Degradation of a fluorescent tracer-PTSA in circulating cooling water: Kinetics, pathways, and degradation efficiency of a polycyclic aromatic hydrocarbon derivative

[Display omitted] •UV-based AOPs was adopted to degrade PTSA in circulating cooling water.•The apparent kinetics constants of PTSA were inversely proportional to initial concentration.•The degradation pathways of PTSA were speculated through theoretical analysis and experiments.•The hydroxylation products of PTSA had stronger cytotoxicity than itself. In industry, various fluorescent tracers were added to the circulating cooling water systems for online monitoring of water treatment agents. PTSA (1,3,6,8-pyrenetetrasulfonic acid, sodium salt) as a pyrene sulfonate was widely used, but there was no effective way to treat it in the discharging process. In this article, a UV-based advanced oxidation process (UV-based AOPs) was used to degrade PTSA in wastewater. The results were: For kinetics, the effects of initial concentration of PTSA, H2O2 concentration, intermediate products, and interference factors (pH and inorganic anions) were investigated. For efficiency, the removal of PTSA and TOC reached 97 % and 35 %, and the fluorescence of the solution disappeared within 60 min. For pathways, by analyzing the charge population and surface electrostatic potential of PTSA molecule, the possible attack site of hydroxyl radical was speculated, and the possible intermediate product was 1,4,5,8-naphthalenetracarboxylic acid, and verified by NMR and HPLC-MS. The cytotoxicity of PTSA and its hydroxylated products were compared to determine the toxicity of PTSA hydroxylation products in degradation process.