Trends in Research on Electrochemical Oxidation

This paper presented a detailed chronological survey of scientific output related to electrochemical oxidation in SCI categories of “environmental sciences, environmental engineering and water re-sources” from 1975 to 2012. Publications were analyzed by distribution of the number of publications and times cited, source categories, source journals, author keywords, KeyWords Plus, and the most cited publications in these years. It was concluded that Pt, boron-doped diamond, TiO2 were currently and would continue to be the predominant focused electrode materials at least over the next decade. And the foci of studied pollutants in the electrochemical oxidation were mainly concentrated in dyes and phenols popularly existing in the practical wastewaters. What’s more, electrochemical degradation, wastewater treatment, electrochemical determination and fuel cell would be the key research topics currently and recently. Fenton, photocatalysis and coagulation were the most-frequent combination technology with electrochemical oxidation based on the bibliometric results. Contribution of Croatian chemists to the field is mentioned

More than One Century of History for Photocatalysis, from Past, Present and Future Perspectives

In this review, we analyzed the history and the past and present trends in photocatalysis research, trying to outline possible scenarios for the future in the medium term. The in-depth analysis of the literature reported here—from a mere bibliometric point of view—allowed us to divide the history of photocatalysis into four different periods characterized by different maturity of the topic and different bibliometric features. The turn of the 20th century saw an explosion in scientific production, which is still continuing now and has reached more than 15,000 papers published each year. Research interest is still growing significantly, and the analysis of different keywords suggests that such growth is substantial and not merely due to “publish or perish” behavior. The analysis of the most-investigated topics in the field of photocatalysis highlighted that, during its history, the focus of the research moved from inorganic oxides to carbon and hybrid materials. Concomitantly, the investigation of the “geography” of photocatalysis allowed us to underline its evolution over the years, with the repositioning of its center of mass from the Atlantic Ocean (USA and Europe) to Asia (China and India). Photocatalysis is active as never before but still awaiting major breakthroughs, which would allow a much broader technological and commercial output. Without such breakthroughs in this decade, the growth in scientific interest could level out or even decrease

Research Trends on Pillared Interlayered Clays (PILCs) Used as Catalysts in Environmental and Chemical Processes: Bibliometric Analysis

Over the last four decades, a large number of studies have been published on pillared interlayered clays (PILCs) used as adsorbent materials and catalysts or supports for transition metals in heterogeneous catalysis. Particularly, PILCs have been used for water treatment through advanced oxidation processes (AOPs) to remove organic pollutants. They have also been studied in various chemical and environmental processes. Because of the growing interest in PILCs, this article is focused on analyzing scientific publications such as research/review articles and book chapters from the last four decades (from 1980 to 2019) through a bibliometric analysis (BA) to visualize and describe research trends on PILCs. By narrowing the bibliographic search to titles, keywords, and abstracts of publications related to PILCs, using Scopus and Web of Science (WoS) (the two scientific databases), a total of 3425 documents have been retrieved. The bibliometric dataset was analyzed by VantagePoint®. The main research trends identified in the last four decades were the use of PILCs in environmental processes (34.4% of total publications) along with chemical processes (petrochemical reactions 17.5%, SCR NOx 10.8%, and decomposition 8.2%). In environmental processes, PILCs have been used in photo-oxidation (32%), CWPO (21.1%), and heterogeneous catalysis (19.4%). Phenols, dyes, and VOCs have been the main pollutants studied using PILCs as catalysts. Fe, Ti, Zr, Cu, and Co are the most supported active phases in PILCs. Other research trends grouped by characterization techniques, countries, research areas, institutes, scientific journals that have published the most on this topic, number of publications per 5-year period, and most frequently used keywords through the last four decades have been identified. It was determined that the number of publications on PILCs has increased since 1980 and the countries with the highest number of publications are China, Spain, and The United States of America.Centro de Investigación y Desarrollo en Ciencias Aplicada

Persistent Organic Pollutants (POPs)

Persistent organic pollutants (POPs) are toxic organic compounds that resist environmental degradation through biological, chemical, and photolytic processes. Many POPs are currently used as pesticides, pharmaceuticals, solvents, and industrial chemicals. Because of their persistence, POPs bioaccumulate and adversely affect human health and the environment. Persistent Organic Pollutants (POPs) - Monitoring, Impact and Treatment deals with several aspects of POP monitoring, occurrence, impact, and treatment technologies. The book is divided into two sections containing nine chapters that address such topics as the effect of POPs on wildlife, their role in hepatocarcinogenesis, treatment of POPs in wastewater, and much more

Contribution à la robustesse des traitements fongiques et enzymatiques de contaminants organiques persistants dans des matrices environnementales complexes

