High adsorption performance of β-cyclodextrin-functionalized multi-walled carbon nanotubes for the removal of organic dyes from water and industrial wastewater

Removal of inorganic and organic pollutants from synthetic and industrial wastewater samples is one of the biggest challenges facing researchers. In this work, glycine-β-cyclodextrin-functionalized carbon nanotubes (MWCNTs/Gly/β-CD) as a novel nano-adsorbent were synthesized and developed for the removal of organic pollutants. The structure and morphology of MWCNTs/Gly/β-CD was characterized by FT-IR, FESEM, TEM, XRD and EDX, and the results showed that the MWCNT was modified with Gly and β-CD. The effects of surface improvement on the adsorption of organic pollutants were studied in a batch system by considering various parameters such as contact time, adsorbent dosage, pH, and temperature. The results indicated that the maximum capacities of MB, AB113, MO and DR1 onto MWCNTs/Gly/β-CD were 90.90 mg g−1, 172.41 mg g−1, 96.15 mg g−1, and 500 mg g−1, respectively. The dye adsorption kinetics, thermodynamics and isotherms were also investigated. The results indicated that pseudo-second-order kinetics model (R2 > 0.999) and Langmuir isotherm model (R2 > 0.995) well describe the adsorption of the tested dyes on the MWCNTs/Gly/β-CD. In comparison with the raw MWCNTs and MWCNTs/Gly samples, the dye removal efficiency was increased for the synthesized MWCNTs/Gly/β-CD nano-adsorbent. Our results confirmed that β-CD-functionalized MWCNTs can be used as an effective adsorbent due to the high adsorption capacity of dyes as well as the short equilibrium time needed. Therefore, MWCNTs/Gly/β-CD was successfully applied to remove organic pollutants from synthetic and industrial wastewater samples with excellent results.