AOPAN@Mg(OH)2多层次电纺纤维膜的制备及除铬性能

以含有—NH₂和C═N的偕胺肟化聚丙烯腈(AOPAN)纳米纤维膜为载体, 通过水热法在AOPAN纳米纤维膜表面原位生长片状Mg(OH)₂纳米粒子, 得到具有多层次结构的有机-无机电纺复合纳米纤维膜AOPAN@Mg(OH)₂], 并研究了AOPAN@Mg(OH)₂的除铬性能. 研究结果表明, 当水热温度为40 ℃, 水热时间为7 h时, AOPAN纳米纤维膜表面形成了明显的多层次结构的Mg(OH)₂纳米晶体. 当溶液pH=2时, AOPAN@Mg(OH)₂复合纳米纤维膜对Cr(Ⅵ)的吸附符合Langmuir模型, 且满足二级动力学方程, 5 h后最大吸附量达到123.5 mg/g. AOPAN@Mg(OH)₂复合纳米纤维膜中含有—NH₂基团和Mg(OH)₂纳米粒子, 在酸性条件下可以质子化为带正电的—N\begin{array}{c}{H}_3^{+}\end{array}和Mg(OH)₂H⁺, 通过静电吸附更易与HCr\begin{array}{c}{O}_4^{-}\end{array}结合. 此类复合纳米纤维膜材料在水体中易取出, 并且在稀NaOH溶液中可以解吸附, 循环使用4次去除率仍可以保持在50%以上.

Preparation of Hierarchically Structured AOPAN@Mg(OH)2 Composite Nanofibrous Membrane and Cr(Ⅵ)-removal Capacity†

The hierarchial aminated polyacrylonitrile(AOPAN)@Mg(OH)₂ composite nanofibrous membrane was obtained by electrospinning technique and surface modification with hydroxylamine chloride prior to hydrothermal method. The composite nanofibrous membranes were characterized by Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), X-ray diffraction(XRD) and transmission electron microscope(TEM) to confirm the formation of Mg(OH)₂ nanoparticles on the AOPAN nanofibers. The results revealed that 40 ℃/7 h was the best hydrothermal condition and Mg(OH)₂ nanoparticles were effectively loaded on the surface of AOPAN nanofibrous membrane. The adsorption process showed pH dependence and the maximum Cr(Ⅵ) adsorption occurred at pH=2. The Langmuir adsorption model described well the experimental adsorption data and estimated a maximum loading capacity of 123.5 mg/g. This is mainly due to the protonation of —NH₂ groups and Mg(OH)₂ nanoparticles under the acid condition, which is benefit for adsorbing HCr\begin{array}{c}{O}_4^{-}\end{array}. The kinetics studies indicated that the adsorption equilibrium was attained after 5 h and the experimental data followed the pseudo-second order model. Meanwhile, the AOPAN@Mg(OH)₂ composite nanofibrous membrane can be easily separated from liquid solutions and shows excellent cyclic utilization performance. The composite membrane maintained over 50% removal rate after rinsing with dilute NaOH solution by four cycles. Therefore, the AOPAN@Mg(OH)₂ composite nanofibrous membrane could be a good candidate for removing Cr(Ⅵ) from wastewater, and the study provides a simple and effective route for the development of new environmental remediation nanomaterials.