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Ferri and ferro coordination polymers in sphere structure were synthesized. Scanning Electron Microscopy (SEM) Energy Dispersive X-Ray Spectroscopy (EDX), Gel Permeation Chromatography (GPC), elemental analysis, and Fourier Transform Infrared Spectroscopy (FT-IR) were performed for chemical and structural characterization of the coordination polymers. Glucose oxidase (GOD) enzyme immobilized to compare of kinetic parameters deal with glucano-1,5 lacton formation. Analyses results illustrate that structures coordination of ions Fe2+ and Fe3+ are different to the same support. It was seen that 2 mol of Fe2+ ion ((PS-N-([Fe(CN)4L]K3)2) was bound per unit structure while 1 mol of Fe3+ ion (PS-N- ([Fe(CN)2L]K)) is attaching. Km values of were found as 15.32 and 10.93 for (PS-NFe2+)- GOD and (PS-N-Fe3+)-GOD, respectively. Km value for (PS-N-Fe3+)-GOD was found to be 0.5 times higher, possible reason of such a case is the larger reduction potential of Fe3+. As the charge on the coordination structure increased, the enzyme's affinity for the substrate increased. After 20 repeated measurements, GOD immobilized on (PS-N-Fe3+) polymer retained 45.47% activity, while GOD immobilized on (PS-N-Fe2+) polymer retained 57.86% activity. [ABSTRACT FROM AUTHOR]

Cerebral microbleeds are microscopic hemorrhages with deposits of blood products in the brain, which can be visualized with MRI and are implicated in cerebrovascular diseases. Hematoxylin and eosin (H&E) and Perl's Prussian blue are popular staining methods used to localize cerebral microbleeds in pathology. This paper compared these two staining techniques in a mouse model of cerebral microbleeds. We used lipopolysaccharide (LPS) to induce cerebral microhemorrhages. C57B6 mice were treated with LPS (5 mg/kg, i.p.) or vehicle at baseline and at 24 hr. The brains were extracted 48 hr after the first injection and adjacent coronal sections were stained with H&E and Prussian blue to compare the effectiveness of the two staining techniques. H&E-positive stains were increased with LPS treatment and were correlated with grossly visible microhemorrhages on the brain surface; Prussian blue-positive stains, by comparison, showed no significant increase with LPS treatment and did not correlate with either H&E-positive stains or surface microhemorrhages. H&E staining is thus a more reliable indicator of acute bleeding events induced by LPS in this model within a short time span.

The Panel on Food Additives and Nutrient Sources added to Food (ANS) provided a scientific opinion re-evaluating the safety of sodium ferrocyanide (E 535), potassium ferrocyanide (E 536), and evaluating the safety of calcium ferrocyanide (E 538) as food additives. The Panel considered that adequate exposure and toxicity data were available. Ferrocyanides (E 535--538) are solely authorised in two food categories as salt substitutes. To assess the dietary exposure to ferrocyanides (E 535--538) from their use as food additives, the exposure was calculated based on regulatory maximum level exposure assessment scenario (maximum permitted level (MPL)) and the refined exposure assessment scenario. Dietary exposure to ferrocyanides was calculated based on mean and high levels consumption of salts in both the regulatory maximum level and the refined scenario. In the MPL scenario, the exposure to ferrocyanides (E 535--538) from their use as a food additive was up to 0.009 mg/kg body weight (bw) per day in children and adolescents. In the refined estimated exposure scenario, the exposure was up to 0.003 mg/kg bw per day in children and adolescents. Absorption of ferrocyanides is low and there is no accumulation in human. There is no concern with respect to genotoxicity and carcinogenicity. Reproductive studies were not available, but a no observed adverse effect level (NOAEL) of 1,000 mg sodium ferrocyanide/kg bw per day (highest dose tested) was identified from a prenatal developmental toxicity study. The kidney appeared to be the target organ for ferrocyanides toxicity and 4.4 mg sodium ferrocyanide/kg bw per day was identified as the NOAEL for the renal effects in a chronic (2-year) study in rats. Assuming that the toxicity of this compound is due to the ferrocyanide ion only, the Panel established a group acceptable daily intake (ADI) for sodium, potassium and calcium ferrocyanide of 0.03 mg/kg bw per day expressed as ferrocyanide ion. The Panel concluded that ferrocyanides (E 535--538) are of no safety concern at the current authorised use and use levels. [ABSTRACT FROM AUTHOR]

