Reversible Adsorption/Release for Anionic Dyes of Magnetic and CO2 Dual-Responsive Degradable Microgels
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摘要: 首先以甲基丙烯酸二乙氨基乙酯为单体,通过反相悬浮聚合制备了CO2响应型可降解微凝胶;然后在该微凝胶中原位合成Fe3O4磁性纳米粒子,制备了磁和CO2双响应型可降解微凝胶。通过傅里叶变换红外(FT-IR)光谱仪、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等对微凝胶的组成和结构进行了表征。结果表明:CO2响应之后的微凝胶对阴离子染料可进行选择性吸附,对茜素红的最大吸附量为1413 mg/g;微凝胶的磁响应性使其能够得到便捷的分离回收,被吸附的染料能够通过碱洗释放,并且在CO2刺激下微凝胶又能够重复使用。Abstract: Degradable magnetic and CO2 dual-responsive microgels were prepared by inverse suspension polymerization and in-situ synthesis of nanoparticles. The structure and morphology of microgels were characterized by Fourier-transformed infrared (FT-IR) spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM). The microgels exhibited magnetic and CO2 responsiveness, and could be degraded upon the treatment of D, L-dithiothreitol (DTT). After treating with the stimulus of CO2, the microgels exhibited a selective adsorption for anionic dyes. The maximum adsorption capacity was up to 1413 mg/g for Alizarin red (AR). The microgels with adsorbates could be separated from solutions under the help of an external magnetic field. Besides, the adsorbates could be described by treating with solution of pH 12. Microgels regenerated with CO2 trigger exhibited high adsorption ability (>90%) after three consecutive recycling trials.
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Key words:
- degradable microgel /
- CO2 response /
- anionic dye /
- adsorption
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图 5 (a)m-MG对混合染料溶液选择性吸附的UV-Vis光谱;(b)染料在溶液中质量浓度和比例的变化;(c)染料的热力学等温吸附曲线;(d)Langmuir等温吸附模型拟合线;(e)Freundlich等温吸附模型拟合线;(f)染料的动力学吸附曲线;(g)准一级动力学拟合;(h)准二级动力学拟合;(i)Weber-Morris内扩散模型拟合
Figure 5. (a)UV-Vis spectra to m-MG selective adsorption to mixed dyes solution; (b)Variation of the mass concentrations of dyes and their ratio; (c)Thermodynamic isothermal adsorption curves of dyes; (d)Langmuir isothermal adsorption model; (e)Freundlich isothermal adsorption model; (f)Kinetic adsorption curves of dyes; (g)Pseudo-first-order kinetics; (h)Pseudo-second-order kinetics; (i)Weber-Morris internal diffusion model
表 1 m-MG吸附染料的等温吸附拟合参数
Table 1. Isotherm adsorgtion fitting parameters of m-MG adsorption dyes
Dyes Qm,exp/(mg·g-1) Langmuir Freundlich Qm,cal/(mg·g-1) KL RL R2 KF n R2 AR 1413 1 460.726 0.044 628 0.0695 0.976 22 100.1 2.98829 0.93348 ARAC 823 877.193 0.026 016 0.1137 0.996 29 54.85 2.42966 0.95973 MEB 734 826.446 0.011743 0.2211 0.997 3 26.99 0.54724 0.82175 PS 673 699.301 0.044369 0.0699 0.988 26 88.44 2.63262 0.96144 表 2 m-MG吸附染料的吸附动力学拟合参数
Table 2. Fitting parameters of adsorption kinetics of m-MG adsorbed dyes
Dyes Pseudo-first-order model Pseudo-second-order model Weber-Morris model Qe/(mg·g−1) R2 Qe/(mg·g−1) R2 R2 AR 1314.6690 0.94483 1550.4620 0.99075 0.95129 ARAC 693.9223 0.96111 970.8738 0.99483 0.90852 MEB 391.1065 0.87950 854.7009 0.99890 0.75012 PS 674.7215 0.96617 819.6721 0.99507 0.92160 -
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