Biblioteca Digital da UPB
Repositório de Publicações da Universidade Politécnica de Bragança
Entradas recentes
Tailored polymer networks for purification of polyphenols in almond subproducts
Publication . Pinto, Vítor Amaro da Costa; Dias, Rolando
The valorization of agro-industrial by-products has aroused great interest nowadays, due to their richness in phenolic compounds, including polyphenols, and their biological activities of high value for various areas. In this work, the recovery and concentration of these compounds, from hydroalcoholic extracts from hull and also blanching water, were studied, being two residues of large volume in the almond industry.
The enrichment is given by sorption/desorption processes in columns packed with Molecularly Imprinted Polymers (MIPs), having used the polymers MIP-OA-3, MIPQUER-2 and MIP-QUER-3, and evaluating the enrichment efficiency against a gradient of several solvents in the elution steps.
The hull extracts were obtained essentially by ultrasound, having worked with a hydroethanolic fraction 50/50 (v/v), due to their yield and equivalent favoring in the extraction of different polyphenolic families, being subsequently submitted to the sorption process. The characterization of the elutions of both by-products was mainly done by determining the total phenolic content (TPC) and the antioxidant activity by the DPPH method (EC50), and the best results were reinforced with chromatographic
analyses by HPLC-DAD at 280 and 360 nm.
The results show that the process allowed the selective fractionation and enrichment of phenolic compounds, observing fractions with a high degree of enrichment when compared to the initial extract, both at the TPC and EC50 levels. The intermediate hydroethanolic fractions, as well as the methanolic fractions, present the best results in terms of enrichment, as evidenced by the inverse relationship between TPC and EC50. It was also possible to verify differences in the enrichment trend between the OA3 column and the Q2 Q3 columns, revealing different affinities provided by the polymers. Chromatograms reveal significant changes in the chemical profile, both between fractions, extract and columns, suggesting and proving the enrichment of certain phenolic compounds, particularly flavonoids.
In general, the results obtained indicate that the MIPs used have a high potential for phenolic enrichment from complex extracts, being able to fractionate and enrich, contributing to strategies for sustainable recovery of waste and development of processes aligned with the principles of green chemistry. Among these results, maximum TPC values of 615.66 ± 28.23 mg GAE/g Extract (hull) and 918.32 ± 34.54 mg GAE/g Extract (blanching water) were observed, together with EC50 values of 0.025 ± 0.000 and 0.028 ± 0.002 mg/mL, respectively. A value of 1135.64 ± 11.55 mg GAE/g Extract and 0.017 ± 0.000 mg/mL was also observed, indicating a high phenolic recovery.
Surfactant removal from industrial effluents by moringa seed-assisted coagulation and photo-fenton oxidation
Publication . Belgacem, Soufienne; Martins, Ramiro
Water pollution caused by surfactant-containing industrial effluents has become an important environmental concern due to the extensive use of detergents in domestic and industrial applications. Among these pollutants, sodium dodecyl sulfate (SDS) is one of the most widely used anionic surfactants and is frequently detected in wastewater because of its low biodegradability and adverse effects on aquatic ecosystems. Consequently, the development of efficient and sustainable treatment technologies for surfactant removal is of increasing importance.
This study investigated the removal of SDS from synthetic industrial wastewater using a combined treatment consisting of Moringa oleifera seed-assisted coagulation followed by the Photo Fenton oxidation process. The coagulation stage was evaluated by studying the effects of coagulant dosage, initial surfactant concentration, and pH on SDS removal. Subsequently, the Photo Fenton process was optimized by evaluating the influence of pH, hydrogen peroxide dosage, ferrous ion concentration, and UV irradiation using Response Surface Methodology (RSM).