The electroanalytical responses of several redox-active species are investigated in authentic human whole saliva. First, we show that ferrocenemethanol (FcCH 2 OH ) and ferrocyanide ([Fe(CN) 6 ] 4− ) display well-defined voltammetry in undiluted saliva at a carbon microdisc electrode without the addition of supporting electrolyte. Second, we demonstrate that dissolved oxygen is detectable in saliva. The ferrocenemethanol oxidation is shown not to be altered by the medium apart from the steady-state currents which change according to the viscosity of the solvent. In contrast, the voltammetry of ferrocyanide oxidation and oxygen reduction in authentic saliva are significantly different from those in synthetic saliva or aqueous electrolyte. It is demonstrated that the electrode is partially blocked by organic molecules or other electrochemically inert species when placed in authentic saliva samples. The distortion in voltammetry thus reflects the different surface sensitivity of the two processes. Ohmic drop is proved to be minimal at microelectrodes even without added electrolyte. Microelectrodes are thus suitable for use in electrochemical analysis of saliva samples. Finally, we demonstrate that uric acid which is a potential biomarker for gout, oral cavity cancer and other several diseases can be directly detected in authentic saliva at a carbon microelectrode with the interference of ascorbic acid and dopamine of no more than 10%. [ABSTRACT FROM AUTHOR]

We examined the feasibility of using handheld mid-infrared (MIR) Fourier-Transform infrared (FT-IR) instrumentation for detecting and analysing cyanide (CN) contamination in field contaminated soils. Cyanide spiking experiments were first carried out, in the laboratory, to test the sensitivity of infrared Fourier transform (DRIFT) spectrometry to ferro- and ferricyanide compounds across a range of reference soils and minerals. Both benchtop and handheld diffuse reflectance infrared spectrometers were tested. Excellent results were obtained for the reference soils and minerals, with the MIR outperforming the near-infrared (NIR) range. Spectral peaks characteristic of the –C≡N group were observed near 2062 and 2118 cm -1 in the MIR region for the ferro- and ferricyanide compounds spiked into soils/minerals, respectively. In the NIR region such peaks were observed near 4134 and 4220 cm -1 . Cyanide-contaminated samples were then collected in the field and analyzed with the two spectrometers to further test the applicability of the DRIFT technique for soils containing aged CN residues. The prediction of total CN in dry and ground contaminated soils using the handheld MIR instrument resulted in a coefficient of determination (R 2 ) of 0.88–0.98 and root mean square error of the cross-validation (RMSE) of 21–49 mg kg -1 for a CN range of 0–611 mg kg -1 . A major peak was observed in the MIR at about 2092 cm -1 which was attributed to “Prussian Blue” (Fe 4 [Fe(CN) 6 ] 3 · x H 2 O). These results demonstrate the potential of handheld DRIFT instrumentation as a promising alternative to the standard laboratory method to predict CN concentrations in contaminated field soils. [ABSTRACT FROM AUTHOR]

Metal ferrocyanides (MFCs) have been studied for many years and are regarded as efficient adsorbents for the selective removal of radioactive cesium (Cs) from contaminated aqueous solutions. Although their efficiency has been demonstrated, various investigations on the physicochemical, thermal, and radiological stability of the solids of MFCs are required to enhance the applicability of MFCs in the treatment process. We observed that the Cs adsorption efficiencies of cobalt and nickel ferrocyanides decreased as their aging period increased, while the Cs adsorption efficiencies of copper and zinc ferrocyanides did not decrease. The tendencies of these ferrocyanides were accelerated by exposure of the solids at a higher temperature for a longer time. Our comprehensive analyses demonstrated that only the oxidizable metals in the MFCs can be oxidized by aging time and increasing temperature; also, this affects the Cs removal efficiency by decreasing the exchangeable sites in the solids. The chemical stability of MFCs is very important for the optimization of the synthesis and storage conditions. [ABSTRACT FROM AUTHOR]

