Effectiveness of carbon nanotube–cobalt ferrite nanocomposites for the adsorption of rhodamine B from aqueous solutions
Effectiveness of carbon nanotube–cobalt ferrite nanocomposites for the adsorption of rhodamine B from aqueous solutions
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DOI：
10.1039/c4ra15446k
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发表时间：
2015-02
期刊：
影响因子：
3.9
通讯作者：
Oluwaseun A. Oyetade;V. Nyamori;B. Martincigh;S. Jonnalagadda
中科院分区：
文献类型：
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作者：
Oluwaseun A. Oyetade;V. Nyamori;B. Martincigh;S. Jonnalagadda
通过一系列的批量实验，研究了铁酸钴纳米颗粒（CoFe2O4）、酸官能化多壁碳纳米管（MWCNT-COOH）和碳纳米管-铁酸钴纳米复合材料对水溶液中罗丹明B （RhB）的吸附效率。考察了吸附量与pH、接触时间、吸附剂剂量、染料浓度和温度的关系。研究了提高MWCNT-COOH在纳米复合材料中的含量对复合材料性能的影响。对CoFe2O4的吸附量最低（5.165 mg g−1），对MWCNT-COOH的吸附量最高（42.68 mg g−1）。纳米复合材料的吸附能力随着MWCNT-COOH用量的增加而增强。最佳吸附pH为7,360 min后达到平衡。吸附动力学符合准一级、准二级、Elovich和颗粒内扩散模型。结果表明，伪二阶模型最能描述数据，反映在残差平方和的最低值。在各种吸附等温线中，Langmuir等温线对平衡数据的拟合效果最好。在20-45℃的温度范围内得到了热力学参数ΔH°，ΔS°和ΔG°。除一种掺杂纳米复合材料为放热吸附外，其余均为自发吸附、吸热吸附和熵驱动吸附。丙酮和乙醇均能较好地解吸RhB，解吸效率在62 ~ 95%之间。
The efficiency of adsorption of rhodamine B (RhB) from aqueous solution was investigated through a series of batch experiments by using cobalt ferrite nanoparticles (CoFe2O4), acid-functionalized multiwalled carbon nanotubes (MWCNT–COOH) and carbon nanotube–cobalt ferrite nanocomposites. The adsorption capacity was evaluated as a function of pH, contact time, adsorbent dose, dye concentration and temperature. The effect of increasing the percentage of MWCNT–COOH in the nanocomposites was also studied. The adsorption capacity was lowest in CoFe2O4 (5.165 mg g−1) and highest with MWCNT–COOH (42.68 mg g−1). For the nanocomposites, the adsorption capacity was enhanced with an increase in the amount of MWCNT–COOH. The optimum pH for adsorption was observed at 7 at which equilibrium was reached after 360 min. The kinetics of adsorption was fitted to the pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models. The results showed that the pseudo-second order model best described the data as reflected in the lowest value for the sum of squared residuals. Among the various adsorption isotherms tested, the Langmuir isotherm provided the best fit to the equilibrium data. The thermodynamic parameters, ΔH°, ΔS° and ΔG°, were obtained over a temperature range of 20–45 °C. Adsorption was spontaneous, endothermic and entropy-driven, except for one of the doped nanocomposites for which adsorption was exothermic. A good desorption of RhB from the loaded adsorbents was obtained by using either acetone or ethanol with a desorption efficiency in the range of 62–95%.