<p>Die vorliegende Arbeit beschäftigte sich mit zwei Themengebieten. Es ging zum einen um die mechanischen Eigenschaften von Polyelektrolythohlkapseln und zum anderen um die Adhäsion von Polyelektrolythohlkapseln.</p> <p>Die mechanischen Eigenschaften wurden mit der AFM „colloidal probe” Technik untersucht. Dabei zeigte sich, dass die Kraftdeformationskurven für kleine Deformationen den nach der Schalentheorie vorhergesagten linearen Verlauf haben. Ebenso wurde die quadratische Abhängigkeit der Federkonstanten von der Dicke bestätigt. Für PAH/PSS findet man einen E-Modul von 0.25 GPa. Zusammen mit der Tatsache, dass die Deformationskurven unabhängig von der Geschwindigkeit sind und praktisch keine Hysterese zeigen, sowie der Möglichkeit die Kapseln plastisch zu deformieren, kann man schließen, dass das System in einem glasartigen Zustand vorliegt.</p> <pt>Erwartungsgemäß zeigte der pH einen starken Einfluss auf die PEM. Während in einem pH-Bereich zwischen 2 und 11.5 keine morphologischen Änderungen festgestellt werden konnten, vergrößerte sich der Radius bei pH = 12 um bis zu 50 %. Diese Radienänderung war reversibel und ging einher mit einem sichtbaren Weicherwerden der Kapseln. Eine Abnahme des E-Moduls um mindestens drei Größenordungen wurde durch Kraftdeformationsmessungen bestätigt. Die Kraftdeformationskurven zeigen eine starke Hysterese. Das System befindet sich nun nicht mehr in einem glasartigen Zustand, sondern ist viskos bis gummiartig geworden.</p> <p>Messungen an Kapseln, die mit Glutardialdehyd behandelt wurden, zeigten, dass die Behandlung das pH-abhängige Verhalten verändert. Dies kann darauf zurückgeführt werden, dass das PAH durch den Glutardialdehyd quervernetzt wird. Bei einem hohen Quervernetzungsgrad, zeigen die Kapseln keine Änderung des mechanischen Verhaltens bei pH = 12. Schwach quervernetzte Kapseln werden immer noch signifikant weicher bei pH = 12, jedoch ändert sich der Radius nicht.</p> <p>Außerdem wurden Multilagenkapseln untersucht, deren Stabilität nicht auf elektrostatischen Wechselwirkungen sondern auf Wasserstoffbrückenbindungen beruhte. Diese Kapseln zeigten eine deutlich höhere Steifigkeit mit E-Modulen bis zu 1 GPa. Es wurde gefunden, dass auch dieses System für kleine Deformationen ein lineares Kraft-Deformationsverhalten zeigt, und dass die Federkonstante quadratisch von der Dicke abhängt. Die Kapseln lösen sich praktisch sofort bei pH = 6.5 auf. In der Nähe dieses pHs konnte das Abnehmen der Federkonstanten verfolgt werden.</p> <p>Außerdem wurde das Adhäsionsverhalten von PAH/PSS Kapseln auf mit PEI-beschichtetem Glas untersucht. Die Adhäsionsflächen waren zu einem großen Teil rund und ließen sich quantitativ auswerten. Der Adhäsionsradius nimmt mit dem Kapselradius zu und mit der Dicke ab. Das Verhalten konnte mit zwei Modellen, einem für die große und einem für die kleine Deformation beschrieben werden. Das große Deformationsmodell liefert um eine Größenordung niedrigere Adhäsionsenergien als das kleine Deformationsmodell, welches mit Werten von ‑0.2 mJ/m² Werte in einem plausiblen Bereich liefert. Es wurde gefunden, dass bei einem Verhältnis von Dicke zu Deformation von etwa eins "buckling" auftritt. Dieser Punkt markierte zugleich den Übergang von der großen zur kleinen Deformation.</p> / <p>This work had two objectives. The first was to study the mechanical properties of polyelectrolyte hollow capsules depending on the pH and the wall composition utilizing the AFM colloidal probe technique. The second objective was to study the adhesion of these capsules varying the radius and thickness.</p> <p>It was found that the AFM colloidal probe technique can be utilized to measure the shells spring constant. The acquired deformation curves for small deformations showed the linear force deformation relation predicted by the shell theory. The stiffness of capsules composed of polyallylamine and polystyrenesulfonate scales quadratically with the thickness giving Young’s modulus of 0.25 GPa.</p> <p>Changing the pH had no effect concerning the morphology and the elastic properties of the afore mentioned capsules up to pH = 11.5. At pH = 12 the capsules’ radius increased between 30 % and 50 % and the elastic modulus decreased by more than one order of magnitude. This pH-change can be viewed as the glass transition of the material, being in a glassy state below pH = 11.5 and becoming rubbery at pH = 12. Introducing crosslinking into the capsule wall inhibited any morphological changes at pH = 12, while leaving the capsule stiffness sensitive for small degrees of crosslinking.</p> <p>It was possible to prove the quadratic thickness dependency of the stiffness for a system where the internal forces keeping together the multilayer were hydrogen bonds (poly(methacrylic acid) / poly-4-vinylpyrrolidone). These apsules are significantly stiffer than the afore mentioned ones (Young’s modulus 0.6 to 1 GPa) and show a strong reaction towards increasing the pH by dissolving within seconds. Close to the dissolution pH these capsules also exhibit a transition from a glassy to a rubbery state.</p> <p>Capsules composed of polyallylamine / polystyrene sulfonate adhered to polyethylene imine coated glass. The radius of the adhesion disc increased with the radius of the capsule and decreased with increasing thickness. This behaviour could be semi quantitatively described with a strong and a weak deformation model giving a value for the adhesion energy of ‑0.02 mJ/m² for the small deformation model. At deformations of the order of the thickness, the theoretically predicted buckling was observed.</p>

