Exploration of the adsorption/desorption behavior and influencing factors of norfloxacin in sediments in the upper reaches of the Yellow River
Norfloxacin(NOR)was selected as the target pollutant,and the sediment in the upper reaches of the Yellow River was taken as the main research object.The adsorption/desorption behavior of NOR on the sediment was studied by using the batch balance method.The adsorption/desorption rule was explored under different environmental conditions(initial concentration,ionic strength and type,pH value,particle size,etc.)to explore the adsorption mechanism.The results show that the kinetics is consistent with the quasi-second-order kinetic model(R2>0.996),indicating that the adsorption and desorption processes are complex mechanisms controlled by multiple actions,and the desorption has obvious hysteresis.The thermodynamic results showed that the Freundlich model had the best fitting result(R2>0.981),followed by the Linear model(R2>0.937),indicating that the multimolecular layer adsorption and hydrophobic distribution on heterogeneous surfaces both affected the key mechanism of NOR adsorption behavior on sediments,and the temperature increase accelerated the migration risk of NOR in the water phase.With the increase of NOR initial concentration,the adsorption capacity increases and the equilibrium time prolongates accordingly.The pH showed that acidity promoted NOR adsorption,and the migration risk increased under alkaline condition.The effect of coexisting soluble ions on NOR adsorption results showed that the larger the concentration of the same ions,the stronger the adsorption inhibition of NOR on the sediment.The influence of different coexisting ions on adsorption is mainly related to the characteristics of coexisting ions,such as ion radius,cation exchange capacity and hydrolysis,etc.The higher the valence state,the stronger the inhibition effect.The smaller the particle size,the larger the adsorption capacity.The results of this study will provide scientific basis for controlling the environmental behavior of antibiotic pollutants in the upper reaches of the Yellow River.
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