Les effluents industriels et domestiques représentent les principales sources de contamination des milieux aquatiques par une variété de substances organiques persistantes. L’élimination de ces substances dans les eaux usées relève d’un défi technologique qui nécessite l’adaptation ou l’amélioration des systèmes de traitement conventionnels des eaux actuelles. Les approches de mycoremédiation exploitant les champignons responsables de la pourriture blanche du bois (WRFs) et celles de biocatalyse enzymatique utilisant des enzymes fongiques isolées constituent des méthodes versatiles et durables pour le traitement de ces matrices complexes. Malgré leur efficacité, ces techniques souffrent d’un manque de robustesse qui freine leur usage à l’échelle industrielle. En effet, la majorité des études concernant leur utilisation ont été réalisées à l’échelle du laboratoire dans des conditions optimales contrôlées et peu représentatives des matrices complexes ainsi que des concentrations ciblées. L’exploitation de ces technologies présente un défi pour la communauté scientifique. Ce projet de recherche vise à mettre en place, et à évaluer des stratégies contribuant à l’amélioration de la robustesse des traitements fongiques et enzymatiques. Les travaux développés dans ce document ont porté sur deux aspects : 1 – la mise en place de stratégies de sélection de souches fongiques dans un effluent industriel de bioraffinerie riche en composés phénoliques. 2 – l’évaluation d’une méthode pour la stabilisation d’un extrait brut de laccase pour l’élimination de contaminants dans les effluents municipaux. Le choix était basé sur l’aptitude de sept souches de champignons à éliminer les phénols totaux de l’effluent, ainsi que sur leur capacité à sécréter la laccase. Les deux stratégies employées (l’une utilisant du glucose et l’autre des copeaux de bois comme cosubstrat pour la croissance des souches) ont permis d’identifier P. dryinus et T. hirsuta. Ces deux souches ont permis d’éliminer les phénols totaux de l’effluent à des taux supérieurs à 94 %, avec les deux stratégies testées. De plus, sur les sept souches étudiées, seules P. dryinus et T. hirsuta ont produit la laccase. Ces résultats établissent la possibilité d’exploiter P. dryinus et T. hirsuta pour le prétraitement de l’effluent issu de la valorisation industrielle des bois traités en fin de vie. Cette conclusion ouvre la voie au développement de procédés de mycoremédiation durables. Cette expérience suggère également que la valorisation des déchets lignocellulosiques peut se révéler une alternative économique pour la mise en place d’une telle approche de traitement. En effet, l’utilisation des copeaux de bois comme cosubstrat a démontré une meilleure efficacité en ce qui concerne la production de la laccase (une enzyme au fort potentiel biotechnologique). Cependant, une pareille approche nécessite encore d’être optimisée. L’insolubilisation reste un des moyens les plus efficaces pour la stabilisation et l’utilisation des enzymes isolées dans des bioprocédés opérant en continu. La laccase brute insolubilisée sous forme de CLEAs (cross-linked enzyme agregates) demeure une méthode prometteuse pour des applications environnementales. Pourtant, la transition de cette technologie vers des applications industrielles est limitée par sa faible résistance mécanique. Cette thèse a permis de confirmer, la possibilité d’employer la méthode EPES (enzyme polymer engineered structure) pour la stabilisation d’un extrait brut de laccase de T. hirsuta. La caractérisation des EPES-CLEAs formés a démontré une nette augmentation de la stabilité des CLEAs dans différentes conditions dénaturantes. De plus, les résultats ont démontré une meilleure recyclabilité et une préservation de l’efficacité du biocatalyseur dans un effluent municipal. En somme, ces travaux apportent de nouvelles connaissances sur l’amélioration des procédés de mycoremédiation et de biocatalyse enzymatique des contaminants organiques persistants dans des matrices complexes. Ils démontrent en particulier l’intérêt de caractériser ces technologies novatrices dans les conditions typiques de l’environnement afin d’augmenter la robustesse des procédés

Valorization of pyrolysis biochar by mild oxidation and its application as adsorbent and catalyst support

