The Cramer's rule for the parametrization of phenol and its hydroxylated byproducts: UV spectroscopy vs. high performance liquid chromatography.

A linear algebra theorem like Cramer's rule was used for the analysis of a system of equations obtained from UV spectroscopy, and results were compared against those obtained from HPLC analysis. This parametrization allowed to quantify the concentration of the main intermediate products detected along the photodegradation of phenol under UV-Vis irradiation of TiO2. UV spectroscopy data for phenol, hydroquinone, and benzoquinone were analyzed using the Cramer's rule. The overlapping interference of the intermediate products in the UV spectra was corrected. It can be concluded that the Cramer's rule can be used for the parametrization of the UV absorbance data of phenol and its main intermediate products. This methodology permitted to obtain the concentration of phenol and their intermediate products by UV-visible with a high precision in comparison of HPLC. The parametrization showed a correlation coefficient of ca. 0.9775 between the phenol concentration obtained by UV spectroscopy and values obtained from HPLC analysis. In this sense, results can be considered with good precision, and accordingly, it can be concluded that the methodology is reliable, and UV-visible spectroscopy can be selected instead of HPLC in much of the experiments concerning with aqueous-phase reactions.

Initial Approximation to the Design and Construction of a Photocatalysis Reactor for Phenol Degradation with TiO2 Nanoparticles.

A photoreactor was designed, built, and optimized to carry out the degradation of phenol. To achieve this, phenol concentration was used as the reference to compare the photocatalysis reaction efficiency obtained through this research with results from other studies. Additionally, during the building process, different types of glass were evaluated with the objective of finding a functional and economic material to build the photoreactor. It was found that Pyrex glass was the most suitable material to work with. As a UV light source to build the photoreactor, a dry gel nail lamp was used with 9 W, λ = 365 nm bulbs. On the other hand, the effects of different parameters (such as the catalyst mass (TiO2 Degussa P-25), stirring speed (RPM), UV lamps, and temperature) over the photocatalysis reaction rate were analyzed. Also, the reaction's thermodynamic parameters were determined and found to be similar to those found in other investigations. Finally, the homogeneity in the distribution of TiO2 particles inside the reactor when stirred at 475 rpm was verified using a COMSOL Multiphysics computer fluid dynamics simulation, which showed the theoretical trajectory of particles inside the reactor depending on the stirring rate of the reactor.