Solid-Contact Electrode with Composite PVC-Based 3D-Printed Membrane. Optimization of Fabrication and Performance

Intense interest in reference electrode design and fabrication has recently been enriched with the application of 3D printing of electrodes with salt-loaded PVC membranes. This type of material is attractive in sensor technology and is challenging to implement in 3D. In this report, several improvements and simplifications in the technology were focused on and supported by a fundamental electrochemical characterization.

Elaboration and characterization of multilayer polymeric membranes: effect of the chemical nature of polymers

The transport phenomena across polymeric membrane may be enhanced by applying various strengths inside or outside the system. Recently, polymer inclusion membrane (PIM) has been considered one of the most popular methods that acts as a sink for the contaminant and immobilizes it. In the literature, there is no report about how to achieve the synthesis of multi-layer PIMs. In this paper, an improvement of a novel category of membrane without carrier for performing ion separation is reported. Different membranes were elaborated from binary mixtures of polymers, cellulose triacetate (CTA), polymethyl methacrylate (PMMA) and polyvinyl chloride (PVC) using 2-nitrophenyl octyle-ether (NPOE) as plasticizer and carrier in the same time, in order to increase specific interactions between the different polymers. The membranes (Polymer 1– NPOE – Polymer 2) were synthesized by phase inversion method modified by changing the procedure of a plasticizer/carrier addition and characterized by FTIR, TGA, SEM, zeta potential and contact angle. The CTA-based membranes exhibited well-defined pores partially filled with the second polymer and NPOE. Overall, our results showed that the addition of NPOE resulted in homogeneous membranes with modified physical properties, such as thickness, and hydrophobicity. A study of transport of Pb(II) using the synthesized membranes was studied. Dialysis experiments of lead ions across a polymeric membrane have shown that (CTA + NPOE + PMMA) and (PMMA + NPOE + PVC) membranes proved a good performance in one stage by fixing 12.15 and 25.31% of lead, respectively, without any additionally added carrier and acids. These results confirm the affinity between a basic polymer (poly-methyl methacrylate) and the metallic ion (Pb2+).

All-Solid-State Ion-Selective Electrodes Based on Graphite Paste for Determination of Calcium(II) and Nitrate

Robust and easy-to-handle ion-selective electrodes in all-solid-state configurations based on graphite paste have been developed for applications in environmental samples. The electrode consists of different functional layers (graphite paste, conducting polymer, ion-selective membrane). The ion-selective compounds have been incorporated in polyvinylchloride (PVC) membranes. Polypyrrole (PPy) acts as a solid contact and an intermediate layer between the ion-selective membrane and the graphite paste. As ion-complexing compounds tridodecylmethylammonium nitrate (TDMA-NO3) for nitrate, N,N,N’,N’-tetra[cyclohexyl]diglycolic acid diamide and N,N-dicyclohexyl-N‘,N‘-dioctadecyl-diglycolic diamide for calcium(II) determinations have been used. The electrodes have been tested in drinking and well water samples by direct potentiometric determination and by titrations. The results have been compared to ion chromatography as the reference method. Both ion selective electrodes exhibit linear response from 10-5 mol/L to 10-1 mol/L respectively. The detection limits for the target ions are below 10-6 mol/L based on the respective ion.