La conversion thermochimique de la biomasse se traduit par un sous-produit solide appelé biochar. Cette substance écologique peu coûteuse a récemment fait l’objet d’une attention croissante pour son utilisation dans plusieurs applications, en raison de ses propriétés de surface uniques, de sa stabilité physique et de son inertie. Les applications les plus courantes du biochar sont dans l’adsorption, l’amendement du sol et comme support de catalyseur. L’efficacité du biochar dans une application ciblée dépend fortement de ses propriétés de surface physicochimiques, nécessitant ainsi une modification de la surface du biochar. Cette thèse de recherche se compose de deux parties générales. La première partie est la modification et la caractérisation de la surface du biochar. Le chapitre 1 destiné aux ingénieurs chimistes débutants, rappelle les bases de la physisorption de l’azote, présentant le principe général de la détermination de la surface spécifique (SSA) et l’estimation de la distribution de la taille des pores (PSD). Ces propriétés, c’est-à-dire SSA et PSD, représentant la morphologie des solides, jouent un rôle vital dans la performance des matériaux carbonés dans les applications susmentionnées. La SSA est généralement déterminée par la théorie de Brunauer-Emmett-Teller (BET) à partir de la branche d’adsorption des isothermes d’adsorption-désorption N2 , par un intervalle de pression relative de 0, 05 < P/P0 < 0, 3. La PSD est estimée en utilisant soit la méthode de Barrett-JoynerHalenda (BJH) de la branche de désorption, soit la théorie fonctionnelle de densité non locale (NLDFT) de la branche d’adsorption. Ce dernier permet une estimation plus raisonnable de la PSD. La modification de la surface d’un biochar obtenu par le procédé de pyrolyse de Pyrovac Inc. a été réalisée par activation à la vapeur et par oxydation ménagée à l’air. Le chapitre 2 résume ainsi les résultats, obtenus par des analyses de caractérisation de surface. Le but de ce chapitre était d’améliorer notre compréhension du contrôle des caractéristiques physicochimiques de la surface du biochar lors de l’activation et de l’oxydation. Les conditions d’activation optimales en termes de combustion du biochar le plus faible avec le SSA le plus élevé ont été trouvées à 900 °C sous une pression partielle de vapeur de 53 kPa sur 60 min. Ces conditions ont conduit à un rendement de 8% (en fraction à poids basé sur la biomasse humide initiale) avec un SSA égal à 1025 m2 g −1 . La concentration de Boehm en groupes iii fonctionnels contenant de l’oxygène du biochar a été réduite de 2.2 à 1.4 mmol g−1 Biochar lors de l’activation. Les conditions optimales d’oxydation en termes de la combustion la plus faible et de concentration carboxylique de Boehm la plus élevée ont été trouvées à 200 °C pour 60 min en utilisant 164 ml min−1 d’air extra sec qui en écoulement. L’oxydation du biochar a abouti à un rendement final de 18% (en fraction à poids basé sur la biomasse humide initiale), augmentant la concentration carboxylique du biochar de 0.4 à 4.2 mmol g−1 Biochar. Les conditions de l’oxydation n’ont cependant pas pu introduire de fonctions carboxyliques à la surface du charbon actif. Dans la deuxième partie, le biochar a été utilisé dans deux applications, reposant sur l’échange de cations. Ces applications sont l’utilisation du biochar dans l’adsorption de cations de métaux lourds des solutions aqueuses et le support de catalyseur. Des observations détaillées faites dans Chapitre 2, ont suggéré que le biochar oxydé est une sélection plus pratique pour des applications ciblées. Chapitre 3 rapporte des observations expérimentales du comportement du biochar envers l’adsorption des cations plomb (Pb2+). Le but de ce chapitre était d’examiner la capacité du biochar pour l’échange de cations avant et après d’oxydation ménagée à l’air. Les résultats ont montré que l’oxydation de l’air améliore la capacité d’adsorption à l’équilibre du biochar de 2.5 à 44 mg g−1 . En utilisant les conditions optimales d’adsorption suggérées par la méthodologie de surface de réponse (RSM), l’analyse SEM/EDX a montré que les bords défectueux du carbone avec la fraction d’oxygène la plus élevée sont les endroits favorables pour adsorber les cations de plomb. Le biochar a été utilisé pour la préparation du catalyseur Ru/C, par échange d’ions en utilisant le précurseur Ru(NH3 )6Cl2 . L’analyse SEM a montré que la surface du biochar oxydé était sur-échangée avec du ruthénium après imprégnation. Les analyses TEM et H2 -chemisorption ont tous les deux démontré que Ru a une dispersion plus élevée (c’est-à-dire double) sur le biochar oxydé que sur le non oxydé. D’après l’analyse XPS, il a été constaté qu’une oxydation ménagée empêche la ségrégation de Ru sur la surface du carbone. L’activité du catalyseur a été étudiée dans l’hydrogénation du furfural (FF) en alcool furfurylique (FA). Dans des conditions discontinu, Ru supporté