Functional Aerogels and Composites for Wastewater Remediation: Targeted Dyes and Antibiotics Adsorption

Abstract

Water pollution is one of the most challenging environmental problems, due to unprocessed wastewater discharge from industries, hospitals, sewage, etc. Antibiotics and organic dyes, stemming from these sources, are pollutants that have damaging effects on human and aquatic life. Due to their high porosity, high surface area and low densities, aerogels and metal-organic frameworks (MOFs) make good candidates as adsorbents in water remediation, tackling these contaminants. This work includes three projects studying different types of these pollutants and adsorbents. The first project focuses on the development of novel metal oxide aerogel/MOF composite materials, prepared via the epoxide-assisted sol-gel process, where different MOFs were incorporated into the sol before the addition of the gelling agent. The synthesized composites were tested for their ability to adsorb various anionic and cationic toxic dyes under different experimental conditions. While the second project investigates the effect of select first-row transition metals on the adsorption capacity and stability of the aerogel network. Here, the sol-gel method was used to synthesize a series of metal-aluminum oxide aerogels, and their performance was evaluated via dye adsorption. Ultraviolet-Visible Spectroscopy was utilized as a primary method for quantification in these two projects. The third project, on the other hand, involves the synthesis of imine-functionalized silica aerogels. Pristine aerogel, prepared using alkoxide precursors, was post-modified by reacting it with a synthesized Schiff base. The adsorption of antibiotics from simulated wastewater onto the synthesized aerogel, under various conditions, was quantified using High-Performance Liquid Chromatography. In all the projects, the aerogels were obtained upon drying the synthesized gels under supercritical carbon dioxide conditions. In addition to kinetics, thermodynamics, and other experimental studies, the structure, porosity, morphology, crystallinity and thermal stability of the synthesized materials were comprehensively characterized using Fourier Transform Infrared Spectroscopy, Nitrogen adsorption-desorption techniques, Scanning Electron Microscopy, X-ray Diffraction, and Thermogravimetric Analysis.