La bioadsorption sur amidon réticulé pour enlever des métaux des effluents industriels

L’industrie de traitement de surface utilise de nombreux produits chimiques, en particulier des métaux toxiques et des substances organiques, qui sont connus pour être nocifs vis-à-vis des humains et de l’environnement. En raison d’une réglementation de plus en plus stricte, les effluents contenant des métaux lourds doivent être traités. Il existe une grande variété de procédés de traitement des eaux usées provenant de la filière traitement de surface. En général, les systèmes conventionnels de détoxification se composent principalement d’un ajustement de pH, d’une oxydation des cyanures et d’une réduction des chromes, suivi d’une précipitation sous forme d’hydroxydes et d’une clarification, et parfois d’une étape d’adsorption sur charbon. Cependant, la technologie sur charbon actif présente plusieurs problèmes tels que la saturation rapide et des problèmes de colmatage des réacteurs. Comme les résines d'échange d’ions, leur utilisation est restreinte due au coût élevé. Pour ces raisons, la plupart des petites et moyennes entreprises ne peuvent pas utiliser de tels traitements. Ainsi, afin de répondre à ces problématiques, de nombreuses études sont menées pour trouver des alternatives peu coûteuses, qui soient efficaces et acceptables pour un usage industriel. Dans cette étude, la bioadsorption sur un adsorbant d’amidon réticulé a été utilisée pour retenir les métaux contenus dans des effluents industriels. L’adsorption a été étudiée en fonction du temps de contact, de la masse d’adsorbant et de la charge polluante. L’influence de ces paramètres sur l’efficacité d’adsorption a été évaluée en utilisant une méthode conventionnelle en mode cuvée. Les résultats ont montré que le matériau présente des capacités d’adsorption élevées vis-à-vis des ions métalliques, ce qui permet de diminuer les concentrations métalliques en dessous des valeurs réglementaires. Des mesures de taux de germination sur des graines de Lactuca sativa, utilisé comme test de phytotoxicité, ont été réalisées sur les rejets industriels avant et après adsorption. Ces tests ont confirmé l’efficacité du procédé pour diminuer fortement la toxicité du rejet. L’abattement chimique et la réduction de la toxicité ont montré que la bioadsorption sur un matériau non conventionnel peut être une étape de finition intéressante pour la détoxification des rejets industriels.The surface-treatment industry consumes and discharges an important range of chemicals, in particular toxic metals and organics, that are known to be harmful to humans and the environment. Because of more and more stringent regulations, effluents polluted with heavy metals must be treated. There are a variety of treatment processes for wastewater from the surface-treatment industry. In general, conventional treatment and detoxification systems consist mainly of pH adjustments, oxidation of cyanide and reduction of chromium bearing wastewaters, followed by hydroxide precipitation, clarification, and sometimes carbon sorption. However, active carbon technology presents several problems such as rapid saturation and clogging of the reactors. Like ion-exchange resins, their widespread use is restricted due to high cost. For these reasons, most small and medium-size enterprises cannot employ such treatments. Thus, in order to overcome these problems, many attempts have been made to find inexpensive alternative sorbents, which are both effective and acceptable for industrial use. In this study, biosorption with a starch-based cross-linked adsorbent was used for the removal of heavy metals from industrial effluents. The adsorption of metals was studied as a function of contact time, adsorbent mass and pollutant load. The influence of these parameters on the adsorption efficiency was evaluated using a conventional batch method. Batch experiments showed that the material exhibited high sorption capacities toward metal ions, leading to concentrations that were below current regulatory values. Measurements of the germination rate of Lactuca sativa seeds, used as a phytotoxicity test, were carried out on discharged industrial waters before and after the finishing sorption treatment. Germination tests confirmed the ability of the sorption step to radically decrease the effluent toxicity. Both the chemical abatement and toxicity mitigation of waste water showed that biosorption onto a non-conventional sorbent may constitute an interesting additional treatment step for the detoxification of industrial wastewater

Chapitre I. Les politiques françaises de l’eau

1. Introduction L’eau est indispensable à notre vie quotidienne et plus généralement à toute forme de vie, à notre santé, à nos loisirs, mais aussi à nos activités économiques, avec des besoins de plus en plus croissants. C’est l’une des raisons pour lesquelles, aujourd’hui, l’eau est au cœur des politiques de tous les pays au monde, qu’ils soient développés, émergents ou en développement. Cependant, tout le monde est également d’accord sur le fait qu’il est devenu urgent de relever un double..

