Adsorption Performance Of Quinolone Antibiotics From Aqueous Solutions By Surfactant Modified Attapulgite

In this paper,Baiyin attapulgite as raw material,modifies it with cationic surfactant cetyltrimethylammonium bromide（CTMAB）,anionic surfactant sodium dodecylben-zenesulfonate（SDBS）,and amphoteric surfactant dodecylbetaine（BS-12）to prepare modified attapulgite.The effects of OFL,CIP,and Lomefloxacin（LOM）adsorption and removal effects of three common quinolone antibiotics,screened the surfactant modified attapulgite with the best removal effect,further adjusted its modification ratio,and selected the modified attapulgite with the best adsorption performance and stability as the adsorbent of this kind of antibiotics.Through batch adsorption experiments,the effects of adsorption time,initial concentration,temperature,solution p H,common coexisting ions,and humic acids on adsorption performance were investigated.Combined with characterization results such as specific surface area,SEM,XRD,and FT-IR,the adsorption performance and mechanism of quinolone antibiotics were explored.The main results are as follows:（1）The static adsorption experiments of OFL,CIP,and LOM on attapulgite soil,CTMAB modified attapulgite soil,SDBS modified attapulgite soil,and BS-12 modified attapulgite soil showed that the attapulgite soil had almost no removal effect on quinolone antibiotics;There are significant differences in the adsorption performance of three different surfactants modified attapulgite,as follows:SDBS modified attapulgite>BS-12 modified attapulgite>CTMAB modified attapulgite.This result indicates that the main adsorption mechanism is electrostatic force and interaction.By comparing the modified ratios of 1%,3%,and 5%of SDBS modified attapulgite,taking into account factors such as adsorption performance and cost,it was determined to use 1%SDBS modified attapulgite as the adsorbent for OFL and LOM,and 5%SDBS modified attapulgite as the adsorbent for ciprofloxacin.Subsequent adsorption experiments were conducted to study its adsorption performance.（2）Compared with SDBS modified attapulgite,there is no significant crystal structure change,the surface becomes rough and uneven,the specific surface area and pore volume decrease,but the average pore size increases.Compared with the original soil,the diffraction peaks of the modified attapulgite shift to a small angle,indicating that the interlayer spacing has increased.XRD and FT-IR and other characterization results confirm that SDBS was successfully loaded on the surface and interlayer of attapulgite.（3）1%SDBS modified attapulgite has a fast adsorption rate and high removal rate for OFL,and the adsorption process is more in line with the quasi second-order kinetic model and Langmuir isotherm model.The entire adsorption process belongs to a spontaneous endothermic entropy increase reaction.Under acidic conditions（p H 2-6）,1%SDBS modified attapulgite has the best adsorption effect on OFL.Na⁺,K⁺,Ca²⁺,Fe³⁺,and SO₄^2-have little effect on the adsorption process,while Mg²⁺,Al³⁺,and CO₃^2-at higher concentrations will inhibit the adsorption of OFL.Humic acid has a significant impact,with a concentration exceeding 1mg/L inhibiting the adsorption of OFL by 1%SDBS modified attapulgite soil.（4）5%SDBS modified attapulgite has a high adsorption removal rate and good stability for CIP,and the adsorption process is more in line with the quasi second-order kinetic model and Langmuir isotherm model.The entire adsorption process belongs to a spontaneous endothermic entropy increase reaction.Under acidic conditions（p H 2-6）,5%SDBS modified attapulgite has the best adsorption effect on CIP.Na⁺,K⁺,Ca²⁺,SO₄^2-have little effect on the adsorption process,while Mg²⁺,Al³⁺,Fe³⁺,and CO₃^2-at high concentrations are not conducive to the adsorption of CIP by 5%SDBS modified attapulgite.Humic acid has weak interference on the adsorption of CIP by 5%SDBS modified attapulgite soil.（5）1%SDBS modified attapulgite has a high adsorption removal rate and good stability for LOM,and the adsorption process is more in line with the quasi second-order kinetic model and the Freundlich isothermal model.The entire adsorption process belongs to a spontaneous endothermic entropy increase reaction.Under acidic conditions（p H 2-5）,1%SDBS modified attapulgite has the best adsorption effect on LOM.Na⁺,K⁺,Ca²⁺,SO₄^2-have little effect on the adsorption process,while Mg²⁺,Al³⁺,Fe³⁺,and CO₃^2-at high concentrations are not conducive to the adsorption of LOM by 1%SDBS modified attapulgite.When the concentration of humic acid increases,the interference on the adsorption of LOM by 1%SDBS modified attapulgite soil is more obvious.