In this thesis the interactions in cellulose systems havebeen studied with emphasis on surface forces and adsorptionphenomenon. The study was limited to surfaces and polymers ofinterest for papermaking. During papermaking both therunability of the paper machine as well as the properties ofthe final paper will depend on the molecular interactionsbetween the components present in the suspension. The objectiveof this work was to gain a better understanding of theseinteraction forces and how they are affected by solutionconditions like pH and electrolyte concentration. The maintechniques employed for this purpose were direct surface forcemeasurements using both the interferometric surface forceapparatus (SFA) and the atomic force microscopy (AFM)colloidal-probe technique. In addition, both electronspectroscopy for chemical analysis (ESCA) and AFM imaging wereused for surface characterisation and to study adsorptionbehaviour. Since a smooth and transparent surface is needed forsurface force studies using SFA, Langmuir-Blodgett films ofcellulose were employed. The interactions between cellulose surfacesand xylansurfaces were studied. Cellulose is the main constituent of thewood fibre. In close association with cellulose in the cellwall are the hemicelluloses, xylan being a commonhemicellulose. Steric forces were found to dominate theinteractions between these substances in aqueous solutions.Still factors like charge density, solution pH and electrolyteconcentration were important. The adhesion between cellulosesurfaces in air depended on the contact area. The effect of acationic polyelectrolyte on the forces between cellulosesurfaces and between cellulose and mineral surfaces wasinvestigated to obtain a better understanding of the effects ofcationic retention and strength additives. In the presence of acationic polyelectrolyte the forces at large distances weredominated by double-layer repulsion. Bridging attraction was insome cases observed, but the presence and magnitude of thisforce was dependent on the properties of the substratesurface. Lignin on the fibre surface affects brightness, swelling andstrength of paper. In addition, dissolved lignin interfereswith added polymers during papermaking. For this reason theadsorption of lignin on cellulose fibre surfaces was explored.The adsorption of lignin was influenced by the concentration oflignin in solution and by the electrolyte composition of thesolution. The retention of lignin was affected by the presenceof a cationic polyelectrolyte and particularly by how thepolyelectrolyte was added. The AFM imaging revealed thestructure of the adsorbed lignin, which varied with the way ofadding the polyelectrolyte, and gave an idea about theadsorption mechanism. The effect of lignin on strengthproperties of paper sheets was also evaluated. Keywords: cellulose, hemicellulose, xylan, lignin, surfaceforces, adsorption, polyelectrolyte, SFA, AFM, ESCA,Langmuir-Blodgett films, chitosan, steric forces,bridging,adhesion

The aims of this study are to first immobilize positively charged gold nanorods to negatively charged cell culture surfaces. Second, to use polyelectrolytes for controlling the distance between gold nanorods and fluorophores. This is used to optimally determine the distance, of which maximum fluorescence enhancement is achieved, between gold nanorods and fluorophores. In order to approach these aims, we use UV/VIS absorption spectroscopy, fluorescence spectroscopy, atomic force microscopy, and ellipsometry. The results show that we could control the immobilization of gold nanorods on plastic microwell plates and create reproducible polyelectrolyte layers, in order to control the distance between the gold nanorods and fluorophores. In addition, the localized surface plasmon resonance wavelength red shifted as the PELs increased. In conclusion, we found that the maximum fluorescence enhancement of the fluorophores (Cy7) is about 2.3 times at a fluorophores-nanoparticles separation of approximately 9-12 nm. This work contributes some research information towards the design of optical biochip platforms based on plasmon-enhanced fluorescence.

