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| Adsorption effects of enrofloxacin by modified spent bleaching earth carbon composites |
| Received:June 18, 2021 |
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| KeyWord:enrofloxacin;modified spent bleaching earth;spent bleaching earth carbon composite material;adsorption mechanism |
| Author Name | Affiliation | | ZHU Xiaoli | School of City and Environment, Northwestern University, Xi'an 710127, China | | ZHANG Ting | School of City and Environment, Northwestern University, Xi'an 710127, China | | WANG Junqiang | School of City and Environment, Northwestern University, Xi'an 710127, China
Xi'an Jinborui Ecological Technology Co., Ltd., Xi'an 710065, China | | ZHAO Hanhong | Mianxian Rural Energy Station, Hanzhong 724200, China | | SHANG Xiaoqing | School of City and Environment, Northwestern University, Xi'an 710127, China
Xi'an Jinborui Ecological Technology Co., Ltd., Xi'an 710065, China | | SHEN Baoshou | School of City and Environment, Northwestern University, Xi'an 710127, China | | CHEN Chao | Xi'an Jinborui Ecological Technology Co., Ltd., Xi'an 710065, China | | WANG Jing | School of City and Environment, Northwestern University, Xi'an 710127, China |
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| Abstract: |
| A&C300, A&C500, and A&C700 were prepared by pyrolyzing spent bleaching earth at 300, 500℃, and 700℃, respectively, under limited oxygen and then modified by H3PO4 activation to prepare HA&C300, HA&C500, and HA&C700. Subsequently, the adsorption effects of enrofloxacin(ENR) by unmodified and modified spent bleaching earth carbon composites were compared, and the material with the highest adsorption ability was selected. The selected material was characterized using a surface area analyzer(BET), scanning electron microscopy-energy spectroscopy (SEM-EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy(XPS), and Fourier transform infrared spectroscopy(FTIR). The determining factors(the initial concentration of ENR, the concentration of the adsorbent, and the pH) on the adsorption effects were investigated. The adsorption mechanisms of ENR by modified spent bleaching earth carbon composites were discussed based on adsorption kinetics, isothermal adsorption model, and adsorption thermodynamics. The data showed that the adsorption of ENR by unmodified spent bleaching earth carbon composites was poor while H3PO4 modified composites showed better adsorption effects, among which HA&C300 had the highest adsorption ability. When compared with A&C300, HA&C300 had more functional groups containing oxygen and a stronger hydrophobicity. The surface area and total pore volume were 45.72 m2·g-1 and 0.10 cm3·g-1, respectively, which were approximately 1.54 times and 1.59 times as large as that of A&C300. When the initial concentration of ENR was 10 mg·L-1 and the concentration of HA&C300 was 0.5 g·L-1, and pH=6(i.e., optimal adsorption conditions) the rate of adsorption of ENR by HA&C300 was 92.34%, which was approximately double that of A&C300. Adsorption models and thermodynamic analysis indicated that the pseudo-second-order kinetic model and Freundlich model could describe the adsorption process of ENR onto HA&C300 better, and its maximum adsorption capacity was 66.79 mg·g-1. The adsorption process was mainly affected by chemical adsorption and was spontaneously endothermic and multi-molecular layer adsorption. The adsorption mechanisms mainly included hydrogen bonds, π-π EDA, hydrophobic interactions, and pore filling. |
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