Optimizing composite microplastics for antibiotics removal in water: An eco-friendly solution

Microplastics (MPs) have the potential to adsorb and transport organic pollutants in aquatic environments. This study investigated the removal of antibiotics ciprofloxacin (CIP) and flucloxacillin (FLU) from water using microplastics made from polyethylene terephthalate (PET) and high-density polyethylene (HDPE). The microplastics were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis. Isotherm models, including Langmuir, Freundlich, Temkin and Jovanovic, were assessed to determine which best fit the sorption data. The equilibrium time for sorption was 30 minutes. Temkin and Jovanovic models showed the best fit for sorption equilibrium data on ciprofloxacin and flucloxacillin, respectively, with R2 values above 0.92 and 0.77, indicating efficient adsorption of ciprofloxacin and flucloxacillin. The heat of adsorption decreased linearly with increased surface coverage, while Jovanovic's model suggested mechanical interactions between the adsorbate and adsorbent. The study found that the sorption capacity decreases with increasing pH, possibly due to electrostatic interactions, and the adsorption shape resembled a type 2 sinusoidal curve. In conclusion, this study highlights the potential of composite microplastics (PET and HDPE) as low-cost adsorbents for removing ciprofloxacin and flucloxacillin from water. It provides a sustainable solution to antibiotic pollution and plastic waste management.