Micro- and nano-fluidic devices represent an exciting field with a wide range of possible applications. These devices, typically made of either silica or glass, ionize when placed in contact with water. Upon the application of an electric field parallel to the wall, a flow is produced by the charged walls called the electro-osmotic flow (EOF). Since electric fields are so often used as the driving force in these devices, EOF is an extremely common phenomenon. For this reason it is highly desirable to be able to control EOF in order to optimize the functioning of these devices. One method which is quite common experimentally is the modification of the surface using polymer coatings. These coatings can be either adsorbed or grafted, and charged or neutral. The first part of this thesis looks at the role of neutral adsorbed polymer coatings for the modulation of EOF. Specifically our simulation results show that for adsorbed coatings made from a dilute polymer solution the strongest quenching of EOF is found for an adsorption strength at the phase transition for adsorption of the polymers. Further evidence is presented that shows that by using a high density of polymer solution and a polymer which has a strong attraction to the surface a very thick polymer layer can be created. Next the case of charged grafted polymer coatings is examined. The variation of the EOF with respect to several key parameters which characterize the polymer coating is investigated and compared to theory. The prediction that the electrophoretic velocity of the polymers is the same as the EOF generated by a coating made up of the same polymers is found to be false though the two values are quite close. The last section presents results which show how hydrodynamic interactions in charged polymer systems can be modeled mesoscopically without the use of explicit charges by forcing a slip between monomers and the surrounding fluid. This model is validated by simulating some surprising predictions made in the literature such as an object with no net charge having a non-zero force when subjected to an electric field, and how the velocity can even be perpendicular to the applied electric field. The thesis can be roughly divided into two topics: using polymer coatings to modulate EOF, and the free solution electrophoresis of polyelectrolytes. While EOF and free solution electrophoresis might seem unrelated it will be shown that the concepts are the same in both cases. In fact while not investigated in this thesis, the mesoscopic simulation methods for electrophoresis could be applied to the modulation of EOF with polymer coatings allowing for the simulation of longer length and time scales or more complex systems such as heterogeneously grafted colloids.

Micro- and nano-fluidic devices represent an exciting field with a wide range of possible applications. These devices, typically made of either silica or glass, ionize when placed in contact with water. Upon the application of an electric field parallel to the wall, a flow is produced by the charged walls called the electro-osmotic flow (EOF). Since electric fields are so often used as the driving force in these devices, EOF is an extremely common phenomenon. For this reason it is highly desirable to be able to control EOF in order to optimize the functioning of these devices. One method which is quite common experimentally is the modification of the surface using polymer coatings. These coatings can be either adsorbed or grafted, and charged or neutral. The first part of this thesis looks at the role of neutral adsorbed polymer coatings for the modulation of EOF. Specifically our simulation results show that for adsorbed coatings made from a dilute polymer solution the strongest quenching of EOF is found for an adsorption strength at the phase transition for adsorption of the polymers. Further evidence is presented that shows that by using a high density of polymer solution and a polymer which has a strong attraction to the surface a very thick polymer layer can be created. Next the case of charged grafted polymer coatings is examined. The variation of the EOF with respect to several key parameters which characterize the polymer coating is investigated and compared to theory. The prediction that the electrophoretic velocity of the polymers is the same as the EOF generated by a coating made up of the same polymers is found to be false though the two values are quite close. The last section presents results which show how hydrodynamic interactions in charged polymer systems can be modeled mesoscopically without the use of explicit charges by forcing a slip between monomers and the surrounding fluid. This model is validated by simulating some surprising predictions made in the literature such as an object with no net charge having a non-zero force when subjected to an electric field, and how the velocity can even be perpendicular to the applied electric field. The thesis can be roughly divided into two topics: using polymer coatings to modulate EOF, and the free solution electrophoresis of polyelectrolytes. While EOF and free solution electrophoresis might seem unrelated it will be shown that the concepts are the same in both cases. In fact while not investigated in this thesis, the mesoscopic simulation methods for electrophoresis could be applied to the modulation of EOF with polymer coatings allowing for the simulation of longer length and time scales or more complex systems such as heterogeneously grafted colloids.

