Adsorption Studies of Cd (II) from Water by Acid Modified Multiwalled Carbon Nanotubes

Abstract

This work aims to decorate carbon nanotubes with oxygenated functional groups for effective removal of Cadmium ions from aqueous media. For that purpose Carbon nanotubes (CNT) was oxidized by nitric acid to give MCNT-HNO 3 . The CNT and MCNT-HNO 3 were characterized by SEM, TEM, FT-IR, Boehm titration, nitrogen adsorption-desorption analysis, point of zero charge and surface pH. The adsorption experiments of Cd(II) onto sorbents were studied using the batch technique and factors affecting the adsorption capacities of Cd(II) were investigated and discussed. The isotherm data were analyzed using Langmuir and Freundlich equations. The equilibrium data fitted well Langmuir isotherm for both CNT and MCNT-HNO 3 . The kinetic results were analyzed using pseudo-first order, pseudo-second order, intraparticle diffusion and the Boyd equations. The rate constants, equilibrium capacities and related correlation coefficients (R 2 ) for each kinetic model were calculated and discussed. Highest values of R 2 were obtained on applying the pseudo second-order with both carbons. Although intraparticle diffusion plays impotent role in rate-controlling step in the adsorption process of Cd(II) onto the investigated sorbents, film diffusion is also controlling this process. The thermodynamic parameters including ΔG°, ΔH° and ΔS° for the adsorption processes of Cd(II) on the carbons were calculated, and the negative value of ΔG° indicated the spontaneous nature of adsorption. The desorption studies revealed that the regeneration of MCNT-HNO 3 can be easily achieved.

Fabrication of High Content Carbon Nanotube–Polyurethane Sheets with Tailorable Properties

“…17 At equilibrium there is a defined distribution of the solute between the liquid and the solid phase, which can generally be expressed by one or more isotherms. Adsorption of contaminants onto CNTs has previously been studied for water decontamination; 18,19 however, to the best of our knowledge, adsorption isotherms have not been applied to describe surface modification of CNTs in the production of CNT−polymer composites. Figure 3A shows the room temperature adsorption data of TPU on CNTs processed in the acetone/methanol mixture, as well as in acetone or THF alone.…”

“…The equilibrium experimental data for adsorbed TPU on CNTs in the acetone/methanol mixture were subjected to analysis based on Freundlich adsorption isotherm, which is purely empirical, and it best describes adsorption on heterogeneous surfaces. 18,20 The following linearized Freundlich equation was used:…”

“…The equilibrium experimental data for adsorbed TPU on CNTs in the acetone/methanol mixture were subjected to analysis based on Freundlich adsorption isotherm, which is purely empirical, and it best describes adsorption on heterogeneous surfaces. , The following linearized Freundlich equation was used: C ads is the amount of TPU adsorbed (mg/g), C eq is the equilibrium concentration of TPU in solution (mg/L), K F is the Freundlich constant (L/g), and 1/ n is the Freundlich exponent. The linear plots of Freundlich isotherm for the adsorption of TPU on the CNTs (acetone/methanol mixture) is presented in Figure B.…”

Insight into the significant roles of microstructures and functional groups on carbonaceous surfaces for acetone adsorption

“…27 AC-N also showed characteristic peaks at 1620 cm À1 and 1538 cm À1 , corresponding to bend band of C-OH and -CONH-, respectively. [52][53][54] The AC-T curve shows that aer thermal treatment, bands at 2922 cm À1 and 1574 cm À1 decreased as most of the surface groups were removed. XPS has also shown to be a useful tool for analysing the surface groups of activated carbons, 37 which provide valuable information by examining the C 1s core region.…”

CNT‐containing redox active nanohybrid: a promising ferrocenyl‐based electrode material for outstanding energy storage application

“…In the FT‐IR result of CNT, the absorption bands at 1630, 1725, 2800–2900, and 3400 can be attributed to the C=C, C=O, C–H, and O–H functional groups, respectively. [ 55 ] All characteristic peaks of PANI and Fc‐POP have appeared in the FT‐IR spectrum of Fc‐POP/PANI nanostructure. As can be seen from Figure 3, the FT‐IR results of Fc‐POP/PANI/CNT 10 , Fc‐POP/PANI/CNT 20 , and Fc‐POP/PANI/CNT 30 are similar and all of the nanocomposites showed the characteristic peaks of PANI, Fc‐POP, and CNT.…”