Skip to content


  • Research article
  • Open Access

Interaction of removal Ethidium Bromide with Carbon Nanotube: Equilibrium and Isotherm studies

Journal of Environmental Health Science and Engineering201412:17

  • Received: 5 November 2013
  • Accepted: 10 November 2013
  • Published:


Drinking water resources may be contaminated with Ethidium Bromide (EtBr) which is commonly used in molecular biology laboratories for DNA identification in electrophoresis. Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. In this study adsorption of Ethidium Bromide on single-walled carbon nanotubes (SWCNTs) and carboxylate group functionalized single-walled carbon nanotube (SWCNT-COOH) surfaces have been investigated by UV–vis spectrophotometer. The effect of contact time, initial concentration and temperature were investigated. The adsorbents exhibits high efficiency for EtBr adsorption and equilibrium can be achieved in 6 and 3 min for SWCNTs and SWCNT-COOH, respectively. The effect of temperature on adsorption of EtBr by toward adsorbents shows the process in this research has been endothermic. The results showed that the equilibrium data were well described by the Langmuir isotherm model, with a maximum adsorption capacity of 0.770 and 0.830 mg/g for SWCNTs and SWCNT-COOH, respectively. The adsorption of EtBr on SWCNT-COOH is more than SWCNTs surfaces. A comparison of kinetic models was evaluated for the pseudo first-order, pseudo second-order models. Pseudo second-order was found to agree well with the experimental data.


  • Adsorption
  • Ethidium bromide
  • Single-walled carbon nanotube
  • Isotherm


The contamination of drinking water with Non-radioactive materials such as Ethiduim bromide (EtBr) has become one of the most serious problems in water environment, especially in urban areas [13]. Ethidium bromide (3,8-diamino-6-phenyl-5-ethylphenanthridinium bromide, EtBr;), a powerful mutagenic [4], is an intercalating agent which resembles a DNA base pair. Due to its unique structure, it can easily intercalate into DNA strand. Therefore, it is commonly used as nucleic acid fluorescent tag in various techniques of the life science field. EtBr is a potent mutagen for which the Environmental Health & Safety advises a detoxification protocol [5], since earlier recommended oxidation by household bleach was recognized to lead to possible byproducts that could be more hazardous than the EtBr itself [6]. Taking the adsorption of dyes and organic pollutant, the usability of various natural and synthetic adsorbents have been studied, such as banana peel [7], orange peel [7], calcined layered double hydroxides [8], hypercrosslinked polymeric adsorbent [9], pinecone derived activated carbon [10]. Usually, the effectiveness of any adsorption process largely depends on the physicochemical properties of the adsorbent used. Since the discovery by Iijima [11], carbon nanotubes (CNTs) have attracted great attention in multidisciplinary areas due to their unique hollow tube structure and their many outstanding mechanical, electronic and optical properties [12]. In particular, carbon nanotubes (both multi-walled (MWCNT) and single walled (SWCNT)) are promising materials for several applications such as high performance composites [1315], components in water filters [16, 17], environmental sensors [18, 19], building blocks for electronic nanodevices [20], drug delivers [21], among others. CNTs are also considered to be extremely good adsorbents and successfully remove many kinds of organic and inorganic pollutants such as pentachlorophenol [22], benzene, toluene, ethylbenzene and p-xylene [23], o-xylene and p-xylene [24] and heavy metal ions such as U(VI) [25], Cr(VI) [26], Zn(II) [27], Cu(II) [28], Pb(II) [29], Hg(II) [30] and Cd(II) [31, 32] from water. Activation of CNTs plays an important role in enhancing maximum adsorption capacity. Activation causes modification in the morphology and functional groups surfaces and causes removal of amorphous carbon. The objective of this study was to investigate the possible use of single walled carbon nanotubes as an alternative adsorbent material for the removal of EtBr from drinking water. Adsorption isotherms and kinetics parameters were also calculated and discussed. The dynamic behavior of adsorption was investigated on the effect of initial EtBr concentration, contact times and temperature of the solution.

