Understanding the fundamentals of chemical transformation of UV absorbing agents by MnO2-mediated oxidation

Project: Research project

Project Details

Description

Manganese dioxide (MnO2 ) plays an important role in natural attenuation of micropollutants in the environment. Considering it is ubiquitous and abundant in soil, sediments and natural waters with a high reduction potential, it is able to effectively degrade many organic compounds. Sunlight is also reported to significantly influence the redox reactivity of colloidal MnO2 in aqueous environments, which may also assist the remedy of micropollutants.

Organic UV absorbing agents are widely used in considerable amounts in plastics, textiles, and personal care products; these agents have endocrine disrupting properties, they are toxic to ecosystems, and can accumulate in both organisms and the environment itself. The massive production and consumption of these UV absorbing agents have resulted in extensive emission to the aquatic environment. However, previous studies of UV absorbing agents and their environmental fate or ecological risk in aqueous environment may have underestimated their risk since most of them are hydrophobic substances with relatively low water solubility and high log Kow value and more intend to partition in sediments and soils.

Therefore, UV absorbing agents are suitable model compounds for studying the mechanisms of MnO2 and light-assisted MnO2 transformation. At this stage, details of the transformation fate and related biological impact of UV absorbing agents’ byproducts after MnO2 or light- assisted MnO2 oxidation remain largely unknown. Our preliminary degradation study has revealed a progressive change of molecular profile and formation of different byproducts under MnO2 alone compared with MnO2 with solar irradiation. Research that can decipher the chemical mechanism of these two natural occurring processes and assess the toxicity of resulting byproducts is therefore of pivotal importance to human health and ecosystem.

To this end, the present work will trace the chemical transformation of three UV absorbing agents undergoing MnO 2 and light-assisted MnO2 oxidation. Chemical structures and identities of individual transformation products will be confirmed by comprehensive instrumental characterizations. Chemical data obtained will be used to establish the MnO2 and light-assisted MnO2 transformation mechanism. The ecological threats of individual transformation products will be predicted collectively by ECOSAR Predictive Model and mobility test. Yeast Estrogen/Androgen Screens will also be carried out to thoroughly evaluate the potential risk of UV absorbing agents’ byproducts to the ecosystem and potential human health.

Due to the low cost and high environmental abundance of MnO2 , the process tested here would also inform efforts to design and develop potential treatment methods for UV absorbing agents based on MnO2 -mediated oxidation.
StatusFinished
Effective start/end date1/01/2131/12/23

UN Sustainable Development Goals

In 2015, UN member states agreed to 17 global Sustainable Development Goals (SDGs) to end poverty, protect the planet and ensure prosperity for all. This project contributes towards the following SDG(s):

  • SDG 3 - Good Health and Well-being
  • SDG 6 - Clean Water and Sanitation
  • SDG 14 - Life Below Water

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