温度/pH双重响应性微凝胶对阳离子染料的吸附

Adsorption of cationic dyes towards temperature/pH dual-responsive microgel

以N-异丙基丙烯酰胺(NIPAM)和甲基丙烯酸(MAA)为单体,采用无皂乳液聚合制备了微凝胶CPMg,并用扫描电子显微镜(SEM)、比表面及孔隙度分析(BET)、傅里叶变换红外光谱(FTIR)、X-射线光电子能谱(XPS)等对其结构、组成和性能进行了表征,并考察了CPMg对亚甲基蓝和罗丹明B等阳离子染料的吸附性能.结果表明,该微凝胶粒径均匀,具有温度和pH双重响应性;MAA含量为30%的微凝胶(CPMg-3)在pH=6时吸附效果最佳;吸附过程符合拟二级动力学和Langmuir等温吸附模型,以单分子层的化学吸附为主,包括静电吸附和氢键作用.298.15 K时,CPMg-3对MB和RhB的Langmuir理论最大吸附量分别达1243.78和1184.83 mg·g^(-1).经过5次循环使用后,CPMg-3对MB和RhB的去除率保持初始去除率的80%以上.该微凝胶的制备方法简单可控,对染料废水的吸附处理具有较大的应用价值.

Microgel CPMg was synthesized via a soap-free emulsion polymerization using N-isopropylacrylamide(NIPAM) and methacrylic acid(MAA) as monomers.The resulting microgel was characterized by scanning electron microscope(SEM),Brunauer-Emmett-Teller(BET) analysis,Fourier transform infrared spectroscopy(FTIR),and X-ray photoelectron spectroscopy(XPS) to assess its structure,composition,and properties.The adsorption properties of CPMg for methylene blue(MB) and rhodamine B(RhB) were investigated.The results showed that the particle size of the microgel was uniform,and it had temperature/pH dual-responsiveness.In particularly,CPMg-3,which contained 30% MAA,exhibited maximum adsorption capacity at pH 6.The adsorption process can be described by pseudo second-order kinetic model and Langmuir isotherm model,indicating that the adsorption process of CPMg towards MB and RhB were dominated by the chemisorption of single-molecule layer,including electrostatic adsorption and hydrogen bonding.At a temperature of 298.15 K,the Langmuir theoretical maximum adsorption capacities of CPMg-3 for MB and RhB reached 1243.78 and 1184.83 mg·g^(-1),respectively.Even after five recycling cycles,CPMg-3 maintained the removal rate of MB and RhB over 80% of the initial removal rate.The proposed microgel preparation method is facile and controllable,exhibiting great application potential for the treatment of organic dyes in industrial wastewater.