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- Activated Carbon Produced from Tanning Industry Residues Used to Remove Carbamazepine from WastewaterPublication . Marques, David; Freitas, Maria Madalena; Silva, P. C.According to UNESCO, emerging pollutants are posing a threat to ecosystems and human health. These compounds can be either synthetic or natural chemicals or microorganisms, that are not usually regulated, and can be found in hospital wastewater, even after conventional treatment processes. Carbamazepine is a mood stabilizing drug and an anticonvulsant. Due to its persistence, carbamazepine is one of the most frequently detected pharmaceuticals in wastewater. Though there are many methods to remove such pollutants, adsorption is one of the most effective treatments. To remove carbamazepine from solution, an activated carbon prepared from leather residues and a commercial activated carbon were used as adsorbents. The adsorption tests show that the leather residue derived activated carbons have higher specific surface area (>1500 m’/g) and higher adsorption capacity (q > 300 mgcnz/g) for carbamazepine when compared to commercial activated carbon (992 m’/g and q < 180 mgcaz/g, respectively).
- Urea as an alternative source of notrogen for microalgae cultivation: Effect on growth and biomass compositionPublication . Corrêa, P.S.; Freitas, M.M.A.; Caetano, N.S.(Excerto introdução) In the present work, C. zofingiensis was cultivated in five different media with respect to nitrogen concentration and source. Higher carotenoids content was observed in biomasses cultivated with higher nitrogen concentration, BBM (U) and BBMSTD, 1.24 and 1.17 mg·g-1, respectively. Moreover, the highest chlorophyll accumulation found in the control condition (10.32 mg·g-1). In contrast, when the nitrogen concentration was reduced, the carotenoids content was almost threefold higher using urea as nitrogen source (0.71 as opposed to 0.22 mg·g-1). Higher lipids accumulation was observed in tenfold nitrogen-reduced media, 45.1 and 40.8 % (BBM (-) and BBM (U-), respectively). Nevertheless, there was no statistical difference between the results of lipids content obtained in NaNO3 and urea media with same nitrogen concentration. Finally, replacing sodium nitrate with urea did not improve the final biomass concentration.
- Preparação de materiais de carbono de elevada área superficial contendo azotoPublication . Monteiro, A.S.; Freitas, M.M.; Silva, P.C.(Introdução) O carvão ativado é um material adsorvente aplicado em áreas como o tratamento de efluentes líquidos e gasosos, a purificação e separação de misturas gasosas ou em catálise. A dopagem de carvão ativado com azoto, criando na superfície grupos funcionais azotados, permite a sua utilização em novas áreas emergentes como o armazenamento de eletricidade ou a captura de dióxido de carbono. Assim, o desenvolvimento de métodos de produção de materiais de carbono de elevada área superficial contendo azoto a partir de resíduos é uma área de grande interesse.
- Preparation of activated and N-doped carbons derived from pineconesPublication . Farias, A.; Monteiro, A.; Freitas, M.M.; Silva, P.C.(Introduction) The increasing impact of environmental issues has driven the development of increasingly cleaner and renewable processes and products. Biomassderived carbons have gained significant attention due to their high specific surface areas, hierarchical porous structures, cost-effectiveness and widespread availability [1]. Given the growing interest in these materials, the substitution of carbon atoms with heteroatoms (N, B, P and S) within the carbonaceous structure emerges as a mechanism to enhance the material's acid-base character. It can also alter the electronic structure of carbon, potentially increasing its electrical conductivity, chemical stability, and electron-donation properties [2]. This study aims to develop carbon materials from pinecones with high surface area, doped with nitrogen.
- Ciprofloxacin and carbamazepine adsorption on activated carbons produced from leather residuesPublication . Marques, David; Mota, Salomé; Freitas, Maria Madalena; Silva, Paula CristinaCiprofloxacin and carbamazepine adsorption was studied using an activated carbon produced from leather residues (wet white shavings) and a commercially available activated carbon (Norit ROW 0.8) and the effect of pH level was studied. The activated carbon produced from wet white shavings showed better results due to its higher specific surface area, confirming that leather residues are a viable precursor for the preparation of activated carbons for the adsorption of these chemicals. The effect of pH on the AC adsorption capacity was not significant in the case of carbamazepine, however lower pH led to higher adsorption capacities for ciprofloxacin.
- Avaliação de extratos de microalgas para potencial aplicação em alimentos funcionaisPublication . Corrêa, P.S.; Freitas, M.M.A.; Caetano, N.S.(Introdução) Microalgas são micro-organismos fotossintéticos, que para além de servirem como fonte de proteínas, também são capazes de produzir uma gama de compostos bioativos, tais como, pigmentos, lípidos e compostos fenólicos. Tais características as tornam bastante promissoras para aplicação de suas biomassas em alimentos funcionais (Pina-Pérez et al., 2019). De modo geral, os alimentos funcionais além de terem elevado valor nutricional, também trazem algum benefício à saúde. Chromochloris zofingiensis, Koliella longiseta e Schizomeris leibleinii são microalgas de água doce, relativamente pouco estudadas na literatura, mas potencialmente interessantes para produção de carotenoides, lípidos e compostos fenólicos (Fogliano et al., 2010; Zhang et al., 2021). A imposição de condições de estresse abiótico (i.e. variação na concentração de determinado nutriente no meio de cultivo, temperature, pH, etc.), é uma das estratégias mais utilizadas para induzir uma maior produção de determinado composto de interesse (Suparmaniam et al., 2024). Desta forma, este trabalho se propôs a estudar o impacte de diferentes condições de cultivo na produção de carotenoides, clorofilas, lípidos e compostos fenólicos. Além disso, foram produzidos extratos em solventes diferentes (i.e. água e etanol) e testado o potencial antioxidante de cada um.
- Experimental design to otpimize Bold's basal medium to increase biomass and pigment production in three microalgae speciesPublication . Corrêa, P.S.; Freitas, M.M.A.; Caetano, N.(Introduction) The great biotechnological potential of microalgae has aroused the interest of many industrial sectors. With biomasses rich in pigments, lipids, proteins and several other compounds, these microorganisms are a potential source of bioactive molecules for multiple applications. According to the literature, Chromochloris zofingiensis is an interesting source of carotenoids, specially astaxanthin 1,2 , Koliella longiseta is mainly reported as a rich source of eicosapentaenoic acid (EPA, ω-3) and arachidonic acid (ARA, ω-6) 3, while Schizomeris leibleinii is mainly studied for wastewater treatment 4,5. The imposition of abiotic stress by changing culture conditions (e.g. nutrient concentration in the culture medium, temperature, light irradiance, among others) directly influences growth and is able to modulate biomass composition. An experimental design was proposed to evaluate the effect of salinity and concentration of nitrate, ferrous sulphate and phosphate on growth and production of carotenoids and chlorophylls in these species. Higher salinity and ferrous sulphate concentration increased the final biomass concentration almost threefold in C. zofingiensis and twofold in S. leibleinii when compared to their controls. Meanwhile, K. longiseta was able to double its biomass concentration only by changing nitrate concentration in the medium. Regarding pigment production, higher carotenoids content was found in C. zofingiensis (3.16 mg·g-1) cultivated in unmodified BBM (Bold´s Basal Medium) and S. leibleinii (3.09 mg·g-1) cultivated under nitrogen limitation and with higher salinity and ferrous sulphate concentration. Finally, higher chlorophyll content was observed in K. longiseta (17.77 mg·g-1) cultivated at higher ferrous sulphate concentration and C. zofingiensis (16.24 mg·g-1) cultivated in absence of phosphate and higher ferrous sulphate concentration.