Material and methods

SWCNTs and SWCNT-COOH (Armchair (6,6), Young’s Modulus (0.94 T TPa), Tensile strength (GPa126.2 T), purity > 95%; diameter 1–2 nm; length, 5–30 nm; surface area, ~ 400 m2/ g; and manufacturing method purchased from NanoAmor Nanostructured & Amorphous Materials, Inc. (USA) and catalytic chemical vapor deposition (CVD)) were prepared from DC-PECVD (Model: SI-PE80) Toseye Hesgarsazan Asia Co. Doubly distilled water was used and all adsorbents were washed before using. A scanning electron microscope (SEM) (JEOL JSM-5600 Digital Scanning Electron Microscope) was used to characterize the SWCNT-COOH and SWCNTs for morphological information. Ethidium bromide (molecular Weight: 394.35; molecular Formula: C21H20BrN3) was supplied by Merck, Germany (maximum purity available, ≥95%). All solutions were prepared with deviations of less than ±0.1% from the desired concentrations.

Adsorption experiments

The determination of ethiduim bromide concentration was performed using Lambda-EZ150UV/Vis Spectrophotometer at a wavelength of 274 nm. The blank used in the experiment was distilled water without any EtBr. Batch adsorption experiments were performed in glass bottles with EtBr solution (1 L) of the prescribed concentration ranging from 10 to 40 mg/L and 20 mg of SWCNTs or SWCNT-COOH was added to each bottle. The amount of SWCNTs or SWCNT-COOH was fixed in all experimental steps. All experiments were conducted by mixing 20 mL of aqueous solutions with 0.02 g of the adsorbent solution composed of SWCNTs with EtBr, solution No. 1 was called and solution composed of SWCNTCOOH with EtBr, No.2 was called. Then, the suspension 1 and 2 were centrifuged at 5000 rpm for 5 min and 2 min, respectively. The amount of the EtBr adsorbed onto the adsorbent was determined by the difference between the initial and remaining concentration of EtBr solution. The adsorption capacity of EtBr on adsorbent was calculated using the following equation [33]:
q e = C i - C t V W
where Ci is the initial EtBr concentration and Ct is the EtBr concentration (mg/ L) at any time, V is the volume of solution (L) and W is the mass of the adsorbents (g). The data analysis was carried out using correlation analysis employing least square method and the average relative error (ARE) is calculated using the following equation [33]:
ARE % = 100 n i n q i , cal - q i , exp q i , exp

where N is the number of data points. Each experiment was conducted in triplicate under identical conditions to confirm the results, and was found reproducible (experimental error within 3%).


To optimize the design of an adsorption system for the adsorption, it is important to establish the most appropriate correlation for the equilibrium curves. Various isotherm equations have been used to describe the equilibrium nature of adsorption. Some of these isotherms are Langmuir and Freundlich. One of the most common isotherm models which are widely used is the Langmuir model. It is observed that the Langmuir isotherms can be linearized to at least four different types. The Langmuir isotherm model can be expressed as:
q e = 1 1 + KCe
where Qm (mg/g) and K (L/mg) are Langmuir constants related to adsorption capacity and energy of adsorption, respectively [3436]. The essential characteristics of the Langmuir isotherm can be expressed in terms of a dimensionless equilibrium parameter (RL) which can be defined by:
R L = 1 1 + KCO
The RL value indicates the type of the isotherm to be either irreversible (RL = 0), favorable (0 < RL <1), linear (RL =1) or unfavorable (RL >1) [37]. Figures 1 and 2 shows the adsorption isotherm Langmuir of EtBr on SWCNTs and SWCNT-COOH surfaces, respectively.
Figure 1
Figure 1

Effect of temperature on the adsorption of EtBr with SWCNTs and SWCNT-COOH, initial concentration, 20 ml, 30 mg / L; adsorbent dosage, 20 mg.

