scholarly journals Combination of interfacial reduction of hexavalent chromium and trivalent chromium immobilization on tin-functionalized hydroxyapatite materials

2021 ◽  
Vol 539 ◽  
pp. 148227 ◽  
Author(s):  
Sebastiano Campisi ◽  
Claudio Evangelisti ◽  
Georgeta Postole ◽  
Antonella Gervasini
Keyword(s):  
Hexavalent Chromium ◽  
Trivalent Chromium

scholarly journals Morphology analysis of hexavalent chromium reduction to trivalent chromium with syrup under different pH conditions

2019 ◽  
Vol 9 (8) ◽  
Author(s):  
Zi-Fang Chen ◽  
Xu Guan ◽  
Yong-Sheng Zhao
Keyword(s):  
Hexavalent Chromium ◽  
Bound State ◽  
Trivalent Chromium ◽  
Batch Experiments ◽  
Chromium Reduction ◽  
Reaction Systems ◽  
Mn Oxide ◽  
Morphology Analysis ◽  
Ph Conditions

Abstract Batch experiments were designed to ascertain the morphology and valence of chromium in the reduction of hexavalent chromium with syrup under different pH conditions. Results indicated that the syrup reduced hexavalent chromium to trivalent chromium, and the existing forms of Cr were mainly Cr(OH)3, CrOOH and CrOOH–Fe. The percentage of Fe–Mn oxide-bound state was 29.28%, 29.28%, 22.22% and 20.12%, respectively, and the percentage of organic binding state was 64.71%, 66.58%, 74.74% and 73.14%, respectively, in the reaction systems at different pH (2.0, 2.5, 3.0 5.6) conditions.

scholarly journals Distribution of chromium in rats exposed to hexavalent chromium and trivalent chromium aerosols.

1984 ◽  
Vol 22 (4) ◽  
pp. 261-277 ◽  
Author(s):  
Yasutomo SUZUKI ◽  
Katsunori HOMMA ◽  
Masayasu MINAMI ◽  
Hiroshi YOSHIKAWA
Keyword(s):  
Hexavalent Chromium ◽  
Trivalent Chromium

Selection and Impact Mechanism of Washing Agents for Chromium Contaminated Building Waste

2012 ◽  
Vol 178-181 ◽  
pp. 1083-1092
Author(s):  
Xing Run Wang ◽  
Yan Xia Zhang ◽  
Jian Min Shu
Keyword(s):  
Particle Size ◽  
Citric Acid ◽  
Organic Acid ◽  
Hexavalent Chromium ◽  
Removal Rate ◽  
Trivalent Chromium ◽  
Acid Condition ◽  
Impact Mechanism ◽  
Removal Mechanisms

With the building wastes contaminated by chromium in Haibei Chemical Plan in China as objects, it studied the contents of total Cr and Cr (Ⅵ) of different sizes, analyzed the effect of 6 different washing agents, discussed the removal mechanisms of 6 different washing agents for Cr in various forms, and finally selected applicable washing agent. As the results, particle size had little impact on the contents of total Cr and Cr (Ⅵ); after one washing with water, the removal rate of total Cr and Cr (Ⅵ) was 75% and 78%, respectively, and after the second washing with 6 agents, the removal rate of citric acid was the highest, above 90% for total Cr and above 99% for hexavalent chromium; the pH of building wastes were reduced by citric acid, and under acid condition, hexavalent chromium was reduced to trivalent chromium spontaneously by organic acid, which led to better removal rate of acid soluble Cr and reducible Cr; due to the complexing action, citric acid had best removal rate for oxidizable trivalent chromium. In conclusion, citric acid is the most applicable second washing agent for building wastes.

scholarly journals Phytoremediation of chromium: distribution and speciation of chromium in Typha angustifolia

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Viky Vidayanti ◽  
Devi N. Choesin ◽  
Iriawati Iriawati
Keyword(s):  
Hexavalent Chromium ◽  
Vascular Bundle ◽  
Trivalent Chromium ◽  
Typha Angustifolia ◽  
Alternative Approach ◽  
Almost All

Chromium (Cr), especially in hexavalent chromium [Cr(VI)] may contaminate water or soil and cause detrimental effects, as it is potentially carcinogenic and teratogenic. Phytoremediation using plants such as <em>Typha</em> <em>angustifolia</em> provides an alternative approach for handling Cr waste. The objective of this study was to determine the mechanism of Cr accumulation in <em>T. angustifolia</em>. Hydroponic media containing <em>T. angustifolia</em> was added with 0, 1, 5, 10 and 20 ppm of Cr (VI) (K2Cr2O7). After 15 days of treatment, distribution and speciation of Cr in roots and shoots of <em>T. angustifolia</em> were analyzed using XAS and μ-XRF. Results showed that Cr was detected in almost all parts of root and shoot at different intensities. Intensities of Cr was higher in roots (especially in the vascular bundle) than in shoot. Cr speciation in the root and shoot was found as trivalent chromium [Cr(III)] which formed as a result of Cr(VI) reduction. Based on the patterns of Cr distribution and speciation, results of this study suggest that <em>T. angustifolia</em> in this study does not reduce Cr(VI) to become Cr(III) inside the plants.

Plasma processing for surface modification of trivalent chromium as alternative to hexavalent chromium layer

2007 ◽  
Vol 201 (15) ◽  
pp. 6601-6605 ◽  
Author(s):  
Sik-Chol Kwon ◽  
Hak-Jun Lee ◽  
Jong-Kuk Kim ◽  
Eungsun Byon ◽  
George Collins ◽  
...  
Keyword(s):  
Surface Modification ◽  
Hexavalent Chromium ◽  
Plasma Processing ◽  
Trivalent Chromium ◽  
Chromium Layer

Competing Ion Effect of Stabilization by Cr(III) & Cr(VI) in Ettringite Crystal Structure

2007 ◽  
Vol 124-126 ◽  
pp. 1629-1632 ◽  
Author(s):  
Kwang Suk You ◽  
Ji Whan Ahn ◽  
Hee Chan Cho ◽  
Gi Chun Han ◽  
Dong Yun Han ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Calcium Hydroxide ◽  
Hexavalent Chromium ◽  
Atmospheric Pressure ◽  
Aqueous Suspension ◽  
Ultrasound Irradiation ◽  
Trivalent Chromium ◽  
Sulfate Anion ◽  
Salt Phase ◽  
Structure In Solution

In this study, the degree of the substitution of Cr3+ and Cr6+ into the ettringite structure has been investigated to extent the immobilization potential of ettringite in the field under specific conditions. Aqueous suspension containing calcium hydroxide, alumium sulfate, CrCl2(trivalent chromium) and CrO3(hexavalent chromium) was subjected to ultrasound irradiation under atmospheric pressure to investigate their effects on synthesis of Cr-ettringite. In the result, the substitution of Cr3+ into Al site takes place in ettringite structure in solution with Cr3+, and monosulfate/friedel’ salt phase is also formed by occurrence of extra Al ion in solution. However, in the case of Cr6+, owing to a higher affinity of sulfate anion to form ettringite than that of Cr6+,most of Cr6+ did not substituted into the crystal structure of ettringite.

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