Investigation the adsorption behavior of functional carbon-based composites for efficient removing anions / cations in single and multicomponent systems

• A novel 3D carbon-based nanocomposite was successfully synthesized. • The adsorbent can selectively adsorb anionic or cationic dyes at different pH values. • The tandem adsorption experiments were executed on an adsorption column confirmed the industrial application of the adsorbent. • Experiments have proved that electrostatic interaction, π-π interaction, hydrogen bond interaction and host–guest interaction are the main mechanisms of dye adsorption. A novel pH-responsive carbon-based nano-adsorbent (MGO-CNT@β-CS-CD) for the adsorption of dyes from aqueous solution was prepared by using graphene oxide, Fe 3 O 4 , multi-walled carbon nanotubes, β-cyclodextrin and Chitosan as raw materials. The structure and adsorption mechanism of adsorbent were performed by FT-IR, SEM, Raman, TGA, VSM, XPS, BET, XRD and ICP-MS. After that, the adsorption behaviors of MGO-CNT@β-CS-CD towards dyes Methylene blue (MB), Methyl orange (MO), Congo red (CR) and Indigo Carmine (IC) were further systematically investigated. Moreover, kinetic adsorption by MGO-CNT@β-CS-CD was well fitted with the pseudo-second-order model. The adsorption isotherms indicated that the results were fitting well with the Langmuir model, the maximum adsorption capacity of MB, MO, CR and IC reached 1580.50, 269.09, 287.43 and 258.13 mg/g, respectively. Additionally, anionic dyes could be selectively adsorbed when the pH value of the anionic and cationic mixed solution was acidic, whereas, when the pH value of the solution was alkaline, MB could be adsorbed from a mixed anion-cation system. Finally, the results showed that the nanoparticle adsorbent could be used as the packing agent of the adsorption column to realize the series adsorption of anionic - cationic - anionic dye systems, which had a good industrial application prospect.