Evaluation of Adsorption Characteristics of Multiwalled Carbon Nanotubes Modified by a Poly(propylene imine) Dendrimer in Single and Multiple Dye Solutions: Isotherms, Kinetics, and Thermodynamics

Abstract

This research investigates the isotherm, kinetics, and thermodynamic parameters of the adsorption of two direct dyes in single and multiple dye solutions onto the modified multiwalled carbon nanotubes using poly(propylene imine) dendrimer (CNT-Den). The surface morphology and functional groups of the prepared CNT-Den were studied using field emission scanning electron microscopy (FESEM) images and Fourier transform infrared (FTIR) spectra, respectively. The Langmuir, Freundlich, and Tempkin isotherms were studied, and the results indicated that the data followed the Langmuir isotherm. The kinetic studies revealed that the pseudo-second order model was best fitted to our results rather than pseudo-first and intraparticle diffusion model. The calculated thermodynamic parameters showed the endothermic and spontaneous nature of the adsorption process. The overall results illustrated that CNT-Den can be effectively used as an adsorbent for the removal of dyes from colored wastewaters especially textile effluents.

Efficient Removal of Cationic and Anionic Dyes from Aqueous Solution Using Cellulose-g-p(AA-co-AM) Bio-Adsorbent

“…In the case of AR1, the corresponding increase was from 54.59% to 80.92% with concentration from 100 to 500 mg·L -1 , beyond which it decreased to 35.34% at 1500 mg·L -1 . This trend might be explained by the fact that plenty of vacant active sites were available for the adsorption at a lower dye concentration, and the saturated sites had difficulty to capture the dye molecules (Eskandarian et al 2014). As for MB dye, the removal efficiency was higher than AR1, which probably was due to the smaller spatial prohibition in the molecular structure of MB and this positive feature makes the adsorption sites of CP bio-adsorbent more accessible to the dye (Ho et al 2016).…”

“…In addition, upon comparison with cellulose, the new peaks were found at 1672, 1560, and 1406 cm -1 in the spectrum of CP bio-adsorbent. Thus, the monomers (AA and AM) were successfully grafted onto the cellulose molecular skeleton, which provided more adsorption sites for dye adsorption (Eskandarian et al 2014;Ho et al 2016;Liu et al 2015). Furthermore, according to the chemical titration method (Saito and Isogai 2004;Atia et al 2008), the contents of 5.5 mmol·g -1 for carboxyl groups and 2.7 mmol·g -1 for amino groups were estimated on the CP bio-adsorbent sample.…”

Adsorption of methylene blue onto Fe3O4/activated montmorillonite nanocomposite

“…8), suggesting that intraparticle diffusion is not the only rate-controlling step (Huang et al, 2011). The values of the intercept, C, are an indication of the thickness of the boundary layer, which play a significant role in the uptake of the dye (Eskandarian et al, 2014). Generally, a larger C value represents a greater boundary layer effect (Dogan et al, 2007).…”

<strong>Preparation of corn cob based bioadsorbent as an effective adsorbent</strong>

“…The removal efficiencies for MO initially increased and then decreased which might be due to the fact that large numbers of vacant active sites were available for the adsorption at a lower initial concentration, and then saturated sites were difficult to capture the dye molecules [12]. Fig.…”

“…4 show the effect of bioadsorbents on the percentage of removal and specific uptake of dye with respect to time. The dye removal efficiency increased dramatically with increasing the bioadsorbent dosage, which was due to the increase of available adsorption sites in bioadsorbent [13]. …”