Applying Ozone to Accelerate Remediation of Petroleum-Contaminated Soils

abstract: Petroleum contamination is ubiquitous during extraction, transportation, refining, and storage. Contamination damages the soil’s ecosystem function, reduces its aesthetics, and poses a potential threat to human beings. The overall goals of this dissertation are to advance understanding of the mechanisms behind ozonation of petroleum-contaminated soil and to configure an effective integrated bioremediation + ozonation remedial strategy to remove the overall organic carbon. Using a soil column, I conducted batch ozonation experiments for different soils and at different moisture levels. I measured multiple parameters: e.g., total petroleum hydrocarbons (TPH) and dissolved organic carbon (DOC), to build a full understanding of the data that led to the solid conclusions. I first demonstrated the feasibility of using ozone to attack heavy petroleum hydrocarbons in soil settings. I identified the physical and chemical hurdles (e.g., moisture, mass transfer, pH) needed to be overcome to make the integration of chemical oxidation and biodegradation more efficient and defines the mechanisms behind the experimental observations. Next, I completed a total carbon balance, which revealed that multiple components, including soil organic matter (SOM) and non-TPH petroleum, competed for ozone, although TPH was relatively more reactive. Further experiments showed that poor soil mixing and high soil-moisture content hindered mass transfer of ozone to react with the TPH. Finally, I pursued the theme of optimizing the integration of ozonation and biodegradation through a multi-stage strategy. I conducted multi-stages of ozonation and bioremediation for two benchmark soils with distinctly different oils to test if and how much ozonation enhanced biodegradation and vice versa. With pH and moisture optimized for each step, pre-ozonation versus post-ozonation was assessed for TPH removal and mineralization. Multi-cycle treatment was able to achieve the TPH regulatory standard when biodegradation alone could not. Ozonation did not directly enhance the biodegradation rate of TPH; instead, ozone converted TPH into DOC that was biodegraded and mineralized. The major take-home lesson from my studies is that multi-stage ozonation + biodegradation is a useful remediation tool for petroleum contamination in soil.Dissertation/ThesisDoctoral Dissertation Civil, Environmental and Sustainable Engineering 201

Lignin and Hemicellulose in Dispersions - as Surfactants and Functional Materials

The aim of thesis was to understand how lignins and hemicelluloses work as plasticizers, dispersing agents, emulsifiers and stabilizer in dispersion applications from the chemistry point of view. An alkali-O2 oxidation (LigniOx) of lignins was discussed in more detail because relevance to the applied part of this thesis. In the applied part, two organosolv and soda lignins provided by Fortum, and oxidized by VTT Technical Research Centre of Finland, were evaluated in special carbon black and titan dioxide dispersions. Rheological measurements and optical microscopy were used as analysis methods. The aim of the applied part was to increase the knowledge of the new type of lignin-based dispersants and give background information for the development of Fortum’s lignins as dispersants in paint, coating, ink, plastic and other dispersion-related applications. The research literature of lignins and hemicelluloses in different dispersion-related applications is broad. However, this does not directly translate to broad amount of developed and existing applications. Hemicelluloses have chemical analogies, such as gums and other hydrocolloids, which are commercially used for example as texture modifiers in foods and cosmetics. The public research of hemicelluloses as dispersants and texture modifiers in other dispersion applications than foods and cosmetics is however still in early phases. The research of new lignin-based dispersants has focused on the applications in which lignosulfonates are already commercially utilized, such as cement plasticization. In these cases, the new lignin-based dispersant should perform better than lignosulfonates, especially if the production costs are higher for these new lignin-based dispersants. Alternatively, new dispersion applications should be found, in which lignosulfonates have not been used or do not work well. In the applied part of the thesis, the rheological measurements and complementary optical microscopy imaging showed that alkali-O2 oxidized (LigniOx) lignins have potential as dispersants especially in carbon black dispersions and to an extent in the titan dioxide dispersions. All the oxidized organosolv and soda lignins had very similar behavior in these dispersions. The optimum amounts of lignin dispersants (7.5-20 wt% lignin of carbon black) in carbon black dispersions were slightly lower compared to commercial lignosulfonate and synthetic polymer references. The lignin dispersants were especially suitable for the special carbon black dispersions because good dispersing performance and no visible change in the color of the dispersions even with high amounts of lignin dispersants. In the case of titan dioxide dispersions, the required amount of lignin dispersants was lower (0.125-0.5 wt% lignin of titan dioxide) compared to the references. However, the brown color of lignin affects the color of titan dioxide dispersions to an extent and the storage stability of titan dioxide dispersions with lignin dispersants needs to be further investigated