For the first time, the use of a membrane based copper ferrocyanide loaded sorbent for removal of Cs from neutral aqueous solution is reported in this work. The results indicated high Cs exchange capacity (1.75 mmol/g), large distribution coefficient, as well as fast absorption of the cation in the membrane. The membrane, inspite of presence of other metal ion, exclusively absorbed Cs from a simulated nuclear waste solution, though the absorption rate is affected due to their presence. This composite membrane showed promising properties for Cs removal from nuclear waste solution. [ABSTRACT FROM AUTHOR]

The use of crystallization inhibitors has been proposed as a potential preventive treatment method against damage and is extensively tested for crystallization of single salts. However, in practice salt mixtures are present. Therefore, before using inhibitors in practice there is a strong need to explore their effect on salt mixtures. In this research, we studied the effect of ferrocyanide ions ([Fe(CN) 6 ] 4− ) on NaCl crystallization in single salt and in salt mixtures of NaCl–KCl and NaCl–LiCl. A series of micro droplet drying experiments were undertaken. Time lapse microscopy of the crystallization was performed along with NMR measurements of hydrogen, sodium and lithium ions. This gives the possibility to visualize the drying of the droplet while simultaneously obtaining information of both NaCl and LiCl concentration in the droplet. For a NaCl solution droplet, in the presence of inhibitor, a significantly higher supersaturation prior to the onset of crystallization and a change in crystal morphology were observed. On the other hand, for salt mixtures, lower supersaturation compared to single salt and dendritic crystal morphology was seen in the presence of inhibitor. In a porous material, such a type of morphology can promote the formation of efflorescence that causes only little structural damage. [ABSTRACT FROM AUTHOR]

The kinetics of cesium sorption onto mixed nickel potassium ferrocyanide supported on hydrated titanium dioxide were studied in different ranges of cesium concentrations. At the cesium concentration in solution from 2 × 10 to 5 mg L, the sorption rate is determined by external diffusion of cesium ions in solution, heterogeneous ion-exchange reaction, and internal diffusion of cesium in the pore space of the sorbent. The slowest step is the breakdown of sorption colloids and uptake of the released cesium ions by the sorbent. At the cesium concentration in solution higher than 50 mg L, the rate-determining step is the precipitation of mixed nickel cesium ferrocyanide in the pore space of the sorbent. [ABSTRACT FROM AUTHOR]

The waste waters from nuclear engineering containing corrosion and fission products fall in the category of medium or low level radioactive wastes. These waste waters must be treated in order to decontaminate prior to be released in rivers or lakes. Additionally these waste waters can contain some organic products, like surfactants from laundry. The ion exchange is the most efficient treatment technology for radionuclides removal from a variety of waste water streams with low and intermediate pollution level. Unfortunately this technology is not selective because all ions from polluted waters are fixed. In the last time the selective separation of radioactive ions from this water type is an important research subject. Sorption with or without chemical interaction in solid phase of radioactive species is a promising procedure. A study regarding removal of 137Cs from radioactive waters from spent nuclear fuel pools using a synthetic inorganic sorbent was performed. Nickel ferrocyanide, precipitated on silica gel, with size of granules 0.5 - 0.8 mm, was used as sorbent. The aqueous radioactive waste initial characteristics were137Cs concentration 3000 Bq/L, pH 6.50, conductivity 6.44 μS/cm, chloride content < 0.01 ppm, and solid residue 3.90 mg/L. No fission or activation gamma emitter was identified. Batch experiments as a function of pH, contact time, sorbent/waste mass ratio were carried out. Isolated and synergic effects of process parameters were determined in order to establish acceptable limits for variability in performance. Simple kinetic and thermodynamic models have been applied to the rate and isotherm sorption data and the relevant kinetic and thermodynamic parameters were obtained. The sorbent capacity was established using the Freundlich and Langmuir adsorption isotherm models. The decontamination factors in terms of separation yield were determined. The checked sorbent has a high separation capacity of Cs+ from aqueous radioactive waste. Computation examples on the practical use of this sorbents are already presented. [ABSTRACT FROM AUTHOR]

