Coffee grounds are an organic waste consisting of the ground, roasted and processed grain for the extraction of coffee, being of great volume the waste obtained, which, if not treated and preserved for a long time, emanates unpleasant aromas and becomes an optimal means for the proliferation of flies, and other pests. Activated carbon has the characteristic of being a material that has a large surface area; because of this, it is used in adsorption, which refers to the retention of atoms, ions, and molecules on its surface. In this paper, the production of activated carbon is presented by means of the physicochemical activation of coffee waste by calcining at 900 °C and subsequent activation with sulfuric acid, as well as the Box–Behnken design of three factors for chromium (III) adsorption optimization. It is determined that the optimal conditions for performing the adsorption are pH = 3 and a contact time of 140 min. According to the analysis of variance for the experimental design, it is determined that the initial chromium formation is not significant for the adsorption process. Under the optimal adsorb conditions of 96%, an application is given to the erasure of coffee for the production of activated carbon, which serves as the adsorbent agent applied to the removal of chromium (III) aqueous. The area of activated carbon obtained is 13657.89 ± 251.09 m²/g determined by the acetic acid adsorption isotherm method.

An exploratory study to determine the effectiveness of discussion sessions as a teaching strategy of Thermodynamics in Basic Physical Chemistry of fundamental concepts in this area as spontaneity by explaining students according to their ideas. A previously validated questionnaire was used as an instrument on Thermochemistry, Enthalpies of Bonding, and Gibbs Function. The performance of the students who participated in the intervention was compared with that of a control group to which the afore mentioned teaching strategy was not applied. The students of the intervened group explained with a higher academic level the concept of spontaneity than those of the control group reaching the level of the development of the process of effective chemical reasoning (DECRP) of the taxonomy of Barrow and Bloom.

Electronegativity is an intrinsic parameter of each chemical element that influences the response, chemical reactivity, polarity, as well as the attraction between molecules among other effects. In this sense, a didactic strategy was developed for teaching at the undergraduate level to determine the effect that electronegativity has on the vibration response of the C-Halogen bond in a molecule, through a practical experience that involved on the one hand the technique of infrared spectrophotometry and organic molecules with the presence of halogen atoms. The didactic strategy was applied to a group of students of the bachelor’s degree in industrial chemistry, which was divided into teams of 5 students who worked based on cooperative learning and with problem-based learning support, they were studying spectroscopy and who had previous knowledge of the infrared spectroscopy technique. After carrying out, the experiment and with the results obtained, the students were able to conclude that due to the strength and distance of the bond between halogen and carbon, the value of the wavenumber (cm-1) is modified, concluding that in shorter bonds a greater energy is required for it to be stretched and in longer and weaker bonds as in the case of Iodine these are stretched to a lower wavenumber. This allowed students to understand this phenomenon and the dependence of electronegativity, bond length, and bond strength on a specific response observed using infrared spectroscopy.

A didactic sequence is presented with the aim of enabling students to integrate the concepts of enthalpy, entropy, chemical reaction, and balance into their daily lives through the Project-Based Learning (PjBL) strategy. The strategy was applied in a group of the High School. A project was assigned to each team of 4-5 students. The projects developed were the obtaining of a white bioglue for home consumption, the neutralization of stomach acidity and the oxidation of hydrocarbons. At each stage of the project, students took responsibility for their own learning and the teacher served only as a guide. Before and after the implementation of the strategy, a questionnaire with multiple-choice and open-ended questions was applied. Based on the results, an improvement was observed in the correlation of the concepts of enthalpy, entropy and equilibrium with chemical reactions and their importance in everyday life. Also, it was evidenced that the alternative conceptions of the concepts of temperature, heat, work, enthalpy, entropy, spontaneity and chemical equilibrium were reduced, when analyzed from chemistry in context.

A Fe3O4/HNTs composite was synthesized, characterized by XRD, FTIR, SEM, and N2 adsorption-desorption, and was used for an ibuprofen adsorption and oxidation study. The response surface methodology (RSM) and Box-Behnken experimental designs were used. The effect of pH, contact time, IBU concentration, and Fe3O4/HNTs dosage on ibuprofen adsorption were evaluated. Additionally, adsorption isotherms and a kinetic study were performed. The effect of pH, H2O2 concentration, and Fe3O4/HNTs dosage for IBU oxidation were also studied. The results of ibuprofen adsorption on Fe3O4/HNTs indicate that adsorption was favored at acidic pH. The adsorption followed pseudo-second-order kinetics and a Freundlich isotherm. A 99.99% IBU oxidation and 99% mineralization were achieved at pH 7, Fe3O4/HNTs dosage of 1.5 g L-1, and 0.5 M H2O2. The Fe3O4/HNTs catalyst prepared in this study was efficient in removing aqueous ibuprofen through heterogeneous Fenton-like reaction.

A Fe₃O₄/HNTs composite was synthesized, characterized by SEM, TEM, XPS, adsorption–desorption N₂, XRD, FTIR, VSM and Zeta potential, and was used for an ibuprofen adsorption and Fenton oxidation study. The response surface methodology (RSM) and Box–Behnken experimental designs were employed. The effects of pH, contact time, ibuprofen concentration, and Fe₃O₄/HNTs dosage on ibuprofen adsorption were evaluated. Additionally, adsorption isotherms and a kinetic study were performed. The effects of pH, H₂O₂ concentration, and Fe₃O₄/HNTs dosage for IBU removal were also studied. The results of ibuprofen adsorption on Fe₃O₄/HNTs indicate that adsorption was favored at acidic pH. The adsorption followed pseudo-second-order kinetics and a Freundlich isotherm. Under mild conditions (pH 7, 298.15 K) with a Fe₃O₄/HNTs dosage of 1.5 g L⁻¹ and 0.5 M H₂O₂, the heterogeneous Fenton-like reaction achieved 99% ibuprofen removal and 60% mineralization. The Fe₃O₄/HNTs catalyst demonstrated high efficiency for aqueous ibuprofen removal under environmentally mild pH and temperature conditions, and it was easily recoverable and reusable.