ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Organic compound removal from water by graphene oxide/Fe₃O₄/Ag nanocomposite: adsorption and degradation with NaBH₄ or H₂O₂

Thi Thu Huong Le, Thi Hong Hanh Nguyen, Thi Thuong Ngo, Thi Thanh Chu, and Thi Phuong Nga Han

Vietnam National University of Agriculture, Gia Lam, Hanoi, Vietnam

E-mail: lethithuhuong@vnua.edu.vn

Received: 17 April 2025  Accepted: 19 July 2025

Abstract:

In a previous study, graphene oxide (GO)/Fe₃O₄/Ag nanocomposite was successfully synthesized with the potential to remove contaminants in water. However, the mechanism of the removal is still unclear. A more precise understanding of the removal process is required to bring the material to actual application. This study was proposed to answer whether the organic compound removal by the material is adsorption or degradation. Methylene blue (MB) was used as the model compound. In addition, the catalyst activity of GO/Fe₃O₄/Ag material in different conditions (oxidation with H₂O₂ and reduction with NaBH₄) was investigated and compared. The previous study showed that at a low concentration of MB (10 ppm), adsorption is enough to remove 100% MB. At the higher concentration of MB (30 ppm), oxidation with H₂O₂ at pH 3 or reduction with NaBH₄ at pH 6 or 9 results in more effective removal with the %MB removal of up to 98.8% and %TOC removal of up to 91.2%. The characterizations by FTIR, BET, FESEM, AAS, and XRD of the material after the degradation showed that an acidic environment can dissolve the materials to some extent and therefore reduce the oxidation removal while the neutral and basic environment maintains the reuse ability of the materials after 5 cycles. With a dye wastewater sample pH = 6.5, using the material and NaBH₄ 0.02 M can reduce COD by 75.9% and TOC by 63.3%. Thus, the material can serve as an excellent candidate for degradation of dye in wastewater.

Keywords: Adsorption; Oxidation with H2O2; Reduction with NaBH4; Dye removal; GO/Fe3O4/Ag

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04270-7

Chemical Papers 79 (11) 7555–7566 (2025)