The coagulation process achieved a maximum SDS removal efficiency of 55.6% under the optimum operating conditions. The subsequent Photo Fenton treatment significantly improved the removal efficiency, reaching 96% SDS removal. Process optimization using Response Surface Methodology predicted a maximum removal efficiency of 99.4% under the optimum conditions of pH 3, 1 mL of H₂O₂, 270 mg of FeSO₄·7H₂O, and a flow rate (Q) of 84 mL min⁻¹.
The results demonstrate that combining Moringa oleifera-assisted coagulation with the Photo Fenton process is an effective and environmentally sustainable strategy for removing anionic surfactants from industrial wastewater. The integration of a natural coagulant with an advanced oxidation process provides a promising alternative for improving wastewater treatment efficiency while reducing reliance on conventional chemical treatments.
Aditivos naturais: potencial conservante na indústria alimentar
Publication . Santos, Beatriz Cavalcante; Pereira, Eliana; Amaral, J.S.; Defendi, Rafael
A crescente procura por alimentos mais saudáveis, sustentáveis e com rótulos mais transparentes tem impulsionado a investigação de alternativas naturais aos conservantes
sintéticos utilizados pela indústria alimentar. Paralelamente, a valorização de subprodutos agroindustriais tem emergido como uma estratégia promissora para a redução do desperdício alimentar e promoção da economia circular. Neste contexto, diferentes matrizes vegetais constituem fontes relevantes de compostos bioativos com potencial aplicação como conservantes naturais.
O presente trabalho teve como objetivo desenvolver e caracterizar um extrato natural rico em compostos bioativos com potencial aplicação como conservante alimentar, recorrendo
à valorização de diferentes matrizes vegetais, nomeadamente urtiga (Urtica dioica), bioresíduos de romã e brócolos. Inicialmente, foram avaliadas as atividades antioxidante e antimicrobiana, bem como a toxicidade dos extratos, de forma a selecionar a matriz com maior potencial bioativo e segurança de utilização. A urtiga foi selecionada para estudos posteriores, tendo o seu processo de extração sido otimizado através da metodologia de superfície de resposta, considerando como variáveis de resposta a atividade antioxidante, o teor de massa seca e o perfil individual de compostos fenólicos.
Posteriormente, o processo de extração foi otimizado através da metodologia de superfície de resposta, utilizando a extração assistida por ultrassom e considerando como
variáveis independentes a potência do ultrassom, o tempo de extração e a proporção etanol/água. A otimização teve como objetivo maximizar a atividade antioxidante, o teor de
massa seca e a recuperação de compostos fenólicos. As condições ótimas determinadas pelos modelos matemáticos foram posteriormente validadas experimentalmente.
O extrato otimizado foi caracterizado por HPLC-DAD-ESI/MS, permitindo a identificação de sete compostos fenólicos, correspondentes a quatro ácidos fenólicos e três
flavonoides, com um teor total de 19,8 mg/g de extrato seco. Os flavonoides constituíram a classe predominante (11,6 mg/g), destacando-se a quercetina-3-O-rutinosídeo (rutina) como
composto maioritário, seguida da quercetina-3-O-glicosídeo. Entre os ácidos fenólicos identificados destacaram-se os ácidos cafeoilquínicos e o ácido dicafeoilmálico. Estes
compostos estão associados a reconhecidas propriedades antioxidantes e anti-inflamatórias, reforçando o potencial bioativo do extrato obtido.
A validação experimental das condições ótimas confirmou a adequação do processo de extração desenvolvido, sendo posteriormente realizada uma comparação com um extrato
comercial de urtiga. Os resultados obtidos demonstram o potencial da urtiga como fonte de compostos fenólicos de interesse para a indústria alimentar, evidenciando a viabilidade da
utilização de extratos naturais como alternativa sustentável aos conservantes sintéticos e contribuindo para o desenvolvimento de ingredientes alinhados com o conceito de clean label.
