Mechanisms and Kinetics for Sorption of CO2 on Bicontinuous Mesoporous Silica Modified with n-Propylamine

We studied equilibrium adsorption and uptake kinetics and identified molecular species that formed during sorption of carbon dioxide on amine-modified silica. Bicontinuous silicas (AMS-6 and MCM-48) were postsynthetically modified with (3-aminopropyl)triethoxysilane or (3-aminopropyl)methyldiethoxysilane, and amine-modified AMS-6 adsorbed more CO(2) than did amine-modified MCM-48. By in situ FTIR spectroscopy, we showed that the amine groups reacted with CO(2) and formed ammonium carbamate ion pairs as well as carbamic acids under both dry and moist conditions. The carbamic acid was stabilized by hydrogen bonds, and ammonium carbamate ion pairs formed preferably on sorbents with high densities of amine groups. Under dry conditions, silylpropylcarbamate formed, slowly, by condensing carbamic acid and silanol groups. The ratio of ammonium carbamate ion pairs to silylpropylcarbamate was higher for samples with high amine contents than samples with low amine contents. Bicarbonates or carbonates did not form under dry or moist conditions. The uptake of CO(2) was enhanced in the presence of water, which was rationalized by the observed release of additional amine groups under these conditions and related formation of ammonium carbamate ion pairs. Distinct evidence for a fourth and irreversibly formed moiety was observed under sorption of CO(2) under dry conditions. Significant amounts of physisorbed, linear CO(2) were detected at relatively high partial pressures of CO(2), such that they could adsorb only after the reactive amine groups were consumed.authorCount :7</p

Uniendo ingeniería y ecología: la protección costera basada en ecosistemas

En un contexto de crecientes impactos y riesgos socio-económicos en las costas del planeta, la protección costera basada en ecosistemas surge como un nuevo paradigma que une los principios de protección, sostenibilidad y resiliencia, a la vez que proporciona múltiples beneficios. Este artículo ofrece una perspectiva sobre qué son y cómo se pueden utilizar las defensas naturales en el diseño, planificación y gestión de costas. La política pública muestra un creciente interés por su implementación general y el cuerpo de conocimiento y experiencia alrededor de la también denominada infraestructura ?verde? es creciente, pero aún existen importantes barreras que salvar. Una de ellas es estandarizar su diseño en términos ingenieriles, así como reconocer los aspectos que los diferencian respecto a enfoques tradicionales. La adaptación climática y la reducción de riesgos son áreas en las que su utilización puede ser más significativa, debido a la variedad de servicios que ofrecen. Tanto desde el punto de vista técnico como económico, existen argumentos sólidos para evitar la degradación de los ecosistemas, avanzando su restauración y conservación, como también desde la perspectiva de la defensa de las costas.In a context of increasing socio-economic impacts and risks in the coastal areas of the planet, coastal protection based on ecosystem features becomes a new paradigm that combines the principles of conservation, sustainability and resilience, while providing multiple benefits. This paper provides a perspective on what these are and how they can be used in the design, planning and management of the coastal zones. Policy-makers are calling for further uptake and implementation across the board and the body of knowledge and experience around the socalled ?green? infrastructure is growing, but there are still major barriers for a widespread uptake. One of them is to standardize designs in engineering terms, recognizing the different characteristics compared to traditional engineering solutions. Climate adaptation and risk reduction are areas where its use may be more significant, for the variety of services they offer. Both technically and economically, there are strong arguments to prevent degradation of ecosystems and to advance in their restoration and conservation, as well as from a coastal defense perspective