References

1. V.K. Gupta, A. Nayak, Cadmium removal and recovery from aqueous solutions by novel adsorbents prepared from orange peel and Fe₂O₃ nanoparticles, Chem. Eng. J., 180 (2012) 81–90.
2. Y. Feng, J.-L. Gong, G.-M. Zeng, Q.-Y. Niu, H.-Y. Zhang, C.-G. Niu, J.-H. Deng, M. Yan, Adsorption of Cd (II) and Zn (II) from aqueous solutions using magnetic hydroxyapatite nanoparticles as adsorbents, Chem. Eng. J., 162 (2010) 487–494.
3. A.S. Sartape, A.M. Mandhare, P.P. Salvi, D.K. Pawar, S.S. Kolekar, Kinetic and equilibrium studies of the adsorption of Cd (II) from aqueous solutions by wood apple shell activated carbon, Desal. Water Treat., 51 (2013) 4638–4650.
4. Ş. Sungur, F. Gülmez, Determination of metal contents of various fibers used in textile industry by MP-AES, J. Spectrosc., 2015 (2015).
5. X.-S. Wei, Y.-W. Wu, L.-J. Han, Determination of lead and cadmium in water and pharmaceutical products by inductively coupled plasma optical emission spectrometry with preconcentration by thiourea immobilized silica, Anal. Lett., 48 (2015) 996–1008.
6. M. Soylak, O. Ercan, Selective separation and preconcentration of copper (II) in environmental samples by the solid phase extraction on multi-walled carbon nanotubes, J. Hazard. Mater., 168 (2009) 1527–1531.
7. P.N. Nomngongo, J.C. Ngila, Hollow fiber solid phase microextraction coupled to square wave anodic stripping voltammetry for selective preconcentration and determination of trace levels of mercury in liquid fuel samples, J. Iranian Chem. Soc., 12 (2015) 2141–2147.
8. P. Liang, Y. Liu, L. Guo, Determination of trace rare earth elements by inductively coupled plasma atomic emission spectrometry after preconcentration with multiwalled carbon nanotubes, Spectrochim. Acta Part B: At. Spectrosc., 60 (2005) 125–129.
9. M. Mirzaei, M. Behzadi, N.M. Abadi, A. Beizaei, Simultaneous separation/preconcentration of ultra trace heavy metals in industrial wastewaters by dispersive liquid–liquid microextraction based on solidification of floating organic drop prior to determination by graphite furnace atomic absorption spectrometry, J. Hazard. Mater., 186 (2011) 1739–1743.
10. P. Liang, H. Sang, Determination of trace lead in biological and water samples with dispersive liquid–liquid microextraction preconcentration, Anal. Biochem., 380 (2008) 21–25.
11. E.Z. Jahromi, A. Bidari, Y. Assadi, M.R.M. Hosseini, M.R. Jamali, Dispersive liquid–liquid microextraction combined with graphite furnace atomic absorption spectrometry: Ultra trace determination of cadmium in water samples, Anal. Chim. Acta, 585 (2007) 305–311.
12. İ. Narin, M. Soylak, L. Elçi, M. Doğan, Determination of trace metal ions by AAS in natural water samples after preconcentration of pyrocatechol violet complexes on an activated carbon column, Talanta, 52 (2000) 1041–1046.
13. M. Soylak, L. Elci, M. Dogan, Determination of trace amounts of cobalt in natural water samples as 4-(2-thiazolylazo) recorcinol complex after adsorptive preconcentration, Synth. React. Inorg. Met.-Org. Chem., 30 (1997) 623–631.
14. L. Moens, T. De Smaele, R. Dams, P. Van Den Broeck, P. Sandra, Sensitive, simultaneous determination of organomercury,- lead, and-tin compounds with headspace solid phase microextraction capillary gas chromatography combined with inductively coupled plasma mass spectrometry, Anal. Chem., 69 (1997) 1604–1611.
