The enthalpies of solution in water of L--methionine and its zinc complexes Zn(Met)Cl2, Zn(Met)2Cl2·2H2O, Zn(Met)(NO3)2·1/2H2O, Zn(Met)3(NO3)2·H2O and Zn(Met)SO4·H2O have been measured at 298.15 K. The standard enthalpy of formation of met(aq) has been calculated. The experimental results have been discussed.
The thermal decomposition behaviour of the complexes of rare earth metals with histidine: RE(His)(NO3)3
H2O (RE=La—Nd, Sm—Lu and Y; His=histidine) was investigated by means of TG-DTG techniques. The results indicated that the thermal decomposition processes of the complexes can be divided into three steps. The first step is the loss of crystal water molecules or part of the histidine molecules from the complexes. The second step is the formation of alkaline salts or mixtures of nitrates with alkaline salts after the histidine has been completely lost from the complexes. The third step is the formation of oxides or mixtures of oxides with alkaline salts. The results relating to the three steps indicate that the stabilities of the complexes increase from La to Lu.
Authors:T. Wang, Y. Lu, M. Zhu, J. Zhang, and S. Ji
The critical furnace chamber temperature (T′ign) of the thermal explosion synthesis reaction Ti+3Al→TiAl3 is studied by isothermal and non-isothermal DSC. The reaction product is characterized by using the X-ray powder diffraction.
The value of T′ign is between 740 and 745C obtained from the isothermal DSC observations, and 729C obtained from non-isothermal DSC curves.
It shows that these two values have a good consistency. With the help of the apparent activation energy of the reaction obtained
by Friedman method and the value of T′ign0 by the multiple linear regression of the T′igns at different heating rates (β), the critical temperature (Tb) of thermal explosion for Ti–75at%Al mixture is estimated to be 785C.
Authors:M. Ji, J. Liu, S. Gao, B. Kang, R. Hu, and Q. Shi
The enthalpies of solution in water of RE(His)(NO3)3
H2O (RE=La—Nd, Sm—Lu, Y) were measured calorimetrically at 298.15 K, and the standard enthalpies of formation of RE(His)aq3+ (RE=La—Nd, Sm—Lu, Y) were calculated. The plot of the enthalpies of solution vs. the atomic numbers of the elements in the lanthanide series exhibits the tetrad effect.
Authors:J. Liu, Y. Hou, S. Gao, M. Ji, R. Hu, and Q. Shi
The eight solid complexes of zinc with L--methionine or L--histidine were prepared. The thermal decomposition processes of these complexes were determined by means of TG-DTG. The results show that their decomposition processes can be divided into three steps except for the complex Zn(Met)2 the decomposition of which is completed in one step. All the final products are ZnO.