Studies of the equilibrium and thermodynamics of the adsorption of Cu2+ onto as-produced and modified carbon nanotubes

Adsorption of 2,4,6-trichlorophenol by multi-walled carbon nanotubes as affected by Cu(II)

“…The isotherms were fit well by the LM and the fitting parameters are given in Table 4. This result is consistent with the studies on the sorption of Cu 2þ , Pb 2þ and UO 2 2þ by CNTs which can be described by Langmuir model (Wu, 2007;Li et al, 2002;Schierz and Zanker, 2009). The total determined oxygen contents of MWCNTs15A and MWCNTs15 by XPS were 3.92% and 1.52%, respectively, and the sorption capacities were 5.26 mg g À1 and 2.35 mg g…”

“…4.86 for nitric oxidized and as-grown MWCNTs, respectively (Wu, 2007), which suggests that the surfaces of oxidized and as-grown MWCNTs were negatively charged at solution pH > 2.85 and >4.86. The negatively charged surfaces of MWCNTs favor the adsorption of Cu(II).…”

“…Considering the pK a value of 6.1 (Wightman and Fein, 1999) for TCP, it appears that the greater sorption at low pH 3-5 may be due to the predominant species of neutral TCP. An increase of solution pH value of 5-8 increased the fraction of negatively charged TCP species and the dissociation of functional groups of adsorbents (Pei et al, 2007;Wu, 2007). Therefore, the repulsion of anionic TCP with the negatively charged surfaces of MWCNTs makes sorption unfavorable.…”

“…Modification of the structure and surface properties of CNTs affected sorption capacity and sorption mechanisms of metals and organic chemicals (Li et al, 2003a;Lu and Chiu, 2006;Wang et al, 2005;Lu et al, 2005;Chin et al, 2007;Cho et al, 2008). The adsorption capacity of Cu 2þ at a given pH followed the order NaOClmodified CNTs > HNO 3 -modified CNTs > as-produced CNTs (Wu, 2007). The extraordinary increase in sorption capacity and decrease in desorption rate of 243 Am(III) after oxidation of multi-walled carbon nanotubes (MWCNTs) suggested that chemisorption rather than physisorption and/or ion-exchange is the main sorption mechanism (Wang et al, 2005 (Li et al, 2003b).…”

Electrical Removal Behavior of Carbon Nanotube and Carbon Nanofiber Film in CuCl2Solution: Kinetics and Thermodynamics Study

“…International Journal of Electrochemistry 3 S4800 3 kV 8.5 mm x6 k SE(U) 5 µm The change in reaction rate constant k is described by the Arrhenius equation [16,17]:…”