Degradation of ibuprofen by thermally activated persulfate in soil systems

Thermally activated persulfate have been applied to dispose of ibuprofen (IBP) in a soil system. Batch experiments were operated to investigate the influencing factors on degradation of IBP such as soil property and activation condition. The obtained results showed that the soil IBP remediation followed a pseudo-first-order model and reaction rate constant fitted well with the Arrhenius equation. According to Eyring equation, entropy (ΔS) and enthalpy (ΔH) of reaction could be evaluated. The IBP decomposition rate increased with ascending persufate dosage and decreased with the increasing initial concentration of IBP. It was found that soil particle size had no significant effect on treatment process. Quenching test indicated that both hydroxyl radicals and sulfate radicals co-exist in a soil system and sulfate radicals take the leading role in detoxication of IBP. Due to synergistic effect of heat activation and metal activation, the IBP deterioration rate increased with decreasing pH and the best removal rate occurred at pH = 4.01. The existence of Humic acid (HA), HCO₃ ⁻ had negative influence on IBP removal, while Cl⁻ exhibited concentration-based dual effect on the transformation of IBP. Contrast test showed IBP was inclined to be degraded at soil solution, later on soil particles. Later, several major intermediate products were accordingly identified according to LC-MS, a plausible reaction mechanism for IBP remediation in soil was proposed, which may be in consistent with IBP management of water solution.