sur le biochar oxydé a entraîné une sélectivité plus élevée en alcool furfurylique, ce qui a permis d’obtenir la valeur la plus élevée de la sélectivité 93% FA à 53% FF. L’étude de l’effet des conditions d’hydrogénation a suggéré que la dissolution ou la diffusion de H2 en phase liquide est très probablement l’étape limitante de vitesse.Biomass thermochemical conversion results in a solid byproduct designated as biochar. This inexpensive eco-friendly substance has recently received increasing attention for use in several applications, owing to its unique surface properties, physical stability, and inertness. The most common biochar applications are in adsorption, soil amendment, and as catalyst support. The efficacy of biochar in a targeted application strongly depends on its physicochemical surface properties, thereby requiring biochar surface modification. This research-based thesis consists of two general parts. The first part is biochar surface modification and characterization. Chapter 1 provides inexperienced Chemical/Material Engineers with nitrogen physisorption tutorial, presenting general principle of specific surface area (SSA) determination, and the estimation of pore size distribution (PSD). These properties, i.e., SSA and PSD, representing the morphology of solids, play a vital role in the performance of carbonaceous materials in the above-mentioned applications. SSA is usually determined by the Brunauer-EmmettTeller (BET) theory from the adsorption branch of N2 adsorption-desorption isotherms, over the relative pressure range of 0.05 < P/P0 < 0.3. PSD is estimated using either BarrettJoyner-Halenda (BJH) method from desorption branch, or non-local density functional theory (NLDFT) from adsorption branch. The latter allows more reasonable estimation of PSD. Surface modification of a biochar obtained by the pyrolysis process of Pyrovac Inc. was achieved by steam activation and by mild air oxidation. Chapter 2 thus summarizes the results, obtained by surface characterization analyses. The aim of this chapter was increasing our understanding of controlling biochar physicochemical surface characteristics upon activation and oxidation. The optimal activation conditions in terms of the lowest biochar burn-off with the highest SSA were found at 900 °C under a steam partial pressure of 53 kPa over 60 min. These conditions led to a yield of 8 wt.% (based on the initial wet biomass) with SSA equal to 1025 m2 g −1 . Boehm’s concentration of oxygen-containing functional groups of the biochar was decreased from 2.2 to 1.4 mmol g−1 Biochar upon the activation. The optimal conditions of oxidation in terms of the lowest burn-off and the highest Boehm’s carboxylic concentration were found at 200 °C for 60 min using 164 mL min−1 of flowing extra dry air. The oxidation of the biochar resulted in a final yield of 18 wt.% (based on the initial wet biomass), v increasing the carboxylic concentration of the biochar from 0.4 to 4.2 mmol g−1 Biochar. These oxidation conditions did not however allow introducing carboxylic functional groups on the surface of the activated carbon. In the second part, biochar was employed in two applications, relying on cation-exchange. These applications are biochar use in adsorption of heavy metal cations from aqueous solutions, and catalyst support. Detailed observations carried out in Chapter 2, suggested that mildly oxidized biochar is more convenient for the targeted applications. Chapter 3 reports experimental observations of the biochar behavior towards lead cations (Pb2+) adsorption. The purpose of this chapter was examining the capacity of biochar for cation-exchange before and after mild air oxidation. Results showed that the mild air oxidation improves capacity of adsorption of the biochar from 2.5 to 44 mg g−1 . Using the optimal conditions of adsorption suggested by response surface methodology (RSM), SEM/EDX analysis showed that defective edges of carbon with the highest oxygen fraction are the favorable places to adsorb lead cations. The biochar was used for preparation of Ru/C catalyst, via ion-exchange using Ru(NH3 )6Cl2 precursor. SEM analysis showed that surface of the oxidized biochar was over exchanged with ruthenium after impregnation. TEM and H2 -chemisorption analyses both demonstrated that Ru has higher dispersion (i.e., double) on the oxidized biochar than on the unoxidized one. From XPS analysis, it was found that mild oxidation prevents Ru segregation from carbon surface. Catalyst activity was investigated in hydrogenation of furfural (FF) to furfuryl alcohol (FA). Under batch conditions, Ru supported on the mildly oxidized biochar resulted in a higher selectivity to furfuryl alcohol, with the highest value of 93% FA selectivity at 53% FF conversion obtained. Investigating the effect of the hydrogenation conditions suggested that H2 dissolution or diffusion in liquid phase is very likely the rate limited step