Valorization of biomass waste for the removal of fluoxetine from aqueous matrices
Publication . Mattos, Kim Nicolas; Queiroz, A.M.; Ribeiro, António E.; Brito, Paulo; Lima, Vanderlei Aparecido de
This research examines the use of olive pit waste to remove fluoxetine, a pharmaceutical drug classified as an emerging pollutant. It is an constituent that threatens the environment due to its bioaccumulation. Conventional wastewater treatment plants cannot remove it completely. The activated charcoal used was previously recovered from olive pits and chemically activated with NaOH.
Kinetic tests showed that as temperature increased, the amount of removal from the material increased as well, reaching up to 98.87% at 45 degrees Celsius. Overall the pseudo second-order kinetic model fit the experimental data the best with a χ2 value equal to 0.003725 at 45 degrees Celsius. The Freundlich model fit the equilibrium study better than the Langmuir model, indicating that adsorbing compounds are done so on heterogeneous surfaces and continue through multiple layers. The maximum capacity of adsorption from Langmuir’s model was identified to be 17.07 mg g-1 with regards to olive pit adsorbent.
For thermodynamic analysis, the activation energy was found to be 42.32 kJ mol-1, and the Gibbs free energy indicated a value of -0.851 kJ mol-1 supporting the conclusion that the adsorption process is both spontaneous and favourable thermodynamically. Based on these results, it can be concluded that activated carbon from olive pits is a sustainable and effective alternative for treating water with pharmaceutical micropollutants.
Development of multifunctional emulsions based on lignin and cellulose for cosmetic application
Publication . Domingos, Giovanna Martins; Barreiro, Filomena; Sipoli, Caroline Casagrande
The growing consumer demand for safer, more natural, and environmentally sustainable cosmetic products has driven the development of alternative formulation strategies. One promising approach involves emulsion systems stabilized by solid particles, rather than molecular surfactants, known as Pickering emulsions. These systems offer improved biocompatibility, enhanced stability, and eco-friendly character. Microcrystalline cellulose (MCC) containing residual lignin is an innovative material that has attracted industrial interest for high-value-added applications. In this context, the present work investigated the use of MCC at different lignin contents as a stabilizing agent in the development of multifunctional Pickering emulsions for cosmetic applications. The influence of lignin content on particle wettability and interfacial behavior was evaluated, as well as the effect of physical modification through high-pressure homogenization (HPH) and lignin particle precipitation within MCC samples. The MCC properties, including size distribution and wettability, were analyzed to correlate structural characteristics with emulsion performance. HPH modified the MCC structure and size, improving its dispersion behavior and Pickering-stabilizing performance. However, the processed samples also exhibited greater heterogeneity, and the significant increase in average particle diameter observed suggests the formation of fibrillar structures, particle aggregation, and/or re-agglomeration after processing. Pickering emulsions were successfully produced using MCC dispersions and Miglyol 812 as the oil phase under a 1:1 oil-to-water volume ratio. The resulting systems were characterized in terms of morphology, droplet size, emulsified layer formation, rheological behavior, and storage stability over time. The results showed that lignin content is a critical parameter governing the performance of MCC-based Pickering stabilizers, with small variations in residual lignin content significantly influencing particle hydrophobicity and emulsion stabilization efficiency. MCC Crude (18.7%) showed the highest stabilizing performance, indicating that the higher residual lignin content favored particle hydrophobicity and interfacial adsorption. In contrast, MCC White (4.0%) exhibited poor stabilization due to its highly hydrophilic nature, even after processing. MCC Blond (6.5%) provided intermediate stability while producing light-colored emulsions, a particular advantage for cosmetic applications. For the MCC Crude sample, the lignin particle precipitation approach altered the interfacial properties of the material; however, the results indicated that HPH processing was more advantageous for improving Pickering stabilization performance. Overall, this work demonstrated the innovative use of MCC samples containing residual lignin as Pickering stabilizers, advancing understanding of, and strategies to improve, their interfacial properties and stabilization mechanisms in high-value Pickering emulsions.