Accurate Removal of Trace 17β-Estradiol and Estrogenic Activity in Blended Systems under a Photoelectrocatalytic Circulating Flow

Abstract

Trace 17β-estradiol (E2) is persistent against advanced treatment when blended with higher concentrations of low-toxicity organics, thus wasting energy. A circulating-flow selective photoelectrocatalysis (CF-SPEC) system is established with a selective E2-TiO2-NR photoanode, accurately reducing 1 μg L–1 E2 to less than 0.1 ng L–1 along with eliminating estrogenic activity even when blended with natural organic matter (NOM) at a thousand times higher concentration. Such high efficiency is derived from the augmented selectivity and activity of E2-TiO2-NRs toward E2 during CF-SPEC. Under a flow, the difference in adsorption capacity between NOM and E2 is further amplified 5.6-fold. Furthermore, the higher initial •OH concentration and faster mass transfer jointly endow CF-SPEC with a stronger oxidation capacity. As a result, the removal of E2 increases by 58.7%, and the elimination of estrogenic activity increases 5.8-fold. In addition, deeper mineralization and less homo- and heterocoupling under CF-SPEC are observed, leading to more thorough estrogenic activity removal. Although additional energy is needed to maintain the flow, there is a 55% decrease in energy consumption due to the accurate removal capacity. This work suggests a combination of flow degradation and surface engineering that can be expanded for the selective removal of toxic trace pollutants in blended systems.

Accurate Removal of Toxic Organic Pollutants from Complex Water Matrices

“…Not only can it provide reliable maximum adsorption capacity data, but it is also more favorable for the study of coadsorption, competitive adsorption, and displacement adsorption. It was recently applied to probe the competitive adsorption of 17β-estradiol and NOM on molecularly imprinted TiO 2 anodes, guiding the selective elimination of estrogen activity under rapid-flow conditions . The breakthrough curve reflects the adsorption equilibrium relationship, adsorption kinetics, and mass transfer mechanism between the mobile phase adsorbate and stationary phase adsorbent.…”

“…(D) enhanced recognition capacity in a circulating flow system, CE = counter electrode. Adapted with permission from ref . Copyright 2021 American Chemical Society.…”

“…Under field condition, however, the removal efficiency of toxic organic pollutants declined obviously, and in some cases, the surge in demand for energy and reagents further limits the application of these novel methods. Interference by coexisting organic and inorganic substances greatly reduces the removal effectiveness of the target toxic organic pollutants, increasing the requirements for treatment technologies and the subsequent costs. − Moreover, the concentration of toxic organic pollutants in water and wastewater are commonly several orders of magnitude lower than those of other coexisting interferents, complicating removal in the presence of abundant competing matter. − If tailored selective methods are developed for various water treatments, they can undoubtedly increase the efficiency of energy and resource use.…”

Perspective on Photoelectrocatalytic Removal of Refractory Organic Pollutants in Water Systems

“…This result shows that selective PEC can reduce the energy cost. In addition, preferential removal of 17β-estradiol can be completed in a circulating flow PEC system . It has been shown that initial hydroxyl radical production greatly increases under flow conditions in a self-designed electron paramagnetic resonance (EPR) device (Figure d).…”

“…(e) Scheme of an integrated medical wastewater treatment system. Reproduced with permission from ref . Copyright 2021 American Chemical Society.…”