Organic Phosphorus Extraction in the Fouling of the Circulating Cooling System

The organophosphate scale inhibitor (HEDP)-containing C-P bond is an agent widely used in the circulating cooling system to ensure the safe operation. In order to explore the effects of its decomposition and migration transformation in the system on the system security, it is necessary to carry out the quantitative and qualitative analysis of organic phosphorus in fouling. According to the Ivanoff method, with the organic phosphorus extraction rate as an indicator, the types and concentrations of extractants, extraction time, and mass of the extracted scale were optimized. When the mass of the extracted scale was 0.4 g, the extraction rates of active organic phosphorus and moderately active organic phosphorus were, respectively, 46.53 and 47.14%, and there was no inactive organic phosphorus and residual phosphorus. The total extraction rate of organic phosphorus was up to 94.32%. The optimum extraction conditions of various organic phosphorus components were determined as follows: 10 h extraction in 0.5 mol/L KHCO₃ for active organic phosphorus and 3 h extraction in 1.0 mol/L HCl solution for moderately active organic phosphorus. The optimized extraction process only involves two steps: acid extraction of active organic phosphorus and acid extraction of moderately active organic phosphorus. The optimized method is characterized by the simple operation and good extraction effect and can be applied in the detection and analysis of organic phosphorus in the fouling of the circulating cooling system.