Electrospinning Equipment: Electrospun Hydrophobically Modified Polyacrylic Acid Hydrogel Nanofibers for Ciprofloxacin Removal

The global water scarcity problem is becoming increasingly severe, mainly attributed to water pollution caused by industrial activities and the growing demand for clean water resources. It is predicted that by 2025, more than two-thirds of the world's population may face water shortages. Antibiotics, as an important class of pollutants, pose a threat to the environment and human health due to their widespread use and difficult - to - degrade properties. Traditional wastewater treatment methods are inefficient in removing antibiotics. Therefore, the development of new adsorption materials to effectively remove these pollutants has become crucial.

Professor Okay and his team from Istanbul Technical University published a research achievement titled "Design of Electrospun Hydrophobically Modified Polyacrylic acid Hydrogel Nanofibers and their Application for Removal of Ciprofloxacin" in the journal Journal of Polymers and the Environment. The team prepared a novel polyacrylic acid - based hydrogel nanofiber through electrospinning machine technology. First, the team copolymerized acrylic acid (AAc) with n - hexadecyl acrylate (C16A) to form a physically cross - linked hydrogel. By introducing hydrophobic interactions, this hydrogel has good solubility in organic solvents, making it suitable for electrospinning device processing. The preparation process is shown in the following figure.

The research found that when the mole fraction of C16A was 35%, the prepared nanofibers exhibited the optimal fiber size and surface smoothness, with excellent adsorption properties and the ability to efficiently remove ciprofloxacin (CIP) from water. (Figure 1)

Figure 1. SEM images and fiber size distributions of electrospun P(AAc - co - C16A) hydrogel nanofibers containing 50% (a), 35% (b), 30% (c), and 25% (d) C16A. The scale bar in the SEM images is 5 μm.

Zeta potential tests showed that the surface of the nanofibers was negatively charged between pH 4 and 10, which is helpful for adsorbing positively charged CIP molecules through electrostatic interactions. Experimental results showed that the nanofibers containing 35 mol% C16A reached adsorption equilibrium within 60 hours, with a removal efficiency as high as 98%. (Figure 2)

Figure 2. Adsorption characteristics of nanofibers for CIP. (a) Changes in CIP concentration in the solution Ct (circles), the amount of CIP adsorbed by the nanofiber qt (triangles), and CIP removal efficiency E (bars) with contact time. The C16A content is 35%. (b) The effect of the C16A content in the nanofibers on the change of CIP concentration over time. The C16A content is indicated. (c) The effect of the initial concentration Co on qe and E. (d) The desorption efficiency of CIP - loaded nanofibers containing 35% C16A.

Adsorption kinetics experiments showed that the pseudo - second - order model (R² = 0.9785) was a better fit to the experimental data than the pseudo - first - order model (R² = 0.9296), indicating that chemisorption was the main mechanism. The Langmuir isotherm model (R² = 0.9998) suggested that the adsorption process was monolayer adsorption. (Figure 3)

Figure 3. Adsorption kinetics model of CIP on nanofibers containing 35% C16A. The symbols and solid lines represent the experimental data and calculated data using the Lagergren pseudo - first - order (a) and pseudo - second - order models (b), respectively.

In short, by introducing hydrophobic interactions, this material showed efficient adsorption and removal of ciprofloxacin (CIP) under laboratory conditions, which could provide new solutions for the sustainable removal of environmental pollutants. However, due to the inherent defects of bulk adsorbents, such as irreversible adsorption and potential fouling in complex matrices, future research will focus on improving the reusability of these hydrogels through structural modifications or the introduction of functional groups that facilitate desorption.

Article source: https://doi.org/10.1007/s10924-025-03504-9