Plants as potential repellent against oryzaephilus species

Stored food pests are a perennial problem in storage facilities and retail stores where they infest and contaminate on a variety of products including grain products, dried fruits, nuts, seeds, dried meats, and in fact, almost all plant products that were used as human foods. The utilization of synthetic pesticides as the main strategy to control food pests has long attracted major concern due to the residue problems and adverse effects to consumers. In view of the above, there is an increasing extensive search for plant species that are showing insecticidal and repellent properties to eradicate these pests that feed on the stored products. These harmful pests include Oryzaephilus surinamensis Linnaeus which is the subject of this review. This review describes the biology of O. surinamensis L. and summarizes on the current state of the alternative methods using plant as a repellent to control this species and other stored product pests within the same niche

Study of azo dye degradation by isolated bacteria cultures from active sludge of a textile industry

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2021.Os efeitos da água residual contendo corante azo no meio ambiente pode ser devastador. Assim, ele precisa ser tratado adequadamente antes de seu descarte - geralmente em corpos d'água. O lodo ativado é uma associação entre muitos (micro) organismos em uma comunidade, composta por bactérias aeróbias e anaeróbias e fungos que degradam o corante, por meio de descoloração e mineralização. No entanto, faltam informações sobre espécies degradantes específicas e suas interações, o que poderia melhorar significativamente os tratamentos de águas residuais contendo corantes azo. Portanto, o objetivo deste estudo foi avaliar a comunidade bacteriana de uma amostra de lodo ativado real de indústria têxtil, por meio do isolamento e identificação de cepas de bactérias degradadoras de corante azo. A dessorção/ionização a laser assistida por matriz, seguida de espectrometria de massas por tempo de voo (MALDI-TOF MS), foi a técnica utilizada para identificar uma ampla gama de espécies de bactérias incluindo aeróbia (Lysinibaciullus fusiformis) e anaeróbia facultativa (Escherichia coli). Dados preliminares indicaram os maiores potenciais de degradação de corante azo Reactive Red 141 (RR-141) por Bacillus thuringiensis e Kosakonia radicincitans. É importante notar que este é o primeiro relato sobre descoloração por K. radicincitans. Brain Heart Infusion (BHI), glicose, e RR-141 foram usados como fontes de carbono. No entanto, apenas nos meios de BHI e glicose detectou-se atividade de descoloração, indicando que o RR-141 não demonstrou ser uma boa fonte de carbono para desenvolvimento bacteriológico. Ambas as cepas exibiram capacidade de descoloração, atingindo 43% de descoloração em BHI por B. thuringiensis, e 21% em meio mineral com glicose por K. radicincitans. O rendimento acima de 40% foi alcançado aplicando-os simultaneamente no mesmo meio reacional, em condições não otimizadas. Frente à falta de dados sobre o microbioma de lodo ativado e a sua influência para avanços na área de biorremediação de corantes azo de efluentes têxteis, este trabalho destaca a técnica de MALDI-TOF-MS para identificação de espécies bacterianas isoladas de lodo ativado de efluente real de uma indústria têxtil. Além de avaliar a capacidade de descoloração destas com o corante azo RR-141, incluindo a Kosakonia radicincitans - maneira inédita.Abstract: The effluent from the textile industry is a complex mixture of recalcitrant molecules that can harm the environment and human health. Biological treatments are usually applied for this type of wastewater, mainly activated sludge, due to its high efficiency and low implementation and operation costs. However, the activated sludge microbiome is rarely well-known due to the variability of its origin. Some studies revealed the most usual presence of Acidobacteria, Bacillus, Clostridium, Pseudomonas, Proteobacteria, and Streptococcus in activated sludges, and Bacillus Pseudomonas are highlighted for bacterial dye degradation. Consequently, the process is not performed on its optimum conditions (yield of treatment). In this sense, this review aims to contextualize the potential environmental impacts of azo dye-containing wastewater from the textile industry; evaluate its toxicity; explore the identification of activated sludge microbiome; and then highlights the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) as a novel, rapid and accurate strategy for the identification of activated sludge microbiome (potential to enhance treatment yield)

