Spectroscopic characteristics of Cr(VI) oxyanions in water solutions

Кондратенко, Н А; Sherstyuk, V. P.

doi:10.1007/bf00524059

Cited by 12 publications

(13 citation statements)

References 7 publications

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“…On the other hand, As, Cr, and in some extent Ni show the enrichment in deeper soil (Table 2), indicating vertical leaching. Since As and Cr forms mobile oxyanions under near-neutral pH and oxidizing conditions (Smedley and Kinniburgh 2002;Kondratenko and Sherstyuk 1987), vertical leaching of these elements is relatively higher (Fig. 6).…”

Section: Discussionmentioning

confidence: 96%

Quantitative Comparison of Heavy Metals and As Accumulation in Agricultural and Forest Soils near Bowling Green, Ohio

Neupane¹,

Roberts

2008

Water Air Soil Pollut

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Soil samples from agricultural and adjacent forest soils in Northwest Ohio were collected and analyzed for As, Cr, Cu, Ni, Pb, and Zn. pH, Eh, electrical conductivity, and moisture content were also measured. Selected samples were also evaluated for grain size and X-rayed to identify clay minerals. In this region, soils contain a large proportion of fines (∼32% clay and ∼37% silt) with illite, dickite, and chlorite as the main clay minerals. Surface soils in the arable land are slightly acidic (pH ∼5.6) while forest soils are near-neutral to slightly basic. All soils become more basic with depth. Soil Eh and electrical conductivity range from 300 to 450 mV and 100 to 375 μS, respectively. In the soil profiles, between 0 and 50 cm depth, As increases from 4.6 to 11 mg/kg, Cr increases from19 to 23 mg/kg and Ni increases 21 to 29 mg/kg. In contrast, Cu decreases from 23 to 17 mg/kg and Pb decreases from17 to 10 mg/kg. Surface enrichment of Cu and Pb can be the result of aerosol deposition, while the downward increase in As, Cr and Ni is related to pedogenic variation. The average concentration of Zn in the samples is 64 mg/kg and does not change with land-use or depth. With the exception of As, the concentration of metals in the agricultural soil is not significantly different from the concentration in forest soil. The concentration of As in the near-surface arable soil (5.6 mg/kg) is significantly different from the concentration of As in the near-surface forest soil (4.3 mg/kg). In both cases, deeper soils have similar As contents. The relative enrichment of As in the surface arable soil could indicate input from herbicides or pesticides. The upward increase in electrical conductivity is interpreted to show that the exchangeable fraction of each metal is higher in the surface soils. However, the near neutral pH and organic, clay-rich soils may limit the mobility. The concentration of these heavy metals and As in the soils are much lower than the limits set by the United States Environmental Protection Agency.

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Section: Discussionmentioning

confidence: 96%

Quantitative Comparison of Heavy Metals and As Accumulation in Agricultural and Forest Soils near Bowling Green, Ohio

Neupane¹,

Roberts

2008

Water Air Soil Pollut

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“…However, Cr(VI) is of high toxicity to human body tissue due to its oxidizing potential. In aqueous medium, the Cr(VI) species may exist in a variety of oxospecies, namely, dichromate (

{Cr}_{2} {normalO}_{7}^{2 -}

), hydrochromate (

{HCrO}_{4}^{-}

), or chromate (

{CrO}_{4}^{2 -}

), depending on the concentration and pH value …”

Section: Introductionmentioning

confidence: 99%

Use of polyethylene films photografted with 2‐(dimethylamino)ethyl methacrylate as a potential adsorbent for removal of chromium (VI) from aqueous medium

Asamoto

Kimura

Ishiguro

et al. 2016

J of Applied Polymer Sci

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A new polymeric adsorbent material based on polyethylene (PE) was prepared by photografting of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) as a positively chargeable monomer to a PE film. The effects of the experimental parameters, such as the pH value, temperature, and grafted amount on adsorption of chromium(VI) (Cr(VI)) ions were investigated for the DMAEMA‐grafted PE (PE‐g‐PDAMEMA) films. The maximum adsorption capacity was obtained at the initial pH value of 3.0 for a PE‐g‐PDMAEMA film with 1.8 mmol/g and the maximum adsorption capacity obtained was higher than or compatible to those of many of the other polymeric adsorbents prepared for Cr(VI) ions. The adsorption kinetics obeyed the mechanism of the pseudo‐second order kinetic model and adsorption of Cr(VI) ions on PE‐g‐PDMAEMA films was well expressed by the Langmuir isotherm model. A high Langmuir adsorption constant suggests that the adsorption of Cr(VI) ions occurs between protonated dimethylamino groups and HCrO4− ions mainly through the electrostatic interaction. Cr(VI) ions adsorbed were successfully desorbed from a PE‐g‐PDMAEMA film in solutions of NaCl, NH4Cl, NH4Cl containing NaOH, and NaOH and a PE‐g‐PDMAEMA film was regenerated and repeatedly used for adsorption of Cr(VI) ions without appreciable loss in the adsorption capacity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43360.

