An In Situ Procedure for the Preparation of Zeolitic Imidazolate Framework-8 Polyacrylamide Hydrogel for Adsorption of Aqueous Pollutants

Metal-organic frameworks (MOFs) have attracted a lot of attention in recent years because of their high surface area and tunable porosities, which allow them to serve as excellent and versatile adsorbents for pollutants in water/wastewater. One of the demanding challenges of using MOFs is that they need to be supported on a substrate or in a matrix to be easier to operate and more efficiently used. This work presents a simple in situ method of synthesizing one of the most popular MOF particles, zeolitic imidazolate framework 8 (ZIF-8), in a polyacrylamide (PAM) hydrogel using a zinc hydroxide PAM composite as a precursor gel. Characterization of the prepared ZIF-8 PAM composite hydrogel by scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy confirms the successful synthesis of ZIF-8 particles on the surface of and inside the PAM hydrogel. To test the potential of this novel material as an adsorbent, its ability to remove humic acid (HA), a model organic pollutant, from water is evaluated. The maximum adsorption capacity for HA is found to be 111.5 +/- 3.0 mg g(-1) ZIF-8, comparable to the performance of other adsorbents for the removal of HA.