| Antibiotics have been largely and extensively used in humans and animals to treat infections,and also as growth promoters of livestock animals.After entering the organism,antibiotics are difficult to absorb and digest completely. Then, a significant fraction is excreted in the parent form or its metabolite form through urine fluid and feces into environmental,which would pose a negative effect on human health and ecological environment.Recently, many researchers have been done lots of studies about the environmental behaviour of antibiotics. However, there is still a lack of understanding and knowledge about the migration and transformation mechanisms of antibiotics in the environment. Meanwhile few studies have been done about the antibiotics in the multiphase media. Therefore, tylosin(TYL) was used as the sorbate,the sorption properties and mechanism of antibiotics on black carbon,complex of minerals(goethite and montmorillonite)and black carbon, complex of humic acid and black carbon were investigated, respectively. The main experiments and conclusions are as follows:1. Sorption of TYL on black carbons was systematically measured.The results showed that the sorption of TYL on rice straw charcoal (RC), motor vehicles of fly ash (MC), and soot (SC) could attain equilibrium within 24hrs,24hrs and 12 hrs.The pseudo-second-order model and intraparticle diffusion model can fit well with the kinetics data of adsorption TYL on black carbon. Slips model fit well with the isotherm data, and the correlation coefficient was more than 0.999. Sorption capacity between black carbons were RC> MC>SC. Besides, The sorption capacity of TYL on black carbons decreased gradually as the pH and ionic strength of the solutions increased. The sorption mechanism of TYL might be related with hydrophobic interaction, π-π EDA interactions, H-bonding and ion exchange.2. The microcosmic interfacial interactions mechanism between minerals(goethite and montmorillonite) and black carbon were studied though the characterization of SEM, XRD and FTIR, respectively. It could found that black carbon could combined with minerals through covalent interaction. The sorption of TYL on the black carbon-goethite(BC-FeOOH)and black carbon-montmorillonite (BC-MT)could attain apparent equilibrium within 12 hrs and 24 hrs. The maximum of sorption capacity of sorption of TYL on BC-FeOOH is 70625 mg/kg, which is 8 times larger than goethite. The maximum of sorption capacity of sorption of TYL on BC-MT is 123221 mg/kg, is 1.5 times as large as black carbon, is 3 times over montmorillonite. The kinetics data of the sorption of TYL on the BC, FeOOH, FeOOH-BC, MT and MT-BC can fit well with pseudo-second-order model, the correlation coefficient was more than 0.997. Then, The sorption capacity of TYL on BC-FeOOH increased gradually while the pH increased. Inversely, The sorption capacity of TYL on BC-MT decreased as the pH increased. Both BC-FeOOH and BC-MT decreased with the increase of ionic strength.3. The microcosmic interfacial interactions mechanism between humic acid and black carbon were investigated though the characterization of BET, SEM, XRD and FTIR, respectively. The sorption properties of TYL on the complex of humic acid (HA)and black carbon(RC,SC) were also studied. The sorption of TYL on complex(HA-RC,HA-SC) could attain apparent equilibrium within 24 hrs. The maximum of sorption capacity of sorption of TYL on HA-RC is 107125 mg/kg,is 32% higher than that of RC. The maximum of sorption capacity of sorption of TYL on HA-SC is 30985 mg/kg,is 72% up compared with SC. Sorption capacity ordered by RC-HA> RC> SC-HA> SC. The kinetics data of the sorption of TYL on the HA-RC and HA-SC can fit well with pseudo-second-order, thus chemical action was devoted to the sorption process. The Henry model and Freundlich model fit well with the isotherm data, thus, allocation mechanism exists in the sorption process. In addition, the sorption capacity of TYL on HA-RC and HA-SC decreased obviously as the pH and ionic strength of the solutions increased. |
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