Improvement of nitrate-leaching control technology using an anion exchange compound on agriculture 1: synthesis of a Mg-Fe system layered double hydroxide and its anion exchange characteristics

Abstract

ABSTRACTA hydrotalcite-like compound for reducing the leaching of nitrogen from farmland was prepared via a new synthesis procedure, and its chemical structure and anion exchange characteristics were described. The advantage of this new synthesis method is that it is a simple, inexpensive process that involves the mixing of only two types of materials, followed by a hydrothermal reaction that does not require pH or gas control. The materials for synthesis are MgO and FeCl3. Chemical analysis, X-ray diffraction, and scanning electron microscopy were used to confirm an Mg-Fe system hydrotalcite-like compound. The anion exchange capacity was 166 cmolc kg−1, which was determined using NO3− ion as an exchangeable anion. That capacity is equivalent to 23 g N kg−1. The nitrate adsorption isotherm of this compound approximately matched to the isotherm that was predicted by the Langmuir formula. The anion exchange selectivity coefficients of the compound were in the following order: NO3− > Cl− > SO42− > HPO42−. The developed compound is a prospective material for reducing leaching of NO3−N from farmland.