Advanced Oxidation Processes

Advanced Oxidation Processes – Applications, Trends, and Prospects constitutes a comprehensive resource for civil, chemical, and environmental engineers researching in the field of water and wastewater treatment. The book covers the fundamentals, applications, and future work in Advanced Oxidation Processes (AOPs) as an attractive alternative and a complementary treatment option to conventional methods. This book also presents state-of-the-art research on AOPs and heterogeneous catalysis while covering recent progress and trends, including the application of AOPs at the laboratory, pilot, or industrial scale, the combination of AOPs with other technologies, hybrid processes, process intensification, reactor design, scale-up, and optimization. The book is divided into four sections: Introduction to Advanced Oxidation Processes, General Concepts of Heterogeneous Catalysis, Fenton and Ferrate in Wastewater Treatment, and Industrial Applications, Trends, and Prospects

THE USE AND CONTROL OF MICROORGANISMS TO IMPROVE THE QUALITY OF FOOD

In this present PhD thesis were examined and evaluated different methods for improving the quality of various food products. The first work involved the study of antibacterial properties of the extract of the leaves of the plant Cocculus orbiculatus, against several serotypes of Listeria monocytogenes. The study of the composition of the extract showed the presence of 26 different compounds, thirteen of which have been extracted by hydro distillation and thirteen compounds by extraction with ethanol. Preliminary, also, the identification of the plant was carried out using molecular techniques. The results showed a bacteriostatic effect of the extract against the target organism under examination. The work presented in the second chapter, is part of a research project on “Qualification of pig genetic resources aimed at enhancement of production for the Protected Designation of Origin of the dry-cured ham San Daniele Friuli (D.O.P. Prosciutto di San Daniele Friuli), the Protected Designation of Origin of the Gran Padano pig (D.O.P. Gran Suino Padano), and to the Protected Geographical Indication (I.G.P. Sauris) of fresh meat and sausages obtained and recognized with the brand AQUA of Friuli Venezia Giulia”. It follows the chain of the pig from birth to slaughter. In particular, it was evaluated the impact of different pig breed on the final quality of the meat, using the same system of breeding and feeding. The breeds tested were Goland and Duroc per Large White mother. The evaluation was made by taking into account both, the meat (M. longissimus dorsi muscle) and San Daniele dry-cured ham, which is one of the transformed products. The results showed that there are no differences in the chemical-physical and microbiological characteristics of the meat as such, nor significant differences of physico-chemical characteristics of the dry-cured ham. The third work involved the use of starter cultures of L. curvatus and L. sakei to improve the shelf-life of cooked ham, sliced and packaged under modified atmosphere packaging (MAP). The use of bioprotective cultures influenced the flavour, odour and colour stability of the sliced cooked ham. In addition, the growth of indigenous lactic acid bacteria was inhibited, preventing the formation of the white superficial slime and consequently extending the shelf-life of the product up to 30 days. The fourth part of this thesis deals with the use of ozone for the decontamination of the equipment and tools used in food chain. Results obtained showed a great variability, depending on both, the type of the tested microorganisms (more or less-resistant, vegetative cells or spores) and the method used to deliver the ozone (wet and dry). As a result, an ozone concentration of 2 or 4 ppm allowed to obtain a reduction from 1 to 5 logs of the target microorganisms. The last part of this work involved a mix of bioprotective cultures, which were Lactobacillus carnosus/Lactobacillus sakei + Staphylococcus xylosus, Lactococcus lactis subsp. lactis/Lactobacillus sakei + Staphylococcus xylosus, also in different ratio, for the improvement of the shelf-life of hamburger packed under modified atmosphere (MAP) and stored at 4 ± 2 °C. Data showed that inoculated cultures extended the hamburgers shelf-life by limiting the ammoniacal molecules production, the development of spoilage and pathogenic microorganisms, in particular Brochothrix thermosphacta, and avoiding the formation of the white slime on the surface of the hamburgers.openDottorato di ricerca in Scienze degli alimentiembargoed_20140921Andyanto, Debbi

