New Attempts to Synthesize Layered Double Hydroxides Intercalated with SO42-/Cs+ Using Co-Precipitation and Exchange Reactions

Abstract

Layered double hydroxides (LDHs) with the compositions (Cs+/NH4+)0.111[M2+0.667Al0.333(OH)2.0 (SO4)0.222] (M2+ = Mn, Zn) and basal distance of ca. 11 Å were obtained by co-precipitating Mn/Al and Zn/Al sulfate salts with aqueous NH3, using excess of Cs2SO4. [Mn0.667Al3+0.333(OH)2] Cl0.333 .nH2O and [M2+0.667Al3+0.333(OH)2](NO3)0.333 .nH2O (M2+ = Mn, Zn) were also synthesized by co-precipitation, presenting respective basal distances of 8.92 and 7.92 Å. After applying exchange reactions with excess of Cs2SO4, materials with basal distances of ca. 11 Å were obtained, indicating the exchange of chloride and nitrate with sulfate, without incorporation of Cs+. When Na+0.111[M2+0.667Al0.333(OH)2.0(SO4)0.222](M2+ = Mn, Zn) obtained by co-precipitation and having basal distances of ca. 11 Å was exchanged with excess of Cs2SO4, the content of sulfate remained constant and Na+ was partially replaced with Cs+, but the amount was lower, indicating the probable composition (Na+/Cs+)y[M2+0.667Al0.333(OH)2-y(SO4)y/2(SO4)0.222-(y/2)](M2+ = Mn, Zn), where some of the hydroxide anions were replaced with grafted SO42-.

Synthesis, Characterization, and Anion Exchange Reactions of Zn2Cr Layered Double Hydroxides Intercalated with Acetate and Chloride

“…3,5 R e c e n t l y, s o m e s t u d i e s i nv o l v i n g L D H intercalated with sulfate with the main formula A(H 2 O) 6 [M 2+ 6 Al 3 (OH) 18 (SO 4 ) 2 ]•6H 2 O (M 2+ = Mn, Mg, Zn, A + = Li, Na, K) have gained importance since they also present the intercalation of cations and have anion and/or cation exchange capacity. [6][7][8][9] However, there are still few reports in the literature of LDHs intercalated with some anions, as is the case of acetate, either the compound obtained by anion exchange or by direct synthesis.…”