University of Puerto Rico at Mayagüez Institutional Repository
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Publication Restricted Hydrophobic hierarchical porous carbon-zeolite composites for direct air capture and closed-loop CO2 removal applications(2026-03-19)Carbon dioxide removal at trace concentrations is critical for closed-volume applications, particularly life support systems, and for sustainable carbon management strategies such as Direct Air Capture. Conventional approaches face significant limitations: amine-based absorption requires energy-intensive regeneration, while microporous zeolitic adsorbents necessitate desiccant pre-treatment stages that increase payload and space requirements—constraints particularly problematic when energy inventory, space availability, and payload are restrictive. Furthermore, conventional adsorbents often suffer from low CO₂ selectivity, poor moisture tolerance, and competitive water adsorption. To overcome these challenges through bottom-up design, this work reports hierarchical alkaline earth metal-functionalized confined-space silicoaluminophosphate composites (Ba²⁺-CSAPO-34 and Sr²⁺-CSAPO-34) for selective physical adsorption of CO₂ at ambient temperature under humid conditions. The chabazite-type SAPO-34 phase was grown in situ within the meso- and macro-pores of activated carbon (AC) via confined-space hydrothermal synthesis, with approximately 80% void occupation confirmed through comprehensive characterization including SEM/EDAX, TEM, pore size distribution profiles, and water contact angle measurements. The confined nucleation mechanism and successful incorporation of alkaline earth metal active sites within the SAPO-34 framework were also verified through equilibrium adsorption tests. Fixed-bed adsorption tests at trace CO₂ concentrations (500–2500 ppm) demonstrated strong CO₂ binding with no roll-up and effective suppression of water affinity, maintaining high selectivity even at 90% relative humidity. The composites exhibited excellent regenerability through vacuum-assisted thermal cycling with no capacity loss across multiple cycles. These findings demonstrate that a synergistic combination of hydrophobicity and enhanced physisorption interactions, achieved through a hierarchical core-shell design, creates a plausible and scalable adsorbent platform that eliminates the need for desiccant pre-treatment. This advancement enables sustainable gas separation technologies for both closed-volume life support systems and ambient Direct Air Capture applications.Person Metadata only Person Metadata only Publication Restricted Tsunami impacts in Puerto Rico: Tectonic sources, propagation modeling, and run-up sensitivity to surface friction(2026-02-18)Puerto Rico, is exposed to tsunamis, this scenario demands accurate characterization of seismogenic sources, rapid and realistic numerical modeling tools, and efficient response strategies. This thesis addresses the problem through three complementary approaches. The main active geological structures in Puerto Rico and the Virgin Islands are identified and segmented using seismic, geological, geophysical, and geodetic data, with an evaluation of their tsunamigenic potential. An updated tectonic model is presented that incorporates detailed fault geometry and patterns of recent crustal deformation, providing a robust foundation for defining realistic tsunami scenarios. Also, the TsunamiBot is developed as an automated monitoring and response system that integrates real-time seismic detection, source parameter generation using the Okada model, GPU-accelerated simulations with Tsunami-HySEA, and immediate alert dissemination via the Telegram API. The system can execute complete simulations in under three minutes, enhancing response capacity for near-field threats. Finaly, the sensitivity of run-up, inundation extent, and hydrodynamic parameters to variations in surface friction is evaluated using spatially variable Manning’s n maps derived from high-resolution land use data. Tsunami-HySEA simulations are conducted for six coastal regions in western Puerto Rico, and a Random Forest model is applied to quantify the relative importance of friction, slope, and bathymetry in the dynamics of inundation. Results confirm that combining detailed tectonic characterization, a fully automated modeling and alert workflow, and a realistic representation of surface friction significantly improves the accuracy and operational value of tsunami models for Puerto Rico and the Virgin Islands.Person Metadata only
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