The Effect of Natural Organic Matter addition to Fenton and Fe(II)-activated persulfate processes for the degradation of Acetaminophen

With the advancement of chemical analytical technology, many emerging contaminants (ECs) which exhibit potential risks both to the human health and ecology have been detected at different levels of concentration. Acetaminophen (ACT), an antipyretic, analgesic and anti-inflammatory drug, is classified as one of the pharmaceutical and personal care products (PPCPs) of ECs. ACT is also an over-the-counter medicine with a high degree of popularity. Inappropriate treatment and disposal of such medicine cause its entrance to the water body impacting the environment and public health.

The purpose of this study is to investigate the Fenton and Fe(II)-activated persulfate processes in the degradation of aqueous acetaminophen. Additionally, the removal efficiency at the presence of natural organic matter (NOM) including humic acid and citrate was explored. The experimental parameters of ACT concentrations, pH, ORP and TOC were measured. The pH was found decreasing during Fenton and Fe(II)-activated persulfate oxidation because of H⁺ production. The ORP increased significantly during the first minute of Fenton process, and exhibited a gradually-decreasing trend after two minutes due to ˙OH consumption. Different from the Fenton process, the ORP of Fe(II)-activated persulfate increased obviously during the first-two minutes, and displayed a slightly-increasing trend after five minutes.

In the present study, when Fenton degradation was carried out with 0.5 mM ferrous sulfate and 0.5 mM hydrogen peroxide, the most effective removal rate was observed as 88.7%. For the Fe(II)-activated persulfate degradation process in which, the ratio of persulfate to ferrous sulfate was maintained the same (i.e., 0.5mM to 0.5mM), the removal rate was only 39.0%. At the presence of humic acid, the best removal efficiency of the Fenton and Fe(II)-activated persulfate increased to 89.8% and to 58.04%, respectively. At the presence of citrate, the removal efficiency of the Fenton process decreased to 84.3%, and the Fe(II)-activated persulfate process increased to 47.7%.