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ABSTRACT
Trace metal ions in aqueous samples may be separated and preconcentrated by solid phase extraction (SPE) prior to their determination by flame atomic absorption spectrometry (FAAS). The trace amounts of heavy metals can form complex with D2EHPA – MWCNTs. The quantitative adsorption was at pH 5.0 with a flow rate of 2 mL−1. The adsorbed metal ions can be eluted with 2.0 mol L−1 HNO3. The highest enrichment factor was 25. The thermodynamic parameter (ΔG) revealed that the adsorption was spontaneous. The procedure was applied to the determination of copper, nickel, lead, zinc and cadmium in laboratory water, well water and electroplating wastewater samples.
Nomenclature
| Ns (mg/L) | = | initial metal ion concentration |
| Nf (mg/L) | = | final metal ion concentration |
| Ce (mg/L) | = | concentration at the equilibrium state |
| Qe (mg/g) | = | adsorption capacity at equilibrium |
| Q (mg g−1) | = | Langmuir constants |
| b (dm3 mg−1) | = | Langmuir constants |
| R2 (dimensionless) | = | correlation coefficient |
| R (8.314J/molK) | = | universal gas constant |
| ∆G (kcal/mol) | = | Gibbs free energy change |
| Kc | = | equilibrium constant |
| Kf (L/g) | = | Freundlich constant |
| 1/n (dimensionless) | = | Freundlich parameter related to intensity of adsorption |
| T (K) | = | absolute temperature |
| t (min) | = | contact time |
| A and B | = | Temkin constant |
Funding
Mr. S. Vellaichamy was thankful to Council of Scientific and Industrial Research (CSIR), New Delhi, India, for providing financial assistance under the award of Senior Research Fellowship scheme (No: 09/468/(0369)/2007EMR-I).
Supplemental data
Supplemental data for this article can be accessed on the publisher’s website.