Preparation Of Modified Attapulgite And Analysis On Adsorption Of Oxytetracycline

As a preventive and therapeutic drug,oxytetracycline(OTC)is widely used in livestock and poultry industry and in clinic.Due to the low efficiency of OTC adsorption,most of them are discharged into the environment through urine as drug prototypes.Thus,migration and transformation of OTC in the environment has become a focus of attention.Since OTC is difficult to be biodegraded in the environment,it becomes an effective means of management to adsorb OTC from waste water with suitable adsorption materials.In this thesis,attapulgite was modified by acidification,thermal and Fe modification.After that,the adsorption capacity of different modified attapulgite for OTC was researched,and the characteristics and adsorption mechanism of the materials were discussed.The conclusions were obtained as follows:(1)The optimum modification condition by HCl modification lOg attapulgite were 20ml with lmol/1,temperature 60?,treatment time 5h.The maximum adsorption capacity of OTC by the HCl modification attapulgite was 24.27mg/g at 25?;The heat of adsorption was 2.88kJ/mol and the entropy increase of adsorption process was 0.0861kJ/mol-K.The adsorption process of HCl modified attapulgite was a spontaneous process of physical adsorption.The optimum modification condition for sulfuric acid modified attapulgite were 20ml with concentration lmol/1,temperature 60?,the treatment time 5h(2)The optimum thermal temperature was 400? for only thermally modified or HCl and thermal synergistic modification attapulgite.For thermal modification attapulgite,the maximum adsorption of OTC was 21.93mg/g at 25?;The heat of adsorption was 7.41kJ/mol and the entropy increase of adsorption process was 0.0990 kJ/mol-K.The attapulgite modified by HC1 and acid thermal synergistic treatment,the maximum adsorption capacity of OTC was 66.23mg/g.The heat of adsorption was 4.87 kJ/mol;the entropy increase of adsorption process was 0.0870kJ/mol-K.The adsorption process of attapulgite only thermal or HCl and thermal synergistic treatment was a spontaneous process of physical adsorption.(3)The best modification condition for iron modified attapulgite were mass fraction of FeCl320%,the oscillating time 5h,thermal temperature 400?.The iron modified attapulgite could adsorbed OTC 69.93mg/g at 25? as a maximum adsorption capacity,and the adsorption heat was 5.30kJ/mol,the entropy increase of adsorption process was 0.0914kJ/mol-K.This was also a spontaneous process of physical adsorption for iron modified attapulgite to absorb OTC.(4)Through the experiment treated OTC simulated wastewater,the removal efficiency of OTC by iron modified attapulgite was the highest and the cost was 4.51CYN/t.