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Berlin Brandenburg

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  • 1
    In: Soil Science Society of America Journal, March-April, 2002, Vol.66(2), p.437(8)
    Description: The Fe-cyanide complexes ferricyanide, [[Fe[(CN).sub.6]].sup.3-], and ferrocyanide, [[Fe[(CN).sub.6]].sup.4-], are of an anthropogenic source in soils. As the complexes are largely charged, sorption on the soil matrix is a possible retention mechanism for these anions. To evaluate soil properties controlling Fe-cyanide complex sorption, experiments were performed with 17 uncontaminated soil horizons by a batch technique. Soil organic matter (SOM) was destroyed in six horizons. The experiments were conducted at soil pH, reaction time of 24 h, and an ionic strength of 0.01 (NaN[O.sub.3]). The affinity of the Fe-cyanide complexes for the soil matrix differed, because 14 samples sorbed higher amounts of ferrocyanide than of ferricyanide. Calculated sorption maxima were quantitatively explained by physical and chemical soil properties using multiple regressions. The regression equations were checked by variance analysis. The regression equations for all samples showed that the sorption of both complexes depended on organic C ([C.sub.org]), clay, and oxalate-extractable Fe ([Fe.sub.o]). The sorption of the complexes on soils containing 〈10 g [C.sub.org] [kg.sup.-1] was governed by pH and clay contents. Clay and oxalate-extractable Al ([Al.sub.o]) were the most important properties influencing ferricyanide sorption on samples containing high amounts of [C.sub.org]. On the same samples, ferrocyanide sorption was governed by [Al.sub.o]. Organic matter promotes the sorption of both complexes, especially on Fluvisol samples. Destruction of SOM of these samples minimized the sorption by up to 99%. Therefore organic matter in these soils may have a special affinity for Fe-cyanide complexes possibly because of the reaction between Fe-cyanide N and reactive groups of SOM.
    Keywords: Soil Science -- Research ; Cyanides -- Research
    ISSN: 0361-5995
    E-ISSN: 14350661
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  • 2
    Language: English
    In: Water Research, 2002, Vol.36(19), pp.4877-4883
    Description: Blast furnace sludge is a waste originating from pig iron production and contains small amounts of iron-cyanide complexes. Leaching of iron-cyanide complexes from deposited blast furnace sludge into the ground water seems to be possible in principle. We investigated the sorption of the iron-cyanide complexes ferrocyanide, [Fe super(II)(CN) sub(6)] super(4-), and ferricyanide, [Fe super(III)(CN) sub(6)] super(3-), in 22 samples of deposited blast furnace sludge in batch experiments. Subsequently, desorption of iron-cyanide complexes was investigated using 1 M NaCl. Sorption in five samples was evaluated with Langmuir isotherms. The blast furnace sludge samples were neutral to slightly alkaline (pH 7.6-9) and consisted of X-ray amorphous compounds and crystalline Fe oxides primarily. X-ray amorphous compounds are assumed to comprise coke-bound C and amorphous Fe, Zn, and Al oxides. The experiments that were evaluated with Langmuir isotherms indicated that the extent of ferricyanide sorption was higher than that of ferrocyanide sorption. Saturation of blast furnace sludge with iron-cyanide complexes was achieved. Sorption of iron-cyanide complexes in 22 blast furnace sludge samples at one initial concentration showed that 12 samples sorbed more ferrocyanide than ferricyanide. The extent of sorption largely differed between 0.07 and 2.76 mu mol [Fe(CN) sub(6)]m super(-2) and was governed by coke-bound C. Ferricyanide sorption was negatively influenced by crystalline Fe oxides additionally. Only small amounts of iron-cyanide complexes sorbed in blast furnace sludge were desorbed by 1 M NaCl (ferrocyanide, 3.2%; ferricyanide, 1.1%, given as median). This indicated strong interactions of iron-cyanide complexes in blast furnace sludge. The mobility of iron-cyanide complexes in deposited blast furnace sludge and consequently contamination of the seepage and ground water was designated as low, because (i) deposited blast furnace sludge is able to sorb iron-cyanide complexes strongly, (ii) the solubility of the iron-cyanide-containing phase, K sub(2)Zn sub(3)[Fe super(II)(CN) sub(6)] times 9H sub(2)O, is known to be low, and (iii) a worst case scenario of the transport of iron-cyanide complexes within the blast furnace sludge deposit indicated strong retardation of the complexes within the next 100 years.