In this research, we investigated a novel rigid-rod polymer sPBI for mono-layer polymer light emitting diode (PLED) fabrication and luminescence emission. sPBI could be a luminescent polymer with a low threshold voltage of 4.5 V and green light electroluminescence emission (530 nm). Its SO3H pendant attached to the p-phenyl ring improved electronic delocalization along the backbone resulted in a red shift of the absorption spectrum. By attaching propanesulfonated pendants to the heterocyclic moiety of intractable fully conjugated sPBI, water-soluble rigid-rod polyelectrolyte sPBI-PS(Li+) was synthesized to promote its processibility in water or common organic solvent. This water-soluble rigid-rod polyelectrolyte sPBI-PS(Li+) was fabricated for polymer light-emitting electrochemical cells (PLECs) with LiCF3SO3 (LiTf) or LiN(CF3SO2)2 (LiTfSI) dopants for investigating the influence of propanesulfonated pendants as well as dopants on the opto-electronic emission and the room-temperature DC conductivity. The effect of lithium salts (LiTf or LiTfSI) on photoluminescence color of doped sPBI-PS(Li+) films was negligible. sPBI-PS(Li+) PLECs doped with 0.41 and 1.01 wt. % of LiTfSI showed higher green light electroluminescence emission (514 nm) with a lower threshold voltage of 3.0 V and -4.6 V, respectively. Emission brightness of the sPBI-PS(Li+) PLEC did not raise upon increasing the ionic conductivity of the luminescent layer.

A novel strategy for fabrication of responsive functional polymer films is based on grafting of several different functional polymers onto a solid substrate at high grafting density, resulting in varied types of polymer brushes. Such an arrangement suggests many interesting applications of the multicomponent polymer brushes, regarding their versatile adaptive surfaces, capable for responding to changes of solvent polarity, pH, temperature, electromagnetic field and other stimuli, generally by reversible swelling. Mixed amphiphilic polystyrene-poly(2-vynil pyridine) (PS-P2VP) brushes are an example for responsive class of smart materials, which can switch between hydrophilic and hydrophobic energetic state upon changes in the quality of surrounding media. The switching of wettability was found to operate in a broad range and was selectively controlled in organic solvents and in aqueous solutions. Another example for an adaptive/switching behavior is addressed to a polymer brush with a remarkable response to the pH and the ionic strength variations of the aqueous solutions. Combination of weak polyacrylic acid, PAA, and weak polybase, P2VP, in the anchored layer allowed one with a small shift of the pH, to obtain a significant effect on the surface and the interfacial properties of the material. Both type of polymer brushes were examined as adsorbing materials for nanoparticles and charged synthetic- and bio-macromolecules. Their adaptive properties were successively linked to the results of the adsorption experiments. The simplest case was adsorption of nano-particles, functionalised with strong ionic groups, onto binary, PAA-P2VP, polyelectrolyte brushes. Maintaining a constant charge density of the adsorbing component (strong polyelectrolyte effect), allowed one to cause and manipulate a privileged swelling of one of the weak polyelectrolyte brush layers, without affecting the adsorbate properties, and to regulate the thickness of adsorbed layer only by the pH signal. In the case of adsorption of macromolecules with tuneable electrical charge (polyampholytes and proteins), the system became more complicated, regarding their environmentally responsive properties, similar to that exhibited by the polymer brushes. The driving forces were regulated by the switching performance of the brush, simply by adjusting the pH and/or ionic strength conditions. The adsorbed amount and morphological changes of polyampholyte layers were investigated as function of pH and was performed on mixed amphiphilic and binary polyelectrolyte brushes. A special emphasis was set on the binary brush capability to take the control over the interfacial performance of attaching proteins. It was found, that the sharp environmental response of the adsorbent (the polymer brush) strongly influences the morphology of adsorbed protein layers, their thickness and properties. Changing the polarity of the substrate allowed one to regulate the adsorption processes qualitatively and quantitatively. The significant aggregation of protein molecules on PS-P2VP brush and their disassembly on PAA-P2VP brush at the same solvent conditions, we devote to the hydrophobic-hydrophilic transition, occurred at the surface by replacing PS with PAA. The protein aggregates, monitored on the surface of PS-P2VP, sufficiently decrease their size, when switching the brush energetic state from hydrophobic to hydrophilic by adjusting the pH of the media. This effect was found to be well controlled by the brush switching phenomenon in hydrophilic-hydrophobic direction and vice versa. In conclusion, we showed how the structural reorganization in thin polymer brush layers of different type may dramatically affect their surface properties. The adaptive behavior in response of external stimuli was found to be a basis for highly specific interactions, depending on geometric factors, conformational state and environment.

