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Epoxy resin composite matrices reinforced with carbon fibers are highly demanded by certain industries such as the aeronautics industry because of their exceptional mechanical properties. Unfortunately, the use of reinforcing carbon fibers makes these composite materials hard to recycle by conventional methods. Therefore, in this study, specific hydrothermal treatments have been employed to recover carbon fibers from the offcuts of composite parts from the aeronautics industry. The resin decomposition rates (DRs) achieved by different settings of the operating parameters, such as the use of alkaline catalysts (KOH, NaOH, or K2CO3), the application of mechanical stirring, the use of different reaction times, the solvent volume/composite mass ratio, the specific surface area (surface area/mass) of the composite pieces, and the operating temperature and pressure (subcritical or supercritical conditions), have been examined and assessed. Under the conditions that have been evaluated, resin decomposition rates nearly as high as 98% have been achieved, while the recycled fibers retained over 95% of their original tensile strength (TS).

In this paper, ozonation is used as a pre-treatment for two different kinds of wastewaters. The first purpose is the study of the effect of ozonation on a landfill leachate treated by a reverse osmosis process prior a concentration step in an atmospheric evaporator. At first sight, an ozone treatment can supply three effects: Defoaming capacity, biocide effect, and pH acidifier to avoid the ammonia striping in the evaporation process. The second purpose of this paper is regarding hydrothermal liquefaction (HTL) of wastewaters. HTL can produce a liquid fuel, normally called crude-oil, alternative to fossil fuels, as well as other products of industrial interest (phenols, furfurals, etc.). The second objective is the study of the possible positive effect that a pre-treatment with ozone can have on the performance of the subsequent HTL. In this work, HTL is applied to liquid surfactant wastes obtaining up to 7% crude-oil yield, with a High Heating Value (HHV) higher than 8.000 cal/g. These results are compared with those obtained when an ozonation pre-treatment is applied before the HTL process. Ozone treatment shows a slight defoaming capacity for the leachate feed but don’t seem to show a significant difference in the HHV of the crude-oils obtained from liquid surfactant. However, there is a noticeable difference in the solid residue generated for this later. Less aggregates of solid particles and a weight reduction of 20% in the filtering step were obtained from ozonated liquid surfactants. The reduction of solid by-products is of great interest for dimensioning an industrial-scale HTL plant due to the problems that these solids can generate in pipes and valves.

The development of technologies to produce fuels from non-fossil sources is of great importance. One of the alternatives is the use of organic biomass feedstock. Hydrothermal liquefaction (HTL) is a technology that enables the transformation of organic matter into bio-crude by means of a reaction in aqueous medium and at high temperature and pressure conditions, although below the critical point of water. Among the different types of organic matter that can be used, marine macroalgae are a very promising feedstock as they are found in abundance within the oceans; in particular, some populations of invasive species cause environmental problems due to their excessive growth beyond their original niche. In fact, large uncontrolled proliferations of algae of the genus Sargassum are found on the coasts of many countries, causing a significant imbalance that affects both the native ecosystems and the tourism sector, which is of great economic importance in the affected areas. Although there are many variables that influence the process, the objective of this study is to carry out preliminary HTL tests of the mentioned macroalgae specie, without being subjected to previous pre-treatment. In the experimental design, operating variables were temperature, reaction time and initial loading of algal biomass. The objective was to find the highest yield and calorific value of bio-crude produced from this raw material. MODDE® Pro 13 was the software employed for both experimental design and results processing. All experiments were carried out in a 300 mL volume PARR stirred high pressure reactor. 150 mL of deionized water were used as reaction medium and an inert nitrogen atmosphere was applied. Bio-crude extractions were performed over the solids obtained in the reaction using dichloromethane as solvent. Among the experiments performed, the yields and high heating values (HHV) were compared at different reaction times at a temperature of 300°C and 95 bar pressure, in a time range from 0 to 60 minutes with an initial biomass load of 15 g (10% w/v). The best result obtained was a crude yield of 10.25% and a crude HHV of 9,240 kcal/kg for the 60 minutes HTL test.

The present review deals with water applications in sub and supercritical conditions with a focus on supercritical water oxidation process (SCWO) as an example of high temperature and pressure technologies. It starts by presenting the advantages of water properties near and beyond the critical point and the major applications exploiting them. Then, it presents a review on SCWO from the description of the process, the reaction mechanism and kinetics to reactor design and modeling. It also presents the main problems and difficulties that delay the SCWO industrial application, and summarizes the main efforts and research to overcome them for a safe, efficient and economic process.

