Electrostatically Spun Fabrication of Fe₃O₄@SiO₂/PVA Membranes for Efficient Methyl Orange (MO) Adsorption and Response Surface Optimization of the Processes

The environmental pollution problem caused by azo dyes urgently needs to be solved. Fe₃O₄@SiO₂/poly(vinyl alcohol) (PVA) membranes were prepared via an electrostatic spinning process. By blending the prepared Fe₃O₄@SiO₂ nanoparticles with PVA, a uniform distribution of Fe₃O₄@SiO₂ nanoparticles within the fibers was achieved, effectively preventing the aggregation of the nanoparticles and demonstrating excellent adsorption performance toward the azo anionic dye methyl orange (MO). The adsorption isotherms and kinetic data for Fe₃O₄@SiO₂/PVA adsorbed MO were consistent with Langmuir and the pseudo-second-order model, respectively. Owing to the electrostatic attraction, hydrogen bonding, and pore-filling effect, Fe₃O₄@SiO₂/PVA effectively removed MO from water, with a maximum adsorption amount of 349.896 mg/g at 25 °C. Very importantly, the Fe₃O₄@SiO₂/PVA membrane can be regenerated and reused efficiently, with no significant decrease in adsorption capacity after five adsorption cycles. In addition, response surface methodology (RSM) was used to analyze the effects of various factors on the MO adsorption performance of Fe₃O₄@SiO₂/PVA membranes, as well as the interactions of various factors. This research indicated that Fe₃O₄@SiO₂/PVA membranes are promising adsorbents for MO due to their low cost, ease of regeneration, and environmental friendliness.