A solid state Cr(VI) ion-selective electrode based on polypyrrole

Abstract

We report on a graphite electrode onto which polypyrrole was electrodeposited and then doped with chromate ion. This electrode can serve as a Cr(VI)-selective solid-state electrode. Electropolymerization of pyrrole was performed potentiostatically at 0.80 V (vs. SCE) using battery graphite as the working electrode in a solution containing 0.10 M of pyrrole and 20 mM of chromate. A platinum wire was used as an auxiliary electrode. The new electrode displays high selectivity, a very wide dynamic range, a sufficiently fast response time and a good shelf lifetime. It shows a linear Nernstian response over 1.0×10 −6 to 1.0×10 −1 M concentration range (with a slope of 26.55±0.20 mV per log of concentration). The detection limit is 0.5 μM, and the pH optimum is 7.0.

Lignosulfonate-Based Conducting Flexible Polymeric Membranes for Liquid Sensing Applications

“…Other metal-sensitive sensors based on different polymeric membrane ion-selective electrodes incorporating ionophores, sensitive to different cations, have been widely reported in the literature [ 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 ]. Most of these sensors exhibit a near-Nernstian or Nernstian response to the different cations studied.…”

Speciation, adsorption and determination of chromium(III) and chromium(VI) on a mesoporous surface imprinted polymer adsorbent by combining inductively coupled plasma atomic emission spectrometry and UV spectrophotometry

“…Cr(VI) is thermodynamically stable and exists mainly in the form of CrO 4 2− and Cr 2 O 7 2− in a relatively high pH value and potential of the medium. While Cr(III) stabilizes in the low pH value and potential medium . Reduction of Cr(VI) to Cr(III) took place if a strong chemical reductant was added and then Cr(III) was removed through precipitation of Cr(OH) 3 by adding sodium hydroxide or lime .…”