Microwave-hydrothermal processing of layered anion exchangers

Abstract

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)8NO3 · nH2O and Ni1-xZn2x(OH)2(CH3COO)2x · nH2O. 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= (Kd = 15,000). Its order of selectivity for various anions in the presence of 0.1 N̲ NaC1 (ratio of C1- to anion in question is 100) increases as follows: PO4= ≫ SO4= > NO3-.