<p>In this thesis the interactions in cellulose systems havebeen studied with emphasis on surface forces and adsorptionphenomenon. The study was limited to surfaces and polymers ofinterest for papermaking. During papermaking both therunability of the paper machine as well as the properties ofthe final paper will depend on the molecular interactionsbetween the components present in the suspension. The objectiveof this work was to gain a better understanding of theseinteraction forces and how they are affected by solutionconditions like pH and electrolyte concentration. The maintechniques employed for this purpose were direct surface forcemeasurements using both the interferometric surface forceapparatus (SFA) and the atomic force microscopy (AFM)colloidal-probe technique. In addition, both electronspectroscopy for chemical analysis (ESCA) and AFM imaging wereused for surface characterisation and to study adsorptionbehaviour. Since a smooth and transparent surface is needed forsurface force studies using SFA, Langmuir-Blodgett films ofcellulose were employed.</p><p>The interactions between cellulose surfacesand xylansurfaces were studied. Cellulose is the main constituent of thewood fibre. In close association with cellulose in the cellwall are the hemicelluloses, xylan being a commonhemicellulose. Steric forces were found to dominate theinteractions between these substances in aqueous solutions.Still factors like charge density, solution pH and electrolyteconcentration were important. The adhesion between cellulosesurfaces in air depended on the contact area. The effect of acationic polyelectrolyte on the forces between cellulosesurfaces and between cellulose and mineral surfaces wasinvestigated to obtain a better understanding of the effects ofcationic retention and strength additives. In the presence of acationic polyelectrolyte the forces at large distances weredominated by double-layer repulsion. Bridging attraction was insome cases observed, but the presence and magnitude of thisforce was dependent on the properties of the substratesurface.</p><p>Lignin on the fibre surface affects brightness, swelling andstrength of paper. In addition, dissolved lignin interfereswith added polymers during papermaking. For this reason theadsorption of lignin on cellulose fibre surfaces was explored.The adsorption of lignin was influenced by the concentration oflignin in solution and by the electrolyte composition of thesolution. The retention of lignin was affected by the presenceof a cationic polyelectrolyte and particularly by how thepolyelectrolyte was added. The AFM imaging revealed thestructure of the adsorbed lignin, which varied with the way ofadding the polyelectrolyte, and gave an idea about theadsorption mechanism. The effect of lignin on strengthproperties of paper sheets was also evaluated.</p><p>Keywords: cellulose, hemicellulose, xylan, lignin, surfaceforces, adsorption, polyelectrolyte, SFA, AFM, ESCA,Langmuir-Blodgett films, chitosan, steric forces,bridging,adhesion</p>

Oily wastewater produced from petroleum and petrochemical refining processes is one of the gravest environmental threats. Oil waste ending up in sewers and dumps each year is equal to 25 times the amount of crude oil spilled in the Exxon Valdez accident (1989). Oil/Water separation covers a broad spectrum of industrial process operations. There are many techniques employed depending on each situation. The byproduct of water recovery from oily wastewater is a sludge rich in oil, surfactants and particles (oily sludge). The oily sludge still contains significant amounts of waters, which need to be recovered prior to its disposal. The use of polyelectrolytes for the flocculation of the emulsified oil and its separation from the aqueous phase is usually one of the steps of the wastewater as well as oily sludge treatment process. The efficiency of polyelectrolytes as floculants is quite often evaluated via trial and error and the appropriate polymer is selected according to the case. Even in scientific investigations it is rather common to use industrial oily sludge samples. The industrial oily sludge is characterized and treated by