Júlia Toffoli de Oliveira

Advanced oxidative processes (AOPs) have been extensively investigated for the removal of a wide range of organic contaminants, including dyes, pharmaceuticals, and other industrial pollutants. However, systematic evaluations of synergistic effects among different AOP configurations remain limited. This study investigated the synergistic interactions between AOPs for the degradation and mineralization of Rhodamine B, a dye widely used as a model compound for industrial effluents. Solutions were treated using photolysis (UV), hydrogen peroxide (H₂O₂), UV/H₂O₂, Fenton (Fe²⁺/H₂O₂), and photo-Fenton (Fe²⁺/H₂O₂/UV) processes. H₂O₂ concentrations ranged from 1.6 to 43.2 mmol/L when applied alone and from 0.53 to 4.8 mmol/L in Fenton and photo-Fenton systems, using Fe²⁺/H₂O₂ ratios of 1:5 and 1:10. The results revealed that the UV/H₂O₂ achieved 69% degradation within 2 h at 14.4 mmol/L of H₂O₂, outperforming the individual treatments. The photo-Fenton process exhibited superior efficiency, achieving complete degradation in half the time required by the Fenton process at 0.5 mmol/L of H₂O₂ and an Fe²⁺/H₂O₂ ratio of 1:5. Furthermore, mineralization increased by 20% when UV was incorporated. This study demonstrates that integrating AOPs enhances the performance, supporting the optimization of the treatments for dye-containing wastewaters and reinforcing the importance of synergistic strategies for environmental remediation.

The growing demand for effective water treatment solutions, particularly in smaller communities in Brazil, highlights the potential of ozonation. However, implementing this technology at a smaller scale presents challenges, including the need to adapt it for compact systems and optimize processes for both efficiency and feasibility. This study investigates the use of a corona discharge ozone generator operating at 60 Hz in compact systems. Experiments evaluated ozone production at different gas flow rates (0.2 to 1.0 L of ozone-containing gas per minute), with the total flow divided between two lines, A (60%) and C (40%), for simultaneous treatment applications. Mass balance tests were performed using caffeine (CAF) and atenolol (ATL) as model compounds to assess molecular interactions. The results highlight the need to stabilize ozone generation to ensure consistent production and process efficiency, confirming ozone’s effectiveness in degrading emerging compounds (ECs), CAF and ATL, by approximately 80%, after process optimization using the compact ozonation unit. Key factors such as the position and diameter of the flow divider, diffuser type, and pollutant characteristics were shown to affect gas distribution, head loss, and ozone transfer efficiency. Thus, this work underscores the critical role of system configuration in optimizing ozonation, offering insights to enhance its feasibility for providing safe potable water during water crises and emergencies in Brazil.

This study addresses the growing concern of water contamination by pharmaceutical residues, focusing on the simultaneous removal of paracetamol (PAR) and metronidazole (MTZ). Batch and fixed-bed column adsorption processes were evaluated using activated carbon. In the batch experiments, the effects of pH (3, 7, and 11), adsorbent mass (0.5, 1.25, and 2 g), and contact time (10, 30, and 60 min) were evaluated, while the fixed-bed column was optimized considering initial pollutants concentration (30, 40, and 50 mg/L), adsorbent mass (0.5, 0.75, and 1 g), and flow rate (5, 10, and 15 mL/min) to improve the maximum adsorption capacity of the bed for both pollutants (q_maxPAR and q_maxMTZ). Parameter estimation and model selection were performed using a Bayesian Monte Carlo approach. Optimal conditions in the batch system (pH = 7, W = 2 g, and time = 60 min) led to high removal efficiencies for both compounds (≥98%), while in the column system, the initial pollutant concentration was the most significant parameter to improve the maximum adsorption capacity of the bed, resulting in values equal to 49.5 and 43.6 mg/g for PAR and MTZ, respectively. The multicomponent Gompertz model showed the best performance for representing the breakthrough curves and is suitable for scale-up (R² ≥ 0.75). These findings highlight the complexity of multicomponent adsorption and provide insights, contributing to the development of more efficient and sustainable water treatment technologies for pharmaceutical residues.

Water pollution, particularly from elevated fluoride ion (F⁻) concentrations, is a significant challenge in many developing countries, particularly those relying on groundwater. The stable form of fluoride, F⁻, poses health risks, leading to concerns about various diseases and harmful effects. Despite global efforts, high F⁻ concentrations (>1.5 mg L⁻¹) persist in numerous countries, requiring effective and sustainable removal methods. Adsorption, known for its simplicity, cost-effectiveness, and efficiency, stands out as a promising technique for F⁻ removal from drinking water. Successful commercial implementation necessitates the optimization of separation conditions. This systematic literature review focuses on the adsorption process for F⁻ removal, exploring parameters such as temperature, adsorbent particle size, pH, adsorbent mass, and co-existing ions for efficient removal. Observations indicate that, despite the utilization of a diverse range of adsorbents, several limitations persist. These include low adsorption capacity, a sluggish adsorption rate, a restricted pH range, and high associated costs. The mechanistic understanding of adsorption and the ongoing development of novel adsorbents remain focal points for future research. Additionally, there is a need to explore alternative kinetic models grounded in statistical factors and give due consideration to thermodynamic studies.