Evaluation of a novel PVC-based efficient potentiometric sensor containing a tripodal diglycolamide (TREN-DGA) ionophore for europium(III) estimation

Polymeric membrane-based electrodes containing a multiple diglycolamide (DGA), such as a N-pivot diglycolamide (diglycolamide-TREN (TREN-DGA) and a C-pivot diglycolamide (tripodal diglycolamide) (T-DGA) as ionophore, and polyvinyl chloride (PVC) as the base polymer were fabricated. These membranes were tested for the potentiometric determination of europium ions in acidic feed solutions. The membrane with a composition of 81.5% PVC and 18.5% TREN-DGA showed a wide dynamic range (3.2 × 10−7 to 1.0 × 10−2 M) with a slope of 17.2 ± 0.4 mV per decade for europium ion. The presence of sodium tetraphenyl borate (NaTPB) as ionic additive in the DGA-TREN containing membrane marginally improved the dynamic range in the detection of europium ion. On the other hand, the membrane with a composition of 77.3% PVC and 22.7% T-DGA does not show any systematic potential response against variation of the concentration of europium ions in the external solution containing 1 M HNO3. The physical characterization of these membranes was carried out using techniques such as thermogravimetry (TGA), Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) in order to understand the effect of the different constituents of the membrane on the potential response for europium ion. AFM measurements revealed that the morphology of the membrane remained intact even after prolonged use of the membrane. The interference effect of Ca2+, Mg2+, Cu2+, Fe3+, Bi3+, Zn2+, Cd2+ and UO22+ on the potential response was investigated. The response time of the proposed sensor was found to be less than five seconds. The lifetime of the sensor electrode was found to be three months under proper storing conditions. The membrane sensor was employed in the determination of Eu3+ in synthetic water samples.