Date of Award
August 2021
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Chemistry
Committee Member
Stephen E. Creager
Committee Member
Rhett C. Smith
Committee Member
Scott M. Husson
Abstract
Although almost 70% of the world is covered by water, less than 3% is fresh. The remainder—most of the Earth’s water is saline. To meet humanity’s increasing and unavoidable need for water, we must convert saline water into freshwater through desalination. Many desalination technologies are available, and membrane-based technologies, such as reverse osmosis (RO), are widely used. Though RO is especially common, desalination through RO faces several challenges. For example, high operation cost due to high pressure during the process or its degradable polymeric active layer in contact with chlorine-containing compounds. In terms of general functionality and energy consumption, water transport through membranes could still be improved by increasing membrane permeability. Still, progress in this area has been impeded by a lack of data about how polymer membrane chemistry and structure affect fundamental transport properties. Current composite membranes have permeability less than two times higher than those produced twenty years ago.One of the most famous and recently studied candidates for use in RO or NF membranes is graphene, which has excellent chemical and mechanical stability. In addition, it is the most prominent thinnest possible membrane, with its one atom thickness acting as the membrane. As a further benefit, graphene manifests greater resistance to chlorine than current polyamide membranes. This research focused on the design and studies of CVD graphene-based membranes on modified support for water treatment applications. In this study, the process of transferring chemical vapor deposition (CVD) Graphene onto a physical, hot pressing, and chemical modified substrate like hydrogel will be discussed. The method of transferring the single layer of graphene to the substrate is challenging because the CVD graphene is fragile and can easily be torn if it is directly transferred to the unmodified support structure. A hydrogel substrate—polyvinyl alcohol (PVA)—has been synthesized and crosslinked to allow graphene transfer without damage. The degree of crosslinking, the thickness of the casting can affect the permeability of a PVA membrane. The graphene is transferred onto the PVA support by a simple but unique approach to decrease the chance that defects will form. Also, physically modification could reduce the surface roughness, in this regardes the hot pressing on the substrate was used to modified the support for a single layer of graphene, and then the results were analyzed. It was reported that by using plasma through the graphene can create sub-nanometer pores that make the graphene more selective and Making tunable nanometer pores by different type of plasma. Consequently, the results of the nitrogen plasma treatment will be discussed with the different conditions used to apply nanometer pores on the graphene surface. Experimental work combined with membrane characterization methods (FESEM, AFM, and LEXT) and membrane performance studies using a direct flow system to examine the graphene as the membrane will be presented. These results will be compared with the other synthesized membrane and different types of supports. This research will provide insights into developing CVD graphene-based membranes with low defects and high water permeability for water treatment applications.
Recommended Citation
Saberi, Mansour, "Design and Studies of CVD Graphene-Based Membranes on Modified Support for Water Treatment Applications" (2021). All Theses. 3611.
https://tigerprints.clemson.edu/all_theses/3611