Sequential injection reductive bio-sorption of Cr(vi) on the surface of egg-shell membrane and chromium speciation with detection by electrothermal atomic absorption spectrometry

Abstract

Egg-shell membrane (ESM) is a unique cell surface with various functional groups, providing the potential for bio-sorption of metal species. We have demonstrated the selective retention of chromium(VI) via a reductive sorption process, while Cr(III) is virtually not retained. This includes adsorption of Cr(VI) onto the ESM surface while charge transfer on the ESM results in the reduction of Cr(VI) to Cr(III) through transient, unstable species of Cr(V) and Cr(IV). A novel procedure for chromium speciation was thus developed in a sequential injection system with detection by electrothermal atomic absorption spectrometry. The procedure includes the separation and preconcentration of Cr(VI) on ESM at pH 2 and its subsequent detection after elution, followed by conversion of Cr(III) to Cr(VI) and total chromium analysis, Cr(III) finally being obtained by subtraction. With a sampling volume of 1000 ml, an enrichment factor of 13.3 was achieved. A linear range of 0.05-1.25 mg l À1 for Cr(VI), along with a detection limit of 0.01 mg l À1 and a precision of 3.2% at the level of 0.5 mg l À1 , were obtained. Chromium speciation was performed by using a certified reference material of riverine water (GBW08608) and cave water.

Non-chromatographic atomic spectrometric methods in speciation analysis: A review

“…Egg-shell membrane [45] has been used for Cr speciation by GF AAS. Egg-shell membrane consists of two-level tissues, i.e., a calcareous layer and an inner lamellar layer.…”

Study on Multi-walled Carbon Nanotubes On-line Separation/ Preconcentration of Chromium(III) and Chromium Speciation

“…16 The adsorption efficiencies of Cr(III) and Cr(VI) on the oxidized MWCNTs surface were investigated by varying the pH values of the sample solutions in the range of 1.0 -11.0 according to the recommended procedure. The results are shown in Fig.…”

“…Various new solid-phase extraction materials have been used for chromium speciation, such as modified silica gel, 5 resin, 6 ion exchanger, 10 diatomite, 11 polytetrafluoroethylene (PTFE), 12 zeolite, 13 oxides 14 and biosorbent. [15][16][17] Out of all the options, carbon nanotubes (CNTs) as an employed novel adsorbent has recently been widely investigated due to its unique properties. [18][19][20][21][22][23] Tuzen et al 24 have established a solid-phase extraction procedure for chromium speciation based on the Cr(VI)-ammonium pyrrolidine dithiocarbamate (APDC) chelate on multi-walled carbon nanotubes (MWCNTs).…”

Development of a novel, fast, sensitive method for chromium speciation in wastewater based on an organic polymer as solid phase extraction material combined with HPLC–ICP-MS

“…Till now, diversities of solid materials have been explored as SPE adsorption substrate for separation and selective preconcentration of chromium species in the environmental samples. Natural abundant material, for example, the ground egg-shell membrane (ESM) has been reported for separation and preconcentration of Cr(VI) at pH 2 (enrichment factor 13.3) via N-acetyl group in ESM surface for subsequent detection after elution, followed by conversion of Cr(VI) to Cr(III) for total chromium analysis using EAAS [16]. Nanomaterials are proved to be the promising adsorbent featured with high specific surface area.…”