The first transuranium element neptunium(Np)exhibits complicated behavior in acidic solutions as it adopts a wide range of oxidation states typically from+3 to+6 and coordinates with a large variety of ligands.In part...The first transuranium element neptunium(Np)exhibits complicated behavior in acidic solutions as it adopts a wide range of oxidation states typically from+3 to+6 and coordinates with a large variety of ligands.In particular,the accurate determination of Np redox potentials in nitric acid solutions is challenging due to overlapping chemical and electrochemical reactions leading to significant experimental uncertainties.展开更多
Decomposition of lead sulfide concentrates in nitric acidic solutions after ferric(Ⅲ)nitrate addition and mechanical preparation has been investigated.It was found out that the decomposition can be achieved in HNO_(3...Decomposition of lead sulfide concentrates in nitric acidic solutions after ferric(Ⅲ)nitrate addition and mechanical preparation has been investigated.It was found out that the decomposition can be achieved in HNO_(3) solution(>1.5 mol·L^(-1))at the temperature above 85℃.The leaching rate of lead can be increased by means of mechanochemical activation.The use of[Fe(NO_(3))_(3)-HNO_(3)-H_(2)O]aqueous salt system allows the decomposition of lead sulfide concentrate at room temperature and in this case the concentration of HNO_(3) does not exceed 0.05-0.1 mol.L^(-1),The degree of lead recovery into solution from PbS concentrate reaches 99.3%-99.6c70 with the mechanochemical activation of this concentrate.The insoluble residues after the leaching contain SiO_(2),S^(0),FeCO_(3) and PbSO_(4).展开更多
Influence of temperature on ruthenium adsorption on activated charcoal from 3 mol/L HNO3 solutions was inves- tigated in the temperature range of 288 K to 308 K. It was observed that the rise in temperature increases ...Influence of temperature on ruthenium adsorption on activated charcoal from 3 mol/L HNO3 solutions was inves- tigated in the temperature range of 288 K to 308 K. It was observed that the rise in temperature increases the adsorption of ru- thenium ions on activated charcoal and follows the kinetics of first order rate law with rate constant values 0.0564?0.0640 min?1 in the temperature range of 288 K to 308 K respectively. The activation energy for the adsorption process was found to be 1.3806 kJ/mol. Various thermodynamics quantities namely ?H, ?S and ?G were computed from the equilibrium constant KC values. The results indicated a positive heat of adsorption, a positive ?S and a negative ?G.展开更多
基金supported by the Laboratory Directed Research and Development Program at the Pacific Northwest National Laboratory operated by Battelle for the U.S.Department of Energy under Contract DE-AC05-76RL01830.
文摘The first transuranium element neptunium(Np)exhibits complicated behavior in acidic solutions as it adopts a wide range of oxidation states typically from+3 to+6 and coordinates with a large variety of ligands.In particular,the accurate determination of Np redox potentials in nitric acid solutions is challenging due to overlapping chemical and electrochemical reactions leading to significant experimental uncertainties.
文摘Decomposition of lead sulfide concentrates in nitric acidic solutions after ferric(Ⅲ)nitrate addition and mechanical preparation has been investigated.It was found out that the decomposition can be achieved in HNO_(3) solution(>1.5 mol·L^(-1))at the temperature above 85℃.The leaching rate of lead can be increased by means of mechanochemical activation.The use of[Fe(NO_(3))_(3)-HNO_(3)-H_(2)O]aqueous salt system allows the decomposition of lead sulfide concentrate at room temperature and in this case the concentration of HNO_(3) does not exceed 0.05-0.1 mol.L^(-1),The degree of lead recovery into solution from PbS concentrate reaches 99.3%-99.6c70 with the mechanochemical activation of this concentrate.The insoluble residues after the leaching contain SiO_(2),S^(0),FeCO_(3) and PbSO_(4).
文摘Influence of temperature on ruthenium adsorption on activated charcoal from 3 mol/L HNO3 solutions was inves- tigated in the temperature range of 288 K to 308 K. It was observed that the rise in temperature increases the adsorption of ru- thenium ions on activated charcoal and follows the kinetics of first order rate law with rate constant values 0.0564?0.0640 min?1 in the temperature range of 288 K to 308 K respectively. The activation energy for the adsorption process was found to be 1.3806 kJ/mol. Various thermodynamics quantities namely ?H, ?S and ?G were computed from the equilibrium constant KC values. The results indicated a positive heat of adsorption, a positive ?S and a negative ?G.
