process was analyzed by adsorption model and molecular simulation, which better explained the mechanism that the adsorption process was chemical adsorption. In this study, the adsorption process was analyzed from the angle of experiment and mechanism, and the results showed that the material had potential application value in adsorbing Pb2+ and Ni2+.