Nanotechnology for Environmental and Biomedical Research

Do you care about your environment and your health? Contamination by hazardous substances in environmental matrices, including landfills, oil fields, and manufacturing and industrial sites, represents a global concern and needs to be remediated since it poses a serious risk to the environment and human health. Particular attention should also be paid to the use of medical devices and recent developments in the use of nanoparticles expressed as drug delivery systems designed to treat a wide variety of diseases. This Special Issue collects a compilation of articles that strongly demonstrate the continuous efforts made in developing advanced and safe nanomaterial-based technologies for nano-remediation and for drug delivery and other biomedical applications. It covers the most recent advances in the safe nanomaterials synthesis field as well as in environmental applications, in the use of restorative materials, drug delivery and other clinical applications, in order to lay the foundations for a cleaner and healthier future

Circular Tutelage: a Sustainable Approach Toward Remediation and Enhancement of Endangered Areas

Nowadays, one of the most important topics in the public dialogue concerns the concept of sustainability and its application in everyday life, given the urgence to reduce or counteract the negative effects partly caused by human activities. Fighting poverty, eradicating hunger and malnutrition, increasing the quality of life, protecting and restoring biodiversity, ensuring access to energy sources are just some of the goals for sustainable development included in the United Nations Organization's 2030 Agenda. Every country is called to make its contribution to jointly face these great challenges, rising from the awareness that the planet's resources are limited, unequally distributed and their exploitation often involves the alteration of delicate environmental balances. In the present work, a very productive transitional area prone to suffer from pollution and dangerous algal blooms, has been studied in order to propose methodologies and solutions which, if adopted, can contribute not only to mitigate environmental damages but also to provide new tools that can contribute to the development of local populations in a circular economy perspective. In particular, research has been carried out aimed at the development of solutions for the environmental restoration of ecosystems threatened by human pressure, proposing highly circular and sustainable processes based on the use of biomass from wastes or by-products. The proposed production processes are aimed at exploiting and valorizing these wastes, avoiding the compromission of the hygiene and quality of the ecosystem. In addition to the environmental sustainability also the economic and social one are considered in the proposed solutions. The area is characterized by a semi-enclosed lagoon structure, depths of up to two meters, over 25 km2. This area alone is responsible for the production of 55% of all clams produced in Italy, with over fifty million euros in turnover; essentially a collective heritage for the cities and economies that depend precisely on mussel farming and supporting activities. In order to mitigate the effects related to the excessive presence of algal biomass in the area, a cost / benefit analysis was carried out to determine the possibility of exploit this biomass as a secondary raw material for the production of market goods such as biofuels, drugs, supplements, and much more. The possibilities for economic exploitations of the biomass would in fact make the collection of this component from the environment advantageous and would avoid negative phenomena in the aquatic environment. The feasibility of the proposed solutions was also accompanied by a foresight analysis in which possible social dynamics were considered which have led, in the past, to the failure of a project whose mission was to safeguard and improve the conditions of the lagoon. In order to carry out the feasibility study, in addition to the composition of the constituent elements of algae determination, their possible contamination by various classes of pollutants, whose presence could constitute an obstacle to their exploitation, was also studied. The thesis also considers another voluminous waste biomass present in the lagoon, namely byproduct seashells which constitute a process waste from the bivalves that are produced in the lagoon and which, unfortunately, are often illegally discharged into the canals or deployed in landfill and classified as special waste. Landfilling not only has an economic impact on small fishing businesses but also reduces the sustainability of aquaculture activities, which according to many, will be a key sector for development in the coming years. Hence, the shell of the clam essentially consists of calcium carbonate and can be used as a constituent of soil conditioners and fertilizers for agricultural purposes or as an adsorbent material in biofilters and in environmental bioremediation methodologies.Oggigiorno, una delle tematiche di maggior rilievo nel dialogo comune riguarda il concetto di sostenibilità e della sua applicazione nel quotidiano per rispondere all’esigenza di ridurre o contrastare vari effetti negativi in parte causati dalle attività umane. Contrastare la povertà, eradicare la fame e la malnutrizione, tutelare e ripristinare la biodiversità, sicurezza energetica, sono solo alcuni degli obiettivi per lo sviluppo sostenibile presenti nell’Agenda 2030 dell’Organizzazione delle Nazioni Unite. Ogni Paese è chiamato a fornire il suo contributo per affrontare in comune queste grandi sfide, nate dalla consapevolezza che le risorse del pianeta sono limitate, distribuite iniquamente e il loro sfruttamento spesso comporta l’alterazione di delicati equilibri ambientali. Nel presente lavoro di tesi si è studiato un ecosistema di transizione molto produttivo, ma fragile, per proporre metodologie e soluzioni che se adottate possano contribuire non solo a mitigare i danni ambientali, ma anche a fornire nuovi strumenti che possano contribuire allo sviluppo delle popolazioni locali in un’ottica di economia circolare. In particolare, si sono effettuate ricerche orientate allo sviluppo di soluzioni per il ripristino ambientale di ecosistemi minacciati dalla pressione antropica, proponendo processi altamente circolari e sostenibili basati sull’utilizzo di biomasse provenienti da scarti o sottoprodotti. I processi produttivi proposti sono orientati a sfruttare e valorizzare questi scarti evitando che compromettano l’igiene e la qualità degli ecosistemi in cui essi sono presenti o in cui vengono riversati. In questo ambito si sono approfonditi argomenti propri della sfera sociale ed economica, per garantire oltre alla sostenibilità ambientale anche quella economica e sociale delle soluzioni proposte. La zona è caratterizzata da una struttura lagunare semichiusa, fondali profondi massimo due metri e complessivamente è uno specchio d’acqua di 25 km2. Quest’area sola è responsabile per la produzione del 55% di tutte le vongole prodotte in Italia, con oltre cinquanta milioni di euro di volume d’affari; sostanzialmente un patrimonio collettivo per le città e le economie che dipendono appunto dalle attività di mitilicoltura e dalle attività consortili e coadiuvanti. Allo scopo di mitigare gli effetti legati alla presenza eccessiva di biomassa algale nella zona, si è svolta una analisi costi / benefici per determinare la possibilità di sfruttare al meglio tale biomassa come materia prima seconda per la produzione di oggetti e beni di consumo, come biocombustibili, farmaci, integratori e tanto altro. La possibilità di sfruttare economicamente la biomassa renderebbe infatti vantaggiosa la raccolta di questa componente dall’ambiente. La realizzabilità delle soluzioni proposte è stata inoltre corredata da un’analisi in previsione in cui si sono considerate possibili dinamiche sociali che hanno portato, in passato, al fallimento di un progetto che aveva la missione di salvaguardare e migliorare le condizioni della laguna. inoltre, è stata studiata la composizione degli elementi costitutivi di alghe e anche la loro possibile contaminazione da parte di varie classi di inquinanti la cui presenza potrebbe costituire un ostacolo per il loro sfruttamento. Nella tesi viene inoltre considerata anche un’altra voluminosa biomassa di scarto presente nella laguna, “il capulerio” che costituisce uno scarto di lavorazione dei bivalvi prodotti. Lo smaltimento in discarica non solo incide economicamente sulle piccole imprese di pescatori, ma riduce la sostenibilità delle attività di acquacultura. In un’ottica di sostenibilità e circolarità, il guscio delle conchiglie è costituito da carbonato di calcio e può trovare impiego come costituente di ammendanti e fertilizzanti per scopi agricoli o come materiale adsorbente in biofiltri e in altre metodologie di bioremediazione ambientale

