The application of conducting polypyrrole (PPy) and polyaniline (PAni) coated substrates in remediation of chromium, Cr(VI), is an area of considerable interest. Here, we discuss the implementation of PPy-coated titanium as a new material for the reduction of Cr(VI) to the less toxic trivalent state, Cr(III). An alkaline-peroxide based etching process was used to ensure the adhesion of the PPy coatings to the underlying titanium. The PPy films showed excellent resistance to acidic Cr(VI) solutions and remained adherent after continuous exposure to the solutions. In order to optimise the remediation process a number of experimental parameters were investigated, including the thickness of the PPy coating, the reduction potential used in pre-treatment of the PPy and the degree of solution agitation. The durability of the materials on exposure to the Cr(VI) test solutions made them suitable for repeated remediation experiments. Following several test-runs, the cleanup efficiency of the material was found to decrease slightly, however, increasing the exposure/experiment time resulted in significantly improved cleanup ability.

The electrochemical behaviour of a glassy carbon (GC) electrode modified with multi-walled carbon nanotubes (MWCNTs) was investigated and characterised using K3[Fe(CN)6] as a probe. An increase in the electroactive surface area and the rate of electron transfer was observed on sonication of the MWCNTs prior to casting on the GC electrode. The modified electrode was also used in the detection of Cr (VI) in both pH 5.0 and pH 2.0 aqueous solutions. Better detection limits were obtained in the acidic solution.