Solar-Driven Chlorine Activation via Photo(thermal) Catalysis for Enhancing Emerging Contaminant Degradation, Bacteria Inactivation, and Disinfection By-product Mitigation

Abstract

Emerging contaminants (ECs) in drinking water, such as pharmaceuticals, personal care products, and industrial chemicals, pose significant risks to human health. Although ECs are still not subjected to regular environmental monitoring due to their low occurrence levels, many of them are continuously and increasingly discharged into surface water bodies, and they can potentially cause chronic health issues even at low concentrations. While conventional disinfection methods like chlorination have effectively controlled pathogenic microorganisms, they often lead to the formation of toxic disinfection by-products (DBPs), which present additional health risks. To address these challenges, it is crucial to develop advanced disinfection techniques that not only degrade ECs effectively but also suppress DBP formation while maintaining robust pathogen inactivation. The solar/chlorine process has emerged as an energy-efficient method for degrading certain ECs; however, it is inefficient against ECs lacking electron-donating groups and often results in high DBP formation because of the generation of Cl•. This research study aims to develop an advanced solar-driven chlorine activation system that synergizes photothermal and photocatalytic processes to enhance chlorine activation under solar radiation, generating more reactive species for efficient EC degradation. Mechanistic investigations reveal that photoinduced charge carriers from photocatalysis can promote chlorine activation while the integration of chlorine inhibits charge recombination. Additionally, material-assisted photothermal process further extends the light absorption to visible and infrared regions, utilizing the full solar spectrum for further accelerating the reaction kinetics. As a result, the process produces additional reactive species, mainly HO• and ClO•, for achieving supervisor EC degradation efficiency. Moreover, DBP formation can be controlled by reducing chlorine exposure, promoting organic mineralization, and regulating pollutant degradation pathways. The developed technique is highly practicable, as it remains largely unaffected by water matrices and exhibits excellent reusability. Overall, the proposed photothermal catalysis/chlorine process represents an advanced, environmentally friendly, and sustainable chlorination method for drinking water disinfection, offering a promising solution to the dual challenges of EC degradation and DBP control.

Date of Award	2025
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Irene Man Chi LO (Supervisor)