Study On The Adsorption Performance Of Ciprofloxacin And Norfloxacin Onto Modified Louts Leaf

Recent years,antibiotics contaminants was detected in water environmental continuously,causing a great threat to ecological environment and human health,thus removing the antibiotics in water is necessary.Lotus leaf(LL),as agricultural byproduct,contains abundant floristic fiber,protein and some functional groups,so it can be used as a low-cost adsorbent.In this paper,adsorption performance of ciprofloxacin(CPX)and norfloxacin(NOR)onto lotus leaf modified by sodium hydroxide(MLL)has been experimented.The effects of various conditions including adsorbent MLL dosage,contact time,initial concentration,pH and temperature on the adsorption of CPX and NOR onto MLL were investigated.The adsorption equilibrium time was 6 h and optimal MLL dosage was 1 g/L.The adsorption of CPX and NOR onto MLL follows the Langmuir and Koble-Corrigan isotherm models well.When the temperature was 298 K,the maximum monolayer adsorption capacity of adsorbent MLL for CPX and NOR were 194.75 mg/g and 202.09 mg/g,respectively.At the 298 K,308 K and 318 K,the thermodynamic parameters ?G for adsorption of CPX and NOR onto MLL were-22.29?-23.19?-24.22 kJ/mol and-22.21?-23.15?-24.34 kJ/mol,respectively.The results indicated the adsorption process of CPX and NOR onto MLL were spontaneous endothermic process.Temperature show a positive influence on the adsorption of CPX and NOR onto MLL.The adsorption process of CPX and NOR onto MLL followed the pseudo-second-order mode,implying that the adsorption might be a chemisorption process,and the boundary layer and intraparticle diffusion may control the adsorption process to some extent.In fixed-bed column experiments of the CPX and NOR,the effects of flow rate,concentration and adsorbent MLL bed height were discussed.The experimental data were fitted by the Thomas and Yoon-Nelson model in order to determine the characteristic parameters of the column adsorption,the results indicated that the adsorption of CPX and NOR onto MLL can be described by the Thomas and Yoon-Nelson model well.And the brekthrough time and the saturated adsorption time for the adsorption process of CPX and NOR onto MLL can be predicted by the bed-depth/service time(BDST)models.The low cost biomass adsorption material MLL had a relatively large CPX and NOR adsorption capacity and can be considered as a biomass adsorbent for the removal of CPX and NOR.