On the origins of some spectroscopic properties of "purple iron" (the tetraoxoferrate(VI) ion) and its Pourbaix safe-space

In this work, the authors attempt to interpret the visible, infrared and Raman spectra of ferrate(VI) by means of theoretical physical-inorganic chemistry and historical highlights in this field of interest. In addition, the sacrificial decomposition of ferrate(VI) during water treatment will also be discussed together with a brief mention of how Rayleigh scattering caused by the decomposition of FeVIO42− may render absorbance readings erroneous. This work is not a compendium of all the instrumental methods of analysis which have been deployed to identify ferrate(VI) or to study its plethora of reactions, but mention will be made of the relevant techniques (e.g., Mössbauer Spectroscopy amongst others) which support and advance this overall discourse at appropriate junctures, without undue elaboration on the foundational physics of these techniques

Environmental risk assessment and toxicity of pharmaceuticals in coastal tropical and temperate organisms

Demographic attributes of the urban society have prompted a milestone shift towards structural aging of global population and increase of life expectancy, crucial to the prominence of cancer as one of the non-communicable diseases leading mortality. Currently, cancer diseases were accountable for about 9.6 million deaths in 2018, with concerning increasing projections of cancer incidence and mortality, by 2030, at a greater proportion in developing countries. As a result, there is an increasing trend of production and consumption of pharmaceuticals applied in cancer treatments. Once administered and metabolized, such drugs are excreted into waterways following to waste water treatment plants (WWTPs), ending up in freshwater and coastal ecosystems, where they can be found at a sub ng to ng L-1 range. Anticancer drugs are designed to damage DNA and disrupt mechanisms of its transcription, replication and synthesis, as well as suppress the cell´s defense, ultimately causing cell death. In cancer therapy, drugs are typically administered in a combinatory cocktail, that covers different molecular targets, reducing the risk of clonal selection based upon cell resistance to a single drug. However, these chemicals may bring potential toxicity if discharged into the aquatic environment, both in temperate and tropical zones, particularly in the benthic compartment, where they are expected to accumulate. In this sense, the present thesis aimed to assess the effects of anticancer agents of different classes, namely the cytotoxic platinum-based cisplatin (CisPt), the alkylating agent cyclophosphamide (CP) and the endocrine disruptor tamoxifen (TAM), on non-target benthic marine species under realistic environmental concentrations, at individual and combined exposures. For this purpose, a multi-biomarker approach was applied including the assessment of behavioural responses, oxidative stress, biotransformation, neurotoxicity, lipid peroxidation and genotoxicity in the temperate polychaete Nereis diversicolor, in addition to the evaluation of acute and chronic effects of drugs in tropical and representative benthic organisms: the sea urchin Echinometra lucunter, the polychaete Scolelepis squamata and the amphipod Tiburonella viscana from the Brazilian coast. The main results revealed that single drug exposures caused alteration of AChE activity, oxidative stress and oxidative damage and, ultimately, DNA damage in N. diversicolor. Besides, alterations in its burrowing behaviour also occurred, as an ecological outcome. These effects were more pronounced in organisms under CisPt at 100 ng Pt L-1, CP at 1000 ng L-1 and TAM at 0.5 ng L-1. Findings from bioassays with N. diversicolor conducted with drugs in tertiary mixtures indicated that each biomarker effect respond differently, according to the trends proposed by models of drugs´s interaction. Toxicity did not increase in a dose-response manner but showed different patterns of effects, in a way that the highest DNA damage was observed at the set of lowest concentrations (Mixture A), an absence of oxidative stress at the intermediary drug levels (Mix B and C), with a potential dominance of TAM´s MoA in organisms exposed to Mixture C and D, suggesting an antagonist interaction between the cytotoxic drugs. Therefore, the effects ruled by single-drug MoAs cannot provide estimations and protective measures for a prospective ERA regarding scenarios of their combination in the environment. Although evidence on estrogen receptors expression is still not disclosed for the herein selected biological models, determination of biochemical