Antimony concentration

Trace quantities of arsenic are added to lead-antimony grid alloys used ia lead—acid batteries (18) (see Batteries, lead acid). The addition of arsenic permits the use of a lower antimony content, thus minimising the self-discharging characteristics of the batteries that result from higher antimony concentrations. No significant loss ia hardness and casting characteristics of the grid alloy is observed (19,20). 

The corrosion of antimony electrodes was also measured using ICP-MS (inductively coupled plasma mass spectrometry) for dissolved antimony in vivo [156], After the electrodes were inserted in the plasma, the antimony concentration showed a linear rise with time at a rate approximately of 94 j,g/L/h (r2 = 0.997). Although the projected antimony concentration is lower than the safe limit, accumulation of dissolved antimony and localized toxic effects in tissue may prevent the antimony electrode from long-term implantable applications. 

The concentration of arsenic can be determined at 600 nm because the Sb-Ag DDTC complex does not absorb light of this wavelength. The molar absorptivity of the antimony complex with Ag DDTC reaches its maximum value at 504 nm, but there is also appreciable light absorbance from the As-Ag DDTC complex at this wavelength. The antimony concentration can be calculated from the total extinction value measured at 504 nm by subtracting the extinction value (at 504 nm) that corresponds to the previously determined arsenic concentration. It is clear that calibration curves of arsenic at 504 and 600 nm and of antimony at 504 nm are needed to perform the calculation. 

Maintenance of Proper Antimony Concentration. Close monitoring of the antimony concentration on the catalyst will assure that maximum benefits are derived from a metals passivation program. The antimony-to-nickel ratio on the equilibrium catalyst has been correlated with hydrogen production in commercial operations (Figure 5), The non-linear shape of the hydrogen production curve has been confirmed in pilot plant tests (Figure 1), The recommended antimony concentration corresponds to a point beyond the breakpoint of the curve, A "cushion" is desired to allow fluctuations in the system without major increases in the yields of hydrogen and coke. 

A laboratory analysis of your household drinking water shows the antimony concentration to be 4 ppb (parts per billion) and that of nickel to be 60 ppb. Determine if the drinking water is safe with respect to the antimony and nickel levels. 

Instrumental neutron activation analysis was used to determine concentrations of several major and trace elements in samples of heavily corroded residues found in crucible fragments excavated at Tel Dan, Israel. The residues were mostly hard, metallic phases admixed with nonmetallic inclusions that appeared to be ceramic material from the loose porous interior of the crucible itself The objective was to identify the metals that had been melted in these crucibles. A method is described that attempts to separate nonmetallic and metallic phase data. In comparison to previous reports on analyses of source materials thought to have been used at Dan in this period (Late Bronze II Age-Early Iron I Age 1400-1000 B.C.), high gold concentrations were found. These appear to be correlated to arsenic and antimony concentrations. This finding is discussed in relation to possible changes in the source of tin at this period. 

Figure 4. Correlation plot of gold relative to antimony concentration.

The overall data may not be used in such an absolute sense as in analysis of a bronze casting, but they do provide some interesting information. Substantial concentrations of gold and arsenic were observed that appear to correlate with one another and with antimony concentration. Further work is needed to find authentic sources of the copper, tin, fluxes, and other materials used at these sites. Apparently, measurement of gold concentrations cannot be used to answer questions about a change in the sources of tin during this period. 

B.C. contain very high antimony concentrations, and two of these are sem-isses (only four semisses were analyzed). The coins from the earliest period to about 160 B.C. contain moderate amounts of antimony (see Figure 9). Most of the coins made from around 160 to 80 B.C. have relatively high antimony contents these same coins also were relatively high in silver. The latest two coins have the very low antimony contents typical of coins minted in the early Roman Empire. 

WiUiams-Jones and Normand (1997) suggest that the conditions of maximum gold concentration in hydrothermal fluids correspond closely to the conditions of maximum antimony concentration, where the dominant aqueous antimony species is HSb2S4- Because stibnite (Sb2S3) solubility increases rapidly with temperature, and because antimony is a rare element, the ratio of the concentration of antimony in hydrothermal solutions to its solubility limit is usually rather low, until temperature drops to the general range of 150-300 °C. Under the restricted conditions of maximum gold solubility, stibnite precipitation is considered by Williams-Jones and Normand to be controlled by the mass action expression... 

FIGURE 31. Effect of fuel flow-rate on antimony absorption A, air-hydrogen flame B, air-acetylene flame. Antimony concentration, lOO/igml in 5% V/V hydrochloric acid air pressure, 35 (flow-meter reading) height above burner, 2 mm wavelength, 217.6 nm. Reproduced from Reference 222 by permission of The Royal Society of Chemistry... 