Environmental applications of water-insoluble beta-cyclodextrin-epichlorohydrin polymers

International audienceChemical cross-linking using epichlorohydrin as cross-linking agent is the most straightforward method to produce water-insoluble beta-cyclodextrin-based polymers. The numerous OH groups available on cyclodextrin (CD) molecules are active sites capable of forming a number of linkages. Although this cross-linking reaction has been known for 50 years and is well documented, and relatively easy to use for the preparation of CD-based networks, some basic questions concerning the reaction still continue to interest the scientific community. The main objectives of this review are (i) to describe the synthesis and characterization of insoluble CD-epichlorohydrin polymers, (ii) to provide useful information on their most important features, (iii) and to summarize the developments in the use of these materials for environmental purposes. In particular, the description of relevant environmental applications such as sorption-oriented processes, detoxification of wastewater, color removal, and concentration and purification of solutions is included. In this aim, an extensive pool of data from the literature, from 270 papers, reviews, patents and books, has been compiled. The various interactions occurring between pollutants and CD-epichlorohydrin polymer in the sorption processes are presented, and future research trends are discussed. (C) 2012 Elsevier Ltd. All rights reserved

Du chanvre dans le traitement des eaux

International audienceLe chanvre est une plante annuelle originaire d’Asie Centrale, connue depuis plus de 2500 ans. La France est le 1er producteur européen de chanvre, et la région Bourgogne Franche-Comté est l’une des régions d’excellence dans la production. Le chanvre industriel (Cannabis sativa) est cultivé pour produire deux types de matières premières avec des applications commerciales bien distinctes, à la fois pour sa paille (ses fibres) et pour sa graine. C’est une culture rustique ne nécessitant pas de protection phytosanitaire. Sa transformation est essentiellement mécanique, sans produits chimiques. Le chanvre s’inscrit donc dans une dynamique de développement durable. De nombreux domaines d’applications industrielles utilisent le chanvre, du secteur du bâtiment à celui de l’industrie du papier et des emballages, en passant par le textile, la cosmétologie, l’alimentation humaine ou animale (dont l’oisellerie, la pêche et l’élevage), la thérapeutique, les biotechnologies, la phytoremédiation ou encore les matériaux composites. Ces multiples applications répondent aux normes du développement durable alliant technologie, innovation, rentabilité et environnement. Malgré ces nombreuses applications, il n’existe pas, à notre connaissance, d’applications concrètes dans le domaine de la dépollution des eaux usées.Cette communication a pour objectif de montrer la faisabilité d’un nouveau matériau à base de feutrine de chanvre pour éliminer des métaux présents en solution aqueuse par un procédé d’adsorption. Ce matériau montre des capacités d’adsorption importantes pour les métaux Cd, Co, Cu, Cr, Ni and Zn que ce soit en solution mono- ou polycontaminée. 1 g de chanvre est capable d’éliminer 13,91 mg des six métaux présents dans 100 mL de concentration initial de 25 mg/L de chaque élément. Les performances sont également indépendantes du pH dans la gamme 4-6. Les résultats sur des effluents réels sont également prometteur

Desulfurization: Critical step towards enhanced selenium removal from industrial effluents

International audienc

Emerging Contaminants Vol. 2

International audienceEmerging contaminants are chemical and biological agents for which there is growing concern about their potential health and environmental effects. The threat lies in the fact that the sources, fate and toxicology of most of these compounds have not yet been studied. Emerging contaminants, therefore, include a large number of both recently discovered and well-known compounds such as rare earth elements, viruses, bacteria, nanomaterials, microplastics, pharmaceuticals, endocrine disruptors, hormones, personal care products, cosmetics, pesticides, surfactants and industrial chemicals. Emerging contaminants have been found in many daily products, and some of them accumulate in the food chain. Correlations have been observed between aquatic pollution by emerging contaminants and discharges from wastewater treatment plants. Most actual remediation methods are not effective at removing emerging contaminants. This second volume presents comprehensive knowledge on emerging contaminants with a focus on remediation

Modificazione chimica di feltri a base di canapa e loro applicazioni per eliminare i metalli da soluzioni acquose

