TiO2 exists naturally in three crystalline forms: anatase, rutile, brookite, and TiO2 (B). These polymorphs exhibit different properties and consequently different photocatalytic performances. This paper aims to clarify the differences between titanium dioxide polymorphs, and the differences in homophase, biphase, and triphase properties in various photocatalytic applications. However, homophase TiO2 has various disadvantages such as high recombination rates and low adsorption capacity. Meanwhile, TiO2 heterophase can effectively stimulate electron transfer from one phase to another causing superior photocatalytic performance. Various studies have reported the biphase of polymorph TiO2 such as anatase/rutile, anatase/brookite, rutile/brookite, and anatase/TiO2 (B). In addition, this paper also presents the triphase of the TiO2 polymorph. This review is mainly focused on information regarding the heterophase of the TiO2 polymorph, fabrication of heterophase synthesis, and its application as a photocatalyst.
The advancement of smartphones that produce high-resolution photos has made their use even more developed. One application that is currently developing is a digital image produced as colorimetry. Digital image-based colorimetry is an easy and simple determination method and can be an alternative for analyzing dyes quantitatively. In this method, the color response of the digital image is analyzed, namely red-green-blue (RGB) with values from 0 to 255. This data is extracted from digital images using ImageJ 1.52a software for quantitative determination. In this study, 2 standard methods were used, namely external standards and standard addition to evaluating the most suitable method to obtain accurate measurements. In addition, 2 methods were used to determine the relationship of response to methylene blue levels. The 1st method used simple linear regression of each color red, green, or blue (univariate). The 2nd method is used in multivariate linear regression of the 3 colors red, green, and blue. The accuracy of the method was validated using UV-Vis spectrophotometry as the reference method. The results showed that the multivariate models produced very good accuracy, namely precision of up to 99 % compared to the simple regression method with the univariate.
HIGHLIGHTS
Smartphone cameras can be applied easily as a simple, fast, and inexpensive colorimetric method for quantitative analysis of methylene blue content
The univariate models for external standard and standard addition methods showed up to 90 % precision for fish drug samples against UV-Vis spectrophotometric methods
The multivariate models for the external standard method provide up to 99 % precision results for fish drug samples against UV-Vis spectrophotometric methods·
GRAPHICAL ABSTRACT
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