(180g) Acetaminophen Degradation in Wastewater Using TiO? Suspension: Photocatalysis with AOP Enhancers

Pharmaceutical pollution has become a growing environmental concern due to the presence of drug residues such as acetaminophen, ibuprofen, diclofenac, among others, in water systems. Convectional treatment plants, including the city wastewater treatment plants, are not designed to fully remove these emerging contaminants from water effluents. As a result, compounds like acetaminophen (N-acetyl-p-aminophenol), are especially problematic due to its widespread usage, water solubility, and partial resistance to biodegradation. Consequently, this contaminant has been detected in surface water, groundwater, and even treated water supplies. Long-term exposure, even at low concentrations, can negatively affect ecosystems and public health. Therefore, the development of effective and sustainable treatment methods has become necessary and in need of additional research to achieve its goals. This research focuses on the photocatalytic degradation of acetaminophen using titanium dioxide (TiO₂) nanoparticles suspended in a batch photocatalytic reactor enhanced by radical production promoters. Specifically, hydrogen peroxide (H₂O₂) is introduced as an enhancer to improve the efficiency of the advanced oxidation process (AOP). The photocatalyst suspension method involves mixing TiO₂ nanoparticles throughout the aqueous solution with the goal of increasing the surface area available for photocatalytic reactions. When irradiated with UV-C light (λ = 253.7 nm), the TiO₂ nanoparticles become photo-excited which generates electron-hole (e⁻/h⁺) pairs that interact with water and oxygen to form hydroxyl radicals (•OH) and superoxide radicals (O₂•⁻). This series of reactions degrade acetaminophen molecules. Suspension reactors provide better mixing and surface interaction compared to immobilized systems by offering enhanced mass transfer and better catalyst dispersion. This results in more effective contact between the photocatalyst and the target pollutant. However, issues like light scattering and post-treatment filtration must be managed carefully. The addition of H₂O₂ has been shown to enhance the system by generating additional radicals and reducing the recombination of electron-hole pairs, ultimately improving the degradation rate (REF).The experiments are conducted in a borosilicate glass batch photoreactor equipped with a 450 W UV-C lamp, magnetic stirring, and a water-cooling jacket. Varying concentrations of Acetaminophen (0.05–0.10 g/500 mL), TiO₂ (0.5–1.0 g/500 mL), and H₂O₂ (1 mL and 5 mL) are tested over 90-minute intervals. The concentration of acetaminophen is measured using UV-Vis spectrophotometry at 243 nm. The highest degradation is achieved using the UV/H₂O₂/TiO₂ combination. Treatments with UV or H₂O₂ alone show minimal effectiveness, and UV/TiO₂ without H₂O₂ is also less efficient. These results demonstrate that the hybrid photocatalytic-AOP approach displays strong synergy. While the TiO₂ suspension provides widespread active surfaces for photon absorption and reaction, the H₂O₂ serves to generate additional •OH radicals and stabilize the reactive environment by capturing free electrons. In order to conduct the research efficiently, the Renaissance Foundry Model (i.e., the Foundry, Arce et. al., 2015) is strategically integrated to guide the different experiments. The Foundry is an innovation driven learning and research framework designed to facilitate the work of students from Challenge identification to the development of a Prototype of Innovative Technology (PIT). The Foundry consists of two main paradigms: the Knowledge Acquisition Paradigm (KAP) and the Knowledge Transfer Paradigm (KTP), coordinated by shared access to Resources. These are implemented through six key elements: Challenge identification, Organizational Tools, Learning Cycles, Resources, the Linear Engineering Sequence (LES), and Prototype of Innovative Technology (PIT). In this study, the challenge is clearly defined as the inability of conventional WWTPs to remove emerging contaminants like acetaminophen effectively. Using Organizational Tools (experimental design, target contaminant concentrations, levels of TiO₂ particles, and treatment time, among other factors), the plan is developed to systematically evaluate and compare various AOP configurations. Learning Cycles are utilized to gain foundational knowledge related to reaction kinetics, photocatalysis, fluid mixing, and radical chemistry that are needed to successfully achieve goals. Specifically, during the Knowledge Acquisition Paradigm (KAP) phase, the research began with a broad exploration of pharmaceutical contaminants and advanced oxidation processes. Initial learning cycles include a comprehensive literature review on various AOP methods. Typical AOP techniques include UV/O₃, UV/H₂O₂, Fenton, and photo-Fenton processes. As knowledge deepened, this broad study is narrowed by evaluating treatment effectiveness, environmental safety, and scalability by focusing on three main sustainability factors: environmental, societal, and economical. Further refinement led to the selection of the suspension method due to its higher surface interaction, faster kinetics, degradation efficiency, and adding H₂O₂ as an AOP enhancer. Experiments then focused on optimizing parameters such as catalyst dosage, treatment time, and the role of H₂O₂. This narrowing process highlights the structured and iterative learning promoted by the KAP. The transition to the KTP involved applying the knowledge gained during KAP to develop and execute of the Linear Engineering Sequence (LES); a structured experimental roadmap and ultimately creating a PIT, which here is focused on determining the level of contaminant degradation and associated kinetic parameters (see more below). Resources such as lab instrumentation, literature, and mentorship supported the design and refinement of a PIT. This PIT consisted of a batch-style photocatalytic reactor using suspended TiO₂ and H₂O₂ as an AOP enhancer for acetaminophen degradation. Iterations are made based on experimental findings in line with the Foundry emphasis on reflection and continuous improvement. Combining technical and educational approaches helps build a systematic approach in a successful way using AOP enhancing in degradation of acetaminophen. The use of suspended TiO₂ allowed for maximum interaction between the catalyst and the contaminant, while H₂O₂ significantly increased hydroxyl radical production, boosting overall degradation performance. The Foundry ensured that each step in this process was student-led, reflective, and aligned with broader innovation goals. In conclusion, the combination of suspended TiO₂ photocatalysis with hydrogen peroxide as an AOP enhancer is shown to be a promising and efficient method for the degradation of acetaminophen in water systems. This research demonstrates how a structured educational model like the Foundry, which includes the use of critical thinking and design thinking approaches, can effectively guide the development of innovative and student-driven engineering solutions. Future work will explore the transition from batch operation to a continuous-flow suspension reactor to improve treatment scalability and performance.