15. M.A.M. da Silva, V.L.A. Frescura, A.J. Curtius, Determination of trace elements in water samples by ultrasonic nebulization inductively coupled plasma mass spectrometry after cloud point extraction, Spectrochim. Acta Part B: At. Spectrosc., 55 (2000) 803–813.
16. S. Mahpishanian, F. Shemirani, Preconcentration procedure using in situ solvent formation microextraction in the presence of ionic liquid for cadmium determination in saline samples by flame atomic absorption spectrometry, Talanta, 82 (2010) 471–476.
17. L. Ranjbar, Y. Yamini, A. Saleh, S. Seidi, M. Faraji, Ionic liquid based dispersive liquid-liquid microextraction combined with ICP-OES for the determination of trace quantities of cobalt, copper, manganese, nickel and zinc in environmental water samples, Microchim. Acta, 177 (2012) 119–127.
18. D.P. Laxen, E.R. Sholkovitz, Adsorption (co-precipitation) of trace metals at natural concentrations on hydrous ferric oxide in lake water samples, Environ. Technol., 2 (1981) 561–568.
19. E. Yilmaz, M. Soylak, Switchable polarity solvent for liquid phase microextraction of Cd (II) as pyrrolidinedithiocarbamate chelates from environmental samples, Ana. Chim. Acta, 886 (2015) 75–82.
20. C. Huang, B. Hu, Silica-coated magnetic nanoparticles modified with γ-mercaptopropyltrimethoxysilane for fast and selective solid phase extraction of trace amounts of Cd, Cu, Hg, and Pb in environmental and biological samples prior to their determination by inductively coupled plasma mass spectrometry, Spectrochim. Acta Part B: At. Spectrosc., 63 (2008) 437–444.
21. Z. Zang, Z. Hu, Z. Li, Q. He, X. Chang, Synthesis, characterization and application of ethylenediamine-modified multiwalled carbon nanotubes for selective solid-phase extraction and preconcentration of metal ions, J. Hazard. Mater., 172 (2009) 958–963.
22. B. Dai, M. Cao, G. Fang, B. Liu, X. Dong, M. Pan, S. Wang, Schiff base-chitosan grafted multiwalled carbon nanotubes as a novel solid-phase extraction adsorbent for determination of heavy metal by ICP-MS, J. Hazard. Mater., 219 (2012) 103–110.
23. M. Zhang, B.L. Cushing, C.J. O’Connor, Synthesis and characterization of monodisperse ultra-thin silica-coated magnetic nanoparticles, Nanotechnol., 19 (2008) 085601.
24. Y.-H. Deng, C.-C. Wang, J.-H. Hu, W.-L. Yang, S.-K. Fu, Investigation of formation of silica-coated magnetite nanoparticles via sol–gel approach, Colloid. Surf. A: Physicochem. Eng. Asp., 262 (2005) 87–93.
25. M. Adeli, Y. Yamini, M. Faraji, Removal of copper, nickel and zinc by sodium dodecyl sulphate coated magnetite nanoparticles from water and wastewater samples, Arab. J. Chem., DOI (2012).
26. G. Cheng, M. He, H. Peng, B. Hu, Dithizone modified magnetic nanoparticles for fast and selective solid phase extraction of trace elements in environmental and biological samples prior to their determination by ICP-OES, Talanta, 88 (2012) 507–515.
27. T. Tuutijärvi, J. Lu, M. Sillanpää, G. Chen, As (V) adsorption on maghemite nanoparticles, J. Hazard. Mater., 166 (2009) 1415– 1420.
28. H.-H. Yang, S.-Q. Zhang, X.-L. Chen, Z.-X. Zhuang, J.-G. Xu, X.-R. Wang, Magnetite-containing spherical silica nanoparticles for biocatalysis and bioseparations, Anal. Chem., 76 (2004) 1316–1321.
29. J. Muñoz, J. Baena, M. Gallego, M. Valcárcel, Development of a method for the determination of inorganic cadmium and cadmium metallothioneins in fish liver by continuous preconcentration on fullerene and flame atomic absorption spectrometry, J. Anal. At. Spectrom., 17 (2002) 716–720.