Overcoming Anaerobic Digestion Toxicity of Aqueous Liquid from Wastewater ‎Solids Pyrolysis

Pyrolysis treats and potentially recovers energy from wastewater solids (WWS). ‎Aqueous pyrolysis liquid (APL), however, is produced and its management is a ‎bottleneck to pyrolysis full-scale application. To overcome this bottleneck, ‎anaerobic digestion (AD) may be a possible method to manage APL, but APL ‎digestion has not been conclusively demonstrated. In AD, a select group of ‎microorganisms convert organic chemicals to biogas containing methane that ‎can be used as a fuel. In this dissertation work, APL derived from WWS pyrolysis ‎was successfully converted into methane as the sole substrate and as a co-‎digestate with synthetic primary sludge in long-term, continuous anaerobic ‎digesters for the first time. Methane production from APL that was previously ‎hindered by APL recalcitrance and toxicity, increased by applying a low organic ‎loading rate (OLR), high solids retention time (SRT), ozone pretreatment, and ‎selecting appropriate microorganisms that were more proficient at APL ‎biodegradation. APLs’ anaerobic degradability produced at 500 and 700 °C ‎pyrolysis temperatures was evaluated in anaerobic toxicity assays using four ‎different anaerobic inocula. Higher pyrolysis temperature resulted in APL with ‎higher toxicity. Pre-ozonation of APL for 2 h or less improved the methane ‎production rate from 700°C APL. In contrast, ozonation did not have a ‎substantial impact on the methane production rate from 500 °C APL. In long-‎term, continuous digestion studies, quasi steady state methanogenesis from 700 ‎‎°C APL was accomplished by employing an appropriate, low APL OLR (0.03 ‎gCOD/L APL) and a sufficiently long SRT (210 days), whereas shorter SRT and ‎higher OLR values inhibited or stopped methane production. Employing a ‎specific anaerobic inoculum from an industrial waste digester that was ‎acclimated to constituents similar to those in APL resulted in more complete and ‎more rapid methane production, compared to municipal anaerobic digester ‎biomass. Microbial communities in digesters inoculated with the industrial ‎biomass were dominated by hydrogenotrophic Methanobacterium, accompanied ‎by an increased relative abundance of syntrophic bacteria belonging to phylum ‎Synergistes and class Clostridia. Bacterial taxa capable of degrading N-‎heterocyclic compounds, Enterococcus, Eubacterium, and Bacillales, were also ‎enriched. The results demonstrate that long-term methanogenesis from APL as ‎the sole substrate in AD is possible. Anaerobic co-digestion of APL with primary ‎sludge at municipal water resource recovery facilities is also a viable approach at ‎facilities that already have digesters treating sludge. In this scenario, APL from ‎pyrolyzed WWS can be added to digesters for increased biogas production, but ‎care must be taken to control the OLR, SRT and biomass inventory to ensure ‎APL digestion success.

