Effectiveness of carbon nanotube–cobalt ferrite nanocomposites for the adsorption of rhodamine B from aqueous solutions

Abstract

The efficiency of adsorption of rhodamine B (RhB) from aqueous solution was investigated through a series of batch experiments by using cobalt ferrite nanoparticles (CoFe 2 O 4 ), acid-functionalized multiwalled carbon nanotubes (MWCNT-COOH) and carbon nanotube-cobalt ferrite nanocomposites. The adsorption capacity was evaluated as a function of pH, contact time, adsorbent dose, dye concentration and temperature. The effect of increasing the percentage of MWCNT-COOH in the nanocomposites was also studied. The adsorption capacity was lowest in CoFe 2 O 4 (5.165 mg g À1 ) and highest with MWCNT-COOH (42.68 mg g À1 ). For the nanocomposites, the adsorption capacity was enhanced with an increase in the amount of MWCNT-COOH. The optimum pH for adsorption was observed at 7 at which equilibrium was reached after 360 min. The kinetics of adsorption was fitted to the pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models. The results showed that the pseudo-second order model best described the data as reflected in the lowest value for the sum of squared residuals. Among the various adsorption isotherms tested, the Langmuir isotherm provided the best fit to the equilibrium data. The thermodynamic parameters, DH , DS and DG , were obtained over a temperature range of 20-45 C. Adsorption was spontaneous, endothermic and entropy-driven, except for one of the doped nanocomposites for which adsorption was exothermic. A good desorption of RhB from the loaded adsorbents was obtained by using either acetone or ethanol with a desorption efficiency in the range of 62-95%.

Kinetics and Thermodynamic Studies for Rhodamine B Dye Removal onto Graphene Oxide Nanosheets in Simulated Wastewater

“…The shorter the equilibrium time, the better the adsorbent. The equilibrium time of 5 min reported in this work is far lesser than those reported for carbon nanotubecobalt ferrite nanocomposites (equilibrium time = 6 h) used for removal of RhB in aqueous solution [57], implying that the GONS has a better affinity for RhB compared to the composites of carbon nanotube-cobalt ferrites. Zhou et al [37] have also demonstrated that GO is a better adsorbent than Fe l O ¡ /GO composites, in terms of enhanced adsorption capacity of former, due to replacement of active adsorption sites on GO by Fe l O ¡ nanoparticles of Fe l O ¡ /GO.…”

Adsorptive removal of aqueous bezafibrate by magnetic ferrite modified carbon nanotubes

“…This fact suggests negative charge exists on the surface of MFe 2 O 4 /CNTs, promoting cationic adsorption during the adsorption process. 24,58 In addition, log K ow and log K oc of BZF are 4.25 and 1.0 at pH ¼ 7.4, 59 respectively, indicating that BZF has a high tendency to sorb onto the organic material. For practical application, the water matrix such as pH and organic carbon content, may have signicant effects on BZF adsorption.…”

“…Among the various magnetic materials, ferrites exhibit high efficiency and are environmentally friendly. 23,24 Some ferrites, such as MnFe 2 O 4 and CoFe 2 O 4 , are excellent adsorbents, and their magnetic properties ensure that they can be magnetically separated. 25 Furthermore, synergistic adsorptive removal of heavy metals from aqueous solution has been reported for combined application of ferrite and carbon materials.…”

CoFe2O4/CHITOSAN MAGNETIC NANOCOMPOSITE: SYNTHESIS, CHARACTERIZATION AND APPLICATION FOR ADSORPTION OF ACIDIC YELLOW DYE FROM AQUEOUS SOLUTIONS

“…As seen from Figure 9 (d), AY17 removal efficiency fell from 78% to 36% as the initial AY17 concentration increased from 2 to 120 mg L -1 at 293 K. The reduction of dye removal efficiency may be due to the fact that at the higher initial dye concentration, the total exiting adsorptive sites are confined as a result of the fixed amount of adsorbent. Hence, saturation of the adsorptive sites of the adsorbent with dye anions may occur as the adsorption process continues, 28 leading to a decrease in dye removal with an increase in dye concentration. Furthermore, from Figure 9 (d), it is observed that the removal efficiency improved from 36% at 293 K to 61% at 323 K at an initial concentration of 120 mg L -1 .…”