• Energy Research

The consumption of batteries and cooking oil have been increasing. Most used batteries are disposed of incorrectly, leading to health and environmental problems because of their composition. In a similar form, cooking oil, once used, is often released by the discharge reaching the wastewater, polluting soil, and water, which affects its treatment. In Ecuador, these environmental passives are recollected and stored without further treatment, which is a temporary and unsustainable solution. To address this issue, the circular economy concept has gained increasing attention. In this study, zinc oxide was prepared from discarded batteries using the hydrometallurgical method to use as a catalyst; it achieved 98.49% purity and 56.20% yield and 20.92% of particles presented a particle size of 1–10 nm. Furthermore, the catalyst morphology was investigated in an SEM, which showed that particle size ranged from 155.69 up to 490.15 nm and spherical shapes. Due to its characteristics, the obtained catalyst can be used in the industry instead of the zinc oxide obtained by mining processes. These processes are known to produce heavy contamination in the ecosystems and human health. Additionally, a zinc oxide lifecycle in the environment was analyzed through a material flow analysis (MFA), taking into consideration two paths, one assuming the disposal of used batteries and the other assuming the recycling of zinc. Biodiesel was produced with a heterogeneous catalyst. This took place with a transesterification reaction with used cooking oil, ethanol, and zinc oxide (ZnO) as catalysts. The biodiesel obtained had the following characteristics: 37.55 kJg−1 of heating power, 0.892 gcm−3 of density, 4.189 mm2/s of viscosity, 0.001% of water content, and a 70.91% yield. Furthermore, the energy consumption in biodiesel production was quantified, giving a total of 37.15 kWh. This kind of initiative prevents that waste from becoming environmental pollutants and potential health risks by giving them a second use as a resource. Moreover, turning waste into a valuable product makes the processes self-sustaining and attractive to be implemented.

The lipids of microalgae are the source for obtaining third-generation biofuels so that fossil fuels can be replaced. The objectives of this study were to determine the composition of the lipids of Chlorella and Scenedesmus microalgae using the gravimetric method; Determine the efficiency of different solvents for the extraction of lipids with the Soxhlet method and compare the lipid recovery productivities of Chlorella microalgae with thermal and physical pretreatments. The highest amount of lipids, 20.37% per dry sample, the microalgae, the chlorella, the solvent mixture, the chloroform:methanol in a 1:2 ratio. The increase in the amount of lipids generated with the use of pretreatments does not justify its use for which it is recommended that no pretreatment be applied. The results allow to establish a baseline in the use of microalgae cultivable in the Ecuadorian mountain to obtain lipids for biofuels. The lipids of microalgae are the source for obtaining third-generation biofuels so that fossil fuels can be replaced. The objectives of this study were to determine the composition of the lipids of Chlorella and Scenedesmus microalgae using the gravimetric method ; Determine the efficiency of different solvents for the extraction of lipids with the Soxhlet method and compare the lipid recovery productivities of Chlorella microalgae with thermal and physical pretreatments. The highest amount of lipids, 20.37% per dry sample, the microalga, the chlorella, the solvent mixture, the chloroform :methanol in a 1:2 ratio. The increase in the amount of lipids generated with the use of pretreatments no justifies its use for which it is recommended that no pretreatment be applied. The results allow to establish a baseline in the use of microalgae cultivable in the Ecuadorian mountain to obtain lipids for biofuels. The lipids of microalgae are the source for obtaining third-generation biofuels so that fossil fuels can be replaced. The objectives of this study were to determine the composition of the lipids of Chlorella and Scenedesmus microalgae using the gravimetric method; Determine the efficiency of different solvents for the extraction of lipids with the Soxhlet method and compare the lipid recovery productivities of Chlorella microalgae with thermal and physical pretreatments. The highest amount of lipids, 20.37% per dry sample, the microalga, the chlorella, the solvent mixture, the chloroform:methanol in a 1:2 ratio. The increase in the amount of lipids generated with the use of pretreatments no justifies its use for which it is recommended that no pretreatment be applied. The results allow to establish a baseline in the use of microalgae cultivable in the Ecuadorian mountain to obtain lipids for biofuels. دهون الطحالب الدقيقة هي مصدر الحصول على الجيل الثالث من الوقود الحيوي بحيث يمكن استبدال الوقود الأحفوري. كانت أهداف هذه الدراسة هي تحديد تركيبة دهون الكلوريلا والطحالب الدقيقة Scenedesmus باستخدام طريقة قياس الجاذبية ؛ تحديد كفاءة المذيبات المختلفة لاستخراج الدهون باستخدام طريقة Soxhlet ومقارنة إنتاجية استرداد الدهون للطحالب الدقيقة Chlorella مع المعالجات الحرارية والفيزيائية. أعلى كمية من الدهون، 20.37 ٪ لكل عينة جافة، الطحالب الدقيقة، الكلوريلا، خليط المذيبات، الكلوروفورم:الميثانول بنسبة 1:2. لا تبرر الزيادة في كمية الدهون الناتجة عن استخدام العلاجات المسبقة استخدامها والتي يوصى بعدم تطبيق أي علاج مسبق عليها. تسمح النتائج بإنشاء خط أساس في استخدام الطحالب الدقيقة القابلة للزراعة في الجبل الإكوادوري للحصول على الدهون للوقود الحيوي.

