Silver nanoparticles supported on UiO-66 (Zr): As an efficient and recyclable heterogeneous catalyst and efficient adsorbent for removal of indigo carmine

As incorporating silver nanoparticles (Ag NPs) into zirconium metal-organic frameworks (UiO-66) offer an extensive potential in numerous applications such as wastewater treatment and catalysis, we herein synthesized UiO-66, followed by incorporating different contents of Ag NPs into UiO-66. The prepared UiO-66 composites were identified by means of various techniques like X-ray-diffraction patterns (XRD), nitrogen adsorption desorption (BET), transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FTIR) analysis. Besides, acidic properties of composites were examined using FTIR of chemisorbed pyridine and non-aqueous potentiometric titration. The results displayed that UiO-66 crystals exhibited sizes of 180 and 240 nm. Their surface area and total pore volume respectively reached 1593 m2 g−1 and 0.834 m3 g−1, and decreased by incorporating Ag NPs to 863 m2 g−1 and 0.432 m3 g−1 at 5.0 wt% Ag/UiO-66. TGA data manifested that adding Ag NPs could improve the thermal stability of the primitive UiO-66. The as-synthesized composites were tested towards indigo carmine (IC) adsorption from aqueous media and in synthesis of 3,4-dihydro-pirimidin-2(1H)-ones (3,4-DHPs). The adsorption data showed that silver nanoparticles incorporation enhanced IC removal performance of UiO-66 and adsorption capacity was augmented from 87.2 mg g−1 (UiO-66) to 312.8 mg g−1 at 2.0 wt% Ag/UiO-66. This performance was efficient relying on adsorption isotherm measurements, indicating that incorporating Ag NPs augmented the number of adsorption sites and π–π interactions between adsorbate and adsorbent were enhanced, resulting in improved adsorption capacity towards anionic dyes. Also, incorporated Ag NPs show better catalytic activity in the preparation of DHPs and the yield reached 88% using 2.0 wt% Ag/UiO-66, imparting excellent recyclability for four cycles. [Display omitted]