Evaluation of metal-organic frameworks, eggshell-derived hydroxyapatite and layered double hydroxides in adsorption and photocatalytic processes

Abstract

This dissertation aims to synthesize novel catalysts, examine their structural features and ultimately evaluate their performances in adsorption and photocatalytic degradation processes. In this respect, the dissertation has three chapters. The first chapter reports TiO2 and ZnO loaded metal- organic frameworks (MOFs). Cu-BTC and ZIF-8 are selected as hydrophilic and hydrophobic MOFs, respectively. The second chapter investigates two supported catalyst systems; ZnO and La-ZnO loaded eggshell and ZnO and La-ZnO loaded eggshell derived hydroxyapatite (HAP). The third chapter examines binary layered double hydroxides (LDHs), fly ash, zeolite and ZIF-8 supported LDHs and ternary LDHs. The crystal structure, surface morphology and functional properties of the as-prepared catalysts are determined using an X-ray diffractometer (XRD), nitrogen adsorption-desorption isotherms (BET), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS). Dark adsorption capacities and photocatalytic performances of the catalysts are controlled in the presence of methyl orange (MO) anionic dye, methylene blue (MB) cationic dye and salicylic acid (SA). The effect of relative humidity (RH) is also studied for the catalysts prepared in the first and second chapters. Dark kinetic analysis is followed via pseudo-first and pseudo-second order models. Langmuir, Freunlich and Temkin isotherms are employed to determine MO, MB and SA interactions with the catalysts. Pseudo-first order kinetic model and Langmuir- Hinshelwood kinetic analysis are studied for experiments under irradiation.