COMPARSION OF HEAVY METALS SORBENTS Katerina Atkovska, Aleksandar Petrovski, Gordana Ruseska, Bosko Boskovski, Perica Paunovik, Kiril Lisickov, Anita Grozdanov Faculty of Technology and Metallurgy, University Ss Cyril and Methodius in Skopje, Republic of Macedonia ABSTRACT Rapid development of industry and urbanization lead to an increase in the amount of various waste (solid, liquid and gaseous emissions). Air, water and soil pollution is a worldwide issue for the eco-environment and human society. Removal of various pollutants, especially heavy metals from the environment is a big challenge. Most of the heavy metals are toxic and their ions are not biodegradable with the tendency to accumulate in the soil and in the living organisms, and hence they are significant environmental pollutants. Therefore, the treatment of the heavy metal ions and their elimination from water and wastewater is very important for environmental protection, and thus the public health. Adsorption is the most commonly used method for removal of the heavy metal ions from large volumes of aqueous solutions. There are a number of materials that can be applied as adsorbents for heavy metals. The clay minerals (bentonite), zeolites, activated carbon, metal oxides, are widely used as conventional adsorbents, and bentonite is one of the most commonly used. Besides the conventional materials, such as the bentonite, used as adsorbents for removing heavy metals from aqueous systems, in recent years, there is a great interest in creating and upgrading new sorption materials for effective removal of these pollutants. The development of nanotechnology enables nanomaterials to find wide application for wastewater treatment, in particular those materials based on carbon, such as graphene and carbon nanotubes. There is a growing number of researches that prove the effectiveness of nanomaterials for adsorption of heavy metal ions. In this paper we will review the comparison of the adsorption abilities of graphene, carbon nanotubes and their modified forms in heavy metal elimination. Also, in this study, graphene, synthesized in our laboratory, marked as G-ASP2, was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X - ray diffraction (XRD), Fourier transform infrared spectrum (FT - IR), Raman spectroscopy and thermogravimetric analysis (TGA). In the future, our aim is to investigate the adsorption effectiveness of graphene, G-ASP2, and its modified forms, in the removal of heavy metal ions from aqueous solutions.
(a)
Figure 1. SEM of G-ASP2
(b)
Figure 2. TEM of G-ASP2 1800000
ASP2 - I proba 1600000 1400000
Intensity
1200000 1000000 800000 600000 400000 200000 0 -200000 0
10
20
30
40
50
60
70
80
90
2, degrees
Figure 3. XRD of G-ASP2
9,34
80
1800
2asp
70
ASP2 - I proba
G-ASP2 9,33
1600
9,32
1400
40
Unsubtracted (Weight)
Raman Intensity
Transmission
60 50
1200 1000 800 600
30 400
20
200
9,31 9,30 9,29 9,28 9,27
0
10
9,26 -200
0
0
1000
1500
2000
2500
3000
3500
4000
Adsorbent
GO GO-SH GNs-SH
Adsorption capacity (mg/g)
Hg(II) Hg(II) Hg(II)
35 190 22
Conditions
RT
Reference
[3]
GO GO-EDTA
Pb(II) Pb(II)
367 479
25oC pH = 6,8
[4]
GO GO-EDTA GO GO-EDTA
Pb(II) Pb(II) Cu(II) Cu(II)
303,0 454,6 166,7 108,7
pH = 3 pH = 3 pH = 5 pH = 5
[5]
GO GO-TiO2 GO GO-TiO2 GO GO-TiO2
Zn(II) Zn(II) Cd(II) Cd(II) Pb(II) Pb(II)
30,1 88,9 14,9 72,8 35,6 65,6
GNs GNs-500 GNs-700
Pb(II) Pb(II) Pb(II)
22,4 35,2 35,5
GO CNTs AC
Cu(II) Cu(II) Cu(II)
46,6 28,5 4-5
GO MWCNTs AC
Cu(II) Cu(II) Cu(II)
