Comparative performance evaluation of Cobalt-MXene for organic pollutant degradation

• Main Author: Chua, Sherwin Xiang Wei
• Other Authors: Darren Sun Delai
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Civil engineering
• Online Access: https://hdl.handle.net/10356/172729
• Institution: Nanyang Technological University

Industrialization has profoundly shaped the world, ushering in transformative economic and technological advancements while significantly impacting the environment and global trade. This rapid industrialization has simultaneously exerted immense pressure on water resources, leading to increased pollution levels, contamination of aquatic ecosystems, and compromised water quality due to the discharge of harmful chemicals by-products and pollutants. Exposure to organic pollutants like Bisphenol-A (BPA) and Acid Orange 7 (AO7) through contaminated water sources are related to serious health issues in humans, including hormonal imbalances, reproductive disorders, and a risk of certain cancers due to them being potential carcinogens. Hence, innovative solutions with MXene were explored to address these challenges, with the aim of producing advanced water treatment technologies to effectively remove organic pollutants from various water sources. In this study, a catalytic Cobalt-MXene nanocomposite was explored and fabricated using a simple metal-ion initiated gelation technique, to treat wastewater containing BPA and AO7 coupled with the integration of advanced oxidation processes (AOPs) by Peroxymonosulfate activation. The fabrication method was modified slightly to include the use of Dimethyl Sulfoxide (DMSO) and hydrothermal reaction, to form a new modified Cobalt-MXene. The performances of both catalysts were compared and analysed to uncover the changes incurred, owing to the new catalyst synthesis method. The performance comparison analysis was investigated under identical experimental conditions, using 0.3g/L of nanocomposite catalyst to degrade organic pollutants of Bisphenol-A (BPA) and Acid Orange 7 (AO7). The original Cobalt-MXene (CoM) catalyst achieved rapid high degradation efficiency ( 93.8% of AO7 in 6 minutes and 100% of BPA in 3.5 minutes). Similarly, modified Cobalt-MXene (MCoM) had exemplary results, albeit lesser removal rate than CoM (90.4% of AO7 in 6 minutes and 92.3% of BPA in 10 minutes). The reusability of these nanocomposites was explored in the form of repeated treatment usage of AO7 and the corresponding degradation results of UV-VIS tests were recorded. Both catalysts were subjected to ICP-OES to evaluate the degree of metal ions leaching during the tests. Evidently, MCoM was found to be the nanocomposite catalyst of higher stability, resulting in higher rate of repeated usage. The removal efficiency of CoM at the fourth cycle of AO7 treatment had drastic decrease to 60% while MCoM retained a high 86.3%. The reusability test pressed forward to a fifth cycle in which both catalysts had drastic decrease in degradation efficiency. The superior performance by MCoM was attributed to the internal structure changes, affected by the method of synthesis hence, the characterization was explored with FESEM, EDX and XRD. In essence, this study exemplifies an improved, time saving technique for the fabrication of a novel catalyst with high performance, stability, reusability, and other dormant potentials.