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The aim of this research was to investigate how post treatment modification, such as those with sodium hydroxide or urea, can influence the capacity of activated carbon (AC) for phenolic compounds removal from liquid media. The ACs modification was performed using urea impregnation followed by pyrolysis at high temperature. With all ACs used, this treatment induced a pore volume increase, a mean pore size broadening, an increase in the point of zero charge and also in the basic character. The modification with sodium hydroxide brings to light the influence of the precursor nature as the achievements are really diverse. With the ACs obtained from PET, a pore volume and mean pore size reduction occurred, with the AC-cloth no textural effect was observed and with the AC obtained from cork, an enlargement of the mean pore size and an increase of the pore volume were confirmed. The difference in the acidic/basic character exhibited by the modified ACs was in agreement with the presence of acidic/basic superficial groups identified by FTIR. The textural and chemical properties of the ACs affect in a direct way the phenolic compounds removal capacity. Particularly, those modified with urea, which exhibited a superior removal capacity for both phenolic compounds.

This work presents a first approach concerning the use of Tectona Grandis tree sawdust (from East Timor) for high activated carbon production, by physical activation with carbon dioxide at different temperatures. The activated carbons (AC) obtained exhibit a well-developed porous structure with a pore size distribution varying from micro to mesopores. Selected AC was successfully evaluated for pesticide removal, specific to 4-chloro-2-methylphenoxyacetic acid, from the liquid phase. The results presented are very promising, allowing to establish that Tectona Grandis sawdust is as an excellent precursor for the basic AC production and allow to expect good performance of theses adsorbents on the removal of a broad range of pollutants. It should also be noted that, this achievement is very relevant for developing countries, such East Timor, where Tectona Grandis sawdust is available and may constitute a source of income creating a handle to the technical and industrial development of this region.

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For the activated carbon (AC) production, we used the most common industrial and consumer solid waste, namely polyethyleneterephthalate (PET), alone or blended with other synthetic polymer such polyacrylonitrile (PAN). By mixing PET, with PAN, an improvement in the yield of the AC production was found and the basic character and some textural and chemical properties were enhanced. The PET-PAN mixture was subjected to carbonisation, with a pyrolysis yield of 31.9%, between that obtained with PET (16.9%) or PAN (42.6%) separately. The AC revealed a high surface area (1400, 1230 and 1117 m g) and pore volume (0.46, 0.56 and 0.50 cm g), respectively, for PET, PAN and PET-PAN precursors. Selected ACs were successfully tested for 4-chloro-2-methylphenoxyacetic acid (MCPA) and diuron removal from the liquid phase, showing a higher adsorption capacity (1.7 and 1.2 mmol g, respectively, for MCPA and diuron) and good fits with the Langmuir (PET) and Freundlich equation (PAN and PET-PAN blend). With MCPA, the controlling factor to the adsorption capacity was the porous volume and the average pore size. Concerning diuron, the adsorption was controlled essentially by the external diffusion. A remarkable result is the use of different synthetic polymers wastes, as precursors for the production of carbon materials, with high potential application on the pesticides removals from the liquid phase.