Nanoporous carbons from sisal residues and their application in hybrid TiO2/carbon photocatalysts for the removal and degradation of phenol in solution

Tese de doutoramento, Química (Química Tecnológica), Universidade de Lisboa, Faculdade de Ciências, 2016The main aim of this PhD thesis was the development of nanoporous adsorbents and catalysts using industrial by-products of low commercial value as precursors and to investigate their application in advanced remediation technologies for the removal and/or degradation of aromatic pollutants in aqueous solution. The first stage of this study consisted on investigating the valorization of rope industry´s wastes through the analysis of their pyrolytic behaviour. The thermal characterization of the residues confirmed that although most decomposition occurs at 400 ◦C, some pyrolytic reactions take place above 550 ◦C. The yields of the different fractions were 22 wt. % of a carbonaceous residue (char), 50 wt. % tars and a gas fraction at 800 ◦C. From the analysis of the different fractions, it was possible to conclude that the produced oil was rich in hydrocarbons and alcohols, while the gas fraction is mainly composed of CO2, CO and CH4, and the carbonaceous solid residue displayed somewhat porous features, with a more developed porous structure as the pyrolysis temperature increased. Further on, the synthesis of copper-doped activated carbons from sisal residues was explored, using a wet impregnation and low temperature calcination procedure. The incorporation of copper was also performed in a bituminous coal for comparison purposes. The role of copper on the physicochemical and structural features of the materials has shown to be strongly dependent on the nature of the carbon matrix. The dual role of copper on the reactivity of the carbons was observed; on one hand, favouring the development of microporosity in the case of the coal-derived activated carbon, due to the catalysed air gasification of the material at a very low temperature (i.e., 325 °C); on the other hand, the immobilization of copper on the sisal-derived carbon, acted as a combustion retardant during the calcination step, protecting the carbon matrix. In both cases, a homogenous distribution of copper within the carbon matrix, and a good preservation of large textural properties were observed. The incorporation of copper on the carbon material was also carried out through a different approach, via impregnation of the carbon precursor followed by activation. This allowed to obtain carbon materials displaying a well-developed nanoporous texture (although comparatively with a marked inhibition of the textural development), and a homogeneous dispersion of copper particles, predominantly as Cu(II) species. These materials were used in the photocatalytic degradation of phenol from solution under visible light, as hybrid titania/Cu-carbon composites. The photo-oxidation tests showed the outstanding role of copper under visible light, in terms of increased phenol conversion, mineralization degree and degradation rate. Similar overall conversions were obtained with half of the amount of the photoactive semiconductor (1:1 composites). The beneficial effect of copper loading was also observed in the marked regioselectivity of the intermediates, towards the preferential formation of catechol. Furthermore, the copper-loaded photocatalyst was found to be stable upon long irradiation exposure. The nanoporous carbons prepared from the activation of sisal wastes were also used as additives to TiO2 powders. The incorporation of the carbon material in the formulation of the photocatalyst (TiO2/carbon) proved to increase the photocatalytic performance of TiO2 regardless the studied illumination conditions, although the effect was more pronounced at λ > 200 nm. The photocatalytic runs performed using the carbon alone as catalyst confirmed a certain level of self photoactivity under different irradiation conditions (λ > 200 nm or λ > 360 nm). An evident deactivation of the carbon photocatalyst was observed after 60 min of irradiation, most likely due to the consumption of the photoactive sites. As for the photo-oxidation mechanism for the carbon component, a marked regioselectivity towards the ortho-substitution was also observed at high energy photons, confirming the strong effect of