The work presented in this thesis is to describe the fabrication of the nano-composites of carbonaceous materials (e.g. graphene oxide) and metal oxides (e.g. Titanium dioxide TiO2) for two specific applications in the field of public health protection: 1.) removal of micropollutants (MPs) in the aqueous environment; 2.) antimicrobial coating.The presence of MPs in aquatic systems threatens ecological and human health. The first objective of this thesis is to develop a robust and self-regenerating adsorbent tailored for MP removal in complex mixtures. Graphene/graphene oxide shows a strong sorption affinity for organic chemicals, but they tend to stack in water spontaneously due to the strong van der Waals force between 2D graphene/graphene oxide nanosheets. 3D crumpled graphene balls (CGBs) are synthesized via a nano-spray drying technique that is structurally stable and exhibits superior adsorption performance compared to granular activated carbon for seven of the eight model MPs on a surface area equivalent basis. The performance of CGB is stable and rapid over a range of field conditions. Adsorption mechanisms, particularly the specificity of adsorption, are probed using sulfonamide(SA)-based compounds and structural analogs. A predictive model of CGB adsorption capacity is formulated based on SA structure/properties. Furthermore, CGB composites with various metal oxides are synthesized to expand the internal adsorptive area (using SiO2) and make the adsorbent photocatalytic and self-regenerating (using TiO2). Eventually, an optimized TiO2:SiO2:GO loading in a composite (called S-MGC) with maximized adsorption and photodegradation ability is determined by using methylene blue as the model contaminant, and the adsorption behavior and photoactivity of S-MGC were investigated via a mixture of MPs. A fixed-bed column is designed to study the in-situ regeneration of S-GMC in a continuous flow reaction system. The overreaching goal is the utilization of S-MGC as a selective and self-regenerating adsorbent for MP control with potential applications in a variety of scenarios (e.g. water/wastewater treatment, targeted pharmaceutical removal in hospital effluents, and source separation to create One Water system). Due to the growing threat of infectious diseases, antimicrobial nanomaterial (ENM) coatings have attracted significant research attention in recent years. The second part of this thesis aims to develop antimicrobial coatings which can help prevent healthcare facility-associated infections. A variety of ENMs, including TiO2, ZnO, CuO, carbonous materials (carbon nanotube and polyaniline), and their composites, were utilized to fabricate antimicrobial ENM-coated surfaces. Two widely used coating technologies (dip-coating and spray-coating) are utilized to prepare nano-sized TiO2 and a variety of composite-coated films (including anatase TiO2, mixed anatase/rutile phase TiO2, silver-anatase TiO2 composite, and carbon nanotube-anatase TiO2 composite) for touch screens in clinical settings. The fabricated thin films show high surface coverage, low surface roughness, super-hydrophilicity, high transparency, and more importantly, robust antiviral performance under LED irradiation. Those properties indicate that TiO2-based coatings are effective in creating antiviral high-touch surfaces with the potential to control infectious diseases and healthcare-associated infections. Also, polyaniline-metal oxide composite (PMC) thin films are fabricated and the participation of PANI is designed to promote the photoactivity of metal oxide coatings (e.g. TiO2, ZnO, CuO) for antibacterial purposes; two strategies for PMC coatings are utilized: i.) PMC particles are synthesized and then coated; ii.) polyaniline is coated onto an existing layer of metal oxide coatings (TiO2, ZnO, and CuO) and forms a bi-layer deposit. PMC coatings using both strategies reveal enhanced antibacterial performance compared to metal oxide-only coatings (E. coil as the model bacteria and Lake Michigan water LMW as the background), which is attributed to the enhanced ROS generation yields of PMC. Yet, the durability test (repeatedly used 3 times) shows a high attenuation occurs to the antibacterial efficiency of PMC coatings because polyaniline becomes non-conductive and inactive in the environment of LMW (pH 7-8). Overall, the results illustrate a proof-of-concept that polyaniline can enhance the antibacterial performance of MO coatings but its pH-sensitivity limits PMC's long-term performance in a realistic environment.

Creator

• Fu, Han

DOI

• https://doi.org/10.21985/n2-e0e8-8v54

Subject

• Environmental engineering

Language

• en

Alternate Identifier

• etdadmin_upload_1013991
• http://dissertations.umi.com/northwestern:16770

Date created

• 2023-01-01

Resource type

• Dissertation

Rights statement

• In Copyright