(242a) Simultaneous Adsorption and Heterogeneous Oxidation of Endocrine Disrupting Compounds in Wastewater Using Nano Metal Catalyst-Deposited Carbon Nanotubes

A process for the removal of bisphenol A (BPA), one of the endocrine disrupting compounds (EDC) from wastewater was developed using nano metal catalyst-deposited carbon nanotubes (CNT). For the past decade BPA have gained more attention as emerging contaminants, and have been linked to multiple cancers below the concentration of ppb. This process relies on simultaneous adsorption and heterogeneous in-situ Fenton oxidation for degradation of BPA. The present study investigated how acidic surface modifications of CNTs and the novel amendment of iron onto the CNTs affect the adsorption and oxidation of BPA. The virgin CNTs were treated with acid to increase acidic surface oxide groups while lowering the pH at the point of zero charge (pH, _PZC) of the CNT, and improve electrostatic interactions with the iron catalyst for enhancing dispersion and deposition of iron onto the CNT. The novel iron amendment method encourages a uniform distribution of iron nanoparticles onto the surface of the CNTs. The SEM and TEM image analysis confirmed the uniform distribution of the iron over the CNT. Adsorption and desorption of BPA onto the CNTs was found to reach equilibrium in less than 5 min. The iron-amended acid-treated CNTs and the iron-amended untreated CNTs followed the Langmuir model of adsorption, indicating a single layer of adsorption. The iron-amended CNTs showed slightly lower maximum adsorption capacity for BPA in water compared to the virgin CNTs. The oxidation of BPA with the iron-amended acid-treated CNTs showed greater than 95% removal of BPA and a H₂O₂ half-life ranging from 36-1386 min at 4.5-45 mmol H₂O₂/mmol BPA at pH 3.5 over the repeated cycle of treatment of BPA_. The heterogeneous Fenton oxidation of BPA in water revealed quick adsorption, effective degradation of BPA, and high regeneration of adsorptive capacity with no iron sludge production compared to homogeneous Fenton oxidation. Since the limitation of the process is the oxidation rate of BPA, further investigation will focus on enhancing the reaction kinetics of BPA oxidation by optimizing the ratio of BPA:H2O2:Fe and operating conditions such as temperature, pH and mixing.