Cation composition during recrystallization of layered double hydroxides from mixed (Mg, Al) oxides

High catalytic activity over novel Mg–Fe/Ti layered double hydroxides (LDHs) for polycarbonate diols (PCDLs): synthesis, mechanism and application

“…So far most papers addressing the question of the formation mechanism of LDHs were concerned with Al 3+ based LDHs, such as the topotactical mechanism for reconstruction from calcined Mg-Al LDH system, [39][40][41][42] dissolution-crystallization for Mg-Al salt system, 42 dissolution-precipitation-recrystallization mechanism for Mg-Al LDH system 43,44 and dissolution-deposition-diffusion mechanism for Al 2 O 3 -MgO system, 45 while no reports have been concerned with the formation mechanism of Mg-Fe/Ti LDHs. Based on the above results and the previous ndings of other groups, a proposed formation mechanism of LDH synthesis is schematically illustrated in Fig.…”

Preparation of Ni(II)/Ti(IV) layered double hydroxide at high supersaturation

“…[28][29][30][31][32][33] Many formation mechanisms have been proposed, such as the topotactical mechanism for reconstruction from calcined Mg-Al LDH system, 28-30 dissolution-crystallization for Mg-Al salt system, 31 one-step formation mechanism for Zn-Cr salt system, 32 and dissolution-deposition-diffusion mechanism for Al 2 O 3 -MgO system. 33 To investigate Ni-Ti LDH formation process, a titration behavior of Ni(NO 3 ) 3 (aq), Ti(SO 4 ) 2 (aq) and their mixed solution with a molar ratio of Ni 2+ to Ti 4+ as 3:1 against alkaline solution was investigated respectively, as shown in Fig.…”

The influence of the UV irradiation intensity on photocatalytic activity of ZnAl layered double hydroxides and derived mixed oxides

“…In order to eliminate the influence of methylene blue concentration change due to other phenomena than the photocatalytic decomposition in the selected test reaction, methylene blue concentrations for both samples (in the dark and under UV irradiation) were monitored, Figure 6. The results show that the adsorption/desorption equilibrium of methylene blue was reached after 30 min in the dark for both ZnAl_LDH and [20][21][22][23], one can speculate that the methylene blue concentration decrease observed for the calcined sample in the dark could be attributed to the memory effect that did occur to some extent resulting in partial LDH structure reconstruction. Nevertheless, the difference in photocatalytic performance, originating mostly from the ZnO phase [7,15] implies that larger amount of this active phase remains in the calcined sample.…”