A Miniature Fabry–Pérot Fiber Interference Sensor Based on Polyvinyl Chloride Membrane for Acoustic Pressure Sensing in Mid–High-Frequency Band

In this paper, a Fabry–Pérot interference fiber sensor was fabricated by using a Polyvinyl chloride membrane (20 μm in thickness) attached at the end of a ferrule with an inner diameter of 1.1 mm. In consideration of the vibration response of the membrane, the feature of the first-order natural frequency of membrane was analyzed by COMSOL Multiphysics. The acoustic sensing performance of the Fabry–Pérot fiber interference sensor was studied in air. The results reveal that the sensor possessed good acoustic pressure sensitivity, in the order of 33.26 mV/Pa. In addition, the noise-limited minimum detectable pressure level was determined to be 58.9 μPa/Hz1/2 and the pressure-induced deflection obtained was 105 nm/Pa at the frequency of 1 kHz. The response of the sensor was approximately consistent with the reference sensor from 1 to 7 kHz. All these results support that the fabricated Fabry–Pérot fiber interference sensor may be applied for ultra-sensitive pressure sensing applications.

Tertiary Amine-Mediated Polyvinyl Alcohol Membrane Over the Porous Support of Polyvinyl Chloride Membrane for CO2 Separation

Great attention has been paid to membrane-based separation technology in various separation fields, including gas separation. It provides the benefits of energy efficiency, environmental friendliness, easy scale-up, and convenience in operation. Different division advancements are being utilized for the expulsion of acid gas carbon dioxide (CO2). The aim of this work is to synthesis the membrane using polyvinyl alcohol (PVA) with treatment (WT) and without treatment (WOT) of the additive that is triethanolamine (TEA), to study the effect of additive on the permeance of membrane towards CO2 and the morphology changes of each membrane. In this research, virgin PVA and PVA with TEA were cast upon the porous support membrane of polyvinyl chloride (PVC). PVA was used as the polymer matrix, and TEA was used as a CO2 facilitating agent. Distilled water was used as a solvent for TEA and PVA in preparing the solution. Dimethyl acetamide (DMAc) and Tetrahydrofuran (THF) were used as solvents for PVC porous membranes. These membranes were tested on CO2 to find out the permeability and flux rates (J). For the morphology of the membrane, we performed SEM; for thermal analysis, we performed DSC and TGA, and for the strength, we performed the tensile test. The results reveal that the presence of TEA changes the morphology and thermal behavior increases the strength and the permeability of CO2. In a nutshell, the presence of TEA enhanced the performance and the morphology of the membrane.

Thiophene-based Schiff base ligand as ionophore for Ni(II)-selective polyvinyl chloride membrane electrode

A synthesized Schiff base 2-acetylthiophene semicarbazone (3) was used for the preparation of Ni2+ selective polyvinyl chloride (PVC) membrane electrode. The prepared electrode with the optimized composition, PVC:3:sodium tetraphenylborate:di-n-butylphthalate as 33:6:3:58 exhibited a Nernstian response over the working range of 5.0 × 10−6–5.0 × 10−2 mol l−1 with a slope of 29.0 ± 0.3 mV/concentration. The electrode showed good selectivity towards Ni2+ with respect to several metal ions in the pH range of 2.5–10.0 in <15 s with a detection limit of 4.7 × 10−6 mol l−1. The electrode showed the additional benefit of working in partially nonaqueous media having up to 15% (v/v) methanol or ethanol. This electrode was also successfully applied in Ni2+ ion potentiometric titration with ethylenediaminetetraacetic acid as an indicator electrode.