Egg yolk/ZIF-8/CLPAA composite aerogel: Preparation, characterization and adsorption properties for organic dyes

Abstract

In this paper, a new composite aerogel egg yolk/zeolitic imidazolate framework-8/crosslinked polyacrylic acid (EY/ZIF-8/CLPAA) was prepared by in situ polymerization of acrylic acid in composite system of egg yolk and ZIF-8. The structure and performance of the composite aerogel were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), in-situ attenuated total reflection Fourier transform infrared spectrometer (FT-IR) and comprehensive thermal analyzer (TG). The results show that the composite aerogel has irregular porous structure inside, and ZIF-8 has 12-sided crystal structure. The composite aerogel has good thermal stability and water stability and can effectively remove dyes in wastewater. It has different equilibrium adsorption capacity for different dyes: Malachite Green: 2338 ​mg/g, Crystal Violet: 489 ​mg/g, Methyl Orange: 447 ​mg/g and Rhodamine B: 299 ​mg/g. The adsorbent still maintains a certain activity after five adsorption-desorption cycles. The EY/ZIF-8/CLPAA aerogel adsorbs organic dyes mainly through electrostatic interaction, π-π interaction and hydrogen bonding. The adsorption data conforms to the pseudo-second-order kinetic model and follows the Langmuir adsorption isotherm.