Evaluating TiO2 Photocatalysis Performance in Microtubes on Paper Background by Smartphone: Principles and Application Examples

Titanium dioxide (TiO2) photocatalysis is a popular and promising technology in water treatment, but the performance evaluation usually depends on expensive equipment. In this study, using smartphone for colorimetric detection, self-invented method based paper microtubes (PMTs) proposed to test photocatalytic of TiO2. Firstly, study has identified that PMTs achieved correlation coefficient above 0.9 between greyscale values concentrations during physical process different color dyes (i.e., rhodamine B (RhB), reactive yellow (RY), methylene blue (MB), mixtures two or three dyes). The results indicate when principle solution follows CMYK (Cyan, Magenta, Yellow, Black) model, its photo white background conforms RGB (Red, Green, Blue) model. Compared obtained from absorbance method, showed high reliabilities up 99.36% monitoring dye solutions. Interestingly, colorless salicylic acid (SA) could also be analyzed by after complexed with Fe(III) ion develop purple solution. These suggest an alternative analysis evaluating chemical reaction processes high-tech equipment unviable.