International audienceNonostante siano stati fatti notevoli sforzi per il settore industriale negli ultimi 30 anni, l’inquinamento delle acque dovuto alla presenza di metalli rimane un problema significativo. E’ necessario impegnarsi costantemente per migliorare la qualità dell’acqua e in teoria, molti metodi potrebbero essere adatti per raggiungere questo obiettivo. Tuttavia, bisogna ricordare che è estremamente difficile rimuovere metalli presenti a basse concentrazioni da effluenti che sono eterogenei e di natura variabile. Generalmente, a questo scopo, può essere considerato un doppio approccio sequenziale: in primis l’adsorbimento su carbone attivo commerciale per rimuovere sostanze organiche e per proteggere la fase successiva del trattamento, in secundis lo scambio ionico e/o chelazione mediante resine organiche polimeriche per rimuovere i metalli. Dal 2013, il nostro laboratorio fa parte di un progetto regionale finanziato dall’Agenzia francese dell’acqua e dall’Europa per il trattamento delle acque reflue non chiarificate con materiali non convenzionali innovativi contenenti molecole naturali come la canapa (Cannabis sativa L.), pianta latifoglia annuale. L’obiettivo principale di questo progetto è quello di trovare materiali adsorbenti alternativi a basso costo, efficaci per la rimozione dei metalli e rispettosi dell’ambiente per far fronte alle esigenze economiche e ambientali connessi con le esigenze industriali. La canapa sta attirando l’attenzione grazie al suo basso costo, all’abbondanza nella maggior parte del mondo, alla disponibilità di grandi quantità e alle sue caratteristiche chimico-fisiche utili come materiali lignocellulosici ad alta potenzialità.In questo lavoro, per la prima volta, si propone l’utilizzo di un materiale a base di canapa sottoforma di feltro contenente gruppi carbossilici per la rimozione di una miscela di sei metalli (Cd, Co, Cu, Mn, Ni e Zn) presenti in soluzione acquosa sintetica mediante un processo di adsorbimento. Questo adsorbante non convenzionale è stato preparato mediante reticolazione delle molecole di maltodestrine con un acido policarbossilico come agente reticolante e il materiale ottenuto è stato caratterizzato mediante tecniche di NMR allo stato solido. Sono qui presentate e discusse le proprietà di adsorbimento per mezzo della tecnica del batch. I risultati degli esperimenti di adsorbimento mostrano l’elevata capacità di adsorbimento del materiale in esame: 1 g di canapa modificato é in grado di rimuovere 22 mg di metalli presenti in 100 mL di soluzione ad una concentrazione iniziale di 50 mg/L per ogni metallo, a differenza del feltro grezzo che, alle stesse condizioni sperimentali, rimuove 7,1 mg di metalli. Il pH ottimale è compreso tra 4 e 6, e il rendimento é concentrazione-dipendente. La cinetica é uniforme e rapida: a pH 5, l’equilibrio di adsorbimento dei metalli viene raggiunto rapidamente, questo è interessante per un futuro sviluppo industriale nel trattamento delle acque reflue. Le prestazioni del materiale a base di canapa possono essere spiegate con la presenza di interazioni tra gli ioni metallici e i gruppi carbossilici tramite meccanismi di chemiadsorbimento (interazione elettrostatica, scambio ionico). In questo studio, il feltro è stato utilizzato mediante tecnica in batch, ma per future applicazioni potrebbe essere utilizzato come un filtro-bag

Emerging Contaminants Vol. 1

International audienceEmerging contaminants are chemical and biological agents for which there is growing concern about their potential health and environmental effects. The threat lies in the fact that the sources, fate and toxicology of most of these compounds have not yet been studied. Emerging contaminants, therefore, include a large number of both recently discovered and well-known compounds such as rare earth elements, viruses, bacteria, nanomaterials, microplastics, pharmaceuticals, endocrine disruptors, hormones, personal care products, cosmetics, pesticides, surfactants and industrial chemicals. Emerging contaminants have been found in many daily products, and some of them accumulate in the food chain. Correlations have been observed between aquatic pollution by emerging contaminants and discharges from wastewater treatment plants. Most actual remediation methods are not effective at removing emerging contaminants. This first volume presents comprehensive knowledge on emerging contaminants with a focus on analysis, toxicity, antibiotic resistance and human health