The Role of Alkaline/alkaline Earth Metal Oxides in CO2 Capture: A Concise Review

Reducing the concentration of CO2 from the atmosphere has attracted a lot of attention given the rapid level of industrialization in the world. Process Industries are one of the major contributors to this pollution in terms of the incessant release of CO2 from flue gas streams. In recent times metal oxides have received a lot of attention as potential adsorbents for solving this problem.They find application in post-, pre-, and oxy-combustion conditions. Their basic sites plus a lower charge to radius ratio increase their ionic nature and site basicity and facilitate the capture of this pernicious gas from flue gas streams by reacting to form carbonates, which when heated liberates an almost pure stream of CO2 which can be sequestered, thereby, aiding the release of environmentally benign flue gas streams to the atmosphere. This work takes a concise review of these metal oxides that have been widely studied.

Optimized CO2 Capture Solutions for Carbon Free Hydrogen Production with Development of New Demixing Solvent Technology DMX™

CO2 capture & storage is foreseen as a necessity to limit global warming, as indicated by the recent reports from International Energy Agency. Major initiatives have to be initiated in a near future with concrete actions to get efficient results in limiting global warming. Based on its decades of experience in gas sweetening AXENS has developed an expertise in CO2 removal technologies. While conventional amine based processes can be used for some CO2 capture applications like for instance the treatment of process gas streams under pressure, other applications for low pressure gas streams like flue gases will require innovative advanced solutions. AXENS has studied various options for the removal of CO2 in SMR based hydrogen schemes, including the treatment of the process gas or the treatment of the flue gases from the SMR furnace, evaluating the respective merits of those options. For the treatment of the flue gases a new technology developed by IFPEN and AXENS based on a second generation amine solvent is considered : DMX™ DMX™ process, is foreseen as a key contributor for the removal of CO2 from all kind of low pressure gas streams. This process allows drastic reduction of CO2 capture cost in comparison to more conventional solvent such as MEA and others available solvents. The specific features of this solvent allows significant reduction of the heat requirements for the regeneration of the solvent. It also allows regenerating the solvent directly under pressure up to 6 bara, reducing the costs for downstream CO2 compression Preliminary techno-economic studies show significant advantage of DMX™ technology relatively to MEA : up to 30 % reduction in OPEX can be obtained for lower or similar CAPEX, depending on the condition. This process has been developed at the lab scale and is now going to be demonstrated in an industrial pilot unit installed in ArcelorMittal's steel mill plant in Dunkirk (France). This demonstration benefits from the support of EU's H2020 programme, under 3D project.

Extragalactic Magnetism with SOFIA (Legacy Program) - II: A Magnetically Driven Flow in the Starburst Ring of NGC 1097*

Galactic bars are frequent in disk galaxies and they may support the transfer of matter toward the central engine of active nuclei. The barred galaxy NGC 1097 has magnetic forces controlling the gas flow at several kpc scales, which suggest that magnetic fields (B-fields) are dynamically important along the bar and nuclear ring. However, the effect of the B-field on the gas flows in the central kpc scale has not been characterized. Using thermal polarized emission at 89 μm with HAWC+/SOFIA, here, we measure that the polarized flux is spatially located at the contact regions of the outer bar with the starburst ring. The linear polarization decomposition analysis shows that the 89 μm and radio (3.5 and 6.2 cm) polarization traces two different modes, m, of the B-field: a constant B-field orientation and dominated by m = 0 at 89 μm, and a spiral B-field dominated by m = 2 at radio. We show that the B-field at 89 μm is concentrated in the warmest region of a shock driven by the galactic-bar dynamics in the contact regions between the outer bar with the starburst ring. Radio polarization traces a superposition of the spiral B-field outside and within the starburst ring. According to Faraday rotation measures between 3.5 and 6.2 cm, the radial component of the B-field along the contact regions points toward the galaxy's center on both sides. We conclude that gas streams outside and within the starburst ring follow the B-field, which feeds the black hole with matter from the host galaxy.

