Evaluation of direct photolysis and UVC/H $_2^{}$ O $_2^{}$ process in the oxidation of benzoic acid: experimental and numerical analysis

Produced water management is a significant challenge for the oil and gas industry. Due to the large volumes and complex composition of this water, treatment requires special attention, resulting in high costs for companies in the sector. Naphthenic acids, known for their recalcitrance, add a layer of complexity to the treatment process. Benzoic acid, a simple aromatic carboxylic acid, has been extensively studied due to its structural similarity to naphthenic acids, highlighting its importance in developing treatment strategies. Advanced oxidative processes, such as UV/H $_2^{}$ O $_2^{}$ , have emerged as promising alternatives for the degradation of recalcitrant organic pollutants. This study aims to enhance the UV/H $_2^{}$ O $_2^{}$ process through experiments, kinetic mechanisms, and mathematical models that allow the simulation of various experimental conditions, providing a clearer and more economical approach to produced water treatment in the oil and gas industry. The results indicate that the oxidation of benzoic acid by the UV/H $_2^{}$ O $_2^{}$ process achieved removals between 12.29 and 83.56% in a batch reactor over 120 min. Additionally, the influence of solution pH and H $_2^{}$ O $_2^{}$ concentration was significant, with better removal rates observed at pH 3. The molar extinction coefficient of benzoic acid was also found to be pH-dependent, indicating a greater photon absorption capacity at lower pH. The mathematical model developed for the UV/H $_2^{}$ O $_2^{}$ process accurately predicted experimental data and process variable effects, offering valuable insights into reaction kinetics and the influence of experimental conditions.