Novel potentiometric sensor for the determination of Cd based on a new nano-composite.

A novel ion selective carbon paste electrode for Cd2+ions based on 2,2′-thio-bis[4-methyl(2-amino phenoxy) phenyl ether] (TBMAPPE) as an ionophore was prepared. The carbon paste was made based on a new nano-composite including multi-walled carbon nanotubes (MWCNTs), nanosilica and room-temperature ionic liquid, 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). The constructed nano-composite electrode showed better sensitivity, selectivity, response time, response stability and lifetime in comparison with typical Cd2+carbon paste sensor for the successful determination of Cd2+ions in water and in waste water samples. The best performance for nano-composite sensor was obtained with an electrode composition of 18% TBMAPPE, 20% BMIM-PF6, 48% graphite powder, 10% MWCNT and 4% nanosilica. The new electrode exhibited a Nernstian response (29.95 ± 0.10 mV decade−1) toward Cd2+ions in the range of 3.0 × 10−8to 1.0 × 10−1 mol L−1with a detection limit of 7.5 × 10−9 mol L−1. The potentiometric response of prepared sensor was independent of the pH of test solution in the pH range 3.0 to 5.5. It had a quick response with a response time of about 6 s. The proposed electrode showed fairly good selectivity over some alkali, alkaline earth, transition and heavy metal ions. [ABSTRACT FROM PUBLISHER]