Reuse of Predesigned Dual-Functional Metal Organic Frameworks (DF-MOFs) after Heavy Metal Removal

Designing porous and functionalized adsorbents and achieving high efficiency in heavy metals removal from wastewater is in the spotlight of environmental science. On the other hand, upon removal, adsorbents are still highly hazardous requiring that great care be taken in its packaging, transporting and storing. A fundamental route in the synthesis of functional extended structures is the ability to combine different chemical entities in a controlled way in order to achieve high performance. Herein, we report the systematic design of dual-functionalized metal organic framework (TMU-81) by incorporating sulfonyl and amide groups for the removal of Cd(II), Cu(II) and Cr(II) ions from simulated aqueous solutions. TMU-81 showed significant enhancement in heavy metals uptake suggesting that the strong host - guest interactions between cations and the donor sites play a major role in adsorption process. The maximum adsorption capacity for Cd²⁺ was 526 mg/g which is among the highest values reported for similar MOFs and other porous materials. The good performance in uptake and selectivity of TMU-81 can be attributed to the network structure that shaping the void, create mono-dimensional channels, decorated by exposed oxygen atom sites selective for Cadmium ion. Environmental "compatibility" of a treated MOFs was studied in order to evaluate its possible recycling as a new template for different applications by using pyrolysis method. Engineering of the pore surface provides a potential for MOF with a hybrid interface to act as a versatile tool for the design of multifunctional nanoparticles to meet specific application requirements.