Antibiotics have been widely used in improving human and livestock health as well as preventing bacterial infection (Gan et al., 2018). After use, most of the unmetabolized antibiotics will be excreted via feces and urines. The hydrophilic nature and undesirable removal efficiency of antibiotics by traditional wastewater treatment technologies resulted in large amounts of their residuals being discharged into environment, which have been widely detected in various waters (e.g., river, lake and groundwater) (Luo et al., 2019). This has attracted global concern due to their effects of antimicrobial resistance (AMR) as well as their acute or chronic toxicity, and these chemicals together with other micropollutants (e.g., PFAS and neonicotinoids etc.) are well known as emerging contaminants (ECs) (Ma et al., 2020a, 2023; Zhang et al., 2023).
Various technologies including advanced oxidation processes (AOPs) (e.g., photocatalytic, activated persulfate (PS) and Fenton systems), adsorption, membrane filtration and biodegradation have been studied to eliminate antibiotics from waters (Chen et al., 2023). AOPs was proved to be a promising approach as it was able to completely remove the target contaminants by oxidizing them into non-toxic (e.g., CO2 and H2O) or less toxic transformed products (TPs). Specially, activated PS technology has aroused broad attention due to its higher redox potential (E0=2.6-3.1 V) and longer half-life (28-40 μs) of SO4•- derived from PS activation (Liu et al., 2023). While the exogenous addition of PS would increase the operational cost and cause secondary pollution. Recent studies suggested that PS could be in-situ electrogenerated at the anode in the solution containing sulphate, which offers the possibility without adding exogenous PS for this technology (Chen et al., 2022). Sulphate is frequently distributed in wastewater and its concentration could reach up to 1000 mg/L, which provides potential precursors for PS in-situ generation by electrochemical oxidation (EO-PS) process (Chen et al., 2022).
Generally, PS has low reactivity toward pollutants, and it is essential to activate persulfate to produce oxidizing SO4•- and •OH (Bai et al., 2021). Carbon-based materials (e.g., biochar) were considered as promising PS activators, which can be synthesized by a variety of feedstocks, such as wheat straw, maize cobs, soya bean dregs, municipal sludge (MS) (Xu et al., 2021) and so on. Comparatively, MS is considered to be a superior feedstock for its high organic matter content, large specific surface area, large pore volume and stability structure (Li et al., 2021). Moreover, MS is a main by-product of municipal wastewater treatment plants and the carbonation of sludge (e.g., sludge biochar (SBC)) favors the immobilization of carbon which can address to dispose the wastes (e.g., sludge) properly (Ma et al., 2020b).
The catalytic activity of biochar is largely dependent on the available sites on their internal or external surface, and the pristine biochar with limited functional groups are usually not ideal for PS activation (Li et al., 2022). Different methods (e.g., N-doping, ball milling and transition metals loading) have been developed to enhance the functionality of biochars for boosting their activation performance for PS (Ma et al., 2023). Additionally, ball milling can break biochar into ultrafine particles to increase its specific surface area (SSA), introduce more oxygen-containing functional groups and develop more porous and defective structures (Qu et al., 2022), which is beneficial for the biochar activation performance with simple operation (Ma et al., 2023) while it has not been much applied for oxidants activation (Tang et al., 2023).
Therefore, this project will aim to develop a sustainable removal technology for emerging contaminants from waters. A major objective of the project is to develop and optimize an in-situ generation technology of EO-PS for ECs (e.g., initially antibiotics and then other ECs such as PFAS and neonicotinoids etc.) removal, including elucidation of the detailed mechanism for PS production. A second key objective is to synthesize functionalized biochar from waste materials (e.g., municipal sludge) to efficiently activate EO-PS. Different modification methods (e.g., N-doping, ball milling and transition metals loading) will be tested for the functionalized biochars synthesis for their activation efficiency. A final objective is to couple in-situ electrogenerated PS with carbon-based material for contaminants (e.g., starting with antibiotics) degradation, including the extension to other ECs elimination and testing for real water treatment.
Applicants are strongly advised to make an informal enquiry about the PhD to the primary supervisor well before the final submission deadline.
Applicants must send a completed Hydro Nation Scholarship application form and their Curriculum Vitae to Dr Zulin Zhang - zulin.zhang@hutton.ac.uk by the final submission deadline of 10th January 2024.
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