both the composition of the catalyst and the illumination conditions on the nature of the degradation intermediates of phenol.O principal objetivo do trabalho que se apresenta nesta tese de doutoramento foi o desenvolvimento de adsorventes e catalisadores nanoporosos usando como precursores subprodutos industriais de baixo valor comercial e avaliar o seu desempenho em tecnologias avançadas para a remediação (remoção e/ou degradação) de poluentes aromáticos em solução aquosa. A primeira etapa do estudo consistiu em investigar a valorização de resíduos de sisal provenientes da indústria de cordoaria. O sisal (Agave sisalana) é uma das fibras naturais de origem lenhinocelulósica mais utilizadas em todo o mundo, devido às suas excelentes características relacionadas com o baixo custo e densidade, boas propriedades mecânicas e ausência de toxicidade. O processo de manufatura de cordas gera uma quantidade elevada de desperdícios, que são claramente subaproveitados, sendo utilizados apenas na produção de cordas de qualidade inferior ou como combustível. Dado o interesse crescente em explorar novas aplicações para estes resíduos, a análise feita neste trabalho relativamente ao seu comportamento pirolítico, permitiu avaliar a potencialidade das fibras de sisal para outras aplicações que não as tradicionais. A caracterização térmica destes desperdícios confirmou que embora a reação de pirólise se inicie a 250 ºC, ocorrendo a maioria da decomposição até 400 ◦C, algumas reações pirolíticas ocorrem acima de 550 ◦C. Os rendimentos obtidos para as diferentes frações foram de 22 % de um resíduo carbonáceo (carbonizado), 50 % de alcatrão e uma fração gasosa a 800 ◦C. A partir da análise das diferentes frações, foi possível concluir que o óleo produzido é rico em hidrocarbonetos e álcoois, enquanto que a fração gasosa é composta maioritariamente por CO2, CO e CH4.e O resíduo sólido exibe alguma porosidade, observando-se um maior desenvolvimento da estrutura porosa com o aumento da temperatura de pirólise. Seguidamente foi explorada a modificação da química superficial de dois carvões ativados resultantes de ativação física dos precursores, resíduos de sisal e carvão betuminoso, com dióxido de carbono e vapor de água, respetivamente. Os carvões foram dopados com cobre através de um processo de impregnação em solução e subsequente calcinação feita a uma temperatura baixa. A influência do cobre sobre as características físico-químicas e estruturais dos materiais mostrou ser altamente dependente da natureza da matriz de carbono. Verificou-se que a influência do cobre na modificação da estrutura depende da reatividade dos carvões, tendo-se constatado que no caso do carvão betuminoso o cobre favorece o desenvolvimento da microporosidade, catalisando a reação de gaseificação do material a uma temperatura muito baixa (325 ° C); enquanto que a imobilização de cobre no carvão derivado de sisal, atuou como um retardante de combustão durante o passo de calcinação, protegendo a matriz de carbono. Em ambos os casos, foi observada uma distribuição homogénea de cobre no interior da matriz de carbono, e uma boa preservação das propriedades texturais. A incorporação de cobre na matriz carbonácea foi também realizada através de uma abordagem diferente, por meio de impregnação do precursor, seguida de ativação. Para tal, impregnaram-se pedaços de sisal primeiro com uma solução de Cu(NO3)2.3H2O (de modo a obter uma concentração de Cu final de 5%) e seguidamente com uma solução de K2CO3, de acordo com a proporção sisal: K2CO3 de 2:1. Os materiais preparados apresentaram uma textura nanoporosa bem desenvolvida, embora para o carvão dopado com cobre se observe uma marcada inibição do desenvolvimento estrutural, comparativamente com o carvão nãodopado. Através da aplicação de diversas técnicas, como espectroscopia fotoeletrónica de raios X, difração de raios X e redução a temperatura programada, foi possível concluir que as partículas de cobre apresentam uma dispersão homogénea na matriz de carbono, e são predominantemente espécies de Cu(II). Estes materiais foram utilizados no processo de fotocatálise heterogénea, uma das tecnologias mais promissoras para a degradação e mineralização de compostos orgânicos recalcitrantes, em meio aquoso. Este processo, que tem sido amplamente estudado na área ambiental, integra os