Colorimetry collaborated with WeChat applet: An on-screen direct-reading solution for end-to-end real-time monitoring of adsorption, degradation and recycle of dyes in water environment

Herein, an on-screen direct-reading solution was initiated for real-time monitoring of adsorption, degradation and recycle of dyes in water by integrating colorimetry with WeChat applet, in which MCM-41 composites were served as an all-rounder. Thanks to electrostatic interaction and mesoporous structures, MCM-41 showed superb binding performance toward dyes with the maximum extraction capacity up to 1.18 mg/mg (basic blue 26) and fast binding equilibrium within 1 min. Colorimetric cards with colors mapping to the dosage gradients of dyes were prepared by dyes-extracted MCM-41 or dye solutions, then RGB values of colorimetric cards were picked and embedded into a lab-made WeChat applet to build underlying digital colorimetric matrixes. Direct-reading analysis could be realized by automatic alignment of color information with inbuilt database of the applet in both online and offline ways with high sensitivity, in which the signal could still be readout even the dosage variations of dyes as small as 0.1 μg/mL. As proof-of-concept assays, this solution was finally applied to real-timely monitor the adsorption, degradation and recycle of dyes in water environment including industrial wastewater, aquaculture pond water and river water. Fine consistence between direct-reading results and those of colorimetry as well as instrumental technique like spectrometry assured high reliability of this strategy.