Production of innovative magnetic adsorbent Fe3O4@PEI®Tween 85 and removal of oxytetracycline from aqueous media

Study of the Efficiency of a Polycation Using the Diafiltration Technique in the Removal of the Antibiotic Oxytetracycline Used in Aquaculture

The presence of antibiotics in aquatic systems in recent years has become a global environmental and public health concern due to the appearance of strains resistant to these antibiotics. Oxytetracycline (OXT) is a high-impact antibiotic used for both human and veterinary consumption, and it is the second most used antibiotic in aquaculture in Chile. Based on the above, this problem is addressed using a linear polymer whose structure is composed of aromatic rings and quaternary ammonium groups, which will help enhance the removal capacity of this antibiotic. To obtain the polycation, a radical polymerization synthesis was carried out using (4-vinylbenzyl)-trimethylammonium chloride as the monomer. The polycation was characterized via Fourier Transform Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR). The removal studies were conducted under different experimental conditions such as pH levels (3.0, 5.0, 7.0, 8.0, and 11.0), ionic strength (0.0-0.50 mg L-1 of NaCl), polymer dose (0.25-25.5 mg), variation of the antibiotic concentration (1-100 mg L-1), and evaluation of the maximum retention capacity, as well as load and discharge studies. The antibiotic retention removal was higher than 80.0%. The antibiotic removal performance is greatly affected by the effect of pH, ionic strength, molar ratio, and/or OXT concentration, as these parameters directly affect the electrostatic interactions between the polymer and the antibiotics. The diafiltration technique was shown to be highly efficient for the removal of OXT, with maximum removal capacities of 1273, 966, and 778 mg OXT g-1 polycation. In conclusion, it can be said that coupling water-soluble polymers to the diafiltration technique is an excellent low-cost way to address the problem of antibiotics in aquatic systems.

Evaluation of ciprofloxacin (CIP) and clarithromycin (CLA) adsorption with weathered PVC microplastics

The sorption kinetics of two of the most frequently used antibiotics onto recycled (weathered) polyvinyl chloride (PVC) was investigated, using Freundlich and Langmuir isotherm models. Various experimental conditions were set, including pH, contact time, rotational speed, temperature, and initial concentration. The batch experimental results indicated that Freundlich model was better fitted than Langmuir (R²: 98.7 and 84.7, for CIP and CLA respectively). Maximum adsorption capacity is 45.9 mg/g and 22.0 mg/g for CIP and CLA, respectively. Enthalpy (ΔH), and entropy (ΔS) values were negative for CIP, indicating that the reaction was exothermic and spontaneous, respectively. It was vice versa for CLA. Field emission scanning electron microscope (FESEM) and Fourier transform infrared spectrometer (FT-IR) analysis confirmed the physical adsorption mechanism. The results demonstrated that the recycled PVC microplastic has a good capacity for adsorption for both antibiotics.