Yankuang ceshi (Jul 2014)
Determination of Lead, Cadmium, Copper and Iron Contents in Water by Multi-walled Carbon Nanotubes-solid Phase Extraction
Abstract
The traditional solid phase extraction sorbent contains certain deficiencies in the progress of processing heavy metals in environmental samples, such as pH instability and co-extraction difficulty. Therefore, it is particularly important to find more efficient sorbents. A solid-phase extraction method using multi-walled carbon nanotube as absorbent materials for Pb, Cd, Cu and Fe in water has been determined. The effects of solution pH, elution solution, sample volume and matrix effects were investigated. Pb and Cd were determined by Graphite Furnace Atomic Absorption Spectrometry; alternatively, Cu and Fe were determined by inductively coupled plasma atomic emission spectrometry. Experimental results show that the extraction of the metal elements is most efficient when the pH value is 9.0 and flow rate is 2 mL/min with 1 mol/L HNO3 as the elution solution by using the unmodified multi-walled carbon nanotube (outer diameter <8 nm). The maximum adsorption capacities of multi-walled carbon nanotube for Pb, Cd, Cu and Fe are 44.91, 42.31, 54.68 and 49.07 mg/g, respectively. K+, Na+, Ca2+, Mg2+, benzene and toluene have little effect on Pb, Cd, Cu and Fe extraction. The recoveries of Pb, Cd, Cu and Fe were 95.3%-99.5%, and RSD values (n=7) were 1.2%-3.2%, respectively. Compared with the traditional extraction method, this new method not only has high recovery and enrichment effect, but also is simple and accurate, which can be used in the detection of Cd, Cu, Fe and Pb in environmental water samples.
