Adsorption of Alizarin Red S Dye by Carbon Nanotubes: An Experimental and Theoretical Investigation

Abstract

This study evaluated the feasibility of removing Alizarin Red S dye (ARS) from aqueous solutions, using nanoadsorbents such as single and multiwalled carbon nanotubes (SWCNT and MWCNT, respectively). The effect of pH, shaking time, and temperature on adsorption was studied. The pH 2.0 was observed to show optimum removal for both of the carbon nanotubes. The equilibrium time (298−318 K) was fixed at 65 and 100 min for SWCNT and MWCNT, respectively. The kinetics of adsorption was calculated using pseudo-first-order, pseudo-second-order, and general-order equations. The calculations revealed that the general-order kinetic equation best-fit the adsorption data. The Liu isotherm model best fit the equilibrium data (298−318 K). The maximum sorption capacity at 318 K for ARS dye was 312.5 and 135.2 mg g −1 for SWCNT and MWCNT, respectively. Change in entropy (ΔS°), Gibb's free energy change (ΔG°), and enthalpy (ΔH°) were calculated for the adsorption of ARS dye. The electrostatic interaction between nanoadsorbent−adsorbate was conveyed using the magnitude of change in enthalpy. Ab initio simulation was used to study the interaction of ARS with (5,5) and (8,0) SWCNTs, and (16,0) and (25,0) SWCNTs with and without vacancy. The theoretical calculations showed that the binding energies between ARS dye and SWCNTs are enhanced as the nanotube diameter gets bigger; however, the distance of binding remains unchanged. Therefore, the results from first principle calculations indicated that electrostatic interaction may be responsible for the adsorption of ARS dye onto SWCNT. The theoretical outcomes were found to be in coordination with the experimental estimates.

Highly Efficient, Rapid, and Simultaneous Removal of Cationic Dyes from Aqueous Solution Using Monodispersed Mesoporous Silica Nanoparticles as the Adsorbent

“…Among these methods and techniques, adsorption is considered to be a promising strategy due to its inherently high efficiency, economic feasibility, good biocompatibility, and simplicity in operation [ 6 , 17 , 18 ]. In recent years, various materials (e.g., activated carbons [ 19 ], ordered mesoporous carbons [ 20 , 21 , 22 , 23 ], carbon nanotubes [ 24 ], graphene-based nanocomposites [ 25 , 26 ], metallogels [ 27 ], metal-organic frameworks [ 7 , 28 , 29 ], and organosilica nanoparticles [ 30 ]) have been used as adsorbents for the adsorption of dyes from wastewater. However, most of these adsorbents are not widely used because of high cost, poor selectivity, complex preparation processes, and difficult disposal [ 31 ].…”

Polyacrylonitrile/α‐Fe2O3 Hybrid Photocatalytic Composite Adsorbents for Enhanced Dye Removal

“…Eqs. (9)-(11) were employed to predict thermodynamic parameters like enthalpy (ΔH°), entropy (ΔS°), and difference in standard Gibbs free energy (ΔG°) for adsorption of MB onto the a-Fe 2 O 3 /PAN hybrid composite adsorbent [41]. From plotting ln(K D ) versus 1/T (as observed in Fig.…”

Porous carbon prepared from lotus leaves as potential adsorbent for efficient removal of rhodamine B

“…Although various materials such as clay and modified clay (Li et al 2018), graphene-based nanocomposites (Zhu et al 2014, organosilica nanoparticles , orderly porous carbon (Peng et al 2014, Chen et al 2016, carbon nanotubes (Machado et al 2016), metallogels (Karan and Bhattacharjee (2016)), metal-organic frameworks (Li et al 2015b, Zhao et al 2015, Jia et al 2016, and cellulose materials (Annadurai et al 2002) have been used for the adsorption of organic pollutants and heavy metal ions, their low adsorption capacities, adsorption rates, selectivities, or complex preparation processes restricted their wide application. Activated carbon is the most effective and widely used adsorbent because of its porous structure, high specific surface area, high adsorption capacity, and several functional groups, which allow the safe and fast removal of dyes without any preliminary treatment (Liu et al 2019).…”