Photodegradation of the endocrine-disrupting chemicals 4n-nonylphenol and triclosan by simulated solar UV irradiation in aqueous solutions with Fe(III) and in the absence/presence of humic acids

4n-Nonylphenol (4n-NP) and triclosan (TCS) are endocrine disrupters that are used widely in personal care products. They are mainly transported in domestic sewage, which can eventually reach natural waters (rivers, lakes or reservoirs). In this work, the photodegradation of 4n-NP and TCS using a solar simulator (300–800 nm) at two different pH levels, two different concentrations of ferric ion, Fe(III), and in the absence/presence of humic acids (HAs) were investigated. A Xe lamp (250 W m−2) was employed as the light source. The conditions were chosen to simulate a natural aquatic environment. The experiments were performed using a factorial design for three factors with eight combinations of the factors studied. Experiments performed in ultrapure water showed that the degradation of 4n-NP was faster than that of TCS. The data showed that first-order reaction kinetics describe the degradation of both compounds well; the half-lives of TCS and 4n-NP were 5.4 h and 2.3 h, respectively. For TCS, the results indicated that the oxidation rate increases in the presence of Fe(III) and at basic pH levels; however, the rate it decreased in the presence HAs. In the case of 4n-NP, synergistic effect was observed for presence of Fe(III) and HAs. The best conditions were a basic medium (pH 9) and an Fe(III) concentration of 2 mg L−1 without HAs for TCS and a pH of 9, an Fe(III) concentration of 2 mg L−1 and a HAs concentration of 1 mg L−1 for 4n-NP. The results of photodegradation of both compounds in water from two reservoirs showed that the photodegradation was highly dependent on the conditions of the aquatic environment.