The Enhanced Actinide Removal Plant (EARP), located on the Sellafield site, is one of the UK's most crucial radioactive effluent treatment plants. EARP removes actinides and select fission products from routine reprocessing effluents by association with a ferric iron oxyhydroxide floc, which is precipitated from acidic effluent streams by the addition of NaOH. The effluent compositions that EARP receives will change in character as the Sellafield site transitions from its current routine reprocessing operations to post-operational clean-out and accelerated decommissioning activities over the next few years. An enhanced understanding of the iron oxyhydroxide formation processes occurring in EARP would help underpin optimisation of current plant efficiency and allow better prediction of changes in efficiency as effluent composition varies. In this study, iron oxyhydroxide formation, properties and evolution with time under EARP-relevant conditions were characterized. These processes were investigated in a pure ferric nitrate system and systems with added sulfate, phosphate and boric acid using a range of techniques including SAXS, TEM and FTIR. In all the experimental systems the iron oxyhydroxide floc was composed of nanoparticulate ferrihydrite aggregated into extensive mass fractal structures. In situ SAXS experiments showed that formation proceeded via a precursor cluster pathway whereby Fe(III) clusters ~ 0.45 nm in radius form rapidly at pH 0.12 - pH 1.5 upon dropwise addition of strong NaOH to the acidic effluent simulants. Further analysis indicates these clusters are Fe13 Keggin clusters, which have previously been shown to be an important structural motif in the ferrihydrite structure. With further pH increase, cluster aggregation occurs along with precipitation of low molecular weight Fe(III) species (mostly monomers), leading to formation of ferrihydrite nanoparticles which preserve the Keggin cluster in the core. Phosphate, sulfate and boric acid exhibit varying interactions with the solid phase throughout the formation process, with both inner and outer sphere adsorption observed for different species. Ageing experiments show that the ferrihydrite floc readily undergoes transformation leading to predominantly hematite formation, except in the presence of phosphate (concentrations > 10 ppm) where transformation is entirely inhibited due to phosphate adsorption to the floc. These results progress the fundamental understanding of the iron oxyhydroxide formation and ageing processes occurring in EARP.

Made available in DSpace on 2015-08-20T17:09:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-09. Added 1 bitstream(s) on 2015-08-20T17:26:41Z : No. of bitstreams: 1 000834118.pdf: 3610140 bytes, checksum: e32d2caddb319b85114ab806394a9da0 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A floculação é etapa fundamental no tratamento de água para abastecimento público sendo essencial para remoção do seu papel material particulado. O conhecimento da distribuição do tamanho das partículas floculentas torna-se de grande valia para a compreensão dos processos que envolvem a remoção desses flocos bem como a tecnologia de tratamento a ser adotada. Neste trabalho, foi avaliado o produto do gradiente médio de velocidade de flobulação (Gf) pelo tempo de floculação (Tf), GT também definido como número de Camp (NC), sob a ótica da distribuição de tamanho de partícula (DTP). Para tal, foi empregada técnica dedicada de captura e de tratamento de imagens visando obtenção da DTP e de seus parâmetros representativos. Foram investigados diferentes valores de NC (18000, 36000, 54000 e 72000) para a avaliação da eficiência da sedimentação em diferentes velocidades associadas (0,5; 1,5; 2,5; 3,5 e 5,0 cm/min). Os resultados demonstraram que o desempenho da sedimentação nas distintas velocidades investigadas é sensível ao valor de NC. Para um mesmo NC o gradiente médio de velocidade foi determinante, sendo os melhores resultados obtidos para Gf de 20s. Mantida a mesma velocidade de sedimentação de 2,5 cm/min verificou-se eficiência de remoção de turbidez praticamente constante, por volta de 70% para valores de número de Camp de 24000, 36000 e 54000 ao passo que para os extremos, 18 e 72 mil houve queda na eficiência. Em relação à DTP verificou-se, por meio da análise de seu parâmetro característico β, que este é sensível a variação do produto GT, sendo mais sensível aos valores de G para determinados valores de T. Em linhas