Figure 2
Figure 2

Langmuir isotherm of EtBr on SWCNTs and SWCNT-COOH; Type 1 (C e /q e vs. C e ), Type 2 (1/q e vs. 1/C e ), Type 3 (q e vs. q e /C e ), and Type 4 (q e /C e vs. q e ).

The Freundlich model assumes a heterogeneous adsorption surface with sites that have different energies of adsorption and are not equally available [3840]. The Freundlich isotherm is more widely used but provides no information on the monolayer adsorption capacity, in contrast to the Langmuir model. Its linearized form can be written as:
lnq e = lnK F + 1 / n lnC e

where KF (1/mg) and n (dimensionless) are the Freundlich adsorption isotherm constants, being indicative of the extent of adsorption and the degree of nonlinearity between solution concentration and adsorption, respectively.

Temkin isotherm [41] describes the behavior of adsorption systems on a heterogeneous surface, and the linear form of Temkin isotherm is expressed as:
q e = βln K T + βln C e

The adsorption data were analyzed according to Eq. (6). KT is the equilibrium binding constant (L/mg) corresponding to the maximum binding energy and constant b = RT/β (KJ/mol) is related to the heat of adsorption.

Redlich and Peterson [42] incorporate three parameters into an empirical isotherm. The Redliche Peterson isotherm has a linear dependence on concentration in the numerator and an exponential function in the denominator. It approaches the Freundlich isotherm at high concentration and is in accordance with the low concentration limit of the Langmuir equation. Furthermore, the R-P equation incorporates three parameters into an empirical isotherm and, therefore, can be applied either in homogenous or heterogeneous systems due to the high versatility of the equation. It can be described as follows:
q e = K R C e 1 + a R C e β
where KR is R-P isotherm constant (L/ g), aR is R-P isotherm constant (1/ mg) and β is the exponent which lies between 1 and 0. That is, the Henry’s Law equation. Eq. 7 can be converting to a linear form by taking logarithms:
ln K R C e q e - 1 = lna R + βlnC e

Therefore a minimization procedure is adopted to maximize the coefficient of determination, between the theoretical data for predicted from the linearized form of Redlich-Peterson isotherm equation and the experimental data.

Kinetics study

Pseudo first-order kinetics

The pseudo first-order equation (Lagergren’s equation) describes adsorption in solid–liquid systems based on the sorption capacity of solids [43]. The linear form of pseudo first-order model can be expressed as:
log q e - q = log q e - k 1 t

where qe (mg/ g) and q are the amount each of EtBr adsorbed on the adsorbents at equilibrium and at various times t and k1 is the rate constant of the pseudo first-order model for the adsorption (1/min) [43].

Pseudo second-order kinetics

The pseudo second-order rate expression, which has been applied for analyzing chemisorption kinetics from liquid solutions [44], is linearly expressed as:
t / q = 1 / k 2 q e 2 + t / q e

where qe and q are defined as in the pseudo first-order model and k2 is the rate constant of the pseudo second-order model for adsorption (g/ mg min) [45].


Characterization of carbon nanotubes

Figure 3 show the scanning electron microscopy images (SEM) of the carbon nanotubes. As seen in Figure 3 is carboxylate group functionalized single-walled carbon nanotube having a negative surface charge and porosity much more than single-walled carbon nanotube. Based on these textural characteristics explained above it is expected that SWCNT-COOH would present higher sorption capacity than the SWCNTs for the EtBr adsorption, besides of presenting a faster kinetic.
Figure 3
Figure 3

SEM images of SWCNT-COOH (a) before adsorption, (b) after adsorption, and SWCNTs (c) before adsorption, (d) after adsorption.

