Reversible Oxygenation of<i>α</i>-Amino Acid–Cobalt(II) Complexes

Zhang, Xincun; Yue, Fan; Li, Hui; Huang, Yan; Zhang, Yi; Wen, Hongmei; Wang, Jide

doi:10.1155/2016/3585781

Cited by 9 publications

(12 citation statements)

References 35 publications

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“…Based on FTIR spectra the same fact has been documented for Cu(II) sorption on wool, too [17]. In addition, as mentioned by Zhang et al [21], depending on the different coordination ability of the amino acids towards Co(II) based on different pH of medium, formation of the complexes can be various. As regards to adsorption studies, those reasons have been mentioned only rarely, if any.…”

Section: Resultssupporting

confidence: 53%

Role of Post-Exposure Time in Co(II) Sorption of Higher Concentrations on Electron Irradiated Sheep Wool

et al. 2019

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Sorption of Co(II) was investigated on natural as well as accelerated electron beam modified sheep wool involving low and high concentrations up to 200 mmol·dm−3. The sorption experiments confirmed the dependence of the sorption capacity not only on sorbate concentration and absorbed dose of energy, but also on post-exposure time. Post-exposure heating to accelerate transformation of the wool structure was of no effect on the sorption comparing with a simple storage for a period of 100 days. Under all tested conditions, the sorption maximum was measured for Co(II) concentration of 125 mmol·dm−3 and that was assigned to form a Co(II) complex with keratin. This assumption was tested on visible spectra of mixed solutions of Arginine and Co(II) to be a simplified model of Co(II) interaction with keratin. The sorption decrease is associated with generation of cross links between macro-chains through ligands of the Co-complex. The nodal points are a hindrance to diffusion of next ions into the fibers. Also, pH variations of aqueous extracts from the wool samples depending on absorbed dose and post-exposure time indicate complexity of the structural transformation being specific for each dose applied.

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Section: Resultssupporting

confidence: 53%

Role of Post-Exposure Time in Co(II) Sorption of Higher Concentrations on Electron Irradiated Sheep Wool

et al. 2019

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“…In the flue gas denitrification process of Co(II)His, as can be inferred from reactions 1–4, nitrate and nitrite might be the final product. Additionally, though Co(II)His have an excellent reversible oxygenation ability, it is still oxidized slowly by autoxidation effect and form cobalt(III)-histidine [Co(III)His], thus losing absorption capability of NO and O 2 (Zhang et al 2016). Hence, the biological reduction of nitrate, nitrite, and Co(III)His under aerobic condition would be another important issue to be studied.…”

Section: Introductionmentioning

confidence: 99%

Effects of cobalt-histidine absorbent on aerobic denitrification by Paracoccus versutus LYM

Sun

2019

AMB Expr

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To overcome the problem that ferrous complexes are easily oxidized by O2 and then lose NO binding ability in the chemical absorption-biological reduction (CABR) process, cobalt(II)-histidine [Co(II)His] was proposed as an alternative. To evaluate the applicability of Co(II)His, the effects of CoHis absorbent on the aerobic denitrification by Paracoccus versutus LYM were investigated. Results indicated that His significantly promoted nitrite reduction. The inhibition effects of CoHis absorbent could be substantially alleviated by increasing the initial His/Co2+ to 4 or higher. CoHis with concentrations of 4, 8, 12, 16 and 20 mM presented no distinct effect on nitrite reduction, but slightly inhibited the reduction of nitrate, resulting in longer lag of nitrate reduction, and obviously promoted the growth of strain LYM. In the presence of 5, 10, 15 and 20 mM CoHis absorbent, the main denitrification product was N2 (not less than 95.0%). This study is of significance in verifying the applicability of Co(II)His in the CABR process, and provides a referable CoHis absorbent concentration as 20 mM with an initial His/Co2+ of 4 for the future experiments.

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“…Formulated by these two requirements, cobalt complexes with amino acid ligands seem to be more promising choices. On the one hand, amino acids, which constitute the material basis of life, may not seriously affect the biological properties of bacteria theoretically, and on the other hand, cobalt complexes with amino acids as ligands can reversibly absorb NO − and O 2 under neutral or weakly alkaline conditions, which is exactly the pH environment required by the CABR process. Thus, to find an efficient absorbent for NO removal from cobalt complexes with ligands of commonly referable amino acids − and that are widely used in ferrous complexes, a screening experiment was performed.…”

Section: Introductionmentioning

confidence: 99%

Complexing Absorption of NO by Cobalt(II)–Histidine

Sun

Zhang

2017

Energy Fuels

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To develop an alternative to ferrous complexes, which easily lose nitric oxide (NO) binding ability as a result of oxidation by O2 in the complexing absorption process, experiments about the NO absorption characteristics of cobalt complexes were performed. First, a screening experiment was conducted, and cobalt(II)–histidine (CoHis) manifested to be the most potent absorbent to both NO and O2 in neutral conditions among industrially available cobalt complexes. Then, the concentration of the cobalt nitrosyl complex, i.e., CoHis–NO, in the NO absorption liquid was measured by the NO transfer reaction with ferrous ethylenediaminetetraacetate [Fe(II)EDTA], thereby the standard curve for CoHis–NO quantification by spectrophotometry was plotted. At last, as implied by NO absorption experiments, the absorption of NO can be promoted by reducing the absorbent temperature, increasing the CoHis concentration, or increasing the absorbent pH appropriately. Furthermore, it was found that CoHis could not promote NO disproportionation.

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Reversible Oxygenation ofα-Amino Acid–Cobalt(II) Complexes

Cited by 9 publications

References 35 publications

Role of Post-Exposure Time in Co(II) Sorption of Higher Concentrations on Electron Irradiated Sheep Wool

Role of Post-Exposure Time in Co(II) Sorption of Higher Concentrations on Electron Irradiated Sheep Wool

Effects of cobalt-histidine absorbent on aerobic denitrification by Paracoccus versutus LYM

Complexing Absorption of NO by Cobalt(II)–Histidine

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