gerais, o trabalho mostrou que o aumento da energia fornecida durante a floculação implica em menor alteração da dinâmica da distribuição de tamanho de partículas, estabelecendo uma relação inversa de proporção entre energia e a variação do parâmetro... / Flocculation is a paramount step in water treatment for public supply, in addition, is essential to remove the particulate material. The knowledge about the distribution of the flocculent particles size becomes important to the flocculent particles size becomes important to understand the process of flocs removal and the treatment technology that must be adopted. In this study was evaluated the product of the average velocity gradient flocculation (Gf) by time of flocculation (Tf), GT is also defined as Camp number (NC), according to the particle size distribution (PSD). In this case, the technique of image treatment was used to obtain the PSD and the others representatives parameters. Wete investigated different values of NC (18000, 24000, 36000, 54000 e 72000) for evaluation of the sedimentation efficiency in different associated velocities (0,5;, 1,5; 2,5; 3,5 e 5.0 cm/min). The results show that NC is fundamental for the sedimentation performance in all velocities. For the same NC the average of the velocity gradient was determinant, being one of the best results for Gf= 20 s. If the velocity of sedimentation is constant (2,5 cm/min) is possible to conclude that the turbidity removal efficiency maintain 70% fir Cam numbers around 24000, 36000 and 54000. In the order hand, for extrem values 18 and 72 thousand exist a reduction of efficiency. In relation with PSD, is possible to analyze your characteristic parameter β that is sensible according with the provided energy. In conclusion, the case of study show that the increase of provided energy during flocculation results in reduction of dynamic alteration about particle size distribution, establishing inverse proportion between energy and variation of the chaacteristic parameter β. This happens due to flocs action of rupture that contributes to reach the equilibrium state of the flocculent particles in less time of flocculation. Moreover,high values of Gf and NC imply high values... / FAPESP: 2013/01634-3

Thesis submitted in fulfillment of the requirements for the degree Master of Technology: Chemical Engineering In the Faculty of Engineering At the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY 2013 / A number of foods, pharmaceutical and industrial products are formulated as emulsions. The immiscibility of oil and water makes emulsions thermodynamically unstable, thus requiring emulsifiers. Natural and synthetic substances have been used as emulsifiers with preference for the former for safety, cost and availability purposes. Bambara groundnut (BGN) is an important source of nutrient in many African communities. Similar to soybean, flaxseed, and other leguminous products, the important blend of high protein and carbohydrate composition of BGN makes it a potential candidate as an emulsifier where, it can serve additional nutritional role in such emulsions. No literature evidence exists to support any earlier study on the potential emulsifying property of BGN. It is therefore of interest to investigate the potential of BGN flour (BGNF) and starch (BGNS) in stabilizing oil-in-water emulsions. The current study aimed to investigate the emulsifying properties of Bambara groundnut flour and starch. A batch of BGN was milled to produce the BGNF. BGNS was extracted from the BGNF. Emulsions were prepared using a wide range of flour-oil-water and starch-oil-water composition as generated through computational modelling. Emulsions were physically observed for stability, and then subjected to various stability studies using the Turbiscan® (which gives kinetic information on the process leading to phase separation; and allows for the detection of two kinds of destabilisation phenomena (particle migration): creaming and sedimentation) and optical microscope (which helps to detect particle size variation or aggregation in order to measure coalescence and/or flocculation). The most stable emulsions (one BGNF-stabilized and the other BGNS-stabilzed) were determined and subjected to same stability studies in the presence of varying physicochemical and physic-mechanical environmental conditions: effects of homogenization speed (9,000 – 21,000 rpm), pH (2 - 10), the presence of salt (2 – 10% w/v NaCl) and vinegar (2 – 