A dithiocarbamate-functionalized Zr4+ MOF with exceptional capability for sorption of Pb2+ in aqueous media

Abstract

Herein, we report the initial example of a dithiocarbamate (DTC)-functionalized metal-organic framework (MOF), A1.5[Zr6O4(OH)4(NH2-BDC)4.5(CS2NH-BDC)1.5] (A-MOR-1-NHCS2) (A = Et3NH+, Na+; BDC2- = terephthalate), which was prepared via post-synthetic modification of an amino-functionalized Zr4+ MOF (MOR-1). The new MOF showed extremely fast sorption for Pb2+, achieving ~100% removal within 1 min and its maximum Pb2+ sorption capacity (334±23 mg g-1) greatly exceeds that (75± 3mg g-1) of the pristine material. Furthermore, the modified MOF was demonstrated to be an excellent Pb2+ sorbent in a wide pH range, as well as in the presence of various coexisting cations. It is also remarkable that the sorption process with the DTC-functionalized MOF has led to final Pb2+ concentrations well-below the acceptable limit of Pb2+ in water (10 ppb). In addition, the amino-functionalized MOR-1 starting material can be fully recovered from the Pb2+-loaded MOF after its treatment with acidic solution, and subsequently be reused for the preparation of new DTC-functionalized sorbent. All the above indicate the DTC-functionalized MOF as one of the most promising Pb2+ sorbents ever reported.