高吸附量有机聚合物的合成及其对亚甲基蓝吸附性能研究

Synthesis and super adsorption performance of a novel polyacrylic acid polymer for methylene blue

为开发高效染料吸附剂,以丙烯酸(AA)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)为单体,N,N′-亚甲基双丙烯酰胺为交联剂,γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)为偶联剂合成了一种新型有机聚合物(KAA),并以红外光谱(FTIR)与扫描电镜(SEM)对其进行表征.选用典型阳离子染料亚甲基蓝(MB)为研究对象,研究KAA对MB的吸附动力学、吸附热力学以及溶液pH值和不同阳离子对吸附的影响.结果表明,实验浓度范围内KAA对亚甲基蓝的最大吸附量为1558 mg·g^-1,能够在1.5 h内达到吸附平衡,吸附动力学符合准一级动力学模型,吸附等温线符合通用等温模型(a general model),吸附热力学数据表明吸附过程为自发、放热的熵减过程.KAA对亚甲基蓝的吸附具有较宽的pH适用范围,吸附剂具有良好的pH缓冲能力,阳离子对吸附具有较强的抑制作用,抑制作用大小为Al^3+> Ca^2+> Na^+.研究表明吸附的主要驱动力为静电作用和π-π相互作用.与其他吸附剂相比,KAA对亚甲基蓝具有超高的吸附量以及酸碱耐受能力,更符合实际应用需求.

A novel poly acrylic based polymer KAA was synthesized with acrylic acid(AA) and 2-acrylamido-2-methylpropane sulfonic acid(AMPS) as monomers. N,N′-methylenebisacrylamide(NMBA) was used as cross-linking agent, and silane coupling agent KH570 was added to modify the polymer. The Fourier transform infrared spectroscopy(FTIR) and scanning electron microscope(SEM) were employed to characterize KAA. The adsorption kinetics of KAA towards methylene blue(MB) was investigated. The results show that KAA presents favorable adsorption towards MB with the maximum adsorption capacity of 1558 mg·g^-1. The adsorption equilibrium was obtained in 1.5 h, and the data fitted the pseudo first kinetic model well. The adsorption under different temperatures matches the general isotherm model, and the calculated thermodynamic parameters indicate that the adsorption process is a spontaneous, exothermic and entropy reducing process. The solution pH exerted weak effects on KAA′s adsorption capacity while the addition of cations inhibited their adsorption of MB, following orders as Al^3+> Ca^2+> Na^+. The main adsorption is attributed to the electrostatic and the π-π bond interactions. Comparing to the recently reported adsorbents, KAA presents super adsorption capacity and favorable resistance ability to acid and alkaline, which makes it satisfy the practical pollution control application.