A competent Magnetic MOF Catalyst of Gadolinium-Nanoparticles-Decorated Graphitic Carbon Nitride (g-C3N4) @ Functionalized UiO-66-COOH as a novel and efficient MOF-Catalyst to remove Heavy Metals

Porous materials have attracted much attention recently because of versatile applications in industry, especially for adsorption, separation, and catalysis. Metal–organic frameworks (MOFs) are typical porous materials composed of both inorganic and organic species. MOFs have been widely studied because of their facile syntheses, high porosity, designable pore structures (from microporous to mesoporous regions), easy functionalization, and potential applications. In particular, a zirconium–terephthalate MOF, UiO-66, is very interesting owing to its high stability, versatile syntheses, and easy modification. UiO-66s with acidic sites, such as carboxylic, have been synthesized for acid catalyses and adsorptions. UiO-66 MOFs with free –COOH groups could be obtained by several methods such as direct synthesis, ligand exchange, and post-modification. For direct synthesis of UiO-66-COOH and UiO-66-(COOH)2, 1,2,4-benzene tricarboxylic acid and 1,2,4,5-benzene-tetracarboxylic acid (BTEC), respectively, were applied as the organic linker. These adsorption studies can not only suggest potential applications of the obtained MOFs but also confirm the presence of free –COOH. In this work, we still confined ourselves to the model MOF system of carboxylic acid-functionalized, Zr-based UiO-66-COOH, in the superior chemical and hydrothermal stability of UiO-66 as well as the COOH -modification-induced improvement in absorption capacity. This work is motivated to identify newly synthesized MOF nano-catalyst via metal-organic frameworks UiO-66-Type with free carboxylic acid as an efficient MOF functionalized magnetic graphitic carbon nitride (Fe3O4/g-C3N4) via decoration of Gadolinium- Nanoparticles. In order to prepare a highly efficient catalyst UiO-66-COOH @ g-C3N4/Fe3O4 @ Gd-NPs as a heterogeneous catalyst for applying to remove Heavy Metals which have been investigated. In this process, the design, synthesis and construction of a type of metal-organic framework UiO-66 under the title UiO-66-COOH was investigated. UiO-66 (Zr)-type metal organic framework with free carboxylic acid was synthesized in one step from zirconium chloride (ZrCl4) and 1,2,4-BTC (1,2,4-benzene tricarboxylic acid). Graphitic carbon nitride (g-C3N4), as a polymeric semiconductor, is promising for some applications because of its suitable electronic structures, together with the low cost, facile preparation, and metal-free feature. Since it exhibits a stacked structure, g-C3N4 is often considered as sp2-hybridized nitrogen-substituted graphene. So, UiO-66-COOH can be decorated to Gadolinium nanoparticles using g-C3N4 nitrogen-substituted.