Use of layered double hydroxides as ionophore for anion selective electrode

Abstract

Layered double hydroxides (LDHs) or hydrotalcite compounds are referred to anionic clays with specific anion adsorption and exchanging properties. These behaviors are similar to ionophores and ionic additives in ion selective electrodes (ISEs). Therefore, in this study LDHs was used to function as tailor-made ionophores for particular anions and ionic additives in ISEs. MgAl LDHs were prepared, and then modified the intercalated anions to be NO3-. The selective polymeric membrane was casted using PVC and MgAl LDHs-NO3-. The membrane containing 30%(w/w) MgAl LDHs-NO3- showed the best ISE characteristics toward NO3- with response slopes of -51.31 mV decade-1 in the concentration range 1.0 x 10-4 to 1.0 x 10-2 M. However, attempts of the selectivity studies using separate solution method (SSM) showed the selectivity coefficients of SCN- and NO3- were not significantly different. The results present an idea for fabrication of tailor-made ionophores for anions which can lead to further development.