Avaliação do impacte de fogos florestais nos recursos hídricos subterrâneos. 3.º Relatório de Execução

O relatório apresenta os trabalhos desenvolvidos no âmbito do Projeto POCI/AGR/59180/2004 entre 1 de janeiro e 31 de dezembro de 2007. O relatório organiza-se pela descrição das seguintes tarefas: T1 – Selecção das áreas de estudo; T2 – Caracterização agro-florestal; T3 – Caracterização de cinzas e testes laboratoriais de combustão; T4 – Modelação do ciclo hidrológico e caracterização da qualidade da água; T5 – Coordenação e integração.Fundação para a Ciência e a Tecnologi

The influence of the textural properties of activated carbons on acetaminophen adsorption at different temperatures

The influence of temperature (20–40 °C) on the acetaminophen adsorption onto activated carbons with different textures was studied. Different temperature dependences, not explained by kinetic effects, were observed for carbons with different micropore size distribution patterns: adsorption capacity increased for pine gasification residues (Pi-fa) derived carbons and decreased for sisal based materials. No significant variation was seen for carbon CP. The species identified by 1H NMR spectroscopy on the back-extraction solution proved that during the adsorption process exist the conditions required to promote the formation of acetaminophen oligomers which have constrained access to the narrow microporosity. The rotation energy of the dihedral angle between monomers (estimated by electronic DFT methods) showed that conformations in the planar form are less stable than the non-planar conformation (energy barrier of 70 and 23 kJ mol-1), but have critical dimensions similar to the monomer and can access most of the micropore volume. The enthalpy change of the overall process showed that the energy gain of the system (endothermic) for Pi-fa samples (˜40 kJ mol-1) was enough to allow a change in the dimer, or even a larger oligomer, conformation to the planar form. This will permit adsorption in the narrow micropores, thus explaining the uptake increase with temperature. Non-continuous micropore size distributions centered at pore widths close to the critical dimensions of the planar form seem to be crucial for a positive evolution of the adsorption capacity with temperature

Avaliação do impacte de fogos florestais nos recursos hídricos subterrâneos

O presente trabalho corresponde ao relatório final do Projecto POCI/AGR/59180/2004 “Avaliação do Impacte de Fogos Florestais nos Recursos Hídricos Subterrâneos” e nele se avalia o impacto dos fogos no meio hídrico superficial e subterrâneo, considerando as alterações quantitativas no meio hídrico – escoamento superficial, recarga, evapotranspiração – e de qualidade. Na avaliação da alteração da qualidade das águas consideraram-se como fontes de contaminação os solos ardidos e as cinzas da matéria vegetal ardida, cuja caracterização foi realizada em ensaios de queima e de lixiviação. Os poluentes avaliados foram os elementos inorgânicos, os metais pesados e os hidrocarbonetos. Os trabalhos de campo visaram a caracterização das unidades florísticas das áreas ardidas, recolha de amostras para os ensaios de queima e lixiviação assim como a amostragem das águas superficiais e subterrâneas para a avaliação das alterações na sua qualidade e a evolução da poluição ao longo do tempo.Fundação para a Ciência e a Tecnologi

Micropore size distribution of activated carbons: a key factor for a deeper understanding of the adsorption mechanism of pharmaceuticals

The elucidation of the pore structure of activated carbons requires complementary adsorption data and is of fundamental importance for the comprehension of the adsorption mechanism of organic molecules, as is the case of pharmaceutical compounds. The present work reports studies developed in the Adsorption and Adsorbent Materials Group highlighting the contribution of the micropore size distribution (MPSD), obtained from the ftting of CO2 adsorption data, for the deeper understanding of kinetic and equilibrium adsorption data of pharmaceutical compounds with distinct dimensions and behaviours in solution.La elucidación de la estructura porosa de carbones activos requiere datos de adsorción complementarios y es de importancia fundamental para la comprensión del mecanismo de adsorción de moléculas orgánicas, como es el caso de compuestos farmacéuticos. El presente estudio reporta los trabajos desarrollados en el Grupo de Adsorción y Materiales Adsorbentes de la Universidad de Lisboa destacando la contribución de la distribución del tamaño de microporos, obtenida mediante lo ajuste de los datos de adsorción de CO2, para la comprensión más profunda de los datos cinéticos y de equilibrio de la adsorción de compuestos farmacéuticos con distintas dimensiones y comportamientos en solución

Synthesis of biomass-derived activated carbons for liquid phase application

In this communication an overview of the studies developed in the Adsorption and Adsorbent Materials Group related with the preparation of biomass-derived activated carbon materials is presented, highlighting the results of the most important research line of the group in the carbon materials thematic, i.e., the assessment of the potentialities of these materials as adsorbents of various pharmaceutical compounds from aqueous solution.En esta comunicación se presenta una visión general de los estudios que se realizan en el Grupo de Adsorción y Materiales Adsorbentes de la Universidad de Lisboa en la temática de los materiales de carbón. Estos trabajos se basan en la preparación de carbones activos derivados de biomasa y el estudio de sus aplicaciones como adsorbentes de diversos compuestos farmacéuticos en disolución acuosa. Aquí se han resaltado los resultados más importantes de esta línea de investigación

Alternative Economic Instruments for Regulating Environmental Spillovers from Aquaculture: An Assessment

Unfavourable externalities are generated by many social and economic activities. Aquaculture is both a source and a victim of several of these spillovers. Such externalities threaten sustainable development and often are sources of economic inefficiency and market failure. Their control can help to sustain economic development and improve the ability of economies to satisfy human wants. However, economic regulation is not costless and different policy instruments often have different side-effects, some of which may be unwanted. Furthermore, their impact can vary depending on the attribute of production to which they are applied, for example, to inputs, outputs, emissions, etc. Consequently, the assessment of alternative economic instruments for regulating environmental spillovers from aquaculture is much more complicated than some economists and non-economists have led us to believe. The following alternative policy instruments for the control of spillovers from aquaculture are among those considered: 1. Limits on, or regulation of stocking rates, or densities of fish, or of aquacultured products. 2. Regulation of the nature of inputs to aquaculture, for example, maximum allowable nitrogen and phosphorous content of fish food in Denmark. 3. Taxes on pollutants or emissions from aquaculture farms. 4. Subsidies for pollution reduction. 5. Tradeable pollution or environmental-use permits. 6. Provision of property rights; bargained solutions. 7. Spacing and zoning regulations. 8. Knowledge and information provision. 9. Controls on the use of inputs, such as water and trash fish, the withdrawal of which is capable of causing environmental damage. 10. Prohibition of the use of specified aquaculture techniques or practices. 11. Preservation or conservation orders, for example, preservation of fringing bands of mangroves for natural treatment of wastewater. In assessing alternative policy instruments for control of spillovers from aquaculture, account must be taken of the comparative agency costs involved in each and limitations on the knowledge available to policy-makers. The relative adaptability of alternative policy instruments to changing circumstances may also need to be considered. These and other factors influence the practicality of using the available alternative policy instruments