The use of composite materials based on metal ferrocyanides combined with natural mineral sorbents for treatment of high salinity Cs-containing liquid radioactive waste (LRW) was investigated. The study indicated that among the investigated composites, the best sorption characteristics for Cs were shown by materials based on copper ferrocyanide. Several factors affecting the removal of cesium from LRW, namely total salt content, pH and organic matter content, were also investigated. High concentrations of complexing organic matter significantly reduced the sorption capacity of ferrocyanide sorbents. [ABSTRACT FROM AUTHOR]

In this study, cellulose-inorganic sorbents based on bleached cotton fibres and ferrocyanides of different d-metals have been prepared and used for separation of Cs from simulated aqueous solutions. Comparative analysis has been carried out of the sorption properties of obtained sorption materials towards to micro- and macroquantities of caesium at different liquid to solid phases ratios. Various characterization methods including X-ray analysis, IR spectroscopy, and differential thermal analysis were used to determine the structural properties of the obtained composite sorbents. It has been confirmed that the sorbents obtained at approximately the same content of the inorganic component are characterized by different values of the recovery rate and Cs distribution coefficient. [ABSTRACT FROM AUTHOR]

Sorption isotherm of caesium from tap water by mixed nickel-potassium ferrocyanide based on hydrated titanium dioxide is obtained for a wide range of concentrations of caesium. It is shown that there are three types of specificity to caesium sorption sites in this sorbent. Sorption chemisms of caesium are studied, factors conditioned high sorption capacity of the sorbent are revealed. It is shown that occupation of sorption sites I and II is well approximated by Langmuir equilibrium and this process can be described within the bounds of theory of ion exchange. The expected sorption chemism of caesium by sorption sites III at high concentrations of caesium (>50 mg L) is precipitation of mixed nickel-caesium ferrocyanide in pore space of the sorbent. [ABSTRACT FROM AUTHOR]

The effect of single-charged cations (Na, K, NH) on the cesium sorption with mixed nickel potassium ferrocyanide sorbent based on hydrated TiO was studied. The K and Na ions exert no effect at their concentrations of up to 0.5 M; the Cs distribution coefficients from KCl and NaCl solutions are (1.1 ± 0.5) × 10 and (8 ± 3) × 10 mL g, respectively. The sorbent is highly specific to Cs in the presence of ammonium ions. The sorption mechanisms were studied. The concentration ranges in which Cs and NH are sorbed by independent mechanisms (Cs, by the ferrocyanide phase; NH, by the phase of hydrated TiO) and in which the Cs distribution coefficient decreases owing to competitive filling of the ferrocyanide phase with ammonium ions were determined. At cesium concentrations in solution exceeding 50 mg L, Cs and NH are absorbed jointly owing to coprecipitation in the mixed ferrocyanide phase in the pore space of the sorbent. [ABSTRACT FROM AUTHOR]

The spent potliner (SPL) landfill liner system provides the primary attenuation mechanism that blocks the leaching of ferrocyanide. If the seepage occurs, however, the off-site leaching potential of ferrocyanide will be enhanced, resulting in contaminant dispersion. In this study, the adsorptive attenuation of ferrocyanide by two common lining materials (kaolinite and montmorillonite) was investigated under various seepage settings, such as influent concentration, liner thickness, and seepage velocity. The attenuation of ferrocyanide through both lining materials was obvious by lowering the maximum concentration and retarding the peak arrival time and was greater than that expected from batch data, likely due to the high mass-volume ratio under seepage condition. In comparison, seepage of ferrocyanide through lining material layer was retarded when (1) influent concentration was halved, (2) liner thickness was 1.5-fold, and (3) seepage velocity was halved. These experimental results strongly support the concentration-specific and rate-limited adsorptive attenuation of ferrocyanide by lining materials during the seepage process. An extended desorption front was observed for all seepage conditions; it was particularly more apparent for montmorillonite with a slow seepage velocity, further supporting that the release of adsorbed ferrocyanide from adsorbent is energetically hysteretic. Among the factors investigated in this study, the greatest retardation of ferrocyanide movement from seepage water was achieved upon doubling liner thickness. Therefore, for the design of a SPL landfill liner to minimize the leaching potential and thus the environmental risk of ferrocyanide, optimization of the liner thickness should be considered foremost. [ABSTRACT FROM AUTHOR]

