Reactions of aquatitanium(ii) with hypervalent chromium species

2009 ◽  
pp. 868-871 ◽  
Author(s):  
Basab Bijayi Dhar ◽  
Ritam Mukherjee ◽  
Edwin S. Gould
Keyword(s):  
Chromium Species ◽  
Hypervalent Chromium

scholarly journals Golgi-Colonnier method: correlation of the degree of chromium reduction and pH change with quality of staining.

1994 ◽  
Vol 42 (3) ◽  
pp. 393-403 ◽  
Author(s):  
A Angulo ◽  
J A Merchán ◽  
M Molina
Keyword(s):  
Chromium Reduction ◽  
Ph Change ◽  
Total Chromium ◽  
Chromium Species ◽  
Cell Staining ◽  
Before And After ◽  
Neuronal Proteins ◽  
Ph Increase

We examined the role of chromium reduction in the Golgi-Colonnier method, correlating the quality of neuronal impregnation with the levels of hexavalent (CrVI) and trivalent (CrIII) chromium in the tissue and in the chromation fluid (CF). The concentrations of both chromium species were assessed by measuring spectrophotometrically the CrVI before and after oxidizing the sample and by calculating the ratio of CrVI to total chromium (chromium ratio, CrR). The CrR was almost identical in the tissue and the CF, decreasing exponentially during chromation due to a progressive consumption of CrVI to form CrIII. Satisfactory cell impregnation was obtained only when the CrR was 0.45-0.7, regardless of other factors. The CrR values could be accurately predicted by the pH increase of the CF; this increase has proven to be a most reliable criterion to decide the endpoint of the chromation process. The dependence of cell staining on the [CrIII], together with the well-known ability of this species to bridge proteins, suggests that the key event for cell impregnation is the cross-linking of neuronal proteins by CrIII polymers.

Analysis of the Distribution Pattern of Chromium Species in Single Cells

2016 ◽  
Vol 88 (24) ◽  
pp. 12437-12444 ◽  
Author(s):  
Xing Wei ◽  
Lin-Lin Hu ◽  
Ming-Li Chen ◽  
Ting Yang ◽  
Jian-Hua Wang
Keyword(s):  
Distribution Pattern ◽  
Single Cells ◽  
Chromium Species

Effective Extraction of Cr(VI) from Hazardous Gypsum Sludge via Controlling the Phase Transformation and Chromium Species

2018 ◽  
Vol 52 (22) ◽  
pp. 13336-13342 ◽  
Author(s):  
Weizhen Liu ◽  
Jiayi Zheng ◽  
Xinwen Ou ◽  
Xueming Liu ◽  
Yao Song ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Chromium Species

scholarly journals Temporal variability of sewage sludge heavy metal content from Greek wastewater treatment plants

2016 ◽  
Vol 23 (2) ◽  
pp. 271-283 ◽  
Author(s):  
Thomas Spanos ◽  
Antoaneta Ene ◽  
Chrysoula Styliani Patronidou ◽  
Christina Xatzixristou
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Wastewater Treatment ◽  
Sewage Sludge ◽  
Temporal Variability ◽  
Metal Content ◽  
Wastewater Treatment Plants ◽  
Chromium Species ◽  
Metal Concentrations ◽  
Metal Contents

AbstractThe aim of this study was to evaluate the temporal variations of selected heavy metals level in anaerobic fermented and dewatered sewage sludge. Sewage sludge samples were collected in different seasons and years from three municipal wastewater treatment plants (WWTPs) located in Northern Greece, in Kavala (Kavala and Palio localities) and Drama (Drama locality) Prefectures. An investigation of the potential of sludge utilization in agriculture was performed, based on the comparison of average total heavy metal concentrations and of chromium species (hexavalent, trivalent) concentrations with the allowed values according to the Council Directive 86/278/EEC and Greek national legislation (Joint Cabinet Decision 80568/4225/91) guidelines. In this regard, all the investigated heavy metals (Cd, Cr, Cu, Ni, Pb, Zn, Hg) and chromium species Cr(VI) and Cr(III) have average concentrations (dry matter weight) well below the legislated thresholds for soil application, as following: 2.12 mg kg−1Cd; 103.7 mg kg−1Cr; 136.4 mg kg−1Cu; < 0.2 mg kg−1Hg; 29.1 mg kg−1Ni; 62.0 mg kg−1Pb; 1253.2 mg kg−1Zn; 1.56 mg kg−1Cr(VI) and 115.7 mg kg−1Cr(III). Values of relative standard deviation (RSD) indicate a low or moderate temporal variability for domestic-related metals Zn (10.3-14.7%), Pb (27.9-44.5%) and Cu (33.5-34.2%), and high variability for the metals of mixed origin or predominantly resulted from commercial activities, such as Ni (42.4-50.7%), Cd (44.3-85.5%) and Cr (58.2-102.0%). For some elements the seasonal occurrence pattern is the same for Kavala and Palio sludge, as following: a) Cd and Cr: spring>summer>winter; b) Cu, Ni and Pb: winter>spring>summer. On average, in summer months (dry season) metal concentrations are lower than in spring and winter (wet seasons), with the exception of Zn. For Kavala and Palio the results demonstrate that the increased number of inhabitants (almost doubled) in summer time due to tourism does not influence the metal levels in sludge. Comparing the results obtained for similar spring-summer-winter sequences in 2007 and 2010/11 and for the spring season in 2007, 2008 and 2010, it can be noticed that, in general, the average heavy metal contents show an increasing tendency towards the last year. In all the measurement periods, the Palio sludge had the highest metal contents and Kavala sludge the lowest, leading to the conclusion that the WWTP operating process rather than population has a significant effect upon the heavy metal content of sludge. Cr(VI)/Cr(total) concentration ratios are higher for Kavala sludge in the majority of sampling campaigns, followed by Drama and Palio sludge. The metals which present moderate to strong positive correlation have common origin, which could be a domestic-commercial mixed source.

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