Magnetically Recoverable Fe3O4@Latex Decorated with ZnO Nanocomposite for Efficient Photocatalytic Treatment of Sugarcane Vinasse

Sugarcane vinasse is a high-strength effluent with a high organic load and intense coloration from melanoidins and phenolic compounds, making conventional biological treatment difficult. This study presents a magnetically recoverable Fe3O4@latex-ZnO nanocomposite, synthesized using natural Hevea brasiliensis latex as a green polymeric interlayer. Transmission Electron Microscopy (TEM) shows a core–shell structure that enhances ZnO anchoring and reduces aggregation. X-ray Diffraction (XRD) confirms the coexistence of spinel Fe3O4 and wurtzite ZnO without secondary phases, while Fourier Transformed Infrared Spectroscopy (FTIR) verifies the latex layer through characteristic organic bands, indicating a stable organic–inorganic interface. Under 4 h of UV irradiation, the nanocomposite significantly reduced vinasse COD from 23,450 to 12,450–13,150 mg L−1 (≈44–47%) and BOD from 11,600 to 4800–5000 mg L−1 (≈57–59%), demonstrating substantial oxidation of the organic fraction. The magnetic core enables quick separation post-treatment, enhancing the practicality of the process. Overall, this innovative approach positions the ZnO nanocomposite as a promising option for vinasse pre-treatment and integrated agro-industrial effluent treatment.