Effect of contact time

Effect of contact time on EtBr adsorption by SWCNT-COOH and SWCNTs were studied by variation of the contact time (0 to 10 min) for constant initial concentrations (30 mg/L). Figure 4 shows the effect of contact time on the adsorption of EtBr on to (a) SWCNTs and (b) SWCNT-COOH.
Figure 4
Figure 4

Effect of contact time on the adsorption of EtBr with (a) SWCNTs and (b) SWCNT-COOH, initial concentration, 20 ml, 30 mg / L; adsorbent dosage, 20 mg and T = 298 ± 1 K.

Effect of EtBr initial concentration

In the present study, the adsorption experiments are performed to study the effect of EtBr initial concentration by varying it from 10 to 40 mg/L, while maintaining the SWCNT-COOH and SWCNTs amount 0.02 g/L.

Effect of temperature on the adsorption

Figure 2 shows the representative plots of adsorption amount of EtBr onto SWCNT-COOH and SWCNTs versus different temperature ranging from 298 to 328°K. In this section, concentration of EtBr was 30 mg/L and contacts time were 3 and 6 min for SWCNT-COOH and SWCNTs, respectively. It was found that the adsorption capacity of EtBr onto carbon nanotubes was found to increase with a rise in temperature.


Figure 5 shows the adsorption isotherm Freundlich of EtBr on SWCNT-COOH and SWCNTs surfaces, respectively. Tables 1, 2 and 3 summarize the coefficients of Langmuir, and Freundlich isotherms for adsorbents, respectively. Figure 6 shows the effect of temperature on the adsorption of EtBr with (a) SWCNTs and (b) SWCNT-COOH. Figures 7 and 8 show the adsorption isotherm Temkin and Redlich-Peterson of EtBr on the adsorbents surfaces, respectively.
Figure 5
Figure 5

Freundlich adsorption isotherm of EtBr on SWCNTs and SWCNT-COOH surface.

Table 1

Langmuir isotherm parameters and ARE parameter for EtBr by SWCNTs surface








Type 1

Ce/qe = 1/KQm + Ce/Qm






Type 2

1/qe = 1/Qm + 1/KQmCe





Type 3

qe = Qm–qe/KCe





Type 4

qe/Ce = KQm - Kqe




Table 2

Langmuir isotherm parameters and ARE parameter for EtBr by SWCNT-COOH surface








Type 1

Ce/qe = 1/KQm + Ce/Qm






Type 2

1/qe = 1/Qm + 1/KQmCe





Type 3

qe = Qm–qe/KCe





Type 4

qe/Ce = KQm - Kqe




Table 3

Freundlich, Temkin and Redlich-Peterson isotherm parameters for removal EtBr by SWCNT-COOH and SWCNTs surface

















KT (L/g)

β (mg/L)

b (KJ/mol)
















aR(l/ mg)

KR(L/ g)
















Figure 6
Figure 6

Temkin adsorption isotherm of EtBr on SWCNTs and SWCNT-COOH surface.

Figure 7
Figure 7

Redlich-Peterson adsorption isotherm of EtBr on SWCNTs and SWCNT-COOH surface.

Figure 8
Figure 8

Pseudo first-order kinetics for adsorption of EtBr on SWCNTs and SWCNT-COOH surface.


Figure 9 shows a plot of linearization form of pseudo first-order model. This Fig. shows a plot of linearization form of pseudo second-order model at constant concentrations studied the results of are presented in Table 4.
Figure 9
Figure 9

Pseudo second-order kinetics for adsorption of EtBr on SWCNTs and SWCNT-COOH surface.

Table 4

Comparison of the pseudo first- and second-order rate constants


Pseudo first-order

Pseudo second-order












(g/ mg min)





















Effect of contact time

According to Figure 4, EtBr adsorption rate increased quickly with time and then reached equilibrium. SWCNT-COOH and SWCNTs surfaces were treated by EtBr solutions (30 mg/ L and T = 298 ± 1 K) in order to optimize contact time respect to EtBr. The amounts of adsorbed ion on the adsorbents were analyzed using UV-visible Spectrophotometer.

