TiO2 material is composited with silica obtained from natural sand with indirect sonochemistry method. The addition of SiO2 increase the photocatalyst activity of TiO2 as an antibacterial against S. aureus and P. aeruginosa.

Silica has become a popular material due to its high abundance and many advantages in various fields. This material can be produced synthetically and extracted from nature with resultant advantages in the application of green production. Therefore, this article deals with the form of silica extracted from quartz sand, leaves, and agricultural wastes found in nature. The extraction process from various sources would be described using thermal, biological, and chemical methods. This review also highlights the potential application of silica as a photo catalytic antibacterial-supporting material and discusses its role in increasing the effectiveness of the process. The discussion was continued with research on this procedure, where synthetic auxiliary materials were compared to the extracted silica. Furthermore, results obtained indicated that the extracted material had very good potential as a photocatalyst adjunct in its application in the antibacterial field.

Titania−silica nanocomposites (TiO 2 −SiO 2 ) show outstanding performance and is very well applied in photocatalysis. In this research, SiO 2 extracted from Bengkulu beach sand will be used as a supporting material of the TiO 2 photocatalyst for application to polyester fabrics. TiO 2 −SiO 2 nanocomposite photocatalysts were synthesized using the sonochemical method. The coating of the TiO 2 −SiO 2 material on polyester was carried out using the sol−gel-assisted sonochemistry method. The method of determining self-cleaning activity uses a digital image-based colorimetric (DIC) method, which is much simpler than using an analytical instrument. The scanning electron microscopy−energy dispersive X-ray spectroscopy results showed that the sample particles adhered to the fabric surface and the best particle distribution was shown in pure SiO 2 and 1:0.5 TiO 2 −SiO 2 nanocomposites. Analysis of Fouriertransform infrared (FTIR) spectroscopy proved the presence of Ti−O and Si−O bonds as well as the typical spectrum of polyester, which indicated that the fabric had been successfully coated with nanocomposite particles. The analysis of the contact angle of the liquid on the polyester surface showed a significant change in the properties of the TiO 2 and SiO 2 pure coated fabrics, but changes occur only slightly in the other samples. Self-cleaning activity against the degradation of methylene blue dye has been successfully carried out using DIC measurement. The test results showed that the best self-cleaning activity was shown by TiO 2 −SiO 2 nanocomposite with a ratio of 1:0.5 with the degradation ratio reaching 96.8%. Furthermore, the self-cleaning property remains after the washing process, which shows excellent washing resistance.

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