A bucky gel consisting of Fe3O4 nanoparticles, graphene oxide and ionic liquid as an efficient sorbent for extraction of heavy metal ions from water prior to their determination by ICP-OES

Bucky gels are gelatinous composite materials consisting of carbon nanotubes and ionic liquids. The authors describe the synthesis of a bucky gel containing Fe3O4 nanoparticles which is shown to be a viable sorbent for the preconcentration of the ions Cu(II), Zn(II), Cd(II), Cr(III), Pb(II) and Co(II) from environmental water samples. The metal ions were first complexed with 1-(2-pyridylazo)-2-naphthol and then extracted by the sorbent. Following magnetic separation, the ions are desorbed from the sorbent with acetonitrile and then submitted to ICP-OES. Experimental design and response surface methodology were applied to optimize the parameters on that affect the performance of the method. Under the optimized conditions, the detection limits for Cd, Co, Cr, Cu, Pb and Zn are 0.5, 0.3, 0.8, 0.1, 1.0 and 0.1 mu g L-1, respectively. The enrichment factors are in the range between 17 and 47, and the relative standard deviations (for n = 6 at a 50 mu g L-1 level) are < 3.2%. Response is linear in the 1.5 to 100 mu g L-1 metal ion concentration range. The method was successfully applied to the determination of trace amounts of the analytes in (spiked) water samples. Relative recoveries (RR%) were achieved within the range of 90.5% to 107.5%, corresponding to relative errors of -9.5% to + 7.5%.