Effect of temperature

According to Figure 1; the adsorption capacity of EtBr onto carbon nanotubes was found to increase with a rise in temperature, suggesting the process in this research has been endothermic [44]. An increase in the amount of equilibrium adsorption of each ion with the rise in temperature may be explained by fact that the adsorbent sites were more active at higher temperatures.

Adsorption isotherms

According to Figure 2 the constants of Langmuir models is obtained from fitting the adsorption equilibrium data and is listed in Tables 1 and 2. A comparison of the R2 and ARE values given in Tables 1 and 2 with 2 indicates that Langmuir isotherm better fits the experimental data than does the other isotherms. The validity of Langmuir isotherm suggests that adsorption is a monolayer process, and adsorption of all species requires equal activation energy. Moreover, K values for various adsorbents followed the order SWCNT-COOH > SWCNTs, suggesting that the affinity of the binding sites for each ion also followed this order. The RL parameter lies between 0.22 and 0.60 which proves that the adsorption process is favorable and SWCNTs and SWCNT-COOH are potential adsorbents for the removal of EtBr from drinking water.

Adsorption Kinetics

The high correlations coefficient and high agreement that exist between the calculated and experimental qe values of the pseudo second-order kinetic model over the other model renders it best in adsorption of EtBr. This confirms that the sorption data for removal of EtBr on SWCNTs and SWCNT-COOH are well represented by the pseudo-second-order kinetics for the entire sorption period.


Repeated usage of CNT filters is one of the critical considerations in a treatment plant from economics standpoint. CNT filters are reusable as evidenced by Brady-Estevez et al. (2008) and Srivatsava et al. (2004). On the other hand CNT filters, due to their excellent mechanical properties prevent such deformational changes. Moreover, CNT filters support simple thermal regeneration techniques, whereas with polymeric membranes it is not possible [46, 47].


This investigation examined the equilibrium and the dynamic adsorption of EtBr on SWCNT-COOH and SWCNTs surfaces. The adsorption capacity was highest when 20 mg/ l SWCNT-COOH and SWCNTs were added. The results suggested that the adsorption of EtBr on SWCNT-COOH and SWCNTs surfaces increased with temperature. The adsorption of mentioned ions on SWCNT-COOH is more than SWCNTs surfaces. SWCNT-COOH and SWCNTs are after adsorption can be recycle and usable. In addition, SWCNT-COOH and SWCNTs are adsorbents have desorption capabilities.



This study was conducted in the Department of Chemistry, Shahr-e-Qods Branch and was financially supported by Islamic Azad University.

Authors’ Affiliations

Department of Chemistry, Shahre-Qods Branch, Islamic Azad University, Tehran, Iran
Department of Virology, School of Genetics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
Department of Environmental Health Engineering, School of Public Health and Center for Air Quality Research, Institute for Environmental Research, Tehran University of Medical Sciences, Tehran, Iran