and genotoxic outcomes from TAM exposure are highlighted, since it is assumed to comprise a targeted therapy on nuclear estrogen receptors. Anticancer drugs´ concentrations that triggered the above-mentioned responses are potentially present in coastal environments, even more prone to be encountered in developing regions, where technologies of WWTPs are not efficient or are lacking. Accordingly, effects regarding the bioassays conducted with the tropical counterparts showed a non-monotonic reduction of viable pluteus larvae of E. lucunter, at CisPt and CP treatment respectively at the range from 0.1 to 10 ng Pt L-1, and from 50 to 500 ng CP L-1, in contrast to the increasing reduction of embryo larval development under TAM exposure, significant over the whole range of concentrations. In polychaetes S. squamata, a significant acute toxicity was exerted at the higher pharmaceutical doses (Mix C and D). In the amphipod T. viscana demonstrated a higher sensitivity to pharmaceuticals, presenting a significant non-linear reduction of survival in Mix B and D, as a potential outstanding effect of TAM when present as mixtures. By virtue of the non-monotonicity addressed in the dose-responses relationships reported in all bioassays, another concern stands out on the urgency to the development of a risk analysis and safety assessment designated to anticancer drugs.Atualmente, a dinamica demográfica global demonstra uma excepcionl tendência de transição regida pelo envelhecimento populacional e pelo aumento da esperança média de vida. Estes fatores, combinados a atributos sociais relacionados aos hábitos modernos e exposição a fatores de risco (e.g. dieta inapropriada, tabaco, sedentarismo, consumo de álcool, agentes infecciosos), aliados à hereditariedade, contribuem para um significativo aumento da incidência dos casos de cancro, classificado como a doença mais preocupante do século, após os distúrbios cardiovasculares. Atualmente, o cancro representa 21,7% dos casos de morte a nível mundial, com projeções preocupantes para 2030, e maiores proporções de incidência em países em desenvolvimento. Dessa forma, estima-se uma consequente expansão na necessidade de produção e consumo de medicamentos anticancerígenos em todo o mundo, com aumento anual entre 6 – 8% estimado para o ano de 2018, comparado com os 6,5% nos últimos 5 anos. Após o consumo, via administração oral ou intravenosa, os fármacos anticancerígenos são excretados na sua forma parental e metabolizada através de efluentes hospitalares e industriais, bem como por descargas de esgotos provenientes de estações de tratamento de águas residuais (ETARs), as quais não possuem tecnologia adequada para a remoção de moléculas orgânicas complexas. Dessa forma, as águas superficiais e marinhas são os destinos finais desses medicamentos. Esta classe terapêutica atua sobre biomoléculas e componentes celulares críticos à proliferação celular, tais como DNA, RNA, proteínas, membrana fosfolipídica, microfilamentos do citoesqueleto e sinalização celular, a fim de causar danos irreversíveis e morte celular. Contudo, estes alvos não são específicos de células tumourais, pois, as drogas interferem em células proliferativas normais, como as dos organismos aquáticos. Apesar da crescente quantidade de informação envolvendo fármacos no âmbito da ecotoxicologia aquática, verifica-se uma escassez de dados sobre o impacto de drogas anticancerígenas no meio marinho. Em países em desenvolvimento, onde são escassas as políticas de saneamento ambiental e a implementação de infraestruturas avançadas em ETARs, o cenário de risco ambiental torna-se ainda mais elevado frente à contaminação por estes fármacos. Além disso, a investigação acerca dos efeitos de fármacos em organismos nativos de ambiente (sub)tropical é escassa, e ausente relativamente aos anticancerígenos, dentro de um âmbito em que os critérios de qualidade ambiental em países em desenvolvimento são baseados em extrapolações de respostas geradas em organismos de zonas temperadas da Europa e América do Norte. O sedimento consiste num compartimento de destino final das substâncias introduzidas nos ecossistemas aquáticos, capaz de acumulá-las em níveis muito mais elevados do que aqueles observados na coluna de água adjacente. Além de atuarem como repositório de compostos químicos, os sedimentos atuam também como fonte de poluição após eventos de remobilização. Portanto, por meio do contato com a água intersticial e material particulado, as espécies bentónicas estão constantemente expostas a misturas de compostos químicos. Dessa forma, a presente tese teve como objetivo avaliar a toxicidade de fármacos anticancerígenos, globalmente administrados em