74,9 2,0 14,7
Hg(II) Hg(II)
10,8 10,9
GO
Cu(II) Zn(II) Cd(II) Pb(II)
294 345 530 1119
GO
Ni(II) Cu(II) Cd(II)
62,3 72,6 83,8
GOS
Pb(II) Pb(II) Pb(II)
842 1150 1850
RGO - MnO2 RGO - Ag
RT pH = 5,6
30oC
RT
pH = 5
[6]
[7]
[8]
[9]
pH = 5
2500
3000
3500
0
4000
100
200
Adsorbent
Adsorption capacity (mg/g)
CNTs CNTs (HNO3)
Pb(II) Pb(II)
1,0 49,95
CNTs CNTs (H2O2) CNTs (KMnO4) CNTs (HNO3)
Cd(II) Cd(II) Cd(II) Cd(II)
1,1 2,6 11,0 5,1
25oC pH = 5,5
SWCNTs SWCNTs(NaOCl) MWCNTs MWCNTs(NaOCl)
Ni(II) Ni(II) Ni(II) Ni(II)
9,22 47,85 7,53 38,46
25oC
SWCNTs SWCNTs(NaOCl) MWCNTs MWCNTs(NaOCl)
Zn(II) Zn(II) Zn(II) Zn(II)
11,23 43,66 10,21 32,68
Dispersed MWCNTs Undispersed MWCNTs Dispersed MWCNTs Undispersed MWCNTs
Pb(II) Pb(II) Cu(II) Cu(II) Cd(II) Cu(II) Pb(II)
92,3 74,5 67,8 51,3 10,86 24,49 97,08
Pb(II) Cd(II)
58,26 31,45
Cu(II) Cd(II)
16,21 16,94
MWCNTs (HNO3)
Amino modified MWCNTs
Conditions
RT pH = 7
pH = 7
400
500
600
[11]
[13]
700
Sample (Temperature)
Figure 6. TGA of G-ASP2 Table 3. Metal adsorption capacities on bentonite
Table2. Metal adsorption capacities on carbon nanotubes Heavy metal ion
300
Reference
[14]
[15]
[16]
Heavy metal ion
Adsorption capacity (mg/g)
Conditions
Pb(II) Pb(II) Cd(II) Cd(II) Cu(II) Cu(II)
83,02 92,85 48,20 57,88 30,99 36,68
RT
[22]
NB AAB TAB ATAB
Cr(III)
60,97 126,58 83,33 243,90
25oC
[23]
NB AAB MCB
Pb(II) Pb(II) Pb(II)
64,29 40,14 123,64
30oC pH = 6
[24]
Adsorbent
NB AAB NB AAB NB AAB
Reference
25oC pH = 7
[17]
pH = 5,6
[18]
NB AB
Cu(II) Cu(II)
7,63 11,44
pH = 5-6
[25]
RT pH = 5
[19]
NB
Pb(II) Cu(II)
32,68 11,34
20oC pH = 5
[26]
45oC pH = 6-7
[20]
20-30oC pH = 6-7
NB [21]
Cu(II) Co(II) Ni(II) Zn(II)
28,85 24,60 24,25 23,45
NB
Cu(II) Ni(II)
13,22 9,29
[27]
[10]
[12] 20oC 40oC 60oC
2000
Figure 5. Raman of G-ASP2
Ag - MWCNTs 30oC
1500
Raman shift, cm
Figure 4. FT-IR of G-ASP2 Table 1. Metal adsorption capacities on graphene-based materials
1000
–1
Wavenumber (cm-1)
Heavy metal ion
500
4500
KIND OF ADSORBENTS Nanosorbents - graphene and carbon nanotubes In recent years, the development of nanoscience and nanotechnology has shown remarkable potential for the remediation of environmental problems. Due to their non-toxicity and high adsorption capacity, carbon-based nanomaterials, such as graphene and carbon nanotubes, are widely used to remove heavy metals from wastewater. Graphene consists of one or several atomic layers of graphite. It is two-dimensional carbon allotrope and attracts great research interest because of its unique structure and physicochemical properties. Graphene has great theoretical specific surface area and graphene oxide (GO) has functional groups and hence their potential for application in adsorption processes. Modification of graphene and graphene oxide with metal oxides or organic compounds, will create different nanocomposite materials with improved adsorption capacity and efficiency of the separation of pollutants from the polluted environment, including ions of heavy metals as one of the most dangerous pollutants in water systems . Table 1 summarizes and compares adsorption capacities of metals on graphene oxide (GO), graphene nanosheets (GNs) and their composites [1]. As a relatively new adsorbents, due to the unique structural, electronic, semiconductor, mechanical, chemical and physical properties carbon nanotubes, CNTs, are widely utilized for heavy metals removing in wastewater treatment. CNTs are divided into two groups, namely, single walled carbon nanotubes (SWCNTs) and