30. A.S. Sartape, A.M. Mandhare, P.P. Salvi, D.K. Pawar, S.S. Kolekar, Kinetic and equilibrium studies of the adsorption of Cd (II) from aqueous solutions by wood apple shell activated carbon, Desal. Water Treat., DOI (2013) 1–13.
31. H.-T. Fan, J.-B. Wu, X.-L. Fan, D.-S. Zhang, Z.-J. Su, F. Yan, T. Sun, Removal of cadmium (II) and lead (II) from aqueous solution using sulfur-functionalized silica prepared by hydrothermal- assisted grafting method, Chem. Eng. J., 198 (2012) 355–363.
32. H.J. Shipley, K.E. Engates, V.A. Grover, Removal of Pb (II), Cd (II), Cu (II), and Zn (II) by hematite nanoparticles: Effect of sorbent concentration, pH, temperature, and exhaustion, Environ. Sci. Pollut. Res., 20 (2013) 1727–1736.
33. Z. Reddad, C. Gerente, Y. Andres, P. Le Cloirec, Adsorption of several metal ions onto a low-cost biosorbent: kinetic and equilibrium studies, Environ. Sci. Technol., 36 (2002) 2067–2073.
34. Z. Chen, W. Ma, M. Han, Biosorption of nickel and copper onto treated alga (Undaria pinnatifida): Application of isotherm and kinetic models, J. Hazard. Mater., 155 (2008) 327–333.
35. J. Shah, M.R. Jan, A.u. Haq, M. Zeeshan, Equilibrium, kinetic and thermodynamic studies for sorption of Ni (II) from aqueous solution using formaldehyde treated waste tea leaves, J. Saudi Chem. Soc., DOI 10.1016/j.jscs.2012.04.004.
36. S.-H. Huang, D.-H. Chen, Rapid removal of heavy metal cations and anions from aqueous solutions by an amino-functionalized magnetic nano-adsorbent, J. Hazard. Mater., 163 (2009) 174–179.
37. N. Atar, A. Olgun, S. Wang, Adsorption of cadmium (II) and zinc (II) on boron enrichment process waste in aqueous solutions: Batch and fixed-bed system studies, Chem. Eng. J., 192 (2012) 1–7.
38. K. Munir, M. Yusuf, Z. Noreen, A. Hameed, F.Y. Hafeez, R. Faryal, Isotherm studies for determination of removal capacity of bi-metal (Ni and Cr) ions by Aspergillus niger, Pak. J. Bot., 42 (2010) 593–604.
39. V.K. Gupta, C.K. Jain, I. Ali, M. Sharma, V.K. Saini, Removal of cadmium and nickel from wastewater using bagasse fly ash—a sugar industry waste, Water Res., 37 (2003) 4038–4044.
40. M. Habila, E. Yilmaz, Z.A. Alothman, M. Soylak, Flame atomic absorption spectrometric determination of Cd, Pb, and Cu in food samples after pre-concentration using 4-(2-thiazolylazo) resorcinol-modified activated carbon, J. Ind. Eng. Chem., 20 (2014) 3989–3993.
41. M. Soylak, Z. Topalak, Multiwalled carbon nanotube impregnated with tartrazine: Solid phase extractant for Cd(II) and Pb(II), J. Ind. Eng. Chem., 20 (2014) 581–585.
42. Ş. Saçmacı, S. Şahan, U. Şahin, Ş. Kartal, A. Ülgen, On-line solid- phase separation/preconcentration for the determination of copper in urine by flame atomic absorption spectrometry, Mater. Sci. Eng: C, 44 (2014) 240–245.
43. M. Ghaedi, A. Shokrollahi, K. Niknam, E. Niknam, A. Najibi, M. Soylak, Cloud point extraction and flame atomic absorption spectrometric determination of cadmium(II), lead(II), palladium( II) and silver(I) in environmental samples, J. Hazard. Mater., 168 (2009) 1022–1027.