Green fabrication of graphene aerogel using pineapple juice for efficient degradation of synthetic dyes†

Synthetic dyes pose significant environmental and health concerns due to their complex chemical structures and resistance to degradation. Conventional water treatment systems often incorporate chemical tanks and aerobic treatment to achieve complete dye removal, however, these methods typically result in high construction costs and operational complexity. In this study, graphene aerogel (GA) incorporated with Fe₃O₄ nanoparticles (NPs) was fabricated using pineapple juice as a reducing agent, denoted as GA@Fe₃O₄. Vibrating sample magnetometry results showed that the saturation magnetization values of Fe₃O₄ and GA@Fe₃O₄ were 58.59 and 18.02 emu g⁻¹, respectively, indicating that the as-prepared GA@Fe₃O₄ could be effectively recovered using an electromagnetic field. Further investigation using scanning electron microscopy and transmission electron microscopy revealed that the Fe₃O₄ NPs, sized approximately 17–20 nm, were evenly distributed on the GA surface. Notably, the GA@Fe₃O₄, with macropore structures ranging from 2 to 10 μm, exhibited degradation capabilities for reactive dye RB222. Kinetic models were subsequently established, demonstrating that the degradation followed a zero-order kinetic model with R² = 0.9863, and a rate constant k = 0.07984 (mg L⁻¹ min⁻¹). The GA@Fe₃O₄ synthesized in this study demonstrated high potential as an effective adsorbent for the degradation of synthetic dyes in the textile industry. Furthermore, pineapple juice, used as a green reducing agent, was demonstrated to be a viable alternative to other harmful reductants commonly used in the preparation of GA.