• Asian-Australasian Journal of Animal Sciences
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• 제18권11호
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• pp.1628-1633
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• 2005

Three hundred and twenty four one day old mixed sex broiler chicks were assigned at random into 9 treatment groups. The experimental design was a 3${\times}$3 factorial arrangement. During the starter period (week 1-3), chicks were fed ad libitum. A cornsoybean meal based diet contained 23% crude protein, 3,200 kcal/kg metabolizable energy (NRC, 1994), and supplemented with organic or inorganic forms of chromium. Two organic chromium products, chromium yeast (Cr-Yeast from Alltech Biotechnology Corporation Limited) and chromium picolinate (Cr-Pic) were supplemented at the rate of 200, 400 and 800 ppb. One inorganic product, chromium chloride, was supplemented at the rate of 200, 400 and 800 ppb. During the finishing period (week 4-7), the corn-soybean meal based diet contained 20% crude protein, 3,200 kcal/kg metabolizable energy (NRC, 1994), and the same levels of chromium as in the starter period were added. No significant difference was observed among treatment groups in average daily gain, feed intake, body weight gain, feed conversion ratio and mortality. The carcass percentage of broilers receiving 200 and 400 ppb organic chromium (Cr-Yeast or Cr-Pic) was significantly increased (p<0.01). In addition, the supplementation of organic chromium reduced (p<0.05) breast meat fat content but increased breast meat protein content. The addition of chromium in the diet had no effect on boneless breast, skinless boneless breast, boneless leg, skinless boneless leg but reduced percentage of sirloin muscle. Total cholesterol and triglycerides were reduced by organic Cr supplementation. Supplementation with 200 and 400 ppb of both Cr-Yeast and Cr-Pic showed the lowest total cholesterol. The effects of type of Cr on HDL and LDL were variable, however, LDL increased with increasing level of Cr supplementation. This trial indicates that organic chromium tended to improve growth performances and carcass composition, reduced total cholesterol and triglycerides. The optimum level of organic chromium supplementation was at 200 ppb.

• 펄프종이기술
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• 제41권4호
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• pp.33-42
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• 2009

This study was performed to evaluate the hexavalent chromium content in flexography inks and organic pigments used as colorants for the ink. The digestion of sample was carried out under alkaline condition, and the content of soluble hexavalent chromium extracted from samples was determined by UV-visible colorimetric analysis method after alkaline digestion. Duplicate sampling system to obtain two digested samples, was applied in this study. To determine the hexavalent chromium content in the flexography ink and organic pigment colorimeteric analysis was employed. Because the organic pigment is the main ingredient of flexography ink it is important to remove the errors associated with the colorant of the ink in colorimetric determination. The duplicate sampling system allowed us to correct the errors associated with the colorimeteric measurement. The additional filtration was found an essential step to exclude colorimeteric error derived from the various precipitates. The soluble hexavalent chromium content in flexography inks was generally less than 5 ppm. Yellow, violet and some magenta colors showed higher soluble hexavalent chromium contents. The content of hexavalent chromium in organic pigments was greater than flexography inks, and yellow, violet and some magenta pigments contained greater amount of hexavalent chromium, which indicated that the hexavalent chromium in inks derives from the colorants. The soluble hexavalent chromium content in linerboards were below 1 ppm, and no hexavalent chromium was detected in UKP. Results suggested that flexography ink is the main factor to cause hexavalent chromium in linerboard and organic pigments.

• 한국환경농학회지
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• 제20권5호
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• pp.346-351
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• 2001

Oxidation of Cr(III) to Cr(VI) can increase availability and toxicity of chromium. In this study, possible mechanisms by which pH and organic matter can control the chromium oxidation and reduction in soil system were examined using four soils of different pHs and organic matter contents. Reduction of Mn-oxides occurred in the soils of higher organic matter content (4.0%), but Mn-oxide was quite stable during the incubation in the soil of pH 7.0 and 0.5% organic matter content. Manganese oxides can be reductively dissolved at lower pH and higher organic matter conditions. The soil of pH 7.0 and 4.0% organic matter content showed the highest Cr-oxidation potential. Reduction of soluble Cr(VI) was observed in all the soils examined. The most rapid reduction was found in soil of pH 5.5 and 4.0% organic matter content, but the reduction was slow in soil of pH 7.0 and 0.5% organic matter content. Thus, the reductive capacity of organic matter added soils was much higher as compared to other two soils of lower organic matter content. In all the soils examined, the reductive capacity of soluble chromium was much higher than the oxidative capacity. Organic matter was found to be the most important controlling factor in the chromium oxidation and reduction. Reduction of Cr(VI) to Cr(III) could be a potentially useful remediation or detoxification process, and availability and toxicity of chromium in soil would be controlled by controlling organic matter content and pH of the soils.

