Highest and Fastest Removal Rate of PbII Ions through Rational Functionalized Decoration of a Metal–Organic Framework Cavity

To overcome the challenge of developing a multipurpose adsorbent for effective removal of toxic and carcinogenic PbII ions from aqueous solutions, a made-for-purpose functional group (N1 ,N2 -di(pyridine-4-yl)oxalamide) was rationally designed and incorporated into the cavities of a Zn metal-organic framework (MOF), namely, TMU-56. Large enough pore size along with high densities of strong metal chelating sites lead not only to the highest uptake capacity for PbII ions, but also the fastest removal rate that has ever been reported for functionalized MOFs, occurring in just 20 s. Moreover, high concentrations of lead ions favor the ion exchange reaction, resulting in a high degree of metal exchange. In addition, TMU-56 can be a practical adsorbent because of its notable performance in the simultaneous removal of several toxic and carcinogenic heavy metals from wastewater, which has rare precedence.