Characterization of Intercalated Ni/Al Hydrotalcites Prepared by the Partial Decomposition of Urea

Abstract

Layered double hydroxides containing Ni 2+ and Al 3+ have been synthesized by homogeneous precipitation through urea hydrolysis. The nature of the interlayer species changes according to the treatment of the samples, formation of interlayer (NH 2 )COOspecies being observed immediately after precipitation, which undergo transformation to carbonate after hydrothermal treatment. Simultaneously, liberation of ammonia during decomposition under hydrothermal conditions gives rise to formation of [Ni(NH 3 ) 6 ] 2+ species in solution.

Homogeneous precipitation of layered Ni(II)–Cr(III) double hydroxides

“…Recently, Kloprogge et al [12] suggested that LDHs synthesized via the urea method intercalate (NH 2 )COO − anions, an interlamellar species that, according to the authors, would account for the apparent C 2v character of the bands assigned to CO 2− 3 . The absence of bands due to NH vibrations (2960-2850 cm −1 ) in Fig.…”

“…The subsequent evolution of the coprecipitated hydroxides to form the final solid depends strongly on the reactivity of the involved metal ions; e.g., for labile ions, such as Cu 2+ and Zn 2+ , double basic carbonates form readily [38]. Thus, owing to the higher lability of Al 3+ than of Cr 3+ (Table 2), less stringent aging conditions are required for the preparation of Al(III)-containing LDHs via the urea method [9][10][11][12]. It should be recognized here that homogeneous nucleation of Zn(II)-Cr(III) LDHs takes place under the conditions provided by slow pH-titration experiments [40].…”

“…Typically, LDHs are synthesized following with slight modifications the recipe advanced by Miyata and Okada [4], i.e., coprecipitation followed by aging at moderate temperatures; the length of the aging stage depends on the degree of crystallinity that is pursued [5] and can be shortened by microwave dielectric heating [6][7][8]. Recently, LDH particles have also been prepared via the urea method [9][10][11][12], in which the rate of homogeneous alkalization is determined by the rate of urea hydrolysis [13], 3 . Contrasting with the abundant literature referring to the synthesis and properties of many different M(II)-M(III) LDHs, the information on Ni(II)-Cr(III) LDHs, which have been envisaged as potential electrode materials for alkaline secondary cells [14], is indeed scarce.…”

Nanosized spinel oxide catalysts for CO-oxidation prepared via CoMnMgAl quaternary hydrotalcite route

“…For example MgMn 2+ Mn 3+ -LDH was synthesized through oxidation of Mn 2+ to Mn 3+ in the solid state [19] and Co 3+ containing LDHs, MgCo II Co IIIand Co II Co III -LDHs was also studied [20][21][22][23]. Several synthetic methods have been used to synthesize hydrotalcites and spinel powder that include the precipitation [24][25][26], hydrothermal [27], salt oxide method [28], urea reduction [29,30], electrochemical [31,32], mechanical activation with subsequent annealing [33], and sol-gel [34]. Co-precipitation is a simple and effective method for the preparation of multi-component oxides [35].…”

Potential application of sludge produced from coal mine drainage treatment for removing Zn(II) in an aqueous phase

“…However, this concept could be acceptable if the pure iron (oxy) hydroxide is present. Although the pH IEP of goethite and CaCO 3 have been generally known to be 8.5 * 9.6 and 7 * 11, respectively (Erdemoglu et al 2004;Kloproeeg et al 2006;Dzombak and Morel 1990), the results of zeta potential measurement showed that the pH IEP values of CMDS were 5 and 4.5 with the suspension of DI and 0.01 M NaCl, respectively (see Fig. 4).…”