Pollution characterization, adsorption, and SERS-based detection of enrofloxacin adsorbed on microplastics in aquaculture water

This study investigates the pollution of microplastics (MPs) in aquaculture and their adsorption of enrofloxacin (ENR), and develops a SERS detection method for ENR adsorbed on the surface of MPs based on hydrophilic membrane enrichment. Surface water samples from three South American white shrimp (Litopenaeus vannamei) ponds were analyzed for MP abundance, distribution, morphology, particle size, and type. Results revealed that MP pollution was widespread, with fibers smaller than 1 mm being predominant, and polypropylene was the main polymer type. The adsorption behavior of ENR onto polypropylene MPs was examined, revealing that factors such as particle size, concentration, pH, and temperature significantly influenced adsorption levels. Kinetic analysis indicated that the adsorption process followed a multi-stage co-control model, and the high correlation coefficient of the Langmuir isotherm suggested adsorption occurred on a monolayer of a homogeneous surface. Given that MPs can act as carriers for ENR, increasing ecological risks in aquaculture, the study developed a rapid detection method based on membrane enrichment and methanol desorption, coupled with surface-enhanced Raman scattering (SERS) technology. This method demonstrated high sensitivity, with a detection limit of 1.6 ng, enabling efficient monitoring of toxic substances adsorbed onto MPs in aquatic environments. The proposed approach offers effective support for pollutant detection in aquaculture systems.