multi walled carbon nanotubes (MWCNTs). To improve the adsorption capacity, CNTs are modified by: oxidation, combining with other metal ions or metal oxides and merger with organic compounds. Maximum heavy metal ions adsorption capacities of raw and surface oxidized carbon nanotubes (CNTs) are given in Table 2 [2]. Conventional adsorbent - bentonite Bentonite is one of the most commonly used conventional adsorbent for heavy metal elimination from wastewaters. Bentonite has a high cation exchange capacity due to the presence of hydrated cations, Ca2+, Na+, K+ etc. on the interlayer surfaces, and these cations can be easily replaced with heavy metal ions. Very often improving the adsorption properties of natural bentonite is carried out by modification using appropriate chemical or thermal treatments. Table 3 contains data for adsorption capacities for natural (NB) and activated bentonite (AB)
20oC
[28]
800
(c)
CONCLUSION Compared with conventional materials, nanostructure adsorbents have exhibited much higher efficiency and faster rates in water treatment. Our future studies are aimed at determining the adsorption properties and capabilities of graphene G - ASP2 and its modified forms in the removal of ions of heavy metals, in particular ions of lead, nickel and iron. According to the characteristics of G-ASP2, obtained by previously given characterization methods, we expect satisfactory results that will correspond to the literature data.
REFERENCES [1] Wang S., Sun H., Ang H. M. and Tade M. O. (2013). Adsorptive remediation of environmental pollutants using novel graphene-based nanomaterials. Chemical Engineering Journal, 226: 336-347 [2] Rao G. P., Lu C. and Su F. (2007). Sorption of divalent metal ions from aqueous solution by carbon nanotubes: A review. Separation and Purification Technology, 58: 224-231 [3] Gao W., Majumder M., Alemany L.B., Narayanan T. N., Ibarra M. A., Pradhan B.K. and Ajayan P. M. (2011). Engineered graphite oxide materials for application in water purification. ACS Applied Materials & Interfaces, 3: 1821-1826 [4] Madadrang C. J., Kim H. Y., Gao G., Waang N., Zhu J., Feng H., Gorring M., Kasner M. L. and Hou S. (2012). Adsorption behavior of EDTA-graphene oxide for Pb(II) removal. ACS Applied Materials & Interfaces, 4: 1186-1193 [5] Isis E. M. C., Joey D. M., Hang N. N., Rigoberto C. A. and Debora F. R. (2014). Graphene oxide functionalized with ethylenediamine triacetic acid for heavy metal adsorption and anti-microbial application. Carbon, 77: 289-301 [6] Lee Y. C. and Yang J. W. (2012). Self-assembled flower-like TiO2 on exfoliated graphite oxide for heavy metal removal. Journal of Industrial and Engineering Chemistry, 18: 1178-1185 [7] Haung Z. H., Zheng X., Lv W., Wang M., Yang Q. H. and Kang F. (2011). Adsorption of lead(II) ions from aqueous solution on lowtemperature exfoliated graphene nanosheets. Langmuir, 27: 7558-7562 [8] Yang S. t., Chang Y., Wang H., Liu G., Chen S., Wang Y., Liu Y. and Cao A. (2010). Folding/aggregation of graphene oxide and its application in Cu2+ removal. Journal of Colloid and Interface Science, 351: 122-127 [9] Ren X.M., Li J. X., Tan X. L. and Wang X. K. (2013). Comparative study of graphene oxide, activated carbon and carbon nanotubes as adsorbents for copper decontamination. Dalton Transactions, 42: 5266-5274 [10] Sreeprasad T. S., Shihabudheen M. M., Lisha K. P. and Pradeep T. (2011). Reduced graphene oxide-metal/metal oxide composites: Facile synthesis