    Keywords: Iron–Cyanide Complexes ; Sorption ; Desorption ; Blast Furnace Sludge ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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  • 3
    Language: English
    In: Critical Reviews in Environmental Science and Technology, 01 November 2011, Vol.41(21), pp.1883-1969
    Description: In the course of industrialization in the 19th century, manufactured gas plant sites were built in almost every larger town in Europe and the United States. Organic and inorganic contaminations pose a continuing threat to groundwater resources at these locations even though the operations were...
    Keywords: Aging ; Alkane ; Carrier ; Colloid ; Cotransport ; Cyanide ; Degradation ; Dissolution ; Gasworks ; Mass Transfer ; Napl ; Natural Attenuation ; Pah ; Raoult ; Sorption ; Volatilization ; Engineering ; Environmental Sciences
    ISSN: 1064-3389
    E-ISSN: 1547-6537
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  • 4
    Language: English
    In: Soil Science Society of America Journal, May-June, 2003, Vol.67(3), p.756(9)
    Description: Iron-cyanide complexes are present in soil and ground water because of anthropogenic inputs. We studied the sorption and the transport of the complexes ferrocyanide, [[Fe[(CN).sub.6]].sup.4-], and ferricyanide, [[Fe[(CN).sub.6]].sup.3-], in goethite-coated sand in column experiments under saturated conditions as influenced by flow velocity and flow interruption. Isotherm parameters obtained from batch experiments of Fecyanide complex sorption on goethite were used to simulate breakthrough curves in goethite-coated sand. The breakthrough curves of ferrocyanide were inversely modeled. The transport of both complexes was retarded and rate-limited. Only ferricyanide breakthrough curves revealed concentration drops after flow interruption. Simulations with batch parameters roughly reflected breakthrough curves of ferricyanide, but not of ferrocyanide. Ferricyanide sorption and desorption could not be described with the same isotherm indicating hysteresis. Since the sorption fronts of ferrocyanide breakthrough curves revealed the formation of a shoulder, it was concluded that ferrocyanide sorption in column experiments could not be described by a single isotherm, which is based on a singular sorption process. Therefore, sorption of ferrocyanide on goethite was assumed to be influenced by more than one sorption mechanism. Inverse modeling of ferrocyanide breakthrough data using the Langmuir isotherm resulted in erroneous sorption maxima.
    Keywords: Sandy Soils -- Contamination ; Soil Remediation -- Methods ; Soil Remediation -- Evaluation ; Soil Chemistry -- Research
    ISSN: 0361-5995
    E-ISSN: 14350661
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  • 5
    Language: English
    In: Journal of Plant Nutrition and Soil Science, June 2006, Vol.169(3), pp.335-340
    Description: Ferricyanide, [Fe(CN)], is an anthropogenic and potentially toxic contaminant in soil. Its adsorption on goethite has been previously studied, but not evaluated with a surface complexation model (SCM) considering the effects of pH and ionic strength. Therefore, we carried out batch experiments with ferricyanide and goethite suspensions with different ferricyanide concentrations (0.075 mM and 0.15 mM), ionic strengths (0.01 and 0.1 M), and pH (ranging from 4 to 7.4). Adsorption data were then interpreted with the 1‐p Stern and the charge distribution model assuming monodentate inner‐sphere ferricyanide surface complexes on goethite (lg = 10.6), which are known from infrared spectroscopy. Furthermore, we applied the SCM to ferricyanide adsorption in previous studies on ferricyanide adsorption in the presence of sulfate and on the solubility of Fe‐cyanide complexes in a suspension of a loess loam. The SCM correctly reflected ferricyanide adsorption in the batch experiments as well as the effects of pH and ionic strength. The SCM also described ferricyanide adsorption in the presence of sulfate, because the ferricyanide adsorption measured and that modeled were significantly correlated ( = 0.80). Furthermore, we applied the SCM to a study on the solubility of Fe‐cyanide complexes in soil under varying redox conditions so that ferricyanide adsorption on goethite and precipitation of Fe‐cyanide complexes were considered. The actual ferricyanide concentrations were rather reflected when applying the SCM compared to those modeled in an approach in which exclusively precipitation was taken into account. We conclude that ferricyanide adsorption on goethite should be included into geochemical modeling approaches on the mobility of Fe‐cyanide complexes in subsoils.
