The main aim of this research is to provide a low cost and sustainable biochar for the removal of organic pollutants from aqueous solution. Wastewater pollution by organic contaminants of emerging concern has become a subject of intense discussion. Removing these contaminants from aqueous solution is paramount to improve water quality for both humans and animal consumption. Traditional adsorption techniques using activated carbon are universal and fast, however, they are very costly. This dissertation therefore seeks to find an alternative low cost adsorbent which can be used to adsorb contaminants from aqueous solution. In chapter one, an overview of some of the selected organic contaminants of emerging concern is given. Pharmaceutical and pesticide entry into the environment, their fate and ecotoxicity are highlighted. Available techniques for the removal of contaminants from aqueous solution are also given. Chapter two is a study on the adsorption of some selected pharmaceuticals using a fast pyrolysis low cost biochar produced from pinewood feedstocks. The pinewood biochar used as the adsorbent in this study was made by fast pyrolysis in an augered reactor at a temperature of 425 oC and a residence time of 20-30 s during bio-oil production. In chapter three, switchgrass biochar has been tested for its potential for remediating water that is contaminated with two phenoxy herbicides, 2,4-dichlorophenoxyacetic (2,4-D) acid and 2-methyl-4-chloro-phenoxyacetic acid (MCPA). The adsorption capacity was remarkable when compared to commercial activated carbon per unit of measured surface area. Furthermore, in chapter four, magnetic and non-magnetic low cost biochars have been tested for the removal of the herbicide metribuzin from aqueous solution under different experimental conditions. The magnetic biochar synthesized from raw switchgrass biochar does not show a detrimental effect on the adsorption capacity. Additional value of this magnetic biochar is the ease of separation from contaminated solution following adsorption.

The growth of Fe₃O₄ and FeOOH crystals was investigated. Growth modifiers were used to alter the formation of iron oxides from ferrous hydroxide precipitates. Multifunctional carboxylic acids were found to have a strong influence on morphology of FeOOH. Dicarboxylic acids, containing two and seven carbons, changed the characteristics of α-FeOOH. These changes included alteration of the isoelectic point of the particulates and changes in particle size and shape. EDTA was found to alter the phase of FeOOH formation, favoring the synthesis of γ-FeOOH over α-FeOOH at temperatures below 50°C. The effects of multifunctional carboxylic acids were dependent upon the time of addition, and the presence of other growth modifiers. The changes in FeOOH formation were postulated to occur due to interaction between the acid molecules and Green Rust II, a common intermediate in iron oxide growth. The growth of Fe₃O₄ was found to be sensitive to solution pH, and the form of the iron starting materials. Examination of reaction intermediates by x-ray diffraction showed that other Crystalline phases formed prior to the production of Fe₃O₄. Different intermediate phases occurred depending on the amount of hydroxide in the reaction, and differences in Fe³⁺ starting materials. The production of different intermediate phases affected the morphology of Fe₃O₄. Early precipitation of Fe₃O₄ led to small particles, while formation of crystalline Fe(OH)₂ led to large crystals. Formation of a mixture of Green Rust II and Fe(OH)₂ early in the oxidation process led to formation of multiple nuclei, and produced smaller average particles with a wide particle size distribution. Fe₃O₄ particles prepared from α-FeOOH seed crystals were spherical, while Fe₃O₄ particles prepared from FeSO₄ alone were octahedral crystals. / Ph. D.

The aim of this diploma thesis is to evaluate the efficiency of two types of granular activated carbon (GAC), Filtrasorb TL 830 and Picabiol 12x40, for the adsorption of cellular peptides with low molecular weight produced by cyanobacterium Microcystis aeruginosa that are hardly removable during the coagulation/flocculation processes. The effect of different carbon properties (surface charge, textural characteristics), peptide properties (molecular size, surface functionality and charge) and solution characteristics (ionic strength and pH value) on the peptide uptake was investigated using laboratory equilibrium and kinetic adsorption experiments. The results showed that adsorption of peptides was influenced by the charge conditions in adsorption system that depend on solution pH. The pH value influences surface charge and the point of zero charge (pHpzc) of GAC as well as dissociation and protonization of peptide functional groups. It was found that efficiency of the peptide adsorption increased with decreasing pH value for both GACs. Under these conditions adsorption was enhanced by attractive electrostatic interactions between GAC surface and peptide functional groups and was also positively influenced by the conformation changes in peptide structure. GAC Picabiol 12x40 showed the total highest...

