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.

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.

Highly efficient low cost carbon adsorbents were prepared from synthetic polymers mixture, such as polyethyleneterephthalate (PET) and polyacrylonitrile (PAN), by chemical activation, with potassium hydroxide or potassium carbonate, at 1073 K. Mixtures polymers carbon activation is more effective with KOH than with K2CO3, since the apparent surface area and the micropore volume were always higher on those prepared with KOH. The activated carbons (ACs) obtained presented a high thermal stability, a basic character and a very high apparent surface area (between 1206 and 2828 m2 g-1), micropore volume (between 0.35 and 1.38 cm3 g-1), with mean pore sizes ranging the supermicropores region. These ACs were successfully tested on 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA) removals from the liquid phase. The results achieved are very promising, as the adsorption capacity of these AC is higher than that obtained with commercial AC used for this end.

This work presents a first approach concerning the valorization of Tectona Grandis tree by-products, from East Timor through their transformation into high activated carbon (AC) by chemical activation with KOH and K2CO3. The better ACs, Teak-KOH-1-1-700 and Teak-K2CO3-1-2-700, presented a high ABET (995 and 1132 m2·g−1) and micropore volume (0.43 and 0.5 cm3·g−1), respectively. Both ACs were tested on the removal of four pesticides, from the liquid phase. Both ACs performed better than existing commercial types, presenting a maximum adsorption capacity of 1.88, 1.67, 1.10 and 0.89 mmol·g−1, for 4-chloro-2-methylphenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, diuron and atrazine, respectively. Pesticide adsorption from diluted and concentrated solutions confirms that diffusion is the limiting factor. The possibility of implementing a production unit for ACs in East Timor is very promising for that country. It presents an opportunity for job creation, biomass waste reduction and a contribution to environmental sustainability, thereby following the principles of a circular economy.