| 圩区河道底泥腐殖酸对重金属和抗生素的共吸附 |
| 摘要点击 2213 全文点击 679 投稿时间：2020-10-22 修订日期：2020-11-18 |
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| 中文关键词 腐殖酸 铜 土霉素(OTC) 诺氟沙星(NOR) 共吸附 |
| 英文关键词 humic acid copper oxytetracycline(OTC) norfloxacin(NOR) coadsorption |
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| 中文摘要 |
| 为识别重金属、抗生素与腐殖酸之间的相互作用，提取圩区河道底泥中腐殖酸，以铜（Cu2+）与土霉素（OTC）及诺氟沙星（NOR）作为探针物，研究了腐殖酸在单一Cu2+体系、单一OTC体系、单一NOR体系以及Cu2++OTC和Cu2++NOR共存体系下的吸附行为，利用扫描电镜、红外光谱、X射线衍射和BET等方法进行了物相表征，并就可能存在的作用机制进行了分析讨论.结果表明，腐殖酸属典型的无定型非结晶体，其表面荷负电，具有非均匀多孔结构，孔径分布在介孔尺度，以3.76~6.40 nm孔体积占比最大.单一体系下，腐殖酸对Cu2+、OTC和NOR的饱和吸附量分别为33.043、19.521和26.676 mg·g-1；在质量浓度比为1：1的Cu2++OTC和Cu2++NOR共存体系下，Cu2+的饱和吸附量分别为38.053 mg·g-1和39.187 mg·g-1，OTC和NOR的饱和吸附量分别为25.965 mg·g-1和32.728 mg·g-1.单一和共存体系下的吸附特征具有相似性，吸附过程符合准二级动力学方程，吸附等温线遵循Sips模型，吸附热力学特征为自由能降低、熵变和熵变增加的自发型吸热反应，反应类型接近于化学性吸附和络合性吸附.共存体系中的Cu2+与OTC及NOR可生成络合物，这增加了腐殖酸可吸附的物种数量，而已吸附的Cu2+亦可通过吸附架桥等形式结合OTC和NOR，吸附量因此较单一体系下有所增加.腐殖酸所含羧基、酚羟基、酮基和醛基等含氧官能团普遍参与了吸附反应. |
| 英文摘要 |
| To clarify the interactions between heavy metals, antibiotics, and humic acid, copper (Cu2+), oxytetracycline (OTC), norfloxacin (NOR), and humic acid samples from river sediment in the Polder area were selected to build single and coexisting systems. Groups of experiments were designed to investigate the kinetics, thermodynamics, and isotherms of Cu2+, OTC, and NOR adsorption onto humic acid in single and Cu2++OTC and Cu2++NOR coexisting systems (concentration ratio=1:1). The physicochemical properties of humic acid were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), BET tests, and IR spectroscopy, and the possible adsorption mechanisms are discussed. The results showed that the humic acid was a typical amorphous material with a negative charge and non-uniform porous structure, and the pore size was at the mesoporous scale. In the single systems, the saturated adsorption capacity (qm) of Cu2+, OTC, and NOR onto humic acid was 33.043, 19.512, and 26.676 mg·g-1, respectively. In the Cu2++OTC system, the qm of Cu2+ and OTC was 38.053 and 25.965 mg·g-1, respectively. In the Cu2++NOR system, the qm of Cu2+ and NOR was 39.187 and 32.728 mg·g-1, respectively. The adsorption behaviors in the single and coexisting systems were similar and the adsorption processes were well fitted by the pseudo-second-order kinetic equation; the Sips model provided good descriptions for the isothermal adsorption equilibrium. Moreover, adsorption thermodynamics were characterized by spontaneous endothermic reactions with the reduction of free energy and the increase of enthalpy and entropy. It can be concluded that Cu2+ combines with OTC and NOR to form complexes, which increases the number of species available for adsorption by humic acid. Also, adsorbed Cu2+ can combine with free OTC and NOR in a bridging manner. Thus, a more favorable adsorption situation occurred in the coexisting systems. The IR characteristics of the carboxyl, phenolic hydroxyl, ketone, and aldehyde groups of humic acid changed by different degrees after adsorption, indicating that oxygen-containing functional groups generally participated in the adsorption reactions. |
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