Abstract: The first fructose sensor using a commercial screen-printed ferrocyanide/carbon electrodes (SPFCE) is reported here. The ferrocyanide is included in the carbon ink of the commercial screen-printed carbon electrode. The immobilization of enzyme d-fructose dehydrogenase (FDH) was carried out in an easy way. An aliquot of 10μL FDH was deposited on the electrode surface and left there until dried (approximately 1h) at room temperature. The sensor, so constructed, shows a good sensitivity to fructose (1.25μA/mM) with a slope deviation of ±0.02μA/mM and a linear range comprised between 0.1 and 1mM of fructose, with a limit of detection of 0.05mM. These sensors show good intersensors reproducibility after a previous pretreatment and a high stability. Fructose was determined in real samples as honey, Cola, fruit juices (orange, tomato, apple and pineapple), red wine, red and white grapes, musts and liquor of peach with a good accuracy. [Copyright &y& Elsevier]

Abstract: Through theoretical modelling based upon a diffusion domain approach, we show that for a basal plane pyrolytic graphite electrode with a 10–20% surface coverage of edge plane sites, minimal differences in the voltammetric response should be expected from that of an edge plane pyrolytic graphite electrode. Further through the use of organic solvents, for the modification of the electrode surface, it is demonstrated that the voltammetry of the oxidation of ferrocyanide in aqueous solution is surface sensitive and we infer that it likely occurs through the formation of a bridging ion complex with the electrode surface. Accordingly it is suggested that the electron transfer mechanism for the oxidation of ferrocyanide at a graphite electrode should not be viewed as being outer-sphere in nature. These results have implications for voltammetric experimentation with both graphite and carbon nanotube modified electrodes. [Copyright &y& Elsevier]

Abstract: The breakthrough curve (BTC) of F− through a lining layer composed of kaolinite and montmorillonite was investigated in a one-dimensional seepage system as functions of the initial F− concentration, liner thickness, seepage velocity and presence of a co-solute. The removal of F− from the seepage system was much greater than that estimated from the batch adsorption result, probably due to the high liner mass-leachate volume ratio. By lowering the F− feed concentration from 30 to 15mg/L, the peak retardation (μ′1) was enhanced by 30–60%, which was consistent with the nonlinear F− adsorption (N<1) for the given materials. From a column with 1.5-times thicker liner (6cm), more than 80% of the peak concentration was reduced with both kaolinite and montmorillonite compared to the thinner layer (4cm). However, when the seepage velocity was doubled from 3.4×10−3 to 6.8×10−4 cm/s, the peak concentration was increased by 20–30% and an early peak arrival was detected. The presence of 0.035mM [Fe(CN)6]4− showed no significant impact, as shown in the batch adsorption system. In conclusion, the thickness of the liner and seepage rate through the liner layer should be primary factors in determining the efficacy of F− removal from SPL-induced leachate. [Copyright &y& Elsevier]

Abstract: Copper(II) ferrocyanide on mesoporous silica (FC-Cu-EDA-SAMMS™) has been evaluated against iron(III) hexacyanoferrate(II) (insoluble Prussian Blue) for removing cesium (Cs+) and thallium (Tl+) from natural waters and simulated acidic and alkaline wastes. From pH 0.1–7.3, FC-Cu-EDA-SAMMS had greater affinities for Cs and Tl and was less affected by the solution pH, competing cations, and matrices. SAMMS also outperformed Prussian Blue in terms of adsorption capacities (e.g., 21.7 versus 2.6mgCs/g in acidic waste stimulant (pH 1.1), 28.3 versus 5.8mgTl/g in seawater), and rate (e.g., over 95wt% of Cs was removed from seawater after 2min with SAMMS, while only 75wt% was removed with Prussian Blue). SAMMS also had higher stability (e.g., 2.5–13-fold less Fe dissolved from 2 to 24h of contact time). In addition to environmental applications, SAMMS has great potential to be used as orally administered drug for limiting the absorption of radioactive Cs and toxic Tl in gastrointestinal tract. [ABSTRACT FROM AUTHOR]

Abstract: 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 13C/12C and 15N/14N of this complexed cyanide (CN) after precipitating it as cupric ferrocyanide, Cu2[Fe(CN)6]·7H2O. 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 13CCN and δ 15NCN 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 BaSO4 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. [Copyright &y& Elsevier]

