In this work, a comparative study between two processes was performed—biodegradation and photocatalysis, as an advanced oxidation process—to discover which one is more efficient to degrade Rhodamine B, a synthetic dye widely used in the textile and food industries. The advantage of this study is that it correlates treatment efficiency with the ecotoxicity of the by-products resulting from the treatments. Since the COVID-19 pandemic, it has been difficult to use activated sludge because of the risk factor of COVID-19 infection. Therefore, biodegradation tests were conducted with the yeast Saccharomyces cerevisiae in this study. For the photocatalysis assays, TiO₂ doped with 5 per cent Cerium was used as a catalyst under UV light irradiation. S. cerevisiae cannot reduce RhB by biodegradation. However, a 13 per cent biosorption was observed with an uptake capacity of 4.2 mg g⁻¹ dry matter of S. cerevisiae cultivated in the presence of 5 mg L⁻¹ of RhB after 150 min. At a 5 mg L⁻¹ of RhB concentration, the 6 h photocatalysis treatment led to 55% color removal and 8.6% COT reduction. The biodegradability of the photocatalyzed solution increased since the BOD₅/COD ratio raised from 0.10 to 0.42. In the presence of glucose as a source of carbon, yeast can grow on the by-products generated by photocatalysis. The phytotoxicity of RhB in solution was measured using the germination index (GI) of watercress seeds. The GI decreases by 75% for an RhB solution of 100 mg L⁻¹ compared to the control sample. The by-products of the photocatalytic treatment, using crustaceans Daphnia magna and conducted with solutions of Rhodamine B, induced a decrease of 24% in the GI. Lethality test. After 3 or 6 h of treatment, no increase in immobilization or mortality of D. magna was observed compared to the negative control.

Nowadays, the contamination caused by emerging pollutants is a global concern due to the lack of scientific evidence to demonstrate the risk or toxicity to humans due to the presence of pharmaceutical residues in the environment. This study aimed to identify and describe the disposal practices of unused and unwanted medications, as well as to analyze and identify the most frequent drugs determined on water bodies adjacent to the biggest urban population in Mexico. A two-phase study with an epidemiological and an ecological assessment was performed. The epidemiological phase was carried out with a descriptive cross-sectional study among citizens from Mexico City and the metropolitan area using an electronic survey applied to 719 subjects aimed to assess practices in which pharmaceutical products are disposed. The ecological phase included a review of scientific reports. The results show that nearly 83.5% of those surveyed use inappropriate practices for disposal medicines, the main ones are through the municipal dump or directly in the drain. The ecological approach was carried out by a systematic literature review of original reports published between 2013 to 2023; information about the class of drugs, active substance, environmental compartments, location, and concentration was extracted and presented. Fifty-one different types of pharmaceutical residues were detected in wastewater in Mexico City in the last decade. The results of this study can contribute to the application of public policies for waste management authorities to mitigate the socio-environmental risks due to the inappropriate disposal of medicines.

In this article we discuss the synthesis of nanoparticles and the preparation of dense nanoceramics of Y-doped <mml:math display="inline"><mml:mrow><mml:msub><mml:mi>CeO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>CeO2 . We prepared the nanoparticles by combustion synthesis and characterized the nanopowders by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy. The good sintering properties of these nanopowders allowed us to obtain very dense ceramics of Y-doped <mml:math display="inline"><mml:mrow><mml:msub><mml:mi>CeO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>CeO2 ( <mml:math display="inline"><mml:mrow><mml:mo></mml:mo><mml:mn>90</mml:mn><mml:mo>%</mml:mo></mml:mrow></mml:math>90% theoretical density) and keep the grain size small, in some cases around <mml:math display="inline"><mml:mrow><mml:mn>100</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>nm</mml:mi></mml:mrow></mml:math>100nm , by using sintering temperatures as low as <mml:math display="inline"><mml:mrow><mml:mn>1250</mml:mn><mml:mo>°</mml:mo><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>1250°C and very short annealing times between 5 and <mml:math display="inline"><mml:mrow><mml:mn>60</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>min</mml:mi></mml:mrow></mml:math>60min . The microstructure of these nanoceramics was analyzed by atomic force microscopy and SEM. The most interesting feature of these nanoceramics is that the electrical measurements in <mml:math display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">N</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>N2 <mml:math display="inline"><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi>p</mml:mi><mml:mrow><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mn>3.5</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>6</mml:mn></mml:mrow></mml:msup><mml:mspace width="0.3em"></mml:mspace><mml:mi>atm</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math>(pO2=3.5×10−6atm) carried out by the four-point dc technique showed a considerable increase in total conductivity in comparison with the measurements in air or oxygen in the range <mml:math display="inline"><mml:mrow><mml:mn>700</mml:mn><mml:mo>–</mml:mo><mml:mn>900</mml:mn><mml:mo>°</mml:mo><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>700–900°C . This conductivity enhancement might be associated with the electronic contribution to the total conductivity and it is clearly higher than the ionic conductivity in the same temperature range.

COVID-19 pandemic has changed the normal course of activities around the World. The measures implemented to slow down the spread of the disease and its impact on the health system have also suggested a change in population dynamics. In the educational aspect, the paradigm of the traditional education had to change completely to a remote environment, representing a challenge for students, teachers, and education institutions. In this work we report the students’ response to the actions taken by the faculty of the Chemistry Sciences School of Universidad La Salle México to face online courses ensuring student accompaniment. After the term, a qualitative and quantitative study was performed to the school population using an electronic survey to address the response of students to the applied strategy. Data was analyzed using SPSS® software. 266 responses were obtained, which represents a response rate of 44%. 75.6% of the alumni reported having a good or excellent disposition regarding virtual sessions. Likewise, 48.9% reported adapting appropriately to the remote working modality. Also, 83.5% of students recognize the labor of the teachers by acknowledging that their effort and dedication was excellent or good. Students showed development of soft skills such as self-time and learning management; written, oral and technological communication. These results suggest the advantages perceived by students during the transition to virtual modality, mostly oriented to self-management of their learning and that could conform the basis for the development of new strategies that can be useful not only for a contingency situation, but also in the structuration and innovation of science programs.

Recently, high ionic conduction has been reported in nanostructured materials. This increase in conductivity can be important in technological applications, including micro‐Solid Oxide Fuel Cells, so the understanding of this phenomenon is essential. In this work, XRD, Raman spectroscopy, SEM, EDS maps, and UV‐Visible spectroscopy measurements are used to have an insight into the relationship between structural and electrical properties in nanostructured ytterbium stabilized zirconia (YbSZ) thin films prepared by ultrasonic spray pyrolysis. Raman measurements allowed the identification of a mixture of tetragonal and cubic phases at 4% of Yb doping, which cannot be detected by XRD, while the compositional maps suggest that Yb can be located preferentially in the grain boundaries. Changes in the activation energy values in bulk and grain boundaries are related to the small grain sizes (≤10 nm). UV measurements support the ionic nature of the charge transport. These results indicate that the high conductivity is a consequence of different physical parameters in the films such as stress in the materials, different crystalline phases, impurities diffusion to the grain boundaries, and the presence or absence of electronic conduction. A model that explains the increase of conductivity in nanostructured materials must include all these aspects.