polyelectrolytes. Nevertheless industrial oily sludge is quite complicated and variable to be approximated by a model. For the systematic study of polyelectrolytes efficiency a stable, realistic and well-defined oily sludge model is necessary. In the present work an oily sludge model was successfully developed and characterized. The model consists on water, oil (kerosene), surfactant (sodium dodecyl sulphate, SDS) and clay particles (Blauton). The emulsifying efficiency of the surfactant and the clay were studied independently. The interactions between the surfactant and the clay including adsorption of the former on the later and cation exchange reactions were investigated. The four components were finally combined to form a series of emulsions varying the relative amounts of the emulsifiers for the highest stability to be encountered. Having concluded on the composition of the oily sludge model the efficiency of various polyelectrolytes was evaluated. Commercial natural (chitosans), synthetic (PolyDADMACs) polyelectrolytes and oilbreaks as well as lab-scale semi-synthetic polymers (modified chitosans) were tested. The flocculation efficiency was determined based on the amount and quality of water that was recovered as well as on the floc stability, size and sedimentation speed. The recovered water was characterized according to the environmental protection agency (EPA). The analysis included measurements on: total organic carbon (TOC), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total suspended solids (TSS) and pH. Selection of the appropriate flocculant also depends on the type of flocs formed in combination to the treatment following the flocculation. When filtration or centrifugation is used as a post-flocculation process the appropriate polymers are those that form large and porous flocs, as the case of the modified chitosans AG95 and AG97. Clarification devices on the other hand require dense flocs as these produced by the use of PolyDADMACs, commercial chitosans, oilbreaks and modified chitosans GA35, GA41 and AG79. Regarding the water quality, some of the polymers used that have low values of COD, TOC and BOD5, may not need the secondary treatment (biological) prior to discharge, such as P187K (PolyDADMAC) and GA41 (modified chitosan). The others require a biological treatment for the regulation limits to be reached. The pH values of modified chitosans (except of AG97), lab-scale PolyDADMACs and an oilbreak (OCAA) are all in range of the regulation limits. The applicability of biopolymers as flocculants for oil sludge dewatering is a relatively new field of investigation. As a consequence of the growing demand for environmentally friendly technologies as well as renewable resources the interest on natural flocculants has increased. The aminopolysaccharide chitosan and its modified derivatives have outstanding properties such as biocompability, biodegradability, hydrophilicity, adsorption, flocculating ability and antibacterial properties. These natural polymers derived from the sea-food industry waste products would be very useful as residue oil adsorbents in any oily wastewater and can be among the most promising candidates as a replacement of the synthetic flocculants. / Ölhaltiges Abwasser, das bei Erdöl- und petrolchemischen Raffinierungsprozessen entsteht, ist eine der größten Umweltgefahren. Dieses Altöl landet jedes Jahr in der Kanalisation und in Deponien. Es handelt sich dabei um die 25-fache Menge an Rohöl, die beim Unfall der Exxon Valdez (1989) ausgeflossen ist. Die Öl/Wasser-Trennung überspannt ein breites Spektrum industrieller Prozesse. Es gibt viele Techniken, die abhängig von jeder Situation eingesetzt werden. Das Nebenprodukt bei der Abtrennung von Wasser aus ölhaltigen Abwässern ist ein Schlamm (Ölschlamm), der reich an Öl, Tensiden und Partikeln ist. Der Ölschlamm enthält noch bedeutende Mengen an Wasser, die vor ihrer Entsorgung verwertet werden müssen. Die Verwendung von Polyelektrolyten zur Ausflockung des emulgierten Öls und seine Trennung von der wässrigen Phase ist in der Regel einer der Schritte zur Behandlung von Abwässern sowie ölhaltigen Schlämmen. Die Effizienz von Polyelektrolyten