denominados Processos de Oxidação Avançados (POAs), que se baseiam na formação de espécies altamente reativas, como por exemplo, os radicais hidroxilo (•OH), que vão atacar as moléculas orgânicas através de reações sucessivas, até à obtenção de dióxido de carbono e água como produtos finais. Estudou-se a degradação fotocatalítica de fenol, o qual foi escolhido como molécula modelo, uma vez que é frequentemente detetado em águas residuais, nomeadamente em águas provenientes de diversas indústrias. Dada a sua persistência, baixa biodegradabilidade e toxicidade, alguns compostos fenólicos são considerados poluentes prioritários pelas agências ambientais. Inicialmente ensaiou-se a degradação de fenol em solução sob irradiação com luz visível, usando como catalisadorTiO2, o semicondutor mais investigado em processos fotocatalíticos e misturas de dióxido de titânio com carvão dopado com cobre, e com carvão não-dopado. Dada a elevada porosidade apresentada pelos carvões ativados, todos os ensaios fotocatalíticos foram precedidos por uma etapa de pré-adsorção de fenol, de modo a eliminar a contribuição do processo de adsorção na reação de fotocatálise. Os testes de fotooxidação demonstraram o papel fundamental do cobre para, sob irradiação com luz visível, promover o aumento da conversão de fenol, do grau de mineralização Os resultados obtidos mostraram os compósitos 1:1 (i.e. onde se tem apenas metade da quantidade do semicondutor fotoativo da utilizada ao ensaiar apenas o semicondutor) permitem alcançar conversões globais semelhantes. O resultado mais elevado para a mineralização de fenol após 6 h de irradiação foi obtido para o fotocatalisador híbrido TiO2/Cucarvão (cerca de 42 %), quase o dobro da mineralização obtida para o compósito TiO2/carvão não-modificado. O efeito benéfico da presença de cobre foi também observado na regiosselectividade acentuada dos compostos aromáticos intermediários, com a formação preferencial de catecol, considerada um percurso reacional preferencial de oxidação de fenol, em relação à formação de quinonas, uma vez que se gera um menor número de intermediários, sendo assim mais efetiva para alcançar a mineralização completa (conversão em CO2 e H2O). Além disso, o fotocatalisador com cobre mostrou ser estável após um tempo relativamente longo de exposição à irradiação, sem ocorrência de lixiviação ou fotorredução das espécies de cobre. A interpretação dos resultados considerou que as espécies de cobre dispersas na matriz de carbono poderão criar um meio de transferência eletrónica rápida, minimizando a recombinação dos pares eletrão/lacuna criados com a iluminação do semicondutor e também sítios hidrofóbicos, nos quais o oxigénio molecular dissolvido é facilmente adsorvido, o que favorecerá a formação de espécies radicais de oxigénio. Os carvões nanoporosos preparados a partir da ativação dos resíduos de sisal foram também utilizados como aditivos ao TiO2. A incorporação do material de carbono na formulação do fotocatalisador (TiO2/carvão) provou aumentar o desempenho fotocatalítico do TiO2 na degradação e mineralização de fenol, independentemente das condições de iluminação estudadas. Contudo o um efeito é mais pronunciado para λ > 200 nm, dada a presença de fotões mais energéticos e de um fluxo fotónico mais elevado, o qual foi medido por actinometria química. Para estas condições de irradiação a mineralização de fenol com o catalisador TiO2/carvão é 1.5 vezes superior ao que obteve usando apenas TiO2, sendo de salientar que no caso da mistura, a quantidade de TiO2 é apenas metade utilizada para o ensaio com apenas o semicondutor. Os testes fotocatalíticos realizados utilizando como catalisador apenas o carvão confirmaram um certo nível de fotoatividade sob diferentes condições de irradiação (λ > 200 nm ou λ > 360 nm). No entanto, quando a luz é filtrada a λ > 360 nm, após 60 minutos de irradiação é observada uma clara desativação do fotocatalisador, provavelmente devida ao consumo dos locais fotoativos. Quanto ao mecanismo de fotooxidação para o componente de carbono, no caso de fotões de elevada energia foi também observada uma regiosseletividade marcada relativamente à substituição na posição orto, o que confirma a forte influência da composição do catalisador e das condições de iluminação sobre a natureza dos intermediários de degradação de fenol