| To solve the technical difficulties in the treatment of antibiotic wastewater,it is considered that although biochar is made of agricultural residues and has the advantages of abundant resources and low cost,it still has some defects such as poor adsorption performance and difficult separation and recovery.In view of the excellent anion exchange performance,unique layered structure and good surface characteristics of hydrotalcite materials,and the high cellulose content in eleocharis dulcis peels,which makes them an ideal raw material for preparing biochar.This thesis aims to prepare biochar(EDB)from eleocharis dulcis peels,and the NiFe-layered double hydrotalcite/eleocharis dulcis peel biochar(NiFe-LDH/EDB)composite magnetic adsorption material is prepared by pyrolysis-co-precipitation two-step method,to achieve the efficient adsorption treatment of antibiotic wastewater.During the study,enrofloxacin hydrochloride(ENR)is used as the target pollutant.By means of investigating the effects of pyrolysis temperature,NiFe-LDH interlayer anion,p H value and EDB addition on the adsorption of ENR by NiFe-LDH/EDB composites,to determine the optimum preparation conditions of NiFe-LDH/EDB,and the materials are characterized by various modern analytical techniques.On this basis,the optimum process conditions for the adsorption of ENR by NiFe-LDH/EDB composites are determined by single factor experiment and response surface experiment.In addition,the adsorption performance of NiFe-LDH/EDB composites is investigated by comparative experiment and cyclic regeneration experiment.Finally,the adsorption mechanism of NiFe-LDH/EDB composites is discussed based on the results of FTIR,XPS before and after adsorption,the analytical results of adsorption kinetics and adsorption thermodynamics.The main results are as follows:(1)NiFe-LDH/EDB composite prepared under the pyrolysis temperature of500℃,Cl~-as interlayer anion,p H value of 11 and EDB content of 0.50 g has the best adsorption effect on ENR.Its specific surface area is 293.44 m~2/g and average pore size is 4.75 nm.Its saturation magnetization is 10.53 emu/g.The material is a kind of magnetic porous material with mesoporous main,rough surface,easy separation and recovery,which is suitable for practical application.(2)The dosage of NiFe-LDH/EDB,the initial concentration of ENR and the initial p H value of wastewater have significant effects on the adsorption and removal of ENR by NiFe-LDH/EDB composite.The interaction between the initial concentration of ENR and the dosage of NiFe-LDH/EDB and the initial p H value of wastewater and the dosage of NiFe-LDH/EDB were significant.It is calculated that when the dosage of NiFe-LDH/EDB is 1.00 g/L,the initial concentration of ENR is20 mg/L,and the initial p H value of wastewater is 6,the adsorption rate can reach85.98%.The adsorption performance of NiFe-LDH/EDB composite is obviously better than that of EDB and NiFe-LDH,and NiFe-LDH/EDB has excellent reuse performance,with three adsorption rates of ENR above 60%.(4)The adsorption of ENR on NiFe-LDH/EDB is more consistent with the quasi-second-order kinetics and Langmuir adsorption isotherm equation.The maximum saturation adsorption capacity at 25℃is 82.37 mg/g by fitting the Langmuir adsorption isotherm equation,and the thermodynamic parametersΔG<0,ΔS>0,ΔH=28.45 k J/mol.Thermodynamic parametersΔG<0,ΔS>0,ΔH=28.45k J/mol.The adsorption process is a spontaneous and endothermic entropy-driven process dominated by chemisorption.The mechanisms of adsorption for ENR are attributed to a combination of the interlayer anion exchange,electrostatic interaction,π-πinteraction,charge-assisted hydrogen bond,metal coordination mechanism,and pore filling. |
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