Enhanced solar light photo-Fenton degradation of refractory organics using algae-derived CQDs modified magnetic α-Fe2O3: Novel synthesis, mechanism insight, and phytotoxicity assessment.

The rapid advancement of chemical, pharmaceutical, and other process industries has resulted in the increasing generation of highly toxic organic wastewater. To address this pressing environmental challenge, this study presents a novel pollutant treatment strategy: a magnetic α-Fe2O3 photocatalyst doped with carbon quantum dots (CQDs), synthesized via a single-step hydrothermal method using algal blooms as a sustainable carbon source, was successfully developed for sunlight-driven photo-Fenton degradation of real-world organic wastewater. Under a H2O2 concentration of 0.0485 mol/L, nearly 100 % removal of Rhodamine B (RhB) was achieved within 30 min. The degradation performance of α-Fe2O3/CQDs was further evaluated using both natural sunlight and a laboratory xenon lamp. Computational analysis based on density functional theory (DFT) revealed that the incorporation of CQDs significantly enhanced the transfer efficiency of photogenerated charge carriers within the α-Fe2O3 structure. Additionally, mung bean germination experiments confirmed that the biological toxicity of actual organic wastewater was markedly reduced after sunlight-induced degradation, thereby meeting discharge standards for subsequent biological treatment processes. This study presents a novel, economically viable, and environmentally sustainable approach for developing magnetic, recyclable, and practical photo-Fenton catalysts using natural biochar materials, providing valuable insights into the treatment of complex real-world organic wastewater.