Abbasi conducted a submicro determination (down to 10 ppb levels) of Sb(III) and Sb(V) in natural and polluted waters and biological materials. The Sb(III) and Sb(V) concentrations obtained were as follows surface sample of reservoir water 0 and 0, near-bottom sample of reservoir water 0.17 and 0.16 ppb, sea water (India) 0 and 0.28 ppb, and polluted water (rubber industry) 0.85 and 1.91 ppb. Total antimony concentrations of goat liver and frog muscle were 0.094 and 0.027 ppb, respectively . ... 

When the waste-containing fire retardant is incinerated, the antimony is emitted to the atmosphere as shown in Table 5. The emission of antimony to the atmosphere and to waterways should continuously increase in the future with the increased use of the product. This necessitates the careful watching of the antimony concentration in the environment. 

Soil samples were collected from pollution-free sites (6 paddy fields, 7 upland fields and 12 forests) in Hokkaido, Fukushima, Shizuoka, Saga Prefectures in Japan and analyzed for bismuth . Average, maximum and minimum values of bismuth and antimony concentrations obtained in dry base were 0.34,0.12 and 0.91 figBig, and 0.37,0.13 and 0.91 fig Sbg respectively. 

At site A in Table 16, concentrations of all metals in the second soil-core depth were higher than those in the first soil-core depth. Bismuth and antimony concentrations in the soil core under the second core depth were less than those of natural concentrations, 0.34 and 0.37 /rgg , respectively. At sites B and C, the profiles of metal concentrations were somewhat different from those in site A The difference is probably due to dissimilarities in pollution history, surrounding circumstances and properties of soil. 

Kubota and coworkers also analyzed soils and sediments from bismuth-polluted sites at which a bismuth smelter had been operated since 1970. Twenty-four soils at sites within 2 km from the smelter were analyzed. Geometric mean, maximum and minimum values of bismuth and antimony concentrations in the soils were 4.2,122 and 0.45, and 3.2, 37.3 and 0.61 ngg in the dry base, respectively. The bismuth and antimony levels from sediments of the exhaust port and downstream of the river were 200-700 and 100-200 times higher than natural concentrations, respectively Effects of the pollution on the ecosystem were not considered. 

In 2008, the largest producers of antimony were China, Bolivia, South Africa, Russia, and Tajikistan. The United States produced some antimony concentrate at a mine in Nevada and some antimony metal and oxide in Montana. According to the U.S. Geological Survey (USGS), other states with antimony resources include Alaska and Idaho. 

Normally, antimony is absorbed slowly when ingested or administered orally. Many antimony compounds are gastrointestinal irritants. The emetic antimony potassium tartrate is easily absorbed and, within 24 h, 50% is excreted in the urine (hamsters). Antimony can concentrate in lung tissue, the thyroid gland, the adrenal glands, the kidneys, and the liver. The trivalent compounds of antimony concentrate in the red blood cells and liver and the pentavalent compounds concentrate in the blood plasma. Both forms are excreted in feces and urine, but generally. 

Inhalation of antimony compounds produces different effects at different concentrations. Chronic inhalation of low concentrations causes rhinitis and irritation of the trachea. At high concentrations, acute pulmonary edema occurs, and bronchitis may occur (the bronchitis may lead to emphysema). Inhaled antimony concentrates in lung tissue as a result, pneumoconiosis with obstructive lung disease has been recorded. Antimony is a suspected human carcinogen. 

It was found that catalysts containing less than 60% antimony retained a surface composition characteristic of their bulk until subjected to temperatures in excess of 400°C. It would appear that enrichment of the surface by antimony begins at this point and is maximized at about 1000°C. However, it is interesting that materials with high bulk antimony content show a marked decrease in surface antimony concentration at 700°-800°C. 

The lower activation energy for the reduction of tin-antimony oxides with hydrogen as compared with that for the pure oxides has been confirmed by Saia and Trifiro (47), and, contrary to other studies, the activity reported to vary with calcination temperature. Some studies (50-52) have reported an increase in activity and selectivity for the oxidation of butene with increasing antimony content and to be maximized at an antimony concentration of about 20% (50). Saia and Trifiro also reported that materials calcined at 900°C showed peaks in activity for butadiene formation at antimony to tin ratios of 0.20 and 0.90 and that selectivity to butadiene increased with antimony content to 80% for the catalyst with a ratio of 0.40. 

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