coquetéis no tratamento contra o cancro, em organismos marinhos bentónicos representativos de zonas temperadas e tropicais. Estes organismos foram expostos a drogas individualmente e em misturas, a concentrações ambientalmente relevantes. Os fármacos selecionados para tal foram os citotóxicos cisplatina (CisPt – 0,1 a 100 ng Pt L-1) e ciclofosfamida (CP – 10 a 1000 ng L-1), aplicadas no tratamento de tumoures sólidos (e.g. ovário, pulmão e bexiga), e o disruptor endócrino tamoxifeno (TAM - 0,5 a 100 ng L-1), mundialmente aplicado no tratamento do cancro da mama. Foram usados como modelos os poliquetas Nereis diversicolor de ambientes marinhos temperados e o ouriço-do-mar Echinometra lucunter, o anfípoda Tiburonella viscana e o poliqueta Scolelepis squamata característicos de ambientes tropicais. Nas experiências de exposição com N. diversicolor, que tiveram a duração de 14 dias, avaliaram-se as respostas de biomarcadores de estresse oxidativo (superóxido dismutase -SOD; catalase – CAT; enzima de fase II glutationa-S-transferase – GST; glutationa peroxidase - GPx), dano oxidativo (peroxidação lipídica - LPO), de efeito neurotóxico (atividade da enzima acetilcolinesterase - AChE), genotoxicidade por dano ao ADN, e alteração do comportamento de escavação. Relativamente aos organismos de ambientes bentônicos tropicais foram efetuados ensaios agudos (mortalidade) e crônicos (desenvolvimento embrio-larval). Os resultados obtidos indicaram que as drogas anticancerígenas, expostas individualmente, causam alterações neutotóxicas significativas, estresse e dano oxidativo e genotoxicidade em N. diversicolor. Além disso, registram-se alterações no comportamento de escavação que podem comprometer a proteção da espécie aos predadores presentes na superfície do sedimento, com consequências a nível ecológico. Estas respostas foram mais significativas em organismos expostos a CisPt (100 ng Pt L-1), CP (1000 ng L-1) e TAM (0,5 ng L-1). Relativamente ao bioensaio conduzido em misturas ternárias, constatou-se que o perfil de toxicidade não ocorreu de maneira monotónica. A mistura contendo os anticancerígenos em menor concentração (Mistura A) foi responsável pelo maior grau de dano em ADN, enquanto que nas concentrações intermedias (Misturas B e C) não se registou estresse oxidativo. Comparando-se com os resultados obtidos na exposição aos fármacos individualmente, as misturas C e D indicaram uma potencial predominância dos efeitos do TAM, com efeito antagônico sobre CisPt e CP. Assim, pode-se inferir que as respostas desencadeadas pelo modo de ação dos fármacos presentes individualmente não são consistentes para gerar estimativas de medidas de proteção de avaliação de risco ambiental relativamente a misturas destes compostos. Os efeitos causados pela concentração do anticancerígeno TAM (0,5 ng L-1), individualmente ou em misturas, indicaram um modo de ação por meio da intrusão da pró-droga na membrana celular. Logo, apesar da ausência de evidências referente à expressão de recetores de estrogénio nos modelos biológicos selecionados, a terapia administrada com TAM é também potencialmente tóxica em organismos não alvos da droga. As concentrações das drogas, responsáveis por desencadear as respostas de toxicidade aguda, foram detetadas em ambientes temperados, e são encontradas em zonas costeiras tropicais. Significativa redução do desenvolvimento embrio-larval do ouriço E. lucunter foi verificada nos bioensaios conduzidos com CisPt e CP, respectivamente em concentrações entre 0.1 a 10 ng Pt L-1 e 50 a 500 ng CP L-1, de maneira não-monotónica. Em contrapartida, o ensaio com TAM indicou uma resposta monotónica de redução significativa da viabilidade larval com o aumento da concentração da droga. O ensaio conduzido com misturas e poliquetas S. squamata demonstrou significativa toxicidade aguda com o aumento da concentração (Misturas C e D), apesar de uma sensibilidade inferior aos anfípodas T. viscana, os quais demonstraram uma redução significativa e não-linear da sobrevivência nas misturas B e D, como potencial efeito da ação do TAM. Devido aos perfis de toxicidade e dose-resposta não-monotónicos reportados em todos os bioensaios conduzidos com concentrações-traço ambientalmente relevantes, destaca-se a vulnerabilidade de espécies costeiras às misturas desses contaminantes emergentes, bem como à urgência de medidas preventivas à entrada desses compostos no meio marinho e ao desenvolvimento ferramentas de avaliação de risco ambiental especialmente dirigida a esses fármacos de expressiva toxicidade.The present thesis was financed and supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq - Brazil), through the Ciência Sem Fronteiras Program (202360/2014-8