Study On Adsorption Characteristics Of Ciprofloxacin And Doxycycline Onto Iron Nanocomposites

The residue and accumulation of antibiotics in water and soil could bring about a great threat to the ecological environment and human health.Therefore,it is particularly important to remove antibiotics from water bodies.Due to its high treatment efficiency and easy operation,the adsorption is one of the effective methods for treating antibiotic wastewater.Using plant extracts containing polyphenols and flavonoids as reducing agents to synthesize metal nanoparticles is a green synthesis method with a wide range of raw materials,low cost,and no pollution to the environment during the production process.In this paper,the iron nanocomposites were synthesized using lotus leaf extract for the removal of ciprofloxacin(CIP)and doxycycline(DOX)from aqueous solution.Firstly,iorn nanocomposites were synthesized using lotus leaf extract as raw material.Taking the adsorption capacity of CIP onto iorn nanocomposites as the index of investigation,the preparation conditions of the iorn nanocomposits were optimized.The iorn nanocomposites were characterized by scanning electron microscope(SEM),X-ray energy spectrometer(EDS),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The adsorption properties of CIP onto iorn nanocomposites were studied.The effects of contact time,adsorbent dose,solution p H,initial CIP concentration and temperature on the adsorption capacity of CIP were investigated.The adsorption mechanism of CIP was discussed.The results showed that the adsorption equilibrium time of iorn nanocomposite for CIP was 240 min,and the adsorbent dose was 0.4 g/L.According to the Langmuir,Freundlich,Redlich-Peterson,Koble-Corrigan and Temkin isotherm models,the non-linear regressive analysis of the equilibrium adsorption data of CIP onto iorn nanocomposites was conducted,respectively.The results showed that the Freundlich and Temkin models can well describe the adsorption behavior of CIP onto iorn nanocomposites.At 298 K,the maximum adsorption capacity of CIP onto iorn nanocomposites was 204.77 mg/g.The adsorption process of CIP onto iorn nanocomposites was a spontaneous and endothermic process,and increasing the temperature is conducive to the adsorption.Kinetic studies indicated that the adsorption of CIP onto iorn nanocomposites followed the pseudo second-order kinetic model,and the adsorption process was controlled by both intraparticle diffusion and membrane diffusion.The adsorption characteristics of DOX on iorn nanocomposites was studied.The effects of contact time and the iorn nanocomposites dose on the adsorption capacity of doxycycline on iorn nanocomposites was investigated.The results show that the adsorption equilibrium time of iorn nanocomposites for doxycycline was 360 min,and the adsorbent dose was 0.4 g/L.The adsorption thermodynamics and kinetics of DOX adsorbed on iorn nanocomposites were studied.The results showed that the adsorption equilibrium data conformed to the Langmuir and Redlich-Peterson isothermal models.The pseudo second-order model could better describe the adsorption process of DOX onto the iorn nanocomposites.Thermodynamic parameters indicated that the adsorption of DOX by iorn nanocomposites was a spontaneous and endothermic process.At 298 K,the maximum monolayer adsorption capacity of DOX onto iorn nanocomposites was 151.39 mg/gThe results indicated that the iorn nanocomposites have good adsorption properties for CIP and DOX,and can be used as an adsorbent for the removal of CIP and DOX from aqueous solution.