Arango Hoyos, B. E., Franco Osorio, H., Valencia Gomez, E. K., Guerrero Sanchez, J., Del Canto Palominos, A. P., Larrain, F. A., et al. (2023). Exploring the capture and desorption of CO2 on graphene oxide foams supported by computational calculations. Sci. Rep., 13(1), 14476.
Abstract: In the last decade, the highest levels of greenhouse gases (GHG) in the atmosphere have been recorded, with carbon dioxide (CO2) being one of the GHGs that most concerns mankind due to the rate at which it is generated on the planet. Given its long time of permanence in the atmosphere (between 100 to 150 years); this has deployed research in the scientific field focused on the absorption and desorption of CO2 in the atmosphere. This work presents the study of CO2 adsorption employing
materials based on graphene oxide (GO), such as GO foams with different oxidation percentages (3.00%, 5.25%, and 9.00%) in their structure, obtained via an environmentally friendly method. The characterization of CO2 adsorption was carried out in a closed system, within which were placed the GO foams and other CO2 adsorbent materials (zeolite and silica gel). Through a controlled chemical reaction, production of CO2 was conducted to obtain CO2 concentration curves inside the system and calculate from these the efficiency, obtained between 86.28 and 92.20%, yield between 60.10 and 99.50%, and effectiveness of CO2 adsorption of the materials under study. The results obtained suggest that GO foams are a promising material for carbon capture and the future development of a new clean technology, given their highest CO2 adsorption efficiency and yield.
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Espinoza, D., Goycoolea, M., & Moreno, E. (2015). The precedence constrained knapsack problem: Separating maximally violated inequalities. Discret Appl. Math., 194, 65–80.
Abstract: We consider the problem of separating maximally violated inequalities for the precedence constrained knapsack problem. Though we consider maximally violated constraints in a very general way, special emphasis is placed on induced cover inequalities and induced clique inequalities. Our contributions include a new partial characterization of maximally violated inequalities, a new safe shrinking technique, and new insights on strengthening and lifting. This work follows on the work of Boyd (1993), Park and Park (1997), van de Leensel et al. (1999) and Boland et al. (2011). Computational experiments show that our new techniques and insights can be used to significantly improve the performance of cutting plane algorithms for this problem. (C) 2015 Elsevier B.V. All rights reserved.
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Pedrouso, A., Tocco, G., val del Rio, A., Carucci, A., Morales, N., Campos, J. L., et al. (2020). Digested blackwater treatment in a partial nitritation-anammox reactor under repeated starvation and reactivation periods. J. Clean Prod., 244, 9 pp.
Abstract: Wastewater source-separation and on-site treatment systems face severe problems in wastewater availability. Therefore, the effect of repeated short-term starvation and reactivation periods on a partial nitritation-anammox (PN/AMX) based processes were assessed treating digested blackwater at room temperature. Two sequencing batch reactors (SBR) were operated, one of them during 24 h/day the whole week (SBR-C, which served as control) and the other with repeated starvation/reactivation periods during the nights and the weekends (SBR-D), using simulated blackwater (300 mg N/L and 200 mg COD/L) as substrate. Results showed no remarkable differences in overall processes performance between both reactors, achieving total nitrogen removal efficiencies (NRE) around 90%. Furthermore, no significant variations were measured in specific activities, except for the aerobic heterotrophic one that was lower in SBR-D, presumably due to the exposure to anoxic conditions. Then, the technical feasibility of applying the PN/AMX system to treat real blackwater produced in an office building during working hours was successfully proved in a third reactor (SBR-R), with the same starvation/reactivation periods tested in SBR-D. Despite the low temperature, ranging from 14 to 21 degrees C, total NRE up to 95% and total nitrogen concentration in the effluent lower than 10 mg N/L were achieved. Moreover, the PN/AMX process performance was immediately recovered after a long starvation period of 15 days (simulating holidays). Results proved for the first time the feasibility and long-term stability (100 days) of applying the PN/AMX processes for the treatment (and potential reuse) of blackwater in a decentralized system where wastewater is not always available. (C) 2019 Elsevier Ltd. All rights reserved.
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Ramirez-Morales, J. E., Tapia-Venegas, E., Campos, J. L., & Ruiz-Filippi, G. (2019). Operational behavior of a hydrogen extractive membrane bioreactor (HEMB) during mixed culture acidogenic fermentation. Int. J. Hydrog. Energy, 44(47), 25565–25574.
Abstract: Fermentative hydrogen production requires a continuous products-removal and effective upgrading steps to improve its general performance. Therefore, implementation of new technologies capable of achieving both requirements is essential. We present the operational behavior of a new process concept based on integration of membranes for gas separation and fermentation technology. This process, which we term as hydrogen extractive membrane bioreactor consists of coupling two dense polymeric membranes to a hydrogen producing culture. The process automatization of this system was essential to maintain the proper operational pressures in the membrane module and in the bioreactorgas-phase. This system was able to extract and partially separate the hydrogen and carbon dioxide generated. The hydrogen partial pressure was reduced from 55.5 to 49 KPa, which means an increase of hydrogen yield of 16.3% (1.1-1.28 mol-H-2/mol-glucose). Simultaneously, the implemented system generated a final hydrogen stream 13% (v/v) more concentrated than a conventional process. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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