Abstract: Soluble salts of marine origin are one of the main agents in the weathering of granitic rocks used in buildings and monuments; they cause a loss of cohesion between the mineral grains, which results in granular disintegration. This deterioration is produced by crystallization–dissolution processes of salts, mainly sodium chloride, in the interior of the rock. Desalination procedures (mainly immersion and application of adsorbent poultices) are the more usual intervention in this circumstance, but complete extraction of the salts is generally difficult to achieve. In this paper we present the results of a study of the effectiveness of two NaCl crystallization modifiers, potassium ferrocyanide and sodium ferrocyanide, in desalinating two types of granitic rock with significantly different pore structure. Evaluations have been made of how these modifiers influence, first, the transport of NaCl solution inside the rocks; second, the susceptibility of the granite to salt crystallization cycles; and third, the effectiveness of desalination by immersion in distilled water. The results obtained are that the effectiveness of the two modifiers is completely different in each of the two granites studied. In one type of rock studied, both ferrocyanides increase the evaporation rate of the saline solution inside the structure of the rock by permitting NaCl to crystallize on surfaces as efflorescences; consequently, first, the intensity of sand disaggregation during the salt crystallization test is reduced, and second, when either of the modifiers is added to distilled water, desalination is more effective than extraction with distilled water only. For the second type of granite evaluated, neither of the modifiers was found to be effective. Therefore, we conclude that the network of fissures in the rock has a significant effect on the behaviour of the solutions with modifiers, since the pore structure of the stone determines the dissolution/evaporation kinetics of the solutions of salts. Thus, generalizations about the effectiveness of specific modifiers in granites are not possible: their effectiveness must be studied for each specific stone. [Copyright &y& Elsevier]

Abstract: Functionalized poly N,N-dimethylaniline film was prepared by adsorption of ferrocyanide onto the polymer forming at the surface of carbon paste electrode (CPE) in aqueous solution. The electrocatalytic ability of poly N,N-dimethylaniline/ferrocyanide film modified carbon paste electrode (PDMA/FMCPE) was demonstrated by oxidation of l-cysteine. Cyclic voltammetry and chronoamperometry techniques were used to investigate this ability. In the optimum pH (6.00), the electrocatalytic ability about 480mV and the catalytic reaction rate constant, (k h), can be seen 3.08×103 M−1 s−1. The catalytic oxidation peak current determined by cyclic voltammetry method was linearly dependent on the l-cysteine concentration and the linearity range obtained was 8.00×10−5 –2.25×10−3 M. Detection limit of this method was determined as 6.17×10−5 M (2σ). At a fixed potential under hydrodynamic conditions (stirred solution), the calibration plot was linear over the l-cysteine concentration range 7.40×10−6 M–1.38×10−4 M. The detection limit of the method was 6.38×10−6 M (2σ). [Copyright &y& Elsevier]

The electrooxidation of d-penicillamine ( d-PA) was studied in the presence of ferrocyanide as a homogeneous mediator at the surface of a carbon paste electrode in aqueous media using cyclic voltammetry (CV) and chronoamperometry. Under optimum pH in CV the oxidation of d-PA occurs at a potential about 380 mV less positive than that in the absence of ferrocyanide. The catalytic oxidation peak current was dependent on the d-PA concentration and a linear calibration curve was obtained in the ranges 4.0 × 10−5–2.0 × 10−3 M and 8.0 × 10−6–1.8 × 10−4 M of d-PA with CV and differential pulse voltammetry (DPV) methods, respectively. The detection limits (3σ) were determined as 1.9 × 10−5 and 3.2 × 10−6 M by CV and DPV methods. This method was also used for the determination of d-PA in pharmaceutical preparations by the standard addition method. [ABSTRACT FROM AUTHOR]

Abstract: A new kind of highly stable /poly(butyl viologen) (PBV) thin film, without any sealing layer, as a modified electrode for dopamine oxidation was proposed. In this work, were entrapped within the PBV film to form a charge transfer complex. The electrochemical and electrocatalytic properties were studied using cyclic voltammetry (CV) and amperometric techniques, in conjunction with a rotating-disk electrode. The results show a highly stable and symmetric redox behavior for the couple with peak–peak separation of 3mV at a scan rate of 5mV/s. The electron transfer rate constant for the couple within the film, the catalytic rate constant between dopamine and , and the Michaelis–Menton constants are investigated. Moreover, the result shows an excellent mediation for dopamine oxidation. [Copyright &y& Elsevier]