    Keywords: Ferricyanide ; Goethite ; Adsorption ; Surface Complexation Modeling ; Adsorption Mechanism
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 6
    Language: English
    In: Journal of Plant Nutrition and Soil Science, December 2001, Vol.164(6), pp.651-655
    Description: The sorption of the iron‐cyanide complexes ferricyanide, [Fe(CN)], and ferrocyanide, [Fe(CN)], on ferrihydrite was investigated in batch experiments including the effects of pH (pH 3.5 to 8) and ionic strength (0.001 to 0.1 M). The pH‐dependent sorption data were evaluated with a model approach by (1999): c = exp(bS)S/(S‐S), where c is the solution concentration; S is the sorbed amount; S is maximum sorption; b is a parameter; and is a parameter at constant pH. Ferricyanide sorption was negatively affected by increasing ionic strength, ferrocyanide sorption not at all. More ferricyanide than ferrocyanide was sorbed in the acidic range. In the neutral range the opposite was true. Fitting the pH‐dependent sorption to the model resulted in a strong correlation for both iron‐cyanide complexes with a common sorption maximum of 1.6 μmol m. Only little negative charge was conveyed to the ferrihydrite surface by sorption of iron‐cyanide complexes. The sorption of iron‐cyanide complexes on ferrihydrite is weaker than that on goethite, as a comparison of the model calculations shows. This may be caused by the lower relative amount of high‐affinity sites present on the ferrihydrite surface. Einfache Modellierung der Sorption von Eisencyankomplexen an Ferrihydrit Die Sorption des Eisencyan(III)komplexes, [Fe(CN)], und des Eisencyan(II)komplexes, [Fe(CN)], an Ferrihydrit wurde in Schüttelversuchen in Abhängigkeit vom pH‐Wert (3,5 bis 8) und von der Ionenstärke (0,001 bis 0,1 M) untersucht. Die Auswertung der pH‐abhängigen Sorption erfolgte nach einem Modellansatz von (1999): c = exp(bS)S/(S‐S), wobei c die Lösungskonzentration, S die sorbierte Menge, S die Maximalsorption, b ein Parameter und ein Parameter bei konstantem pH ist. Nur die Sorption des Eisencyan(III)komplexes wurde negativ durch die Erhöhung der Ionenstärke beeinflusst, die des Eisencyan(II)komplexes nicht. Der Eisencyan(III)komplex wurde im Sauren in höherem Maße als der Eisencyan(II)komplex gebunden, im Neutralen war das Gegenteil der Fall. Die Anpassung der pH‐abhängigen Sorption beider Eisencyankomplexe an das Modell zeigte einen engen Zusammenhang mit einem gemeinsamen Sorptionsmaximum von 1,6 μmol m. Durch die Sorption von Eisencyankomplexen wurde nur wenig negative Ladung auf die Ferrihydritoberfläche übertragen. Ein Vergleich der Modellierungen an Ferrihydrit und Goethit zeigt, dass die Eisencyankomplexe an Ferrihydrit schwächer gebunden werden. Dies kann mit einem geringeren relativen Anteil von Sorptionsplätzen mit hoher Affinität begründet werden.
