Degradation of 17β-estradiol by Zero Valent Iron

Endocrine disrupting compounds (EDCs) in aquatic environments are often found as a result of industrial, agricultural, and sewage runoff from wastewater treatment plants. One prevalent EDC, 17β-estradiol, is of great environmental concern due to its only partial removal by wastewater treatment plants. The purpose of this study was to: first, explore the potential degradation of 17β-estradiol in water when contacted with zero valent iron (ZVI); next, if effective, quantify the degradation kinetics of 17β-estradiol in water when contacted by ZVI; and lastly, determine if treatment of 17β-estradiol by ZVI can be related to the amount of ZVI present. The research found that ZVI effectively degraded 17β-estradiol in water and displayed a pseudo-1st order degradation rate. The degradation rate constants were 0.523 hr-1, 0.425 hr-1, and 0.406 hr-1 for volume of solution-to-mass of iron ratios of 2:1, 4:1, and 8:1, respectively. Also, half-lives for the varying ratios were calculated as 1.33 hr, 1.63 hr, and 1.71 hr for the volume of solution-to- mass of iron ratios of 2:1, 4:1, and 8:1, respectively. Results also showed that >99% of the initial 2 ppm concentration of 17β-estradiol mass in water degraded in the presence of ZVI. Increase in ZVI mass relative to aqueous volume resulted in higher degradation rates and lower half-lives for 17β-estradiol. These results compared favorably with ZVI treatment of other contaminants in water provided in the literature, including other EDCs, pesticides, and chlorinated organics. After degradation of 99% of the mass of 17β-estradiol, no appreciable oxide formation was noted by SEM analysis of the ZVI. Overall, ZVI has been shown to effectively degrade 17β-estradiol in aqueous environments with increased effectiveness with greater mass of the substrate included. The optimization of this treatment process can improve cost effectiveness, cost efficiency, and overall sustainability in remediating harmful and EDCs from water systems.