功能化纳米碳管对水溶液中Pb2+吸附的动力学、平衡与等温线

Kinetics, equilibrium and isotherms of Pb2+ adsorption from aqueous solutions on carbon nanotubes functionalized with 3-amino-5a,10a-dihydroxybenzo indeno furan-10-one

  • 摘要: 以3-Amino-5a,10a-dihydroxybenzo indeno furan-10-one(ADIF)功能化改性的纳米碳管(MWCNT-ADIF)为吸附剂,除去水溶液中的Pb2+。采用FT-IR,SEM,TGA及DTG对MWCNT-ADIF样品进行表征。探讨了pH值、Pb2+初始浓度、吸附量和接触时间对吸附动力学与平衡的影响。采用4种二参数模型(Langmuir、Freundlich、Tempkin与Dubinin-Radushkevich)和6种三参数模型(Redlich-Peterson,Khan,Sips,Radke-Prausnitz,Toth,Hil)研究Pb2+吸附等温线。通过伪一阶动力学模型、伪二阶动力学模型和粒子内扩散模型分析吸附动力学。采用3种误差分析方法、相关系数、卡方值和平均相对误差来确定最佳拟合等温线和动力学模型。结果表明,吸附动力学与伪二阶动力学模型相吻合。误差分析表明,三参数模型比二参数模型更适合描述Pb2+吸附数据。等温线数据与Langmuir、Hill和Sips models相符。MWCNT-ADIF在pH=3溶液中能脱除92%的Pb2+,并且回收后的MWCNT-ADIF能重复使用5个再生周期。

     

    Abstract: Multi-wall carbon nanotubes functionalized with 3-Amino-5a, 10a-dihydroxybenzo indeno furan-10-one (ADIF), (MWCNT-ADIF), were used as the adsorbent to remove lead ions (Pb2+) from aqueous solutions. The samples were characterized by FT-IR, SEM, TGA and DTG. Effects of pH, initial Pb2+ concentration, adsorbent dosage and contact time on adsorption kinetics and equilibrium were investigated in a batch mode. Adsorption isotherms of Pb2+ ions were investigated using four two-parameter models (Langmuir, Freundlich, Tempkin, Dubinin-Radushkevich) and six three-parameter models (Redlich-Peterson, Khan, Sips, Radke-Prausnitz, Toth, Hill). Adsorption kinetics were investigated by the pseudo first-order kinetic model, the pseudo second-order kinetic model and the intra-particle diffusion model. Three error analysis methods, correlation coefficient, chi-square test and average relative errors, were used to determine the best fitted isotherm. Results indicated that adsorption kinetics was best described by the pseudo second-order kinetic model. Error analysis indicated that three-parameter models described the Pb2+ sorption data better than the two-parameter models. The isotherm data were best fitted by the Langmuir, Hill and Sips models. Pb2+ ions could be desorbed from MWCNT-ADIF up to 92% at pH=3 and the recycled MWCNT-ADIF could be reused for 5 regeneration cycles.

     

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