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

Using a biphasic system and digital imaging analysis with chemometric tools for simultaneous determination of Cu2+ and furfural in cachaça

The present study reports, for the first time, the development and application of a highly efficient method based on digital imaging analysis for the simultaneous determination of Cu²⁺ and furfural in cachaça samples using a two-phase system and chemometrics tools. Furfural reacts with aniline in an acidic medium to form a Schiff base, which exhibits a pink color. On the other hand, Cu²⁺ reacts with cuprizone in a basic medium to form a blue complex. The two reactions were performed on a porcelain plate, and a smartphone was used to capture the colorimetric images. Partial least squares (PLS) regression was used to construct the prediction models for Cu²⁺ and furfural contents in cachaça samples. After finding the best PLS models, the ordered predictor selection (OPS) analysis was performed in order to select the most predictive variables. The method developed was found to be effective in estimating the amounts of Cu²⁺ and furfural in cachaça samples, with a mean absolute error of 0.2 mg L^-1 for the Cu²⁺ model, and 0.3 mg per 100 mL of anhydrous alcohol for the furfural model. The method proposed in this study is simple and straightforward; it does not require complex technical knowledge and can be used by the producers themselves in the cachaça manufacturing process.

Preparation of molecularly imprinted Ag-TiO2 for photocatalytic removal of ethyl paraben

Herein, MI-Ag-TiO₂ was prepared by one-step sol-gel method, and its photocatalytic and characterization performance were fully analyzed. Within 120 min, the photocatalytic degradation rate of MI-Ag-TiO₂ to ethyl paraben was 93.4%, which was 1.48 times that of naked TiO₂. Compared with Ag-TiO₂, MI-TiO₂, and TiO₂, the photocatalytic selectivity of MI-Ag-TiO₂ to target pollutants increased by 24.5%, 31.5%, and 100%, respectively. Hence, the one-step molecular imprinting method can simply and quickly improve the photocatalytic performance of TiO₂. This research may help to further promote the practical application of molecularly imprinted photocatalysts in the future.

Evaluation of photodegradation performance by paper microzones

Currently, the performance evaluation of catalysts usually requires expensive instruments. Hence, it is imperative to develop an alternative, green and sustainable method to investigate the photocatalytic reaction processes. Herein, the variation of degradation performance of different wastewaters with different dosage of P25 TiO₂ was evaluated to verify the reliability of the paper microzones method (PMZs). The optimum P25 TiO₂ dosage of 1 g/L for the degradation of methylene blue (MB) (UV light for 6 mins) and 0.5 g/L for the degradation of fuchsin basic (FB) (UV light for 5 mins) was obtained by the PMZs method. For the photocatalytic degradation of trivalent iron ion complexed salicylic acid (Fe(III)-SA) solution, the R² values of 0.904 and 0.801 were obtained for the photocatalytic reaction kinetics by PMZs and spectrophotometry, respectively, which again indicated the high reliability of PMZs. The accuracy of the results obtained by PMZs method relative to the spectrophotometric method ranged from 68.80% to 87.54% when degrading MB, FB, mixture of MB and FB, and Fe(III)-SA by P25 TiO₂. Therefore, the PMZs method is all in line with the requirements of low-carbon environmental protection and green chemistry, and has broad application prospects in the future.