Abstract: Uptake, assimilation, and toxicity of exogenous iron cyanide complexes in plants were investigated. Pre-rooted young weeping willows (Salix babylonica L.) were exposed to hydroponic solutions spiked with potassium ferrocyanide at 24.0±1°C for 192h. Transpiration rates, chlorophyll contents, soluble protein, and activities of superoxide dismutases (SOD), catalase (CAT), and peroxidase (POD) of the plants were monitored to determine toxicity to the cuttings. Of all selected parameters, POD activity in leaves was the most sensitive bioindicator to the increase of ferrocyanide concentrations. Between 11% and 19% of applied ferrocyanide in the solutions was removed by willows at the end of the incubation period. Only small amounts of ferrocyanide were recovered in different parts of the plant materials. Mass balance analysis showed that more than 90% of the ferrocyanide taken up from the hydroponic solutions was assimilated by plants. The assimilation of ferrocyanide by plants showed a dose-dependent manner. These findings suggest that phytoremediation of ferrocyanide-contaminating wastewater and soils can be possible for the environmental cleaning up. [Copyright &y& Elsevier]

Cyanide is commonly found as ferrocyanide [FeII(CN)6]−4 and in the more mobile form, ferricyanide [FeIII(CN)6]−3 in contaminated soils and sediments. Although soil minerals may influence ferrocyanide speciation, and thus mobility, the possible influence of soil enzymes has not been examined. In a series of experiments conducted under a range of soil-like conditions, laccase, a phenoloxidase enzyme derived from the fungi Trametes versicolor, was found to exert a large influence on iron-cyanide speciation and mobility. In the presence of laccase, up to 93% of ferrocyanide (36–362ppm) was oxidized to ferricyanide within 4h. No significant effect of pH (3.6 and 6.2) or initial ferrocyanide concentration on the extent or rate of oxidation was found and ferrocyanide oxidation did not occur in the absence of laccase. Relative to iron-cyanide–mineral systems without laccase, ferrocyanide adsorption to aluminum hydroxide and montmorillonite decreased in the presence of laccase and was similar to or somewhat greater than that of ferricyanide without laccase. Laccase-catalyzed conversion of ferrocyanide to ferricyanide was extensive though up to 33% of the enzyme was mineral-bound. These results demonstrate that soil enzymes can play a major role in ferrocyanide speciation and mobility. Biotic soil components must be considered as highly effective oxidation catalysts that may alter the mobility of metals and metal complexes in soil. Immobilized enzymes should also be considered for use in soil metal remediation efforts. [Copyright &y& Elsevier]

A comparative study of the rates of ferrocyanide-catalyzed oxidation of several oxymyoglobins by molecular oxygen is reported. Oxidation of the native oxymyoglobins from sperm whale, horse and pig, as well as the chemically modified (MbO2) sperm whale oxymyoglobin, with all accessible His residues alkylated by sodium bromoacetate (CM-MbO2), and the mutant sperm whale oxymyoglobin [MbO2(His119→Asp)], was studied. The effect of pH, ionic strength and the concentration of anionic catalyst ferrocyanide, [Fe(CN)6]4–, on the oxidation rate is investigated, as well as the effect of MbO2 complexing with redox-inactive Zn2+, which forms the stable chelate complex with functional groups of His119, Lys16 and Asp122, all located nearby. The catalytic mechanism was demonstrated to involve specific [Fe(CN)6]4– binding to the protein in the His119 region, which agrees with a high local positive electrostatic potential and the presence of a cavity large enough to accommodate [Fe(CN)6]4– in that region. The protonation of the nearby His113 and especially His116 plays a very important role in the catalysis, accelerating the oxidation rate of bound [Fe(CN)6]4– by dissolved oxygen. The simultaneous occurrence of both these factors (i.e. specific binding of [Fe(CN)6]4– to the protein and its fast reoxidation by oxygen) is necessary for the efficient ferrocyanide-catalyzed oxidation of oxymyoglobin. [ABSTRACT FROM AUTHOR]