als Flockungsmittel wird ganz häufig über Versuch und Fehler bewertet, und das passende Polymer wird entsprechend dem jeweiligen Fall ausgewählt. Sogar in wissenschaftlichen Untersuchungen ist es eher üblich, industrielle Ölschlamm-Proben zu verwenden. Der industrielle Ölschlamm wird charakterisiert und mit Polyelektrolyten behandelt. Dennoch ist der industrielle Ölschlamm ziemlich kompliziert und variabel und muss durch ein Modell angenähert werden. Für die systematische Untersuchung der Effizienz von Polyelektrolyten als Flockungsmittel ist ein stabiles, realistisches und klar definiertes Ölschlamm-Modell notwendig. In der vorliegenden Arbeit wurde ein Ölschlamm-Modell erfolgreich entwickelt und charakterisiert. Das Modell besteht aus Wasser, Öl (Kerosin), Tensid (Natriumdodecylsulfat, SDS) und Tonteilchen (Blauton). Die Emulgiereffizienz des Tensids und des Tons wurden unabhängig voneinander untersucht. Die Wechselwirkungen zwischen dem Tensid und dem Ton, die sowohl die Adsorption des Ersteren auf dem Letzteren einschließen als auch einen Kationenaustausch, wurden untersucht. Die vier Komponenten des Ölschlamm-Modells wurden schließlich kombiniert und es wurde eine Reihe von Emulsionen hergestellt, bei denen die relativen Mengen der Emulsionsmittel verändert wurden, um eine möglichst hohe Stabilität zu erreichen. Nachdem ein geeignetes Ölschlamm-Modell zur Verfügung stand, wurde die Effizienz der verschiedenen Polyelektrolyte als Flockungsmittel bewertet. Kommerzielle natürliche (Chitosane), synthetische (PolyDADMACs) Polyelektrolyte und Oilbreaks sowie Labor-semi-synthetische Polymere (modifizierte Chitosane) wurden getestet. Die Flockungseffizienz wurde sowohl basierend auf der Menge und Qualität des Wassers, das zurückgewonnen wurde, als auch bezogen auf die Flockenstabilität, die Flockengröße und die Sedimentationsgeschwindigkeit bestimmt. Das zurückgewonnene Wasser wurde entsprechend der Vorschriften der Behörde für Umweltschutz (EPA) charakterisiert. Die Analysen enthielten die Bestimmung des gesamten organischen Kohlenstoffs (TOC), des chemischen Sauerstoffbedarf (CSB), des biochemischen Sauerstoffbedarfs (BSB5), des Gesamtgehalts an suspendierten Partikeln (TSS) und die Bestimmung des pH. Die Auswahl geeigneter Flockungsmittel hängt auch von der Art der gebildeten Flocken, in Kombination mit der Behandlung, die den Flockungsprozess folgt, ab. Wenn als Postflockungsprozess Filtration oder Zentrifugation folgen, sollten Polymere verwendet werden, die große und poröse Flöckchen bilden, wie im Fall der modifizierten Chitosane AG95 und AG97. Andererseits verlangen Geräte zur Klärung von Abwässern dichte Flocken, wie solche, die beim Einsatz von PolyDADMACs, kommerziellen Chitosanen, Oilbreaks und den modifizierten Chitosanen GA35, GA41 und AG79 entstehen. In Bezug auf die Wasserqualität erhält man mit einigen der verwendeten Polymere so niedrige Werte von CSB, TOC und BSB5, dass wie im Falle von P187K (PolyDADMAC) und GA41 (modifiziertes Chitosan) keine biologische Sekundärbehandlung notwendig ist. Im Falle der anderen Polymere ist eine biologische Behandlung nötig, um die vorgeschriebenen Grenzen zu erreichen. Die pH-Werte der modifizierten Chitosane (außer der AG97), der im Labor hergestellten PolyDADMACs und des Oilbreak OCAA sind alle in Bereich der vorgeschriebenen Grenzen. Die Anwendbarkeit von Biopolymeren als Flockungsmittel für die Ölschlammentwässerung ist ein relativ neuer Forschungsbereich. Als Folge der wachsenden Nachfrage nach umweltfreundlichen Technologien sowie erneuerbarer Ressourcen hat das Interesse an natürlichen Flockungsmitteln zugenommen. Das Aminopolysaccharidchitosan und dessen modifizierte Produkte haben hervorragende Eigenschaften wie Biokompatibilität, Biodegradierbarkeit, Hydrophilie, Adsorption, die Fähigkeit zur Flockung und antibakterielle Eigenschaften. Diese natürlichen Polymere, die aus Meeresfrüchte-Industrieabfallprodukten gewonnen werden, sollten als Restöl-Adsorbentien bei der Aufarbeitung jedes ölhaltigen Abwassers sehr nützlich sein und können zu den vielversprechendsten Kandidaten als Ersatz der synthetischen Flockungsmittel werden.

No description available.