Activated Carbons Produced from Mixtures of Synthetic Polymers by Physical and Chemical Activation: Application on MCPA Removal

The production of AC was achieved using the most common industrial and consumer solid waste, namely PET, alone or blended with other synthetic polymer such PAN. The PET-PAN mixture (1:1 W/W %) was subjected to carbonization, with a pyrolysis yield off 31.9%, between that obtained with PET (16.9%) or PAN (42.6%) separately. By mixing PET, as a raw material, with PAN (different ratio), an improvement in the final yield of the AC production, for the same activation time, with CO2, was found.

Production of activated carbons from single and mixtures of synthetic polymers

The production of activated carbons (ACs) involves two main steps: the carbonization of the carbonaceous of raw materials at temperatures below 1073 K in the absence of oxygen and the activation had realized at the temperature up to 1173 but the most useful temperature at 1073 K. In our study we used the most common industrial and consumer solid waste, namely PET, alone or blended with other synthetic polymer PAN. By mixing the two polymers in different ratios, an improvement of the yield of the AC production was found and some textural properties were enhanced by comparison with the AC prepared using each polymer separately. When all the samples were exposed through the carbonization process with a pyrolysis the mixture of PAN-PET (1:1w/w) yield around 31.9%, between that obtained with PET (16.9%) or PAN (42.6%) separately. The combine activation, with CO2 at 1073 K, allow ACs with a lower burn-off degree isothermally, when compared with those attained with PET or PAN alone, but with similarly chemicals or textural properties. The resultant ACs are microporous in their nature, as the activation time increase, the PET-PAN mixture AC are characterized by a better developed porous structure, when associated with the AC prepared from PAN. The AC prepared from PET-PAN mixture are characterized by basic surface characteristics, with a pHpzc around 10.5, which is an important characteristic for future applications on acidic pollutants removals from liquid or gaseous phase. In this study we had used the FTIR methods to determine the main functional groups in the surface of the activated carbons. The adsorbents prepared from PAN fibres presents an IR spectrum with similar characteristics to those obtained with PET wastes, but with fewer peaks and bands with less intensity, in particular for the PAN-8240 sample. This can be reflected by the stretching and deformation modes of NH bond in the range 3100 – 3300 cm-1 and 1520 – 1650 cm-1, respectively. Also, stretching mode associated to C–N, C=N, can contributed to the profile of IR spectrum around 1170 cm-1, 1585 – 1770 cm-1. And the TGA methods was used to study the loses of the precursors mass according to the excessive of the temperature. The results showed that, there were different decreasing of the mass of each precursors. PAN degradation started at almost 573 K and at 1073 K, PAN preserve more than 40% of the initial mass. PET degradation started at 650 K, but at 1073 K, it has lost 80% of the initial mass. However, the mixture of PET-PAN (1:1w/w) showed a thermogravimetric profile between the two polymers tested individually, with a final mass slightly less than 30%. From a chemical point of view, the carbonisation of PET mainly occurs in one step between 650 and 775 K.

SELECCIÓN DE ÁREAS PROPICIAS PARA LA INSTALACIÓN DE RELLENOS SANITARIOS, PROVINCIA DE HEREDIA

Durante la década de los años 90 Costa Rica tomó conciencia del problema que significa el mal manejo de los desechos sólidos. En la provincia de Heredia durante estos años se formó una comisión interinstitucional e intermunicipal con el objetivo de darle una solución integral provincial a esta problemática. La Universidad Nacional, a través de la Escuela de Ciencias Geográficas (Progra­ma Morfoclimatología Aplicada y Dinámica Exógena, MADE), formó parte de esta comisión, para la cual realizó la primera etapa de un estudio tendiente a identificar los sitios óptimos para la instalación de un relleno sanitario provincial. La metodología utilizada se basó en la que se desarrolló en el Plan Nacional de Manejo de Desechos elaborado por el Gobierno de Costa Rica y la GTZ (Deutsche Gesellschaft für Technische Zusammenarbeit). Se identificaron cinco áreas técnicamente aptas, todas en el sector sur de la provincia, estas, dos presentan las condiciones menos adversas y, por lo tanto, consideran las áreas candidatas, estas se ubican al este de la provincia y son parte del cantón de San Isidro. Se recomienda realizar los estudios de detalle, considerados indispensables. En este sentido, recientemente la Empresa de Servicios Públicos Heredia (ESPH) ha utilizado como base esta investigación para efectuar mencionados estudios. ABSTRACT During the 1990s, Costa Rica began concentrating on the problem of poor  solid waste management. In the province of Heredia during these years, inter-institutional and inter-municipal commission was formed to seek integral solution to this problem at the province level. The Universic Nacional in Costa Rica, through the School of Geographical Sciences (Progr Morfoclimatología Aplicada y Dinámica Exógena, MADE), formed part of this commission and did a preliminary study in order to identify the optimum sites for installing a provincial sanitary refill. The methodology used was based on the one developed in the National Waste Management Plan designed by the government of Costa Rica and German agency GTZ (Deutsche Gesellschaft für Technische Zusammenarbeit ). Five technically suitable áreas were identified, all located in the southern sec of the province. Of these, two present less adverse conditions and therefore considered candidate áreas. These are located in the eastern part of this sector  and are in the cantón of San Isidro. Further detailed studies are recommended and are considered crucial, this sense, the Empresa de Servicios Públicos de Heredia (ESPH) has utilized this research as base study to perform the abo ve mentioned studies.

ESTADO ACTUAL DE LOS SITIOS DE DISPOSICION DE DESECHOS SOLIDOS MUNICIPALES EN COSTA RICA

En Costa Rica como consecuencia directa del crecimiento urbano acelerado y del cambio en los hábitos de consumo de los pobladores, se da un aumento en la cantidad de desechos sólidos generados así como un cambio en la composición de los mismos, ocasionando entonces el problema de su disposición.En el país, muchos de los sitios municipales actuales se consideran como vertederos a cielo abierto, además, se ubican de manera  que afectan directa o indirectamente los cuerpos de agua (superficiales y subterráneos). Aunado a lo anterior se cuenta en la mayoría de los sitios con el problema de que no se posee control de acceso suficiente, de tal forma que existe  mayor riesgo de que desechos peligrosos se depositen en ellos. ABSTRACTIn Costa Rica, as a direct consequence of accelerated urban growth and changing consumption patterns, there has been an increase in the quantity of generated solid waste as changes in its composition, thus causing a disposal problem.Many of the final disposal sites in the country don’t have the necessary conditions to handle these changes in quantity and quality of generated solid waste.The majority of current municipal disposal sites are considered exposed dumps and are located where superficial and subterranean water bodies are affected. Controls to access are insufficient in the majority of the sites, thus there is greater risk that hazardous waste is deposited in them.