Nanoadsorbents: classification, preparation, and applications (with emphasis on aqueous media).

Nanometer titanium dioxide immobilized on silica gel as sorbent for preconcentration of metal ions prior to their determination by inductively coupled plasma atomic emission spectrometry.

The removal of the chromium (VI) ion from aqueous solutions with the Lewatit FO36 ion-exchange resin is described at different conditions. The effects of adsorbent dose, initial metal concentration, contact time and pH on the removal of chromium (VI) were investigated. The batch ion exchange process was relatively fast and it reached equilibrium after about 90 min of contact. The ion exchange process, which is pH dependent showed maximum removal of chromium (VI) in the pH range 5.0–8.0 for an initial chromium (VI) concentration of 0.5 mg/dm3. The equilibrium related to Lewatit FO36 ion- exchange capacity and the amounts of the ion exchange were obtained using the plots of the Langmuir adsorption isotherm. It was observed that the maximum ion exchange capacity of 0.29 mmol of chromium (VLVg for Lewatit FO36 was achieved at optimum pH value of 6.0. The ion exchange of chromium (VI) on this cation-exchange resin followed first-order reversible kinetics.

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Removal of chromium (VI) from aqueous solutions using Lewatit FO36 nano ion exchange resin

The development of new sorbents and their application in preconcentration methods for determination of trace elements is a subject of great interest. This review summarizes and discusses several analytical methods involving the preparation and use of new solid‐phase materials. The performance and general properties of sorbents such as carbon nanotubes, imprinted ions, biosorbents, nanoparticles, and fullerene are discussed in detail. The perspective and future trends in the use of these materials are also considered.

New Materials for Solid‐Phase Extraction of Trace Elements

Ultrasound assisted-deep eutectic solvent based on emulsification liquid phase microextraction combined with microsample injection flame atomic absorption spectrometry for valence speciation of chromium(III/VI) in environmental samples

Speciation of Cr(III) and Cr(VI) by nanometer titanium dioxide micro-column and inductively coupled plasma atomic emission spectrometry

The adsorption behavior of Cd, Co and Zn on nanometer-size TiQ2 was investigated. At pH 9.0, Cd, Co and Zn were retained on the nanometer-size TiO2, then eluted with 0.1 mol x L(-1) HNO3 and determined by ICP-AES. The adsorption capacities of nanometer TiO2 were found to be 8.1, 6.9 and 15.1 mg x g(-1) for Cd, Co and Zn respectively. The detection limits (3sigma) for Cd, Co and Zn are 5.1, 3.4 and 2.9 ng x mL(-1) respectively. The proposed method has been applied to the determination of trace Cd, Co and Zn in environmental samples with satisfactory results.

Han-bing Lu

Papers

Speciation of Cr(III) and Cr(VI) by nanometer titanium dioxide micro-column and inductively coupled plasma atomic emission spectrometry

[Nanometer-size titanium dioxide separation/preconcentration and ICP-AES for the determination of Cd, Co and Zn].