Utilization of non-plasticized polymer inclusion membrane for highly selective colorimetric sensor detection of zirconium in environmental samples

Abstract

A pioneering colorimetric optical sensing system utilizing polymer inclusion membranes (PIM) devoid of plasticizers has been innovated for the discerning identification of zirconium(IV) within environmental specimens, characterized by its simplicity, speed, selectivity, and sensitivity. The assembly of this optical sensor relies on a physical immobilization technique, specifically the encapsulation method, which leads to the creation of the sensor membrane. The key components of the PIM sensor include 5-(2-benzothiazolylazo)-8-hydroxyquinolene (BTAHQ) as the reagent, polyvinyl chloride (PVC) serving as the base polymer, and Aliquat 336 functioning as an extractant. Empirical studies reveal that the responsiveness of the optical sensor is significantly affected by diverse parameters including the presence of PVC as the base polymer, thickness of the film, concentrations of BTAHQ and Aliquat 336, temperature, stirring conditions, and the pH level of the aqueous solution. Optimization endeavors have resulted in characterizing the sensor, establishing a linear dynamic range from 4.0 to 110 ng mL⁻¹ for Zr(IV), showcasing quantification and detection limits of 3.95 and 1.20 ng mL⁻¹, respectively. The sensor demonstrates a swift response time of absorbance for the PIM-based sensor which is observed at λ_max 622 nm. Furthermore, the advanced PIM formulation exhibits stability, and retains its sensitivity, selectivity, and reusability. The method has been successfully applied to determine zirconium in real environmental samples, encompassing soil, water, plant materials, and ore samples.