Research On Removal Of Antibiotic Pollution In Water Body Based On Biomass Material Composite Adsorption Technology

With the emergence of new pollutants,more and more attention has been paid to the protection of global ecological environment.It is necessary to develop low-cost and environmentally friendly adsorption materials based on biomass materials and apply them to water pollution prevention and environmental remediation.In this study,two nanocomposites,graphene oxide-cellulose nanocrystalline nanocomposites（CNCs-GO）and montmorillonite-cellulose nanofiber nanocomposites（CMNFs-MMT）were prepared by using nano cellulose,graphene oxide and montmorillonite as matrix respectively.The two nanocomposites were used as adsorbents to adsorb levofloxacin hydrochloride（Levo-HCl）in water Adhesion and desorption experiment.The factors influencing the adsorption effect were considered as follows:initial concentration of antibiotics,dosage of adsorbent,initial p H value of solution and contact time.The influencing factors were optimized by response surface methodology to explore the optimal adsorption conditions,adsorption capacity and removal rate under the optimal adsorption conditions;the adsorption kinetic model and adsorption isotherm model were explored to determine the adsorption mechanism.Exploring the renewable performance of the two adsorbents by carrying out adsorption-desorption cycle experiments.By FT-IR,SEM,TEM,EDS,XPS,XRD,DLS,BET method and other characterization tests of the two synthetic processes,changes in the structure and surface properties were analyzed.After systematic experimentation,the following main conclusions are obtained:1)Optimization test of influencing factors.This paper firstly determined the main influencing factors and the best experimental conditions for the adsorption of Levo-HCl by CNCs-GO and CMNFs-MMT.The first is CNCs-GO adsorbent.The test uses response surface method.The optimal test conditions are as follows:Levo-HCl initial concentration is 10.00 mg·L^-1,p H is 4,CNCs-GO dosage is 1.00 g·L^-1.The adsorption equilibrium is reached after 4 h,and the optimal removal rate can reach 80.12%.For CMNFs-MMT adsorbent,the test method is the same as the previous material,and the optimal test conditions are as follows:CMNFs-MMT dosage is0.45 g·L^-1,Levo-HCl initial concentration is 6.40 mg·L^-1,p H is 4.33.The adsorption equilibrium is reached after 92 minutes,and the optimal removal rate can reach 92.30%.2)The adsorption mechanism of Levo-HCl by nanocomposite adsorbent.In order to explore the adsorption mechanism,the adsorption process of CNCs-GO and CMNFs-MMT were tested with kinetics and isotherm respectively.Kinetic models include:pseudo first-order dynamic model,pseudo second-order dynamic model,and intra-particle diffusion model.The adsorption isotherm models are:Langmuir isotherm model,Freundlich isotherm model and Sips isotherm model.After testing,the maximum adsorption capacity of CNCs-GO and CMNFs-MMT for Levo-HCl is 55.74 mg·g^-1 and 65.90 mg·g^-1,respectively.3)Recycling performance experiment.In order to explore the effect of the regeneration performance of the two nanocomposite adsorbents and the effect that the adsorption performance is interfered by natural water bodies,a repeated use experiment was carried out.The results show that:CNCs-GO and CMNFs-MMT both show good resistance to natural water interference and reusability.Compared with pure water,the removal rate of CNCs-GO in natural water decreased by 8.75%.After 6 times of repeated use,the removal rate of Levo-HCl only decreased by 9.14%.The removal rate of CMNFs-MMT in natural waters decreased by 3.60%compared to pure water,and the removal rate of Levo-HCl decreased by only 7.00%after repeated use for 6 times.Structural characterization proves that both adsorbents have large specific surface area and high porosity,and this structure is beneficial to adsorption.Characterize the adsorbent after adsorption.SEM and TEM images show that the surface structure of the adsorbent has changed significantly.EDS analysis shows that the surface of the adsorbent contains antibiotic molecules;after desorption,it returns to the original state,which proves that the prepared adsorbent has excellent regeneration performance.