Microwave-hydrothermal processing of layered anion exchangers

We have compared the microwave-hydrothermal (M-H) processing with conventional hydrothermal (C-H) processing in the preparation of two layered anion exchangers, i.e., Mg3Al(OH)(8)NO3 . nH(2)O and Ni1-xZn2x(OH)(2)(CH3COO)(2x). nH(2)O. Both these phases can be crystallized more rapidly (an order of magnitude) under M-H processing compared to C-H processing. The above layered mixed basic salt of Ni and Zn was found to exhibit very high selectivity for PO4= (K-d = 15, 000). Its order of selectivity for various anions in the presence of 0.1 (N) under bar NaCl (ratio of Cl- to anion in question is 100) increases as follows: PO4= much greater than SO4= > NO3-.