Preconcentration of Pb(II) by Schiff base-chitosan-grafted multiwalled carbon nanotubes adsorbed on surfactant coated C(18) before determination by FAAS

A simple, highly sensitive, accurate and selective method for determination of trace amounts of Pb(II) in water samples is presented.a novel Schiff base-chitosan-grafted multiwalled carbon nanotubes (S-CS-MWCNTs) solid-phase extraction adsorbent was synthesized by covalently grafting a Schiff base-chitosan (S-CS) onto the surfaces of oxidized MWCNTs. The stability of a chemically(S-CS-MWCNTs) especially in concentrated hydrochloric acid which was then used as a recycling and pre-concentration reagent for further uses of (S-CS-MWCNTs). The method is based on selective chelation of Pb(II) on surfactant coated C(18), modified with a Schiff base-chitosan-grafted multiwalled carbon nanotubes (S-CS-MWCNTs). The retained ions were then eluted with 4 ml of 4 M nitric acid and determined by flame atomic absorption spectrometry (FAAS) at 283.3 for Pb. The influence of flow rates of sample and eluent solutions, pH, breakthrough volume, effect of foreign ions on chelation and recovery were investigated. 1.5 g of surfactant coated C(18) adsorbs 40 mg of the Schiff’s base which in turn can retain 15.0±0.9mg of each of the two ions. The limit of detection (3σ) for Pb(II) was found to be 3.20 ng l -1. The enrichment factor for both ions is 100. The mentioned method was successfully applied on determination of lead in different water samples. The ions were also speciated by means of three columns system.

Keywords:

Determination of lead , Preconcentration , Schiff base-chitosan-grafted multiwalled carbon nanotubes (S-CS-MWCNTs) , FAAS