| Nowadays,antibiotics are detected continually in water environment,especially in drinking water sources.The problem of antibiotic contamination has been paid more and more attention,which also gives a challenge to drinking water treatment.Since the conventional process of drinking water has little effect on the removal of antibiotics,it is urgent to seek the technique of antibiotic reduction.With the increasing application of low-pressure membrane in water treatment,it is significant to use low pressure membrane for antibiotic reduction technology.In addition,water quality characteristics(such as particulate matter and organic matter,etc.)also influence on the reduction of antibiotics.Therefore,combined the influence factor such as kaolin and organic,it is important to investigate the effect of low pressure membrane on antibiotics.Based on the establishment of the detection method of oxytetracycline,the adsorption of the antibiotic on kaolinite or organic matter was investigated,and then the effects of the water quality factors such as kaolinite and organic matter on the static adsorption and the dynamic filtration of the antibiotic in the ultrafiltration membrane process were conducted.The results showed that the adsorption of oxytetracycline on kaolinite well fitted pseudo-second-order model and intra-particle diffusion model.Multi-mechanisms were obtained for the adsorption of oxytetracycline on kaolinite,which is both Langmuir model and Freundlich model were well fitted by experimental data.Moreover,thermodynamics analysis indicatedthe adsorption of oxytetracycline on kaonilite was spontaneous process and mostly chemical action.The effect of natural organic matter(humic acid,fulvic acid)on the adsorption of oxytetracycline by kaolinite found that organic matter was beneficial to the reduction of oxytetracycline,and the effect of fulvic acid on kaolinite adsorption was better than humic acid and fulvic/humic acid.The static adsorption and dynamic filtration of oxytetracycline on polyvinylidene fluoride(PVDF),polyethersulfone(PES),polyacrylonitrile(PAN)ultrafiltration membranes were studied.The results showed that the adsorption of oxytetracycline on three ultrafiltration membranes were well fitted the pseudo-second-order model and intra-particle diffusion model.The adsorption isotherms of PES mainly fitted Freundlich model,and PVDF and PAN are fitting with Langmuir model.The adsorption of oxytetracycline on three ultrafiltration membranes was endothermic process.The removal rates of oxytetracycline by PAN,PVDF and PES were 19%,28% and 15%,respectively.Membrane filtration results showed that membrane flux of PAN was better than PVDF and then PES during three membranes for oxytetracycline.The static adsorption and dynamic filtration of the oxytetracycline on different membranes with different water quality characteristics(kaolinite,humic acid and fulvic acid)found that the kaonilite/humic/fulvic acid process is the most favorable for the improvement of the adsorption capacity of oxytetracycline during the static adsorption of the ultrafiltration membrane.Then,the improvement followed by the humic acid,fulvic acid and humic/fulvic acid.At last,kaolinite lightly influenced theadsorption capacity of oxytetracycline.During the filtration process,organic matter and kaolinite is beneficial to the removal of the oxytetracycline by the ultrafiltration membrane.The removal rates of oxytetracycline increased with the increase of the concentration of organic matter and kaolinite.There were differences in the membrane flux of three ultrafiltration membranes during different process: the effect of kaolin on the membrane specific flux of PVDF and PES was not obvious,but the decrease of membrane specific flux of PAN was significant in the presence of kaolinite,and in the presence of organic matter and kaolinite,the membrane specific flux of PVDF and PES was greatly affected,but the membrane specific flux of PAN was less affected by the presence of organics and kaolinite. |
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