An All-Solid-State Silicate Ion-Selective Electrode Using PbSiO₃ as a Sensitive Membrane

Ion-Selective Electrode (ISE) is an emerging technology for in situ monitoring of the chemical concentrations of an aqueous environment. In this work, we reported a novel all-solid-state silicate ISE, using an Ag/Pb/PbSiO₃ electrode. This electrode responded to aqueous SiO₃^2- with a reasonable slope of -31.34 mV/decade and a good reproductivity. The linear range covered from 10^-5 M to 10^-1 M, for the Na₂SiO₃ solutions and the response time was generally less than 5 s. Its potentiometric response to pH and silicate indicated that the prepared electrode was sensitive to silicate, rather than pH. Compared to the traditional liquid ISE, our all-solid-state silicate electrode was resistant to high pressure and could be used in situ, in deep water. In addition, the miniaturized electrodes (diameter of 0.4 mm and a length of 2⁻3 cm) could be easily integrated into a multi-modal sensor, which could simultaneously determine multiple parameters. Our prepared silicate ISE could potentially be used to determine the presence of silicate in a low-chloride aqueous environment, where the ISE exhibited better selectivity for silicate, over interfering ions such as, SO₄²^-, NO₃^-, CH₃COO^-, CO₃²^-, and PO₄³^-.