Chemical Engineering courses are often designed to be divided into two types of lessons: lecture and experimental. In the second one, students develop the knowledge in a hands-on way by attending a pilot plant equipped with different instruments. Hence, a thorough understanding of the different unit operations is needed and, therefore, the implications of changing the operational variables in a process. In this context, the use of new digital technologies is emerging as support tools with the aim of both improving the learning and the motivation of students. Specifically, Augmented Reality (AR) provides a modified physical environment overlaid with multimedia content in the form of text, graphics, video and/or audio. Thus, the incorporation of AR systems in the learning of science has proven to be useful, because it can present multiple benefits for students and teachers related to the improvement of spatial abilities, the increase of memory retention, the decrease of cognitive overload, and a boost in student motivation. This study has carried out a search for resources, projects, software, and applications to implement AR-based tools in the experimental sessions of a Chemical Engineering educational pilot plant. Based on all the information found, several AR projects were proposed by the teachers. Later, some of them were selected according to previously defined criteria and implemented as educational tools for students in the course called Experimentation in Chemical Engineering I. Finally, this tool was evaluated through subsequent post-surveys, being very positively rated by both students and teachers, mainly in the items related to helping to understand concepts or the operating procedures of the equipment.

Chemical Engineering is a complex discipline that is mainly applied to the industrial context, which makes it difficult to approach real equipment and systems in the classroom to students. Nevertheless, Information and Communication Technologies (ICTs) are particularly useful to encourage active and autonomous learning, normally associated with deeper levels of engagement and understanding of the subjects taught. In this way, several studies have demonstrated that immersion has the potential to increase learning experiences and improve creativity and engagement, Virtual Reality (VR) being a remarkable example. In this context, we created and shared with students two immersive resources based on VR: (a) a laboratory 360° video tour, which was used to disseminate the Chemical Engineering Degree in an Open Door Days organized for high school students; and (b) an experiential learning tool integrated with Moodle, which was available previously to face-to-face practical lessons of the subject Separation Operations. In both cases, the feedback from the participant students was positive. High school students increased their interest in Chemical Engineering Degree after viewing the 360° video, meanwhile undergraduate students found the immersive tool useful in the subsequent performance of real practical activities. From the perspective of professors, creation of these resources required purchase of equipment, time and effort, but they were highly valued as a tool for disseminating and supporting teaching, being an initial starting point for the creation of more enhanced VR-based materials.

Lithium-ion batteries (LIBs) have gained much interest in recent years because of the increasing energy demand and the relentless progression of climate change. About 30% of the manufacturing cost for LIBs is spent on cathode materials, and its level of development is lower than the negative electrode, separator diaphragm and electrolyte, therefore becoming the “controlling step”. Numerous cathodic materials have been employed, LiFePO4 being the most relevant one mainly because of its excellent performance, as well as its rated capacity (170 mA·h·g−1) and practical operating voltage (3.5 V vs. Li+/Li). Nevertheless, producing micro and nanoparticles with high purity levels, avoiding the formation of iron oxides, and reducing the operating cost are still some of the aspects still to be improved. In this work, we have applied two heating rates (slow and fast) to the same hydrothermal synthesis process with the main objective of obtaining, without any reducing agents, the purest possible LiFePO4 in the shortest time and with the lowest proportion of magnetite impurities. The reagents initially used were: FeSO4, H3PO4, and LiOH, and a crucial phenomenon has been observed in the temperature range between 130 and 150 °C, being verified with various techniques such as XRD and SEM.

Supercritical Water Gasification (SCWG) has the capacity to generate fuel gas effluent from wet biomass without previously having to dry the biomass. However, substantial efforts are still required to make it a feasible and competitive technology for hydrogen production. Biomass contains cellulose, hemicellulose and lignin, so it is essential to understand their behavior in high-pressure systems in order to optimize hydrogen production. As the main component of biomass, cellulose has been extensively studied, and its decomposition has been carried out at both subcritical and supercritical conditions. Most previous works of this model compound were carried out in batch reactors, where reaction times normally take place in a few minutes. However, the present study demonstrates that gasification reactions can achieve efficiency levels of up to 100% in less than ten seconds. The effect of temperature (450–560 °C), the amount of oxidant (from no addition of oxidant to an excess over stoichiometric of 10%, n = 1.1), the initial concentration of organic matter (0.25–2 wt.%) and the addition of a catalyst on the SCWG of cellulose in a continuous tubular reactor at short residence times (from 6 to 10 s) have been studied in this work. Hydrogen yields close to 100% in the gas phase were obtained when operating under optimal conditions. Moreover, a validation of the experimental data has been conducted based on the theoretical data obtained from its kinetics.