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
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
The publication of trifluoroacetic acid(TFA)concentrations in the Atlantic Ocean in 2022-2023 prompted an inventory update to include the period 2000 to 2020 for fluorspar(CaF2)production,use,TFA emissions,and their c...The publication of trifluoroacetic acid(TFA)concentrations in the Atlantic Ocean in 2022-2023 prompted an inventory update to include the period 2000 to 2020 for fluorspar(CaF2)production,use,TFA emissions,and their contri-bution to TFA in the Atlantic Ocean.The update accounts for 90%of the acid spar used to produce hydrogen fluoride in the period 2000 to 2020.Emissions of TFA due to fluorocarbons(HFCs,HFOs,HCFOs,HCFCs,and anaesthetics)are estimated at 503,700 tonnes in this period.Generation of TFA from the use of pesticides is estimated at 239,000 to 796,000 tonnes globally,assuming a 30%to 100%yield of TFA.In total,estimated emissions of TFA,from 1930 to 2020,are 1,019,000 tonnes,with a theoretical upper limit of 2,283,000 tonnes,which includes the quantity of TFA manufactured,where production is assumed to equal emissions.The estimated emissions of TFA to the Atlantic Ocean from 1930 to 2020 are 467,000 tonnes,with a theoretical upper limit of 1,215,000 tonnes.This is not consistent with the measured TFA concentrations,which suggest the Atlantic Ocean contains at least 40 million tonnes of TFA,possibly over 80 million tonnes,and must therefore include a large natural burden.展开更多
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.
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.
基金supported financially by the EFCTC trade association.
文摘The publication of trifluoroacetic acid(TFA)concentrations in the Atlantic Ocean in 2022-2023 prompted an inventory update to include the period 2000 to 2020 for fluorspar(CaF2)production,use,TFA emissions,and their contri-bution to TFA in the Atlantic Ocean.The update accounts for 90%of the acid spar used to produce hydrogen fluoride in the period 2000 to 2020.Emissions of TFA due to fluorocarbons(HFCs,HFOs,HCFOs,HCFCs,and anaesthetics)are estimated at 503,700 tonnes in this period.Generation of TFA from the use of pesticides is estimated at 239,000 to 796,000 tonnes globally,assuming a 30%to 100%yield of TFA.In total,estimated emissions of TFA,from 1930 to 2020,are 1,019,000 tonnes,with a theoretical upper limit of 2,283,000 tonnes,which includes the quantity of TFA manufactured,where production is assumed to equal emissions.The estimated emissions of TFA to the Atlantic Ocean from 1930 to 2020 are 467,000 tonnes,with a theoretical upper limit of 1,215,000 tonnes.This is not consistent with the measured TFA concentrations,which suggest the Atlantic Ocean contains at least 40 million tonnes of TFA,possibly over 80 million tonnes,and must therefore include a large natural burden.