  1. Kikuchi H: The investigation about the nature measurement result of 1999 groundwater quality and a groundwater-contamination example. Water Waste 2001, 43: 396.Google Scholar
  2. Dobaradaran S, Nabizadeh R, Mahvi AH, Mesdaghinia AR, Naddafi K, Yunesian M, Rastkari N, Nazmara S: Survey on degradation rates of trichloroethylene in aqueous solutions by ultrasound. Iran J Environ Health Sci 2010, 7: 307.Google Scholar
  3. Nakano Y, Li QH, Nishijima W, Shoto E, Okada M: Biodegradation of trichloroethylene (tce) adsorbed on granular activated carbon (gac). Water Res 2000, 34: 4139. 10.1016/S0043-1354(00)00199-8View ArticleGoogle Scholar
  4. Stenzel MH: Remove organics by activated carbon adsorption. ChemEng Prog 1993, 89: 36.Google Scholar
  5. Golden TC, Sircar S: Gas adsorption on Silicalite. J Colloid Interface Sci 1994, 162: 182e8.Google Scholar
  6. Yun JH, Hwang KY, Choi DK: Adsorption of benzene and toluene vapors on activated carbon fiber at 298, 323, and 348 K. J Chem Eng Data 1998, 43: 843e5.View ArticleGoogle Scholar
  7. Annadurai G, Juang RS, Lee DJ: Use of cellulose-based wastes for adsorption of dyes from aqueous solutions. J Hazard Mater 2002, 92: 263. 10.1016/S0304-3894(02)00017-1View ArticleGoogle Scholar
  8. Ni ZM, Xia SJ, Wang LG, Xing FF, Pan GX: Treatment of methyl orange by calcined layered double hydroxides in aqueous solution: adsorption property and kinetic studies. J Colloid Interface Sci 2007, 316: 284. 10.1016/j.jcis.2007.07.045View ArticleGoogle Scholar
  9. Huang JH, Huang KL, Liu SQ, Wang AT, Yan C: Adsorption of Rhodamine B and methyl orange on a hypercrosslinked polymeric adsorbent in aqueous solution. Colloids Surf A: Physicochem Eng Aspects 2008, 330: 55. 10.1016/j.colsurfa.2008.07.050View ArticleGoogle Scholar
  10. Samarghandi M, Hadi M, Moayedi S, Askari F: Two-parameter isotherms of methyl orange sorption by pinecone derived activated carbon. Iran J Environ Health Sci Eng 2009, 6: 285.Google Scholar
  11. Iijima S: Helical microtubules of graphitic carbon. Nature 1991, 354: 56. 10.1038/354056a0View ArticleGoogle Scholar
  12. MortezaAli A, Sani S: Study of growth parameters on structural properties of TiO 2 nanowires. J Nanostruct Chem 2013, 3: 35. 10.1186/2193-8865-3-35View ArticleGoogle Scholar
  13. Shokrieh MM, Saeedi A, Chitsazzadeh M: Mechanical properties of multi-walled carbon nanotube/polyester nanocomposites. J Nanostruct Chem 2013, 3: 20. 10.1186/2193-8865-3-20View ArticleGoogle Scholar
  14. Banerji B, Pramanik SK, Pal U, Maiti NC: Dipeptide derived from Benzylcystine forms unbranched Nanotubes in aqueous solution. J Nanostruct Chem 2013, 3: 12. 10.1186/2193-8865-3-12View ArticleGoogle Scholar
  15. Wang M, Pramoda KP, Goh SH: Enhancement of the mechanical properties of poly (styrene-co-Acrylonitrile) with poly(methyl Methacrylate)-grafted multiwalled carbon nanotubes. Polymer 2005, 46: 11510. 10.1016/j.polymer.2005.10.007View ArticleGoogle Scholar
  16. Tadjarodi A, Imani M, Kerdari H: Adsorption kinetics, thermodynamic studies, and high performance of CdO cauliflower-like nanostructure on the removal of Congo red from aqueous solution. J Nanostruct Chem 2013, 3: 51. 10.1186/2193-8865-3-51View ArticleGoogle Scholar
