Sophorolipid-modified nanoscale zero-valent iron activated peroxydisulfate for norfloxacin removal: Performance and reduction of agglomeration

• Published in: Separation and purification technology 2025-07, Vol.361, p.131467, Article 131467
• Main Authors: Xue, Chengjie, Fang, Zhanqiang
• Format: Article
• Language: English
• Subjects: Advanced oxidation process; Antibiotics; Biosurfactant; Nano zero-valent iron; Peroxydisulfate; Sophorolipid
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2025.131467

•Sophorolipid improved the dispersion and reduce the agglomeration of nZVI.•Modification of nZVI with biodegradable and environmentally friendly sophorolipid as biosurfactants.•SL-nZVI + PDS increased the system reaction rate by 3.2-fold compared to nZVI + PDS. Various modification methods such as metal doping, surface coating, emulsification and loading have been developed to deal with the challenge of controlling the release of high activity from nano zero-valent iron (nZVI). However, these modification methods are accompanied by risks such as secondary contamination. In this study, the sophorolipid modified nano zero-valent iron (SL-nZVI) was modified using environmentally friendly biosurfactants (sophorolipid) and used to activate peroxydisulfate (PDS) for degradation of norfloxacin (NOR). Characterization of the material showed that SL-nZVI was successfully prepared and distributed as a chain with a protective layer encapsulating the nZVI. This indicated that sophorolipid modification not only changed the hydrophilicity of nZVI particles, but also affected its ability to activate PDS, and that sophorolipid facilitated the transfer of nZVI electrons. The SL-nZVI + PDS system increased 3.2-fold for the NOR removal rate compared to nZVI + PDS. Multiple reactive oxygen species (ROSs) were proposed to be involved in PDS activation by SL-nZVI, including sulfate radical (SO4·-), singlet oxygen (1O2), superoxide radicals (·O2–), and high-valent ferrous oxide species (FeIV = O), hydroxyl radical (·OH) (1O2: 42.1 % >SO4·-: 28.7 % >·O2–: 26.1 %). The SL-nZVI + PDS system still removed over 93 % of NOR in the presence of anions (except CO32–) and natural organic matter, demonstrating excellent system resistance. In the SL-nZVI + PDS system, Fe2+ accelerated the activation of PDS, and almost all NOR was removed within 15 min at a low Fe2+ concentrations, Fe2+ accelerated the activation of PDS. This demonstrates that SL-nZVI is more favorable for the pollutant removal of practical wastewater.