and application in water purification. Journal of Hazardous Materials, 186: 921-931 [11] Sitko R.,Turek E.,Zawisza B.,Malicka E.,Talik E., Heimann J.,Gagor A.,Feist B. and Wrzalik R. (2013). Adsorption of divalent metal ions from aqueous solutions using graphene oxide. Dalton Transactions, 42(16): 5682-5689 [12] Ping T., Jian S., Yongyou H., Zheng F., Qi B., Yuancai C. and Jianhuan C. (2015). Adsorption of Cu2+, Cd2+ and Ni2 from aqueous single metal solutions on graphene oxide membranes. Journal of Hazardous Materials, 297: 251-260 [13] Zhao G., Ren X., Gao X., Tan X., Li J., Chen C., Huang Y. and Wang X. (2011). Removal of Pb(II) ions from aqueous solutions on fewlayered graphene oxide nanosheets. Dalton Transactions, 40: 10945-10952 [14] Li Y. H., Wang S., Wei J., Zhang X., Xu C., Luan Z., Wu D. and Wei B. (2002). Lead adsorption on carbon nanotubes, Chem. Phys. Lett. [15] Li Y.H., Wang S., Luan Z., Ding J., Xu C. and Wu D. (2003). Adsorption of cadmium(II) from aqueous solution by surface oxidized carbon nanotubes, Carbon 41:1057–1062 [16] Lu C. and Liu C. (2006). Removal of nickel (II)from aqueous solution by carbonnanotubes. J. Chem. Technol. Biotechnol., 81: 1932–1940 [17] Lu C. and Chiu H. (2006). Adsorption of zinc (II) from water with purified carbon nanotubes. Chem. Eng. Sci., 61: 1138–1145 [18] Tian, Y., Gao, B., Morales, V. L., Wu, L., Wang, Y., Munoz-Carpena, R., Cao, C., Huang, Q. and Yang, L. (2012).Methods of using carbon nanotubes as filter media to remove aqueous heavy metals. Chemical Engineering Journal, 210: 557-563 [19] Li Y. H., Ding J., Luan Z., Di Z., Zhu Y., Xu C., Wu D. and Wei B. (2003). Competitive adsorption of Pb2+, Cu2+ and Cd2+ ions from aqueous solutions by multiwalled carbon nanotubes, Carbon 41 [20] Vukovic, G. D., Marinkovic, A. D., Skapin, S. D., Ristic, M. D., Aleksic, R., Peric-Grujic, A. A., and Uskokovic, P. S. (2011). Removal of lead from water by amino modified multi-walled carbon [21] Venkata Ramana, D. K., Yu, J. S., and Seshaiah, K. (2013). Silver nanoparticles deposited multiwalled carbon nanotubes for removal of Cu(II) and Cd(II) from water: Surface, kinetic, equilibrium and thermal adsorption properties. Chemical Engineering Journal, 223: 806-815 [22]Budsaereechai S., Kamwialisak K. and Ngernyen Y. (2012). Adsorption of lead, cadmium and copper on natural and acid activated bentonite clay. KKU Research Journal, 17(5): 800-810 [23]Ahmed A. M., Ali M. R. and Ibtihal N. A. (2015). Chromium ions removal from wastewater using activated Iraqi bentonite. International Journal of Innovative Research in Science, Engineering and Technology, 4(2): 15-25 [24]Eren E., Afsin B. and Onal Y. (2009). Removal of lead ions by acid activated and manganese- coated bentonite. Journal of Hazardous Materials, 161: 677–685 [25]Boukerroui A., Ali O. and Mohand S. O. (2012). Copper (II) ions removal from aqueous solution using bentonite treated with ammonium chloride. American Journal of Physical Chemistry, 1(1): 1-10 [26]Melichova Z. and Hromada L. (2013). Adsorption of Pb2+ and Cu2+ ions from aqueous solutions on natural bentonite. Polish Journal of Environmental Studies, 22(2): 457-464 [27]Ghormi F., Lahsini A., Laajeb A. and Addaou A. (2013). The removal of heavy metal ions (copper, zinc, nickel and cobalt) by natural bentonite. Larhyss journal, 12: 37-54 [28]Al-Jlil A. S. (2014). Adsorption of Cu & Ni on bentonite clay from wastewater. Athens journal of Natural and Formal Sciences, 1(1): 21-30