• 한국토양비료학회지
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• 제30권4호
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• pp.370-376
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• 1997

우리나라에서 가장 많이 소비되고 있는 채소중의 하나인 무를 실험종으로 선택하여 토양중 크롬의 농도, 토양 pH, 공존중금속 첨가, 복토, 유기물처리의 요인을 변수로 하여 무의 생육상태 및 무에 의한 크롬의 흡수이행량 차이를 조사하였다. 무종자의 발아율은 크롬농도 50mg/kg에서는 발아에 영향이 없었으나 100% 이상이었으며, 250mg/kg에서는 63% 정도의 발아율을 나타내었다. 토양중에 처리된 크롬농도가 증가할수록 무의 초장, 근장, 건물량이 감소하는 경향이었으며 크롬농도 100mg/kg 까지는 대조구와 비슷하게 생육하였으나 크롬농도 250mg/kg에서 건물량의 약 45%의 생육저해가 나타났다. 토양 pH가 증가함에 따라 무로 흡수이행되는 크롬의 함량이 감소하는 역의 상관을 나타내었으며(줄기: $r=-0.803^*$, 뿌리: $r=-0.840^*$) Fe, Zn, Cu와 같은 공존이온 첨가시 무의 생육 및 흡수이행되는 크롬함량간에 유의성이 인정되지 않았다(줄기, 뿌리 P>0.1). 복토, 유기물처리를 하였을 경우 대조구에 비하여 생육상태가 진전되었으며, 복토처리시 무로의 흡수이행량은 큰 차이를 나타내지 않은 반면에 유기물 처리시 무로 흡수이행되는 크롬의 함량이 감소하는 경향이었다.

• Asian-Australasian Journal of Animal Sciences
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• 제14권8호
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• pp.1164-1169
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• 2001

A five-week trial was conducted to evaluate the effect of organic chromium from different sources on growth performance, immune response and serum parameters of weaned pigs. One hundred and eighty Tianjin white pigs weaned at $35{\pm}1$ days of age, were allotted to three treatments with six replicates and10 pigs per pen. Pigs were fed corn-soybean-whey-fishmeal basal diets with either no supplemental Cr, $200{\mu}g/kg$ Cr as chromium picolinate (CrPi), or $200{\mu}g/kg$ Cr as chromium yeast (Cr-yeast). To assess humoral immune response, all pigs were immunized with swine fever virus on day 21 and two pigs from each pen were immunized with pure albumin on day 14. Cell-mediated immunity was measured by determining the double skinfold thickness (DST) of two pigs from each pen before and 24h after stimulation with phytohemagglutinin (PHA) on day 28. The results indicated that: (1) diets with Cr-yeast increased average daily gain (ADG, p<0.05) and tended to increase average daily feed intake (ADFI, p<0.10). Diets with CrPi did not increase ADG and ADFI (p>0.05). (2) Dietary CrPi or Cr-yeast supplementation did not affect blood urea nitrogen, glucose, or cholesterol (p>0.05), but blood urea nitrogen in CrPi and Cr-yeast supplemented groups and blood glucose in the Cr-yeast supplemented group were significantly influenced by sampling days (p<0.05). (3) Serum proteins (TP, ALB, and GLB) were influenced by sampling days (p<0.05), but not by dietary Cr treatment (p>0.10). (4) There were no significant differences among treatments in the titers of albumin antibody and swine fever virus antibody (p>0.05) or DST before and after PHA stimulation (p>0.05), indicating that organic chromium has no significant effect on the immune function of weaning pigs. Therefore, these results agree with other research that the effects of supplemental Cr are variable in weanling pigs.