    Keywords: Sorption ; Iron‐Cyanide Complexes ; Ferrihydrite ; Goethite ; Ph ; Ionic Strength
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 7
    In: Soil Science, 2002, Vol.167(8), pp.504-512
    Description: The occurrence of the iron-cyanide complexes ferrocyanide, [Fe(CN)6], and ferricyanide, [Fe(CN)6] in soil and groundwater is caused by disposal of industrial wastes and by the use of road salt containing ferrocyanide. We investigated the sorption and transport of iron-cyanide complexes in sandy uncontaminated soil (Ap horizon, Dystric Gleysol; 857 g sand kg, organic C 18 g kg, pH 5.8) in column experiments at saturated conditions and two concentrations, 0.03 and 10 m M [Fe(CN)6]. When using 10 m M, flow was interrupted for 36 h. Batch desorption experiments using phosphate and chloride were conducted to evaluate fractions of sorbed iron-cyanide complexes differing in their affinity for the soil matrix. Tracer breakthrough experiments using chloride indicated strongly advective flow in all experiments. The transport of both iron-cyanide complexes was characterized by rate-limited and nonlinear sorption affected by hysteresis. Rate-limited sorption was shown by the decrease of effluent concentrations after flow interruptions and by tailing. Nonlinear sorption became evident by the retardation of the breakthrough curves, depending on influent concentrations. Breakthrough of ferrocyanide took longer than that of ferricyanide, indicating stronger sorption of ferrocyanide. The extent of iron-cyanide complex desorption depended on (i) the amount of iron-cyanide complexes sorbed previously, (ii) the type of complex sorbed, and (iii) the solution used to desorb. For the experiment, higher amounts of iron-cyanide complexes sorbed resulted in lower desorption. More ferricyanide than ferrocyanide was desorbed, and phosphate desorbed more iron-cyanide complexes than chloride. Precipitation of iron-cyanide complexes following desorption experiments was indicated by the presence of blue precipitates in the soil matrix. Consequently, the sorption behavior of iron-cyanide complexes in uncontaminated soil was complex due to rate-limited and nonlinear sorption and precipitation. The experiments revealed that soils may act as a sink for iron-cyanide complexes at low concentrations, e.g., those originating from the use of road salt or occurring in contaminated seepage and groundwater. However, the long-term behavior of iron-cyanide complexes in this soil is characterized by continuous desorption.
    Keywords: Environmental Geology ; Geochemistry Of Rocks, Soils, And Sediments ; Agriculture ; Breakthrough Curves ; Chloride Ion ; Chlorine ; Complexing ; Cyanides ; Effluents ; Europe ; Ferricyanide ; Ferrocyanide ; Gleysols ; Halogens ; Haplaquepts ; Hysteresis ; Inceptisols ; Iron ; Laboratory Studies ; Mechanism ; Metals ; Netherlands ; Physicochemical Properties ; Pollutants ; Pollution ; Precipitation ; Soils ; Sorption ; Tracers ; Transport ; Wageningen Netherlands ; Western Europe;
    ISSN: 0038-075X
    E-ISSN: 15389243
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  • 8
    Language: English
    In: Journal of environmental quality, 2002, Vol.31(3), pp.745-51
    Description: Soils are contaminated with potentially toxic iron-cyanide complexes by some industrial activities. The influence of sulfate on the sorption of the iron-cyanide complexes ferricyanide, [Fe(CN)6]3-, and ferrocyanide, [Fe(CN)6]4-, on goethite was investigated in batch experiments. The experiments were conducted as influenced by pH and varying sulfate/iron-cyanide complex concentration ratios. Furthermore, the desorption of iron-cyanide complexes sorbed on goethite was studied using phosphate and chloride solutions as influenced by pH and anion concentration. Over the whole pH range (pH 3.5 to 8), ferricyanide and sulfate showed similar affinities for the goethite surface. The extent of ferricyanide sorption strongly depended on sulfate concentrations and vice versa. In contrast, ferrocyanide sorption was only decreased (approximately 12%) by sulfate additions at pH 3.5. Ferricyanide was completely desorbed by 1 M chloride, ferrocyanide not at all. Unbuffered phosphate solutions (pH 8.3) desorbed both iron-cyanide complexes completely. Even in 70-fold excess, pH-adjusted phosphate solutions could not desorb ferrocyanide completely at pH 3.5. For ferricyanide we propose a sorption mechanism that is similar to the sulfate sorption mechanism, including outer-sphere and weak inner-sphere surface complexes on goethite. Ferrocyanide appears to form inner-sphere surface complexes. Additionally, we assume that ferrocyanide precipitates probably as a Berlin Blue-like phase at pH 3.5. Hence, ferrocyanide should be less mobile in the soil environment than ferricyanide or sulfate.
