title: Optimization of ethylenediamine-grafted multiwalled carbon nanotubes for solid-phase extraction of lead cations.
abstract: BACKGROUND
  Ethylenediamine-grafted multiwalled carbon nanotubes (MWCNTs-EDA-I and MWCNTs-EDA-II) are optimized and employed to investigate the preconcentration of lead ions (Pb(II)) in trace level.
  
  
  RESULTS
  The results show that Pb(II) can be adsorbed quantitatively on the optimized MWCNTs in the range of pH 4-7 and MWCNTs-EDA-I has a higher maximum Pb(II) adsorption capacity (157.19 mg/g) than MWCNTs-EDA-II (89.16 mg/g). The adsorbed Pb(II) can be eluted completely using 5 mL of 1 mol/L HNO(3).
  
  
  CONCLUSIONS
  A new approach using a microcolumn packed with the obtained MWCNTs-EDA-I has been developed for the preconcentration of trace amount of Pb(II). Parameters influencing the preconcentration of Pb(II), such as pH of the sample, sample volume, elution solution, and interfering ions, have been examined and optimized in detail. Under optimum experimental conditions, the limit of detection is 0.30 ng/mL with the enrichment factor of 60. The relative standard deviation (R.S.D) was 2.6% at the 20 ng/mL Pb(II) level.
  
  
  CONCLUSIONS
  The method has been applied for the preconcentration of trace amount of Pb(II) in environmental water samples with satisfying results.
authors: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Siping Rd 1239, Shanghai 200092, People's Republic of China. huzjun@tongji.edu.cn
authors: Zhang-Jun
authors: ZJ
authors: Hu
authors: Yang
authors: Y
authors: Cui
authors: Shan
authors: S
authors: Liu
authors: Yuan
authors: Y
authors: Yuan
authors: Hong-Wen
authors: HW
authors: Gao
mesh_terms: D000327:Adsorption; D005029:Ethylenediamines / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D052616:Solid Phase Extraction; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D005029:Ethylenediamines; D037742:Nanotubes, Carbon; D014874:Water Pollutants, Chemical; D007854:Lead; C031234:ethylenediamine