Photodegradation of 4-alkylphenols using BiVO_4 photocatalyst under irradiation with visible light from a solar simulator

摘要

A visible-light-driven photocatalyst,BiVO_4,has been applied for degradation of a series of linear 4-n-alkylphenols under irradiation from a solar simulator.Degradation rates become faster with increasing alkyl chain length.Half-life of 4-n-nonylhenol (4-n-NP) is 18 min,which is about eight times shorter than that of ph3enol.The rate law of disappearance for heptyl-,octyl-and nonylphenols exhibits zero-order kinetics.The amount of adsorption on BiVO_4 surface is much larger for longer hydrophobic alkylphenols.It is thus concluded that BiVO_4 is suitable for degradation of hydrophobic alkylphenols such as nonyl-and octylphenols nominated as endocrine disruptors.Degradation of ranched 4-nonylphenol (mixture of isomers) has also been examined,and disappearance of its estrogenic activity was comfirmed by means of the yeast two-hybrid assay.A gas chromatography-mass spectroscopy (GC-MS) analysis after solid-phase extraction indicates that the major product is cis,cis-4-alkyl-6-oxo-2,6-hexadienoic acids,and the minor products are 4-alkylcatechols and 4-(1-alkenyl)phenols.