• 한국표면공학회지
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• 제47권3호
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• pp.116-120
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• 2014

The addition of cyclo propane carbonyl (cpc) to chromium electroplating bath resulted in a chromium deposit which had greatly improved mechanical properties compared to conventional chromium deposits in condition of heat treatment at high temperature. The as-deposited layers had a Vicker's hardness of about 1170, which is comparable to that of conventional chromium plating deposits. With annealing, the hardness goes through a maximum of 1650 at $600^{\circ}C$. Generally speaking, the hardness of conventional plating decreases monotonically with heat treatment. X-ray diffraction show that annealing up to above $400^{\circ}C$ causes formation and growth of chromium crystallites and that chromium carbides form at above $500^{\circ}C$ temperature.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2207-2219
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• 2018

Activated carbon (AC) was synthesized from Phoenix dactylifera stones and then modified by $CoFe_2O_4$ magnetic nanocomposite for use as a Cr(VI) adsorbent. Both $AC/CoFe_2O_4$ composite and AC were fully characterized by FTIR, SEM, XRD, TEM, TGA, and VSM techniques. Based on the surface analyses, the addition of $CoFe_2O_4$ nanoparticles had a significant effect on the thermal stability and crystalline structure of AC. Factors affecting chromium removal efficiency like pH, dosage, contact time, temperature, and initial Cr(VI) concentration were investigated. The best pH was found 2 and 3 for Cr adsorption by AC and $AC/CoFe_2O_4$ composite, respectively. The presence of ion sulfate had a greater effect on the chromium sorption efficiency than nitrate and chlorine ions. The results illustrated that both adsorbents can be used up to seven times to adsorb chromium. The adsorption process was examined by three isothermal models, and Freundlich was chosen as the best one. The experimental data were well fitted by pseudo-second-order kinetic model. The half-life ($t_{1/2}$) of hexavalent chromium using AC and $AC/CoFe_2O_4$ magnetic composite was obtained as 5.18 min and 1.52 min, respectively. Cr(VI) adsorption by AC and $AC/CoFe_2O_4$ magnetic composite was spontaneous and exothermic. In general, our study showed that the composition of $CoFe_2O_4$ magnetic nanoparticles with AC can increase the adsorption capacity of AC from 36 mg/L to 70 mg/L.

• 분석과학
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• 제20권3호
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• pp.246-250
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• 2007

The quantitative determination of chromium(VI) by separation from chromium(III) complex of 8-hydroxyquinoline using solvent extraction has been studied. The reaction conditions for chromium(III) complex of 8-hydroxyquinoline and the solvent extraction of complex were investigated in detail. The chromium(III) complex was extracted with organic solvent (n-hexane) and residual chromium(VI) was determined by ICP-AES in aqueous layer. This technique is quantitative in the pH range of 8-9 and the limitations such as interfering ions were discussed.

• 한국표면공학회지
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• 제44권1호
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• pp.7-12
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• 2011

The effect of organic additives, polyethylene glycol (PEG), on the trivalent chromium electroplating was analysed in the view point of current efficiency, solution stability and metallurgical structure. It was measured that PEG-containing trivalent chromium solution had about 10% higher current efficiency than pure solution and controlled the micro-crack density of electrodeposits. PEG exhibited profound effect on the solution stability by reducing the consumption rate of formic acid which acts as a complexant to lower the activation energy required for electrochemical reduction of trivalent chromium ions. It was also revealed that the formation of chromium carbide layer was facilitated in the presence of polyethylene glycol, which meant easier electrochemical codeposition of chromium and carbon, not single chromium deposition. Trivalent chromium layer formed from PEG-containing solution was amorphous with local nano-crystalline particles, which were prominently developed on the entire surface after non-oxidative heat treatment.

• 한국표면공학회지
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• 제43권6호
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• pp.297-303
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• 2010

The effect of solution acidity and organic additives, polyethylene glycol (PEG), on the trivalent chromium electroplating was systematically investigated in the view point of electroreduction of trivalent chromium ions and solution stability. It was found that solution acidity controlled at pH 2.5 showed the widest current range for bright electrodeposits in the presence of PEG additives, which reduced the local current intensification at high current densities. Through complex interaction between PEG additives and hydrogen ion, that is, solution acidity, electrode potential was moved in the negative direction in the bulk solution, while it shifted in the positive when electric potential was scanned. In conjunction with electrochemical quartz crystal microbalance (EQCM), it was found that PEG additives had a role in promoting the electron transfer to trivalent chromium ion complexes in bulk solution and their adsorption at the electrode surface as well as interfering with hydrogen ion reduction process below pH 2.5. The PEG additives developed the nodular morphology during electroreduction of trivalent chromium ions with the increase of solution acidity and enhanced its current efficiency by maintaining the consumption of complexant, formic acid, at low speed.