Norfloxacin removal efficiency by a carbon filtration column under the influence of nanoplastics: mechanistic analysis and prediction model

Abstract

Abstract Activated carbon is often used in the drinking water advanced treatment process, which has good antibiotic removal capacity. However, the presence of nanoplastics (NPs) as carriers may increase the risk of antibiotic leakage in the carbon filtration column. We designed experiments with the polystyrene nanoplastics (PSNPs) concentration, norfloxacin (NOR) concentration, flow rate, and ionic strength as four orthogonal factors to investigate the effects of each factor on NOR removal by carbon filtration columns. The influence mechanism of PSNPs was inferred by combining with NOR transport curves and characterization analysis, and a prediction model of NOR removal efficiency was established through back-propagation (BP) network. The results showed that the increase of both PSNPs concentration and flow rate decreased the NOR removal efficiency. There was an optimal value of NOR concentration to maximize the NOR removal efficiency, while with increasing ionic strength, the NOR removal efficiency decreased, then increased, and finally decreased again in an inverted ‘N’ pattern. Furthermore, PSNPs can affect NOR removal efficiency via carrier function and aggregation on the activated carbon surface. On the other hand, the relative errors of the predicted and experimental values for two evaluated samples were 3.37 and 6.62%, respectively, indicating a good prediction effect.