Adsorption of Reactive Blue 4 dye from water solutions by carbon nanotubes: experiment and theory

Abstract

Multi-walled and single-walled carbon nanotubes were used as nanoadsorbents for the successful removal of Reactive Blue 4 textile dye from aqueous solutions. The adsorbents were characterised by infrared and Raman spectroscopy, N(2) adsorption/desorption isotherms and scanning and transmission electron microscopy. The effects of pH, shaking time and temperature on adsorption capacity were studied. In the acidic pH region (pH 2.0), the adsorption of the dye was favourable using both adsorbents. The contact time to obtain equilibrium isotherms at 298-323 K was fixed at 4 hours for both adsorbents. The general order kinetic model provided the best fit to the experimental data compared with pseudo-first order and pseudo-second order kinetic adsorption models. For Reactive Blue 4 dye, the equilibrium data (298 to 323 K) were best fitted to the Liu isotherm model. The maximum sorption capacity for adsorption of the dye occurred at 323 K, attaining values of 502.5 and 567.7 mg g(-1) for MWCNT and SWCNT, respectively. Simulated dyehouse effluents were used to check the applicability of the proposed nanoadsorbents for effluent treatment (removal of 99.89% and 99.98%, for MWCNT and SWCNT, respectively). The interaction of Reactive Blue 4 textile dye with single-walled carbon nanotubes (SWCNTs) was investigated using first principles calculations based on density functional theory. Results from ab initio calculations indicated that Reactive Blue 4 textile dye could be adsorbed on SWCNT through an electrostatic interaction; these results are in agreement with the experimental predictions.

Complexation of aromatic drugs with single-walled carbon nanotubes

“…It is seen from Table 1 that the equilibrium binding constants have an order of magnitude 10 4 -10 5 M -1 , which is in agreement with the order of magnitude of Langmuir equilibrium constants obtained from adsorption studies of various aromatic dyes with SWCNT (Kuo et al 2008;Machado et al 2012). It is also worth noting that the obtained magnitudes of binding affinities with nanotubes well agree with the K values for the binding of the same ligands with C 60 fullerene (Evstigneev et al 2013), having a similarly curved carbon surface as that for SWCNT.…”

“…Equation (3) is identical to standard Langmuir-type isotherm, q e ¼ KL 1 q m 1þKL 1 , extensively used in the adsorption studies of drugs binding with nanotubes [see (Kuo et al 2008;Machado et al 2012;Yang and Xing 2010) and references in the ''Introduction'' section], where q e : KL 1 N 1 , q m : N s . It is a common practice in Langmuir approach to determine L 1 and q e in separate experiments.…”

“…Nowadays, several novel CNT-based tumortargeted drug delivery systems have been developed demonstrating ability to suppress proliferation of cancer cells, thus providing a new promising approach in antitumor therapy (Adeli et al 2013;Chen et al 2008). As a consequence, investigations of CNT complexation with antibiotics (Ji et al 2009(Ji et al , 2010Wang et al 2009), dyes (Chagovets et al 2012;Gupta et al 2013;Koh et al 2012;Kuo et al 2008;Liu et al 2008;Machado et al 2012;Yao et al 2010), and other types of ligands (Pan and Xing 2008;Yan et al 2008;Yang and Xing 2010), have been undertaken with an aim to determine the binding parameters in solution.…”

Kinetic and Equilibrium Models of Adsorption

“…3.12 [17]. Figure 3.13 presents the Elovich Chemisorption kinetic plot of the RB-4 dye using SWCNT as adsorbent at pH 2.0 and 25 °C [17].…”

Equilíbrio E Termodinâmica Da Adsorção De Corante Catiônico Utilizando Quitina Tratada via Ultrassom

“…Na Tabela 2, pode ser observada a redução da constante de equilíbrio com o aumento de temperatura, indicando que a adsorção de MB em quitina tratada foi favorecida a 298 K. Os valores negativos de ∆G 0 indicam que a adsorção foi um processo espontâneo e favorável. O processo de adsorção é considerado exotérmico devido aos valores negativos de ΔH 0 , e a partir da magnitude dos valores obtidos, pode-se inferir que ocorreram interações físicas entre MB e quitina tratada (Machado et al, 2012). Os valores negativos de ΔS 0 mostram a redução da desordem na interface sólido-líquido durante a adsorção.…”