Identifying Appropriate Locations for the Accelerated Weathering of Limestone to Reduce CO2 Emissions

The reduction in CO2 emissions is a major task for the coming decades. Accelerated weathering of limestone (AWL) can be used to capture CO2 from effluent gas streams and store it as bicarbonate in marine environments. We give an overview of the fundamental aspects of AWL, including associated CO2 emissions during the operation of AWL, characteristics of the accumulating bicarbonate-rich product water, and factors influencing the outgassing of CO2 from the ocean back into the atmosphere. Based on these aspects, we identify locations where AWL could be carried out favorably. The energy demand for AWL reduces the theoretical CO2 sequestration potential, for example, by only 5% in the case of a 100 km transport of limestone on roads. AWL-derived product water is characterized by high alkalinity but low pH values and, once in contact with the atmosphere, passive outgassing of CO2 from AWL-derived water occurs. This process is mainly driven by the difference between the fCO2 in the atmosphere and the oceanic surface layer, as well as the sea surface temperature at the discharge site. Promising sites for AWL may be in Florida or around the Mediterranean Sea, where outgassing could be prevented by injections into deep water layers.

Membrane Engineering for Biogas Valorization

Membrane operations nowadays drive the innovative design of important separation, conversion, and upgrading processes, and contribute to realizing the main principles of “green process engineering” in various sectors. In this perspective, we propose the re-design of traditional plants for biogas upgrading and integrating and/or replacing conventional operations with innovative membrane units. Bio-digester gas streams contain valuable products such as biomethane, volatile organic compounds, and volatile fatty acids, whose recovery has important advantages for environment protection, energy saving, and waste valorization. Advanced membrane units can valorize biogas by separating its various components, and establishing environmentally friendly and small-scale energivorous novel separation processes enables researchers to pursue the requirements of circular economy.

A Scientometric Analysis of Research on Bio Filtration of Waste Gas Streams During 1989-2020

Biofiltration is a superior method of pollution control technologies among the various physical, chemical and biological methods. This process uses active microorganisms and to degrade pollutants produce innocuous end products. Microbes present in the filter materials used in remove of contaminants from the air effectively. A total of 1386 bibliographic records from the Web of Science (WoS) database were extracted and analyzed to report the analysis of scientific state of the authors, journals, countries, and categories. Histcite and VoSviewer software’s are used for analyzing records. In the study, we have analyzed annual contribution, authorship pattern, type of document, language, degree of collaboration, Collaborative index, Co-author index, relative growth rate and doubling time, Bradfords law, h-index, subject wise, countries and co-occurrence keywords. The results indicate that USA and China are the most contributing countries in biofiltration. This study therefore, provides an extensive understanding about the trends and research patterns of biofilter of air efforts worldwide. Finally, research gaps and environment pollution issues are highlighted and the scope for future also discussed.

Two Decades of Triazine Dendrimers

For two decades, methods for the synthesis and characterization of dendrimers based on [1,3,5]-triazine have been advanced by the group. Motivated by the desire to generate structural complexity on the periphery, initial efforts focused on convergent syntheses, which yielded pure materials to generation three. To obtain larger generations of dendrimers, divergent strategies were pursued using iterative reactions of monomers, sequential additions of triazine and diamines, and ultimately, macromonomers. Strategies for the incorporation of bioactive molecules using non-covalent and covalent strategies have been explored. These bioactive materials included small molecule drugs, peptides, and genetic material. In some cases, these constructs were examined in both in vitro and in vivo models with a focus on targeting prostate tumor subtypes with paclitaxel conjugates. In the materials realm, the use of triazine dendrimers anchored on solid surfaces including smectite clay, silica, mesoporous alumina, polystyrene, and others was explored for the separation of volatile organics from gas streams or the sequestration of atrazine from solution. The combination of these organics with metal nanoparticles has been probed. The goal of this review is to summarize these efforts.