Ozone-Based Photoactivated Synergistic Digestion Method for the Determination of Total Dissolved Phosphorus in Water

Aiming at the drawbacks of conventional methods for the digestion of total dissolved phosphorus (TDP) in water, a novel ozone-based photoactivated synergistic oxidative digestion device based on a high-voltage discharge ozone generator with an oxygen source and a jacketed bubbling reactor was presented. The effects of reaction temperature, reaction time, ozone flow, initial pH of solution, common inorganic anions (Cl^–, \({\text{CO}}_{3}^{{2 - }}\) , \({\text{HCO}}_{3}^{ - }\) ), and total nitrogen on the digestion efficiency were investigated. Combining the improved ammonium molybdate spectrophotometric method, proposed the new determination method for TDP and verified its performance within the range of 0.1–2.0 mg/L. Results showed that this method has good linearity (R² = 0.9997), precision (0.40%), accuracy (–0.50%), and a low limit of detection (0.0042 mg/L) under the optimized digestion process conditions (reaction temperature of 40°C, reaction time of 20 min, ozone flow of 0.6 L/min, initial pH of 5). This method provides a promising approach for routine analysis or online monitoring of TDP in water.