There is a generally accepted conclusion that trifluoroacetic acid (TFA) does occur naturally, in part based on the large quantities of TFA in the oceans (61 - 205 million tonnes, measured in 1998-2002). However, the ...There is a generally accepted conclusion that trifluoroacetic acid (TFA) does occur naturally, in part based on the large quantities of TFA in the oceans (61 - 205 million tonnes, measured in 1998-2002). However, the recent review paper “Insufficient evidence for the existence of natural trifluoroacetic acid” concludes that “the presence of TFA in the deep ocean and lack of closed TFA budget is not sufficient evidence that TFA occurs naturally, especially without a reasonable mechanism of formation”. Industrial sources of TFA can only result from the use of fluoride minerals in industrial processes. Major industrial uses of fluorspar started significant expansion from about the same time (1930s). Over 190 million tonnes of fluorspar have been mined in the period 1930 to 1999. An inventory has been developed (1930-1999), accounting for most of the fluorspar production (86%) and estimating emissions of TFA. Industrial emissions of TFA are estimated as 230,000 to 470,000 tonnes. Significant other industrial uses of fluorides have not been identified that could account for the large burden of TFA in the oceans. This inventory provides complementary evidence that the quantity of TFA in the oceans must include a large natural burden.展开更多
Yttrium and ytterbium were extracted from sulfuric acid medium using triphenylarsine （TPAs） dissolved in kerosene. The influence of different factors, such as shaking time, extractants, metal ions, sulfate ion conce...Yttrium and ytterbium were extracted from sulfuric acid medium using triphenylarsine （TPAs） dissolved in kerosene. The influence of different factors, such as shaking time, extractants, metal ions, sulfate ion concentrations, as well as temperature, was studied in detail. From the slope analysis method and IR measurements, the structure of the extracted species was suggested as MSO4（HSO4）.TPAs, where M refers to Y（III） or Yb（III）. The equilibrium constants （Kex） and thermodynamic parameters, such as the change in enthalpy （△H）, free energy （△G）, and entropy （△S）, were calculated. The method of extraction and stripping was applied to obtain the aforementioned metals from a sample of fluorspar mineral giving a recovery yield of 88.2% and 83.5% for yttrium and ytterbium, respectively.展开更多
文摘There is a generally accepted conclusion that trifluoroacetic acid (TFA) does occur naturally, in part based on the large quantities of TFA in the oceans (61 - 205 million tonnes, measured in 1998-2002). However, the recent review paper “Insufficient evidence for the existence of natural trifluoroacetic acid” concludes that “the presence of TFA in the deep ocean and lack of closed TFA budget is not sufficient evidence that TFA occurs naturally, especially without a reasonable mechanism of formation”. Industrial sources of TFA can only result from the use of fluoride minerals in industrial processes. Major industrial uses of fluorspar started significant expansion from about the same time (1930s). Over 190 million tonnes of fluorspar have been mined in the period 1930 to 1999. An inventory has been developed (1930-1999), accounting for most of the fluorspar production (86%) and estimating emissions of TFA. Industrial emissions of TFA are estimated as 230,000 to 470,000 tonnes. Significant other industrial uses of fluorides have not been identified that could account for the large burden of TFA in the oceans. This inventory provides complementary evidence that the quantity of TFA in the oceans must include a large natural burden.
文摘Yttrium and ytterbium were extracted from sulfuric acid medium using triphenylarsine （TPAs） dissolved in kerosene. The influence of different factors, such as shaking time, extractants, metal ions, sulfate ion concentrations, as well as temperature, was studied in detail. From the slope analysis method and IR measurements, the structure of the extracted species was suggested as MSO4（HSO4）.TPAs, where M refers to Y（III） or Yb（III）. The equilibrium constants （Kex） and thermodynamic parameters, such as the change in enthalpy （△H）, free energy （△G）, and entropy （△S）, were calculated. The method of extraction and stripping was applied to obtain the aforementioned metals from a sample of fluorspar mineral giving a recovery yield of 88.2% and 83.5% for yttrium and ytterbium, respectively.