    Keywords: Ferricyanides -- Chemistry ; Ferrocyanides -- Chemistry ; Iron Compounds -- Chemistry ; Soil Pollutants -- Analysis
    ISSN: 0047-2425
    E-ISSN: 15372537
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 9
    Language: English
    In: Journal of Plant Nutrition and Soil Science, April 2005, Vol.168(2), pp.233-237
    Description: The iron‐cyanide complexes ferrocyanide, [Fe(CN)], and ferricyanide, [Fe(CN)], are anthropogenic contaminants in soil. We investigated their sorption on goethite, α‐FeOOH, in batch experiments in a time range from 1 d to 1 yr, their desorption by phosphate and chloride as well as their surface complexes on goethite by Fourier‐transform infrared spectroscopy (FTIR). The sorption of both complexes continued over the whole time range. Percent desorption of ferricyanide by phosphate decreased, whereas that of ferrocyanide increased until it amounted to approximately 87% for both complexes. By FTIR spectroscopy inner‐sphere complexation of both complexes on the goethite surface was indicated. With both complexes, a Berlin‐Blue‐like layer (Fe[Fe(CN)]) was formed initially on the goethite surface which disappeared with increasing reaction time. After at least 30 d reaction time, ferricyanide was the only sorbed iron‐cyanide complex detected even when ferrocyanide was initially added. This resulted from slow oxidation of ferrocyanide, most probably by dissolved oxygen. Based on all results, we propose that ferricyanide forms monodentate inner‐sphere complexes on the goethite surface. Sorption von Eisencyankomplexen an Goethit in Langzeitversuchen Die Eisencyankomplexe Ferrocyanid, [Fe(CN)], und Ferricyanid, [Fe(CN)], sind anthropogene Schadstoffe in Böden. Wir untersuchten in Schüttelversuchen ihre Sorption an Goethit, α‐FeOOH, über einen Zeitraum von einem Tag bis zu einem Jahr, ihre Desorption durch Phosphat und Chlorid sowie ihre Oberflächenkomplexe auf Goethit mittels Fourier‐Transformations‐Infrarotspektroskopie (FTIR). Die Sorption beider Komplexe schritt über den gesamten Zeitraum fort. Die prozentuale Desorption von Ferricyanid durch Phosphat nahm mit der Zeit ab, die von Ferrocyanid zu, bis sie nach einem Jahr für beide Komplexe ca. 87% betrug. Die FTIR‐Spektren von beiden sorbierten Komplexen wiesen auf inner‐sphärische Komplexierung auf der Goethitoberfläche hin. Bei beiden Komplexen bildete sich zunächst eine Berliner‐Blau‐artige Schicht (Fe[Fe(CN)]), die mit zunehmender Reaktionszeit verschwand. Nach mindestens 30 Tagen Reaktionszeit war Ferricyanid der einzige sorbierte Eisencyankomplex, auch wenn Ferrocyanid ursprünglich hinzu gegeben wurde, was auf eine langsame Oxidation von Ferrocyanid, höchstwahrscheinlich durch gelösten Sauerstoff, hindeutet. Auf der Grundlage aller Ergebnisse schlagen wir vor, dass Ferricyanid einzähnige inner‐sphärische Komplexe auf der Goethitoberfläche bildet.
    Keywords: Sorption ; Desorption ; Iron‐Cyanide Complexes ; Goethite / Mechanism ; Ftir Spectroscopy
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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