Br-PADAP embedded in cellulose acetate electrospun nanofibers: Colorimetric sensor strips for visual uranyl recognition

In this work, a new visual colorimetric strip based on cellulose acetate nanofiber mats modified by 2-(5-Bromo-2-pyridylazo)-5-(diethylamino) phenol was successfully prepared via electrospinning technology. The prepared colorimetric strip showed high sensitivity towards UO₂²⁺ with the yellow-to-purple color change signal. Upon the optimal conditions of solution pH at 6.0 and response time for 80min, the detection limit for UO₂²⁺ can reach 50 ppb. Moreover, the strip also exhibited excellent anti-interference ability in the presence of other metal ions. In order to achieve the quantitative detection for UO₂²⁺, a color-differentiation map was established, which was prepared from converted H values. Finally, the strip was also used to detect UO₂²⁺ in the seawater and showed high sensitivity.