Activation of persulfate by vanadium oxide modified carbon nanotube for 17β-estradiol degradation in soil: Mechanism, application and ecotoxicity assessment

Abstract

Steroid hormones in the environment have attracted public attention because of their high endocrine-disrupting activity even at rather low exposure level. Excessive hormones in the soil from the pollutant discharge of intensive farming would pose a potential threat to the ecology and the human health. Vanadium oxide modified carbon nanotube (VOX-CNT) was synthesized and applied as persulfate (PDS) activator to reduce17β-estrogen (17β-E2) in soil. 86.06 % 17β-E2 could be degraded within 12 h. Process of materials exchange during oxidation was interfered by soil, resulting in insufficient degradation of 17β-E2, but the active species involved in 17β-E2 degradation would also be enriched by it. 17β-E2 was adsorbed on the VOX-CNT surface and directly degraded mainly by the active species generated on the catalyst surface, and •OH dominated the degradation of 17β-E2 in VOX-CNT/PDS system. CO, defective sites and vanadium oxides on the surface of VOX-CNT contributed to the generation of activate species. Oxidizer dosage, catalyst dosage, water-soil ratio and soil properties would affect the degradation of 17β-E2. The ecotoxicological impact on soil caused by VOX-CNT/PDS was acceptable, and would be weakened with time. Additionally, a rapid decrease in the concentration of 17β-E2 and the promotion of maize growth were observed with VOX-CNT/PDS in situ pilot-scale remediation. Those results reveal that VOX-CNT/PDS is a potential technology to remove excessive steroid hormone from soil around large-scale livestock and poultry farms.