Date of Defense
5-12-2024 3:00 PM
Location
F3-040
Document Type
Thesis Defense
Degree Name
Master of Science in Chemical Engineering (MSChE)
College
College of Engineering
Department
Chemical and Petroleum Engineering
First Advisor
Dr. Salem Alzahmi
Keywords
carbon fiber, CO2 capture, rejected brine water, surface treatment.
Abstract
Brine water, defined as hot and high salt content water, can be produced in large amounts from water desalination. The potential environmental impacts of brine disposal were evaluated in several studies. Minor variations in water salinity and temperature can significantly influence marine ecosystems. Elevated salinity levels disrupt the osmotic equilibrium between aquatic organisms and their surroundings, which leads to cell dehydration. Various disposal techniques have been implemented recently, including surface water discharge, sewage discharge, deep-well injection, evaporation ponds, and land application. However, these brine disposal techniques are unviable due to their high capital costs and limited applicability. In recent years, carbon fibers have received significant interest because of their strength, high surface area, and ability to resist chemicals and corrosion. In 2022, global carbon fiber consumption will reach 194 kilotons; by 2025, an annual production of 20 kilotons of carbon fiber is expected. Consequently, there is a growing need for better and more effective recycling because of the rising demand for carbon fibers and the associated rise in plastic waste. Three leading technologies have been classified for recycling carbon fibers. Mechanical recycling involves shredding, crushing, or milling carbon fibers into small sizes. The second process is thermal recycling, which requires heat to break down the scrap composite and burn the resin matrix; the carbon fiber then can be recovered. The final recycling technique is chemical recycling; in this technique, chemical solvents must be used to degrade the resin. Usually, this approach results in a clean fiber with high mechanical properties. This research thesis presents a novel method for utilizing carbon fiber waste in rejected brine water desalination. The methodology includes thermally recycling carbon fiber waste, followed by chemical treatment with strong alkaline and acids, and then utilized to purify and treat the rejected brine water. Accordingly, the process focuses on carbon fiber waste utilization, reject brine treatment, and CO2 capture. However, the efficiency of treated carbon for brine treatment can be influenced by many factors, such as the concentration of salts and heavy metals in the brine, the surface area of the recycled carbon fiber, and the contact time. Therefore, it is essential to design the treatment system appropriately and optimize the conditions to achieve the desired level of salts and contaminant removal. As per the obtained findings, surface modification of the recycled fibers showed a significant increase in the surface roughness with the rise of the concentration of the alkaline or acid in the treatment, which can enhance the adsorption rate of brine salts on the surface of the recycled fibers. Furthermore, the lowest recovery percentage achieved was 13.1%, in which recycled carbon fibers were immersed in brine water for 4 hours. However, it increased and reached 92% recovery after reducing the treatment time and treating the surface of the recycled fiber with 3M sodium hydroxide. The presented research is a promising way to utilize waste carbon fiber for brine management and effectively capture CO2.
Included in
DEVELOPING A NEW METHOD FOR BRINE PURIFICATION AND REDUCING SALINITY USING RECYCLED CARBON FIBER
F3-040
Brine water, defined as hot and high salt content water, can be produced in large amounts from water desalination. The potential environmental impacts of brine disposal were evaluated in several studies. Minor variations in water salinity and temperature can significantly influence marine ecosystems. Elevated salinity levels disrupt the osmotic equilibrium between aquatic organisms and their surroundings, which leads to cell dehydration. Various disposal techniques have been implemented recently, including surface water discharge, sewage discharge, deep-well injection, evaporation ponds, and land application. However, these brine disposal techniques are unviable due to their high capital costs and limited applicability. In recent years, carbon fibers have received significant interest because of their strength, high surface area, and ability to resist chemicals and corrosion. In 2022, global carbon fiber consumption will reach 194 kilotons; by 2025, an annual production of 20 kilotons of carbon fiber is expected. Consequently, there is a growing need for better and more effective recycling because of the rising demand for carbon fibers and the associated rise in plastic waste. Three leading technologies have been classified for recycling carbon fibers. Mechanical recycling involves shredding, crushing, or milling carbon fibers into small sizes. The second process is thermal recycling, which requires heat to break down the scrap composite and burn the resin matrix; the carbon fiber then can be recovered. The final recycling technique is chemical recycling; in this technique, chemical solvents must be used to degrade the resin. Usually, this approach results in a clean fiber with high mechanical properties. This research thesis presents a novel method for utilizing carbon fiber waste in rejected brine water desalination. The methodology includes thermally recycling carbon fiber waste, followed by chemical treatment with strong alkaline and acids, and then utilized to purify and treat the rejected brine water. Accordingly, the process focuses on carbon fiber waste utilization, reject brine treatment, and CO2 capture. However, the efficiency of treated carbon for brine treatment can be influenced by many factors, such as the concentration of salts and heavy metals in the brine, the surface area of the recycled carbon fiber, and the contact time. Therefore, it is essential to design the treatment system appropriately and optimize the conditions to achieve the desired level of salts and contaminant removal. As per the obtained findings, surface modification of the recycled fibers showed a significant increase in the surface roughness with the rise of the concentration of the alkaline or acid in the treatment, which can enhance the adsorption rate of brine salts on the surface of the recycled fibers. Furthermore, the lowest recovery percentage achieved was 13.1%, in which recycled carbon fibers were immersed in brine water for 4 hours. However, it increased and reached 92% recovery after reducing the treatment time and treating the surface of the recycled fiber with 3M sodium hydroxide. The presented research is a promising way to utilize waste carbon fiber for brine management and effectively capture CO2.