Browsing by Author "Zhang, Yuanxun"

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    Exploring a chemical input free advanced oxidation process based on nanobubble technology to treat organic micropollutants
    (Elsevier, 2024-01-01) Wang, Bangguo; Wang, Lijing; Cen, Wenxi; Lyu, Tao; Jarvis, Peter; Zhang, Yang; Zhang, Yuanxun; Han, Yinghui; Wang, Lei; Pan, Gang; Zhang, Kaili; Fan, Wei
    Advanced oxidation processes (AOPs) are increasingly applied in water and wastewater treatment, but their energy consumption and chemical use may hinder their further implementation in a changing world. This study investigated the feasibility and mechanisms involved in a chemical-free nanobubble-based AOP for treating organic micropollutants in both synthetic and real water matrices. The removal efficiency of the model micropollutant Rhodamine B (RhB) by oxygen nanobubble AOP (98%) was significantly higher than for air (73%) and nitrogen nanobubbles (69%). The treatment performance was not significantly affected by pH (3–10) and the presence of ions (Ca2+, Mg2+, HCO3−, and Cl−). Although a higher initial concentration of RhB (10 mg/L) led to a slower treatment process when compared to lower initial concentrations (0.1 and 1 mg/L), the final removal performance reached a similar level (∼98%) between 100 and 500 min. The coexistence of organic matter (humic acid, HA) resulted in a much lower reduction (70%) in the RhB removal rate. Both qualitative and quantitative analysis of reactive oxygen species (ROSs) using fluorescent probe, electron spin resonance, and quenching experiments demonstrated that the contributions of ROSs in RhB degradation followed the order: hydroxyl radical (•OH) > superoxide radical (•O2−) > singlet oxygen (1O2). The cascade degradation reactions for RhB were identified which involve N-de-ethylation, hydroxylation, chromophore cleavage, opening-ring and final mineralisation processes. Moreover, the treatment of real water samples spiked with RhB, including natural lake water and secondary effluent from a sewage works, still showed considerable removals of the dye (75.3%–90.8%), supporting its practical feasibility. Overall, the results benefit future research and application of chemical free nanobubble-based AOP for water and wastewater treatment.
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    Tailoring mesoporous Y-Zeolite molecular sieve for effective removal of micropollutants from water
    (American Chemical Society, 2025-12-31) Cen, Wenxi; Wang, Bangguo; Huang, Yuwei; Ye, Shengying; Ma, Jian; Xu, Rui; Cui, Liwei; Han, Yinghui; Zhang, Yuanxun; Lyu, Tao; Wang, Lijing
    Overuse and misuse of antibiotics have led to persistent antibiotic residues in water, challenging conventional remediation approaches. This study developed a tailored molecular sieve material, i.e., mesoporous Y-zeolite (M-Y zeolite), through hydrothermal synthesis for tetracycline (TC) removal from simulated and real water matrices. The average pore size of M-Y zeolite was 3.16 nm, more than 1.7 times the second-widest dimension of the targeted TC molecule (0.81 nm), allowing for effective adsorption. With a specific surface area of 516 m2 g–1, M-Y zeolite achieved a maximum adsorption capacity of 88 mg g–1. The pseudo-second-order and Freundlich models indicated that adsorption occurred on a multilayer heterogeneous surface through chemisorption. The intraparticle diffusion model indicated that the adsorption process was governed by both liquid film diffusion and intraparticle diffusion. Mechanistic studies identified pore filling, complexation, and electrostatic interactions as the main adsorption mechanisms. After four regeneration cycles, the M-Y zeolite retained 66% of its initial adsorption capacity. In real water tests, removal efficiency slightly declined (4–14%) at 10 mg L–1 TC due to competing ions and organic matter but remained >99% at 0.1 and 1 mg L–1 TC. These findings offer a promising mesoporous material for antibiotic removal, marking a significant advancement in water treatment.