Hydrogen produced from biomass is an alternative energy source to fossil fuels. In this study, hydrogen production by gasification of the banana plant is proposed. A fixed-bed catalytic reactor was designed considering fluidization conditions and a height/diameter ratio of 3/1. Experimentation was carried out under the following conditions: 368 °C, atmospheric pressure, 11.75 g of residual mass of the banana (pseudo-stem), an average particle diameter of 1.84 mm, and superheated water vapor as a gasifying agent. Gasification reactions were performed using a catalyzed and uncatalyzed medium to compare the effectiveness of each case. The catalyst was Ni/Al2O3, synthesized by coprecipitation. The gas mixture produced from the reaction was continuously condensed to form a two-phase liquid–gas system. The synthesis gas was passed through a silica gel filter and analyzed online by gas chromatography. To conclude, the results of this study show production of 178 mg of synthesis gas for every 1 g of biomass and the selectivity of hydrogen to be 51.8 mol% when a Ni 2.5% w/w catalyst was used. The amount of CO2 was halved, and CO was reduced from 3.87% to 0% in molar percentage. Lastly, a simulation of the distribution of temperatures inside the furnace was developed; the modeled behavior is in agreement with experimental observations.

In certain countries where fresh water is in short supply, the effluents from wastewater treatment plants are being recycled for other uses. For quality assurance, tertiary disinfection treatments are required. This study aims to evaluate the inactivating efficacy with an ultraviolet (UV) system on fecal bacteria from effluents of urban wastewater treatment facilities and the post-treatment influence of the environmental illumination. The effect from different UV doses was determined for native and standardized lyophilized strains of Escherichia coli right after the irradiation as well as after 24 h of incubation under light or dark conditions. To achieve 3 log-reductions of the initial bacterial concentration, a UV dose of approximately 12 mJ cm−2 is needed for E. coli ATCC 8739 and native E. coli. However, there is a risk of the reactivation of 0.19% and 1.54% of the inactivated organisms, respectively, if the treated organisms are stored in an illuminated environment. This suggests that the post-treatment circumstances affect the treatment success; storing the treated water under an illuminated environment may pose a risk even if an effective inactivation was achieved during the irradiation.

Hydrogen is considered one of the most important forms of energy for the future, as it can be generated from renewable sources and reduce CO2 emissions. In this review, the different thermochemical techniques that are currently used for the production of hydrogen from biomass from plantations or crops, as well as those from industrial or agro-industrial processes, were analyzed, such as gasification, liquefaction, and pyrolysis. In addition, the yields obtained and the reactors, reaction conditions, and catalysts used in each process are presented. Furthermore, a brief comparison between the methods is made to identify the pros and cons of current technologies.

Due to the environmental impact of using fossil fuels, alternatives for the generation of biofuels are being studied. An option for this problem is to obtain biodiesel from recycled vegetable oil. Studies show that basic homogeneous catalysis has advantages such as speed over other types of catalysis. However, most of these studies are conducted with unused or little-used oils. Therefore, this study aims to obtain biodiesel from recycled vegetable oil collected from municipal oil collection centers by transesterification applying NaOH or KOH as catalysts. The used oil was filtered, washed, and dried to remove impurities. The transesterification reaction catalyzed with NaOH and KOH was carried out; each catalyst was tested at two concentrations: 0.5% and 1% w/w. All reactions were carried out at 55 °C, 350 rpm, methanol, and alcohol/oil ratio of 6/1 for 1.5 h. The best yield was found with the KOH with a concentration of 0.5%. The biodiesel obtained presented the following properties: density of 0.8807 g/mL, a viscosity of 4.694 mm2/s, an acid number of 0.355 mg KOH/g, and corrosion 1a, a calorific value of 39,726 J/g, and a FAME of 93%.