Abstract
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 a smartphone for colorimetric detection, a self-invented method based on paper and microtubes (PMTs) is proposed to test the photocatalytic performance of TiO2. Firstly, the study has identified that PMTs achieved a correlation coefficient of above 0.9 between the greyscale values and concentrations during the physical process of different color dyes (i.e., rhodamine B (RhB), reactive yellow (RY), methylene blue (MB), and mixtures of the two or three dyes). The results indicate that when the principle of solution color follows the CMYK (Cyan, Magenta, Yellow, Black) color model, its photo color on white paper background conforms to the RGB (Red, Green, Blue) color model. Compared to the results obtained from the absorbance method, the PMTs method showed high reliabilities up to 99.36% on the monitoring of the photocatalytic process of the different dye solutions. Interestingly, the colorless solution of salicylic acid (SA) could also be analyzed by the PMTs after complexed with Fe(III) ion to develop a purple solution. These results suggest that the PMTs could be an alternative analysis method to evaluating physical and chemical reaction processes when the high-tech analysis equipment is unviable.
Highlights
Color Greyscale-Concentration Curves of Different Dyes Measured by the paper and microtubes (PMTs) Method
The R2 of the standard-curve fits acquired by the PMTs method and the absorbance method were 0.950 and 0.999, respectively, indicating that the PMTs method has a good reliability in the experiment
A new chemistry the PMTs method, was to detect physical and chemical-reaction processes based on color variation
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Most of the current paper-based detection research focuses on the detection of the color development principle, and the research on the application principle of PAD itself is slightly insufficient. Moreira et al (2020) developed a novel paper-based assay device (PAD) combined with LED-induced fluorescence (fPAD) assay, using Corel Draw 9 software in combination with the fPAD method for simple, rapid, low-cost, and sensitive detection of Phe in neonatal blood sample [15]. People have developed an interesting color recognition software using the ImageJ analysis software [16], RGB mobile phone application software, and paper-based analysis devices to carry out the experimental research [17]. China) is a powerful office presentation software Combining it with a paper-based analysis method to identify color features may make the data reading process easier. PMTs as a quick and easy evaluation method could be conductive to screen out efficient photocatalysts more quickly and conveniently
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