Detoxification of ferrocyanide in asoil-plant system.

The detoxification of iron cyanide in a soil-plant system was investigated to assess the total cyanide extracted from contaminated soil and allocated in the leaf tissue of willow trees (Salix caprea). They were grown in soil containing up to 1000 mg/kg dry weight (dw) of cyanide (CN), added as 15N-labeled potassium ferrocyanide and prepared with a new method for synthesis of labeled iron cyanides. CN content and 15N enrichment were monitored weekly over the exposure in leaf tissue of different age. The 15N enrichment in the young and old leaf tissue reached up to 15.197‰ and 9063‰, respectively; it increased significantly over the exposure and with increasing exposure concentrations (p < 0.05). Although the CN accumulation in the old leaf tissue was higher, compared to the young leaf tissue (p < 0.05), the 15N enrichment in the two tissue types did not differ statistically. This indicates a non-uniform CN accumulation but a uniform 15N allocation throughout the leaf mass. Significant differences were detected between the measured CN content and the C15N content, calculated from the 15N enrichment (p < 0.05), revealing a significant CN fraction within the leaf tissue, which could not be detected as ionic CN. The application of labeled iron CN clearly shows that CN is detoxified during uptake by the willows. However, these results do not exclude other detoxification pathways, not related to the trees. Still, they are strongly indicative of the central role the trees played in CN removal and detoxification under the experimental conditions.

RETRACTED: Multifunctional magnetic reduced graphene oxide dendrites: synthesis, characterization and their applications.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief following concerns raised by a reader. The article uses an electron micrograph identical to another publication despite being labelled as different samples. Fig. 3F is the same as Fig. 1D published in Biosensors and Bioelectronics Volume 89 Part1, 15 March 2017, Pages 620-626, 10.1016/j.bios.2015.12.085. In addition, the extraordinary similarities observed between the data presented in Fig. 3C and in Fig. 3C in ACS Biomater. Sci. Eng., 2017, 3 (9), pp 2120­2135, 10.1021/acsbiomaterials.7b00089, Fig. 4A in Colloids and Surfaces B: Biointerfaces, Volume 142, 1 June 2016, Pages 248-258 10.1016/j.colsurfb.2016.02.053 and Fig. 4C in Biosensors and Bioelectronics, Volume 97, 15 November 2017, Pages 208-217, 10.1016/j.bios.2017.06.003 are highly unlikely. This problem with the data casts doubt on all the data, and accordingly also the conclusions based on that data, in this publication. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

Optimized enrichment and purification of ferrocyanide for 13/12C and 15/14N isotope analysis of aqueous solutions.

The occurrence of ferrocyanide, Fe(CN)(6)(4-), in aqueous environments is of concern, since it is potentially hazardous. For tracing the source of ferrocyanide in contaminated water we developed a method that relies on the determination of the stable isotope ratios of (13)C/(12)C and (15)N/(14)N of this complexed cyanide (CN) after precipitating it as cupric ferrocyanide, Cu(2)[Fe(CN)(6)] · 7H(2)O. The precipitate was combusted and the isotope ratios were determined by continuous flow isotope ratio mass spectrometry. At first, ferrocyanide enrichment from synthetic water containing cyanide with known isotopic composition was studied by using six commercial anion-exchange resins. Five resins revealed a quick and complete sorption of ferrocyanide. A nearly quantitative desorption was achieved using NaCl solutions of 5 and 10% by weight for four resins. Subsequent determination of the δ(13)C(CN) and δ(15)N(CN) values of the ferrocyanide revealed that no significant isotope fractionation occurred during this procedure. These results were reproduced even in column experiments using larger water volumes. Potential interferences were also addressed. Sulfate in excess competes for exchange sites but can be precipitated as BaSO(4) prior to ferrocyanide enrichment. Non-cyanide carbon compounds may co-precipitate with cupric ferrocyanide, thus possibly modifying the isotope ratios. However, neither dissolved inorganic carbon nor highly soluble organic compounds did interfere with the method. Poorly soluble organics like BTEX and PAH can be eliminated by passing the samples through appropriate adsorber resins in a prior step. The proposed method is an excellent way of precise determination of the stable cyanide-carbon and cyanide-nitrogen isotope ratios in ferrocyanide-containing aqueous samples, which was successfully applied to four contaminated groundwater samples since measured aqueous isotopes ratios match those of corresponding cyanide-bearing solid wastes.

Effect of temperature on removal of iron cyanides from solution by maize plants.

GOAL, SCOPE, AND BACKGROUND: Cyanide is commonly found in soils and groundwater complexed with iron as ferro- and ferri-cyanide. It is evident that plants are capable of tolerating, transporting, and assimilating iron cyanides. The objectives of this study were to investigate the influence of temperatures on the removal and bioaccumulation of two chemical forms of iron cyanides by maize seedlings. MATERIALS AND METHODS: Maize (Zea mays L. var. ZN 304) seedlings were grown hydroponically and treated with ferro- or ferri-cyanide in solution for 5 days. Six different temperatures were tested ranging from 12 to 27 degrees C. Total cyanide in solution phase and plant tissues was analyzed spectrophotometrically. The temperature coefficient (Q (10)) was also determined for maize exposed to both iron cyanides. RESULTS: The dissociation of both iron cyanides to free cyanide in solution was below the detection limit. Maize seedlings showed a significantly higher removal potential for ferro-cyanide than ferri-cyanide at all treatment temperatures. Analysis of mass balance revealed that the majority of these iron cyanides taken up from the hydroponic solutions was assimilated by maize, and roots were the major sink for cyanide accumulation. The Q (10) values were determined for ferro- and ferri-cyanide to be 2.31 and 2.75, respectively. DISCUSSION: Due to the significant difference in the removal rate between the two species of iron cyanides by plant, the conversion of ferri- to ferro-cyanide in aqueous solution prior to uptake is unlikely. Compared to the treatments amended with ferro-cyanide, more cyanide was recovered in plant materials of maize when exposed to ferri-cyanide, implying that ferri-cyanide is less sensitive to degradation than ferro-cyanide. Although the velocity of botanical assimilation of ferro-cyanide was faster than that of ferri-cyanide at any of the treatment temperatures, the removal of ferri-cyanide by maize was more sensitive to changes in temperature than that of ferro-cyanide. CONCLUSIONS: Removal of both iron cyanides by maize seedlings was observed to be positive in response to temperatures. Changes in temperatures have a substantial influence on not only the uptake and assimilation of ferro- and ferri-cyanide by maize but also cyanide accumulation in plant tissues. RECOMMENDATIONS: As one of the crucial abiotic factors involved in phytoremediation, temperature shows a positive influence on the removal of iron cyanides by plants. Further investigation on the fate of ferro- and ferri-cyanide in plant tissues would have helped distinguish the differences in the botanical assimilation pathways between the two iron cyanides. PERSPECTIVES: The ability of maize to remove iron cyanides has important implications on the vegetation management of environmental contamination.