The Ph.D. thesis deals with the characterization of algal organic matter (AOM), which is difficult to remove in water treatment, and on the basis of AOM character, various methods for its elimination, e.g. coagulation, oxidation with subsequent coagulation and adsorption onto activated carbon are assesed. Special emphasis is placed on identifying the optimal conditions of the processes and on describing the mechanisms and interactions involved. In terms of anthropogenic micropollutants, the thesis deals with the highly topical issue of the occurrence of microplastics in water. It was found that the removal efficiency of the individual AOM components varies substantially depending on the elimination method used. The identified optimum conditions of individual methods and especially the mechanisms that apply to the removal of target substances varied widely. The non-proteinaceous fraction of AOM was removed with very low efficiency (max. 25%) by conventional coagulation even under optimized conditions (pH 6.6- 7.5 for aluminium sulfate as the coagulating agent and pH 7.5-9.0 for polyaluminium chloride) and it was given by the high content of low molecular weight (LMW) substances that are difficult to coagulate. The dominant coagulation mechanism was adsorption onto aluminium hydroxide precipitates....

Depuis la première synthèse du graphène, la spectroscopie Raman s'est imposée comme un standard pour la caractérisation de celui-ci. Le dopage et les défauts du graphène ont tous deux été étudiés abondamment à l'aide de spectromètres Raman en configuration confocal. Cependant, l'origine de toutes les bandes dans le spectre Raman du graphène n'est pas encore totalement comprise. Les bandes liées à la présence de défauts impliquent des processus de deuxièmes ordres qui se complexifient davantage avec le dopage du graphène. Aussi, la configuration confocal n'offre aucune information spatiale sur l'échantillon. Il est possible de générer une carte Raman par la prise de mesure point par point, mais ceci est un processus long et laborieux. Le RIMA, un appareil conçu dans le laboratoire du professeur Martel en collaboration avec Photon Etc, permet de pallier à ce problème. Avec un peu plus d'un million de spectres Raman mesurés en quelques heures sur une grande région, le RIMA permet de générer des cartes Raman d'une qualité exceptionnelle. Le RIMA est alors l'outil de choix pour l'étude présentée dans ce mémoire. L'objectif de ce mémoire est de mettre au point une méthode pour étudier l'effet du dopage et des défauts sur le spectre Raman du graphène. Pour obtenir des échantillons propices à l'étude, certains paramètres de la croissance du graphène par dépôt chimique en phase vapeur ont été étudiés. Le graphène a été dopé avec le couple oxydoréducteur Pt/PtO et des solutions tampons. Des cartes Raman ont été produites avec le RIMA. Ces cartes ont été prises à trois niveaux de dopage avant et après bombardement par ions d'argon. Les expériences sur la croissance ont permis d'obtenir des échantillons qui contiennent peu de bicouches, ce qui a permis de prendre des mesures sans tenir compte de leurs effets. Le dépôt de platine a été optimisé pour obtenir des particules dispersées de façon uniforme sur l'échantillon. Le dopage par le couple oxydoréducteur n'a pas été aussi efficace qu'attendu. L'analyse des cartes Raman a permis de révéler que le bombardement ne donne pas un résultat uniforme sur l'échantillon. L'hypothèse proposée pour expliquer l'écart du dopage et la non-uniformité des défauts est la présence de résidus de polymères à la surface du graphène avant le dépôt de platine. Ces résidus affecteraient le transfert de charge lors du dopage du graphène et protégeraient l'échantillon des ions d'argon lors du bombardement. / Since the first synthesis of graphene, Raman spectroscopy has become a standard for its characterization. Both doping and defects in graphene have been studied extensively using Raman spectrometers in confocal configuration. However, the origin of all bands in the Raman spectrum of graphene is not yet fully understood. The bands related to the presence of defects involve second order processes that become more complex with the doping of graphene. Also, the confocal configuration does not offer any spatial information on the sample. It is possible to generate a Raman map by taking point by point measurements, but this is a long and laborious process. The RIMA, a device designed in Professor Martel's laboratory in collaboration with Photon Etc, overcomes this problem. With a little more than a million Raman spectra measured in a few hours over a large area, the RIMA allows to generate Raman maps of exceptional quality. The RIMA is then the tool of choice for the study presented in this master's thesis. The objective of this master's thesis is to develop a method to study the effect of doping and defects on the Raman spectrum of graphene. To obtain suitable samples for the study, some parameters of graphene growth by chemical vapor deposition were studied. Graphene was doped with the redox couple Pt/PtO and buffer solutions. Raman maps were produced with the RIMA. These maps were taken at three doping levels before and after argon ion bombardment. Growth experiments yielded samples with few bilayers, allowing measurements to be taken without regard to their effects. Platinum deposition was optimized to obtain uniformly dispersed particles on the sample. Doping with the redox couple was not as effective as expected. The analysis of the Raman maps revealed that the bombardment does not give a uniform result on the sample. The hypothesis proposed to explain the doping discrepancy and the non-uniformity of the defects is the presence of polymer residues on the graphene surface before the platinum deposition. These residues would affect the charge transfer during the doping of the graphene and would protect the sample from argon ions during the bombardment.