Nanomembrane Canister Architectures for the Visualization and Filtration of Oxyanion Toxins with One-Step Processing

Nanomembrane canister-like architectures were fabricated by using hexagonal mesocylinder-shaped aluminosilica nanotubes (MNTs)-porous anodic alumina (PAA) hybrid nanochannels. The engineering pattern of the MNTs inside a 60 μm-long membrane channel enabled the creation of unique canister-like channel necks and cavities. The open-tubular canister architecture design provides controllable, reproducible, and one-step processing patterns of visual detection and rejection/permeation of oxyanion toxins such as selenite (SeO₃ ^2-) in aquatic environments (i.e., in ground and river water sources) in the Ibaraki Prefecture of Japan. The decoration of organic ligand moieties such as omega chrome black blue (OCG) into inorganic Al₂O₃@tubular SiO₂/Al₂O₃ canister membrane channel cavities led to the fabrication of an optical nanomembrane sensor (ONS). The OCG ligand was not leached from the canister as observed in washing, sensing, and recovery assays of selenite anions in solution, which enabled its multiple reuse. The ONS makes a variety of alternate processing analyses of selective quantification, visual detection, rejection/permeation, and recovery of toxic selenite quick and simple without using complex instrumentation. Under optimal conditions, the ONS canister exhibited a high selectivity toward selenite anions relative to other ions and a low-level detection limit of 0.0093 μm. Real analytical data showed that approximately 96 % of SeO₃ ^2- anions can be recovered from aquatic and wastewater samples. The ONS canister holds potential for field recovery applications of toxic selenite anions from water.