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“…Em ambos os casos, o número de fatores selecionados para o modelo foi igual a dois, os quais foram atribuídos as espécies bicromato (HCrO 4 -) e cromato (CrO 4 2-), respectivamente. As atribuições foram feitas com base nos perfis de pH estimados e nos espectros das espécies obtidos em seguida, através do método da matriz k. As estimativas da distribuição das espécies em função do pH, para os conjuntos de Os perfis de pH obtidos para a distribuição bicromato-cromato estão em boa concordância com a literatura 8,[16][17][18][20][21][22]49,52 , levando em conta que, na concentração de Cr(VI) analisada, menor que 3,3 x 10 -4 mol L -1 , a presença da espécie dicromato pode ser considerada insignificante 8,[19][20][21][22] . A constante de dissociação para o íon bicromato pode ser estimada através do cruzamento das linhas na 18 .…”

Section: Análise De Fatores Do Tipo Q De Imbrie Seguida De Rotação Vunclassified

“…Entretanto, muitos trabalhos contradizem esta hipótese e reafirmam a existência e a importância das espécies protonadas de Cr(VI) [12][13][14][15][16][17][18] . Outro aspecto que causa polêmica diz respeito às faixas de predominância das espécies em função da concentração total de Cr(VI) e do pH [19][20][21][22] . Valores de constante de equilíbrio para as equações (1) e (2) encontrados na literatura chegam a diferir em mais de uma ordem de grandeza 12,13,[16][17][18][21][22][23][24][25] .…”

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“…Outro aspecto que causa polêmica diz respeito às faixas de predominância das espécies em função da concentração total de Cr(VI) e do pH [19][20][21][22] . Valores de constante de equilíbrio para as equações (1) e (2) encontrados na literatura chegam a diferir em mais de uma ordem de grandeza 12,13,[16][17][18][21][22][23][24][25] . De toda esta discussão, é possível propor algumas linhas gerais para a existên-cia e predominância das espécies de Cr(VI) 17,20 : H 2 CrO 4 só deve existir em soluções de pH abaixo de 0; HCrO 4 -deve predominar na faixa de pH entre 1 e 6 e, acima de uma certa concentração (em torno de 10 -3 mol L -1 ), deve coexistir com Cr 2 O 7 2-; em valores de pH acima de 8, deve existir somente CrO 4 2-.…”

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Aplicação de métodos quimiométricos na especiação de Cr(VI) em solução aquosa

Sena¹,

Collins²,

Scarmínio³

2001

Quím. Nova

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Recebido em 31/5/00; aceito em 21/9/00 CHEMOMETRIC METHODS APPLIED TO THE SPECIATION OF AQUEOUS Cr(VI) SOLUTIONS. The equilibria, the spectra and the identities of the species of Cr(VI) that are present in aqueous solution have long been an active subject of discussion in the literature. In this paper, three different chemometric methodologies are applied to sets of UV/Visible spectra of aqueous Cr(VI) solutions, in order to solve a chemical system where there is no available information concerning the composition of the samples nor spectral information about the pure species. Imbrie Q-mode factor analysis, followed by varimax rotation and Imbrie oblique projection, were used to estimate the composition of Cr(VI) equilibrium solutions and, by combining these results with the k-matrix method, to obtain the pure spectra of the species. Evolving factor analysis and self modeling curve resolution were used to confirm the number of the species and the resolution of the system, respectively. Sets of 3.3×10 -4 and 3.3×10 -5 mol L -1 Cr(VI) solutions, respectively, were analyzed in the pH range from 1 to 12. Two factors were identified, which were related to the chromate ion (CrO 4 2-) and bichromate ion (HCrO 4 -). The pK of the equilibrium was estimated as 5.8.

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Spectroscopic characteristics of Cr(VI) oxyanions in water solutions

Cited by 12 publications

References 7 publications

Quantitative Comparison of Heavy Metals and As Accumulation in Agricultural and Forest Soils near Bowling Green, Ohio

Quantitative Comparison of Heavy Metals and As Accumulation in Agricultural and Forest Soils near Bowling Green, Ohio

Use of polyethylene films photografted with 2‐(dimethylamino)ethyl methacrylate as a potential adsorbent for removal of chromium (VI) from aqueous medium

Aplicação de métodos quimiométricos na especiação de Cr(VI) em solução aquosa

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