High Efficiency and Fast Removal of Trace Pb(II) from Aqueous Solution by Carbomethoxy-Functionalized Metal-Organic Framework

Lead (Pb) is one of the most widespread toxic heavy metals, and how to quickly and completely remove trace Pb(II) is a global concern. Herein, we prepared a novel metal-organic framework (MOF) {[Cd(ADB)L-2]center dot 1.5DMF center dot 2H(2)O}(n) (1) decorated with carbomethoxy groups and investigated the Pb(II) removal performance as well as the underlying mechanism. The MOF exhibits a fast kinetics with the kinetic rate constant k(2) of 0.162 g mg(-1) min(-1), which is 1-3 orders of magnitude higher than the reported Pb(II) adsorbent materials. In addition, even in a concentration of 0.1 ppm, a high removal efficiency (96%) was still obtained after the treatment with the metal-organic framework, and the concentration was reduced to 0.004 ppm, which is well below the drinking water standard of the World Health Organization (0.01 ppm). The possible adsorption mechanism was systematically verified by Fourier-transform infrared and X-ray photoelectron spectroscopy investigations. The significant affinity between carbomethoxy groups and Pb(II) is responsible for the good removal performance.