ИСТИНА

Although there is a large group of layered inorganic compounds with cation-exchange properties, the number of materials with positively charged host layers, i.e., anion-exchange capacity, is extremely limited [1]. For a long time, hydrotalcite-like layered double hydroxides (LDH) have been known as the only layered inorganic materials with anion-exchange capacity. Recently, a new family of layered rare-earth hydroxides (LRHs) (RE = rare-earth elements) was found [2, 3]. These materials include positively charged layers and charge-balancing anions (X = chloride, nitrate, etc.) sandwiched between these layers. Similar to LDHs, these layered rare-earth hydroxides are anion-exchangers. This novel class of materials is attractive due to promising combination of rare-earth chemistry and anion exchangeability. All known LRH synthetic procedures are very time-consumable (up to tens or hundreds hours). The first type of procedures includes the precipitation of LRH from aqueous solutions of rare-earth salts (nitrates or chlorides) in the presence of hexamethylenetetramine (HMTA) at low temperatures [4]. The second one is based on hydrothermal treatment of rare-earth hydroxocompounds preliminarily precipitated by inorganic or organic bases [5]. In the present work we introduce a novel method for LRH synthesis which is based on homogeneous precipitation from aqueous solutions of RE(NO3)3 and NaNO3 in the presence of HMTA under microwave-assisted hydrothermal treatment. The use of this method results in significant decrease in the synthesis duration (less than 1 hour) and provides a high yield (~80-90%) of the final product. We have shown that thus synthesized LRHs consist of sphere-shaped aggregates consisting of plate-like particles. Their anion exchangeability was successfully checked on an example of dodecylsulfate ions. The work was supported by RFBR 14-03-00907.