  17. Mauter MS, Elimelech M: Environmental applications of carbon-based nanomaterials. Environ Sci Technol 2008, 42: 5843. 10.1021/es8006904View ArticleGoogle Scholar
  18. Hierold C, Jungen A, Stampfer C, Helbling T: Nano electromechanical sensors based on carbon nanotubes. Sensors Actuators A Phys 2007, 136: 51. 10.1016/j.sna.2007.02.007View ArticleGoogle Scholar
  19. Fujiwara A, Ishii K, Suematsu H, Kataura H, Maniwa Y, Suzuki S: Gas adsorption in the inside and outside of single-walled carbon nanotubes. ChemPhysLett 2001, 336: 205.Google Scholar
  20. Romo-Herrera JM, Terrones M, Terrones H, Meunier V: Guiding electrical current in nanotube circuits using structural defects, a step forward in nanoelectronics. ACS Nano 2008, 2: 2585. 10.1021/nn800612dView ArticleGoogle Scholar
  21. Najafi F: Investigation of a QM/MM study on interaction of a carbon nanotube with cytarabine drug in various solvents and temperatures. J Nanostruct Chem 2013, 3: 23. 10.1186/2193-8865-3-23View ArticleGoogle Scholar
  22. Salam MA, Burk RC: Thermodynamics of pentachlorophenol adsorption from aqueous solutions by oxidized multi-walled carbon nanotubes. Applied Surface Sci 1975, 2008: 255.Google Scholar
  23. Sua F, Lu C, Hu S: Adsorption of benzene, toluene, Ethylbenzene and p-xylene By NaOCl-oxidized carbon nanotubes. Colloids Surf A: Physicochem Eng Aspects 2010, 353: 83. 10.1016/j.colsurfa.2009.10.025View ArticleGoogle Scholar
  24. Chin CJM, Shih LC, Tsai HJ, Liu TK: Adsorption of o-xylene and p-xylenefrom water by SWCNTs. Carbon 2007, 45: 1254. 10.1016/j.carbon.2007.01.015View ArticleGoogle Scholar
  25. Schierz A, Zanker H: Aqueous suspensions of carbon nanotubes: Surface oxidation, colloidal stability and uranium sorption. Envi Pollution 2009, 157: 1088. 10.1016/j.envpol.2008.09.045View ArticleGoogle Scholar
  26. Hu J, Chen C, Zhu X, Wang X: Removal of chromium from aqueous solution by using oxidized multi-walled carbon nanotubes. J Hazard Mater 2009, 162: 1542. 10.1016/j.jhazmat.2008.06.058View ArticleGoogle Scholar
  27. Ruparelia JP, Duttagupta SP, Chatterjee AK, Mukherji S: Potential of carbon nanomaterials for removal of heavy metals from water. Desalination 2008, 232: 145. 10.1016/j.desal.2007.08.023View ArticleGoogle Scholar
  28. Demirbasa E, Dizge N, Sulak MT, Kobya M: Adsorption kinetics and equilibrium of copper from aqueous solutions using hazelnut shell activated carbon. Chemical Engineering J 2009, 148: 480. 10.1016/j.cej.2008.09.027View ArticleGoogle Scholar
  29. Wang H, Zhou A, Peng F, Yu H, Yang J: Mechanism study on adsorption of acidified multi-walled carbon nanotubes to Pb(II). J Colloid Interface Sci 2007, 316: 277. 10.1016/j.jcis.2007.07.075View ArticleGoogle Scholar
  30. Safavi A, Maleki N, Doroodmand MM: Fabrication of a selective mercury sensor based on the adsorption of cold vapor of mercury on carbon nanotubes: Determination of mercury in industrial wastewater. J Hazardous Materials 2010, 173: 622. 10.1016/j.jhazmat.2009.08.130View ArticleGoogle Scholar
  31. Vukovic’a GD, Marinkovic’a AD, Ristic’a MD, Aleksic’a R, Perić-Grujić AA, Cˇ olic’b M: Removal of cadmium from aqueous solutions by oxidized and ethylenediamine-functionalized multi-walled carbon nanotubes. Chemical Engineering J 2010, 157: 238. 10.1016/j.cej.2009.11.026View ArticleGoogle Scholar
