Catalytic Adsorptive Stripping Voltammetric Determination of Chromium(VI) in Overlying and Interstitial Waters Isolated from Sediments Contaminated by Tannery Waste

Abstract

In the present paper, catalytic adsorptive stripping voltammetry (CAdSV) has been applied for the first time in a chromium speciation study conducted in pore sediments and overlying waters containing Cr(VI) in the presence of a great excess of Cr(III) and organic matter. The method is based on the adsorptive accumulation of the active Cr(III)-DTPA (diethylenetriammine-N,N,N 0 ,N 00 ,N 00 -pentaacetic acid) complex, which is formed instantaneously on the electrode surface as a result of Cr(VI) reduction to Cr(III), its complexation with DTPA, reduction to Cr(II)-DTPA, and its catalytic oxidation to Cr(III)-DTPA with nitrate. The main efforts were focused on the elimination of the influence of dissolved organic matter including organic surface-active substances (SAS) that adsorb at the electrode surface, and disturb the Cr(VI) determination or, in extreme cases, make it impossible. Of the three procedures applied for the elimination of this negative effect caused, namely, the matrix-exchange method, the removal of SAS by means of fumed silica, and their adsorption on the XAD-7 Amberlite resin present directly in voltammetric vessel, the last one proved to be the most useful. The matrix-exchange procedure also provides accurate and precise results but requires more reagents and time. The CAdSV method combined with the adsorption of surface-active substances on the XAD-7 Amberlite resin was successfully applied for the determination of the Cr(VI) in vertical profile in sediments from Dunajec River, which are severely polluted with chromium from tannery wastes.

Trace level voltammetric determination of lead and cadmium in sediment pore water by a bismuth-oxychloride particle-multiwalled carbon nanotube composite modified glassy carbon electrode

“…Electrochemical techniques have often been used to study environmental processes related to water and sediment quality either in the field or in the laboratory [10,[55][56][57][58][59][60][61][62][63]. Frequently measured target analytes are usually various elements, such as Fe, Mn, Cr, Co, Pb, etc., and sulphur or phosphorus in its different form in the water as well as in the sediment samples.…”

Chromium bioavailability in aquatic systems impacted by tannery wastewaters. Part 1: Understanding chromium accumulation by indigenous chironomids

“…Triplicate measurements for Cr(VI) agreed to 25% or better. Recovery of Cr(VI) from spiked samples was 93% or higher (Bobrowski et al, 2012).…”

“…In some cases, pore waters from different sediment layers were combined to obtain enough volume for voltammetric measurements that were performed in triplicate for all samples. To reduce possible interferences due to the presence of large quantities of dissolved organic carbon (DOC) in pore waters, Amberlite XAD-7 resin was added to the (stirred) voltammetric cell five minutes before Cr(VI) determination (Bobrowski et al, 2012).…”

“…In the Maniowy core, Cr concentrations in pore waters from the uppermost 2 cm were more variable (43±15 µg L -1 , n=3), but decreased below this depth ( Table 2). The proportion of Cr(VI) relative to total Cr could not be measured for all the pore water samples collected from the various layers due to the water volume required for voltammetric measurements (Bobrowski et al, 2012). Based on the available 'combined values' (Table 2), the proportion of Cr(VI) relative to the total Cr content of pore waters varied between 0.5% and 15% at Waksmund and between 5% and 15% at Maniowy.…”

Sensitive adsorptive stripping voltammetric method for determination of trace concentration of titanium in the presence of chloranilic acid as a complexing agent

“…In order to eliminate the influence of organic substances on the AdSV procedures the adsorptive properties of polymeric Amberlite XAD resin were satisfactorily exploited in previous procedures for the determination of different metal ions [25][26][27][28]. Hence XAD-7 resin was chosen to eliminate the interferences of surfactants and humic substances in the course of titanium determination.…”