The electrocoagulation (EC) process has been widely studied in recent years to remove a wide range of contaminants present in different types of water: fluorides, arsenic, heavy metals, organic matter, colorants, oils, and recently, pharmaceutical compounds. However, most of the studies have been aimed at understanding the process factors that have the most significant effect on efficiency, and these studies have been mainly on a batch process. Therefore, this review is focused on elucidating the current state of development of this process and the challenges it involves transferring to continuous processes and the recent exploration of its potential use in the removal of pharmaceutical contaminants and its implementation with other technologies.

Anthocyanidins in the gas phase and under the effects of solvents such as water, ethanol, n-hexane, and methanol have been studied using DFT and TDDFT electronic structure calculations for applications as natural dyes in photocatalysis. The results include HOMO and LUMO orbitals, HOMO-LUMO gap, chemical properties, reorganization energies, and excited states. Malvidin presented the lower HOMO-LUMO gap energy. After the inclusion of solvents, HOMO-LUMO gap energy increased in all cases, presenting malvidin with n-hexane as the narrower gap energy. Conceptual DFT results showed that cyanidin, malvidin, and pelargonidin present good charge transfer properties. Cyanidin presented a lower electron reorganization energy (λe) when water is used as the solvent. TDDFT has been used for excited states calculation and absorption data show the main peaks in a wavelength between 479.1 and 536.4 nm. The UV–Vis absorption spectra were generated and the solvent effects in each case are discussed. In consequence, pigments selected in this attempt are suitable to work in the visible part of the electromagnetic spectrum and display the main peak in the green region. These pigments are found as good options for photocatalysis applications, and the best choices for dye sensitization are cyanidin, malvidin, and petunidin after including the more common anthocyanidins in the analysis.

Cosensitization has emerged as a method to improve performance of dye sensitized solar cells (DSSCs) and photocatalysis. In this work, it is proposed to use organic dyes as cosensitizers due to their friendliness with the environment and to the benefits of having two or more different dyes with complementary optical absorption characteristics. Several organic dyes are analyzed as cosensitizers to identify which dye combinations may be good choices to approach a panchromatic absorption spectrum emulating the solar emission spectrum. In addition to the analysis on the prospective sensitizers, it is presented results of titanium dioxide (TiO2) nanoclusters cosensitized with two anthocyanidins using density functional theory (DFT) and time-dependent DFT (TD-DFT). The nanocluster size proved to be definitive in the interactions with two molecule dyes. The selected (TiO2)4–5 nanoclusters cosensitized with two anthocyanidins produce data for a prospective analysis to suggest which dyes are good options for DSSCs and photocatalysis based on dye co-sensitization applications. At the end, one can look at this work as a perspective of which organic dyes may work well as cosensitizers and a contrast to original data from our experimentation with a couple of TiO2 nanoclusters cosensitized with two different anthocyanidins.

Soil health is a great concern worldwide due to the huge variety of pollutants and human activities that may cause damage. There are different ways to remediate and make a better use of soil and a choice may be using zeolite in activities like gardening, farming, environment amending, among others. In this work is proposed a model to simulate how mixing zeolite with soil may be beneficial in different ways, we are especially interested in interactions of mixed soil-zeolite with water. This model is based in different flow regimes where water interacts with two layers formed by nanostructured zeolite and soil in a vertical arrangement. The analysis is approached as a bi-layer porous material model resolved by using the mathematical model implemented in ANSYS-Fluent. Such model uses a multi-fluid granular model to describe the flow behavior of a fluid–solid mixture where all the available interphase exchange coefficient models are empirically based. Despite the great capabilities of numerical simulation tools, it is known that at present time, the literature lacks a generalized formulation specific to resolve this kind of phenomena where a porous media is analyzed. This model is developed to obtain a systematic methodology to test nanomaterials with porous features produced in our laboratory which is the next step for near future work within our research group.

A photocatalytic reactor is a device mostly used for degrading the contaminants in aqueous solutions, as well as may be used for contaminant removal from the air, wastewater treatment, and water splitting. Fundamental concepts regarding the design process of such a device are analyzed in this chapter, which includes concepts related with sunlight usage as a clean energy source, which is known as a highly desirable renewable technology. The main interest of this proposal relies on modeling the hydrodynamics of a helical pipeline that will be used in a photocatalytic reactor subject to a turbulent flow regime where sunlight is used to activate a chemical reaction to degrade water pollutants. Numerical calculations are based in computational fluid dynamics (CFD) using ANSYS-Fluent⁽™⁾. The different steps, geometric domain, preprocessing steps, setup, and postprocessing steps are described to analyze a numerical calculation for this kind of reactors. The turbulent flow models used are briefly explained so the design intent is better understood by the reader. All the modeling, numerical calculations and analysis are carried over in ANSYS-Fluent⁽™⁾, a powerful multi-physics program suite suitable for hydrodynamics simulations.