Abstract: The behavior of the neutral and basic aqueous ferrocyanide system under irradiation is investigated using the coupling of a LINAC with infrared spectroscopy. The comparison between the neutral and basic system evidences the formation of the hydroxopentacyanoferrate (III) ions and gives information on the reaction mechanisms. The pseudo-protective effect of the dissolved dioxygen on the ferrocyanide is explained via a mechanism implying the superoxide radical anion. [Copyright &y& Elsevier]

Abstract: A polypyrrole containing ferrocyanide ions Fe(CN)6 3− (FCN) as doping anions were prepared by anodic electropolymerization onto iron and onto thermally pre-treated iron electrodes, in an aqueous solution containing pyrrole, potassium hexacyanoferrate (K4Fe(CN)6) and potassium tetraoxalate (C4H3KO8). The electrochemical behaviour of these modified electrodes was studied by cyclic voltammetry method. The electrostatic ability of these modified electrodes (PPy/FCN/Fe and PPy/FCN/Fe3O4/Fe) was demonstrated towards the oxidation of ascorbic acid (H2A). The results show that Fe(CN)6 3− anions incorporated into the PPy matrix improve the electrocatalytic activity of these films. The (PPy/FCN/Fe3O4/Fe) modified electrode showed greater ability and redox electroactivity than the (PPy/FCN/Fe) modified electrode and than the unmodified Fe electrode. It has been found that under optimum pH condition (pH 7), the oxidation of ascorbic acid at the surface of PPy/FCN/Fe3O4/Fe occurs at a potential about 200mV less positive than at PPy/FCN/Fe and at Fe surfaces. The catalytic oxidation peak current showed a linear dependence on the ascorbic acid concentration and a linear calibration curve was obtained in the range 0.5–9mM of ascorbic acid with a correlation coefficient of 0.9994 and good sensitivity (0.24μA/μM). The detection limit (2σ) was determined and found to be equal to 0.15mM. [Copyright &y& Elsevier]

This study is an attempt to desulfurize organic sulfur from lignite samples with ferrocyanide ion as the electron transferring agent. Effect of temperature, particle size and concentration of ferrocyanide ion on desulfurization from the lignite samples has been investigated. The desulfurization process has been found to be continuous and gradually increases with increase of temperature from 298 to 368 K. The particle size has no significant impact on sulfur removal from the lignite samples. Particle size has no profound impact on the amount of sulfur removal. The desulfurization reaction has been found to be dependent on the concentration of potassium ferrocyanide. Gradual increase in the concentration of potassium ferrocyanide raised the magnitude of desulfurization, but at a higher concentration, the variation is not significant. [ABSTRACT FROM AUTHOR]

A plant uptake model is applied to describe free cyanide and ferrocyanide transport and fate in willow ( Salix eriocephala var. Michaux) grown in hydroponics. The model is applied to experimental data to determine best-fit parameter values, their associated uncertainty, and their relative importance to field-scale phytoremediation applications. The fitted model results, using least-squares optimization of the observed log concentrations, indicate that free cyanide volatilization from leaf tissue and free cyanide cell wall adsorption were negligible. The free cyanide maximum uptake rate and assimilate (noncyanide 15 N) first-order leaf loss rate were the only coefficients that significantly affected the model goodness of fit and were concurrently sensitive to data uncertainty in the parameter optimization. Saturation kinetics may be applicable for free cyanide uptake into plants, but not for ferrocyanide uptake, which may occur via preferential protein-mediated or inefficient transpiration stream uptake. Within the free cyanide system, the relative magnitudes of the saturation uptake parameters and the demonstration of an active role for plants in uptake relative to transpiration suggest the potential importance of preferential diffusion through the cell membranes as reported in the literature, rather than protein-mediated uptake. The fitted 13-parameter model matched the observed data well except for the predicted stem and leaf tissue assimilate concentrations, which were significantly underestimated, particularly in the free cyanide system. These low predicted values, combined with the slightly underestimated solution free cyanide removal, suggest that noncyanide 15 N redistribution in phloem should be considered. [ABSTRACT FROM AUTHOR]