  32. Li Y, Wang S, Luan Z, Ding J, Xu C: Adsorption of cadmium(II) from aqueous solution by surface oxidized carbon nanotubes. Carbon 2003, 41: 1057. 10.1016/S0008-6223(02)00440-2View ArticleGoogle Scholar
  33. Moradi O, Zare K: Adsorption of Pb(II), Cd(II) and Cu(II) Ions in Aqueous Solution on SWCNTs and SWCNT –COOH Surfaces: Kinetics Studies, Fullerenes. Nanotubes Carbon Nanostruct 2010, 19: 628.View ArticleGoogle Scholar
  34. Karimi L, Zohoori S: Superior photocatalytic degradation of azo dyes in aqueous solutions using TiO 2 /SrTiO 3 nanocomposite. J Nanostruct Chem 2013, 3: 32. 10.1186/2193-8865-3-32View ArticleGoogle Scholar
  35. Lu C, Chiu H: Adsorption of zinc (II) from water with purified carbon nanotubes. Chem Eng Sci 2006, 61: 1138. 10.1016/j.ces.2005.08.007View ArticleGoogle Scholar
  36. Hu Y, Li I, Ding J, Luan Z, Di Z, Zhu Y, Xu C, Wu D, Wei B: Competitive adsorption of Pb 2+ , Cu 2+ and Cd 2+ ions from aqueous solutions by multi-walled carbon nanotubes. Carbon 2003, 41: 2787. 10.1016/S0008-6223(03)00392-0View ArticleGoogle Scholar
  37. Webber TW, Chakkravorti RK: Pore and solid diffusion models for fixed-bed adsorbers. AlChE J 1974, 20: 228. 10.1002/aic.690200204View ArticleGoogle Scholar
  38. Ayad MM, El-Nasr A: Anionic dye (acid green 25) adsorption from water by using polyaniline nanotubes salt/silica composite. J Nanostruct Chem 2012, 3: 3. 10.1186/2193-8865-3-3View ArticleGoogle Scholar
  39. Rao MM, Ramesh A, Rao GPC, Seshaiah K: Removal of copper and cadmium from the aqueous solutions by activated carbon derived from Ceibapentandrahulls. J Hazard Mater B 2006, 129: 123. 10.1016/j.jhazmat.2005.08.018View ArticleGoogle Scholar
  40. Bulut Y, Gozubenli N, Aydın H: Equilibrium and kinetics studies for adsorption of direct blue 71 from aqueous solution by wheat shells. J Hazard Mater 2007, 144: 300. 10.1016/j.jhazmat.2006.10.027View ArticleGoogle Scholar
  41. Olgun A, Atar N: Equilibrium and kinetic adsorption study of basic Yellow 28 and Basic Red 46 by a boron industry waste. J Hazardous Mater 2009, 161: 148. 10.1016/j.jhazmat.2008.03.064View ArticleGoogle Scholar
  42. Redlich O, Peterson DL: A useful adsorption isotherm. J Phys Chem 1959, 63: 1024. 10.1021/j150576a611View ArticleGoogle Scholar
  43. Ho YS, McKay G: Sorption of dye from aqueous solution by pit. Chem Eng J 1998, 70: 115.View ArticleGoogle Scholar
  44. Niu JJ, Wang JN: Effect of temperature on chemical activation of carbon nanotubes. Solid State Sci 2008, 10: 1189. 10.1016/j.solidstatesciences.2007.12.016View ArticleGoogle Scholar
  45. Wang S, Zhu ZH: Effects of acidic treatment of activated carbons on dye adsorption. Dyes Pigments 2007, 75: 306. 10.1016/j.dyepig.2006.06.005View ArticleGoogle Scholar
  46. Brady-Estevez AS, Kang S, Elimelech M: A single walled carbon nanotube filter for removal of viral and bacterial pathogens. Small 2008, 4: 481. 10.1002/smll.200700863View ArticleGoogle Scholar
  47. Srivatsava A, Srivatsava ON, Talapatra S, Vajtai R, Ajayan PM: Carbon nanotube filters. Nat Lett 2004, 3: 610.View ArticleGoogle Scholar


© Moradi et al.; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.