10% v/v). Results were expressed in terms of relative stability (using creaming/sedimentation rate) and absolute oil droplet growth (coalescence and flocculation). The emulsifier-oil compositions (emulsifier and water make 100 mL gelatinized mixture before the addition of oil) that gave the most stable emulsions were 9 g BGNF-39 g oil and 5 g BGNS-30 g oil. The two emulsions had only 15% and 30% growth in oil droplet diameter respectively by day 5, compared to over 3000% in the unstable ones. The emulsions were generally observed physically to be stable till day 5 with minimal creaming. Emulsions prepared with BGNS were physically observed to have increasing viscosity with time. There was microbial growth on the emulsions after 3 days. This might have been encouraged because of the rich nutritional composition of BGN. The stability of the emulsions increased significantly (p < 0.05) with the speed of homogenization (up to 15, 000 rpm beyond which the difference in stability was not significant). Compared to control (pH 7), emulsion stability decreased significantly (p < 0.05) with decreasing (up to 16% instability by Day-5 at pH 2) and increasing pH (10% instability at pH 10) with corresponding increase in droplet size. Emulsion stability increased significantly (p < 0.05) with increasing NaCl concentration (35% instability at 2% NaCl compared to 18% instability at 10% NaCl). Stability however decreased sharply with increasing concentration of vinegar (55% instability at 10% vinegar compared to 19% instability at 2% vinegar). The BGNF-stabilized emulsions were more stable (ordinarily and in the presence of the additives) than the BGNS-stabilized ones. Instability values in the BGNS emulsions, in most cases, double those for BGNF. Emulsions were successfully stabilized with BGNF and BGNS. The emulsions were optimal when prepared at a homogenization speed of 15,000 rpm and at neutral pH. The higher the concentration of salt, the more stable the emulsions. Increasing concentration of vinegar however, destabilized the emulsions.

Orientador: Rodrigo Braga Moruzzi / Banca: Jorge Hamada / Banca: Lyda Patricia Sabogal Paz / Resumo: A floculação é etapa fundamental no tratamento de água para abastecimento público sendo essencial para remoção do seu papel material particulado. O conhecimento da distribuição do tamanho das partículas floculentas torna-se de grande valia para a compreensão dos processos que envolvem a remoção desses flocos bem como a tecnologia de tratamento a ser adotada. Neste trabalho, foi avaliado o produto do gradiente médio de velocidade de flobulação (Gf) pelo tempo de floculação (Tf), GT também definido como número de Camp (NC), sob a ótica da distribuição de tamanho de partícula (DTP). Para tal, foi empregada técnica dedicada de captura e de tratamento de imagens visando obtenção da DTP e de seus parâmetros representativos. Foram investigados diferentes valores de NC (18000, 36000, 54000 e 72000) para a avaliação da eficiência da sedimentação em diferentes velocidades associadas (0,5; 1,5; 2,5; 3,5 e 5,0 cm/min). Os resultados demonstraram que o desempenho da sedimentação nas distintas velocidades investigadas é sensível ao valor de NC. Para um mesmo NC o gradiente médio de velocidade foi determinante, sendo os melhores resultados obtidos para Gf de 20s. Mantida a mesma velocidade de sedimentação de 2,5 cm/min verificou-se eficiência de remoção de turbidez praticamente constante, por volta de 70% para valores de número de Camp de 24000, 36000 e 54000 ao passo que para os extremos, 18 e 72 mil houve queda na eficiência. Em relação à DTP verificou-se, por meio da análise de seu parâmetro característico β, que este é sensível a variação do produto GT, sendo mais sensível aos valores de G para determinados valores de T. Em linhas gerais, o trabalho mostrou que o aumento da energia fornecida durante a floculação implica em menor alteração da dinâmica da distribuição de tamanho de partículas, estabelecendo uma relação inversa de proporção entre energia e a variação do parâmetro... / Abstract: Flocculation is a paramount step in water treatment for public supply, in addition, is essential to remove the particulate material. The knowledge about the distribution of the flocculent particles size becomes important to the flocculent particles size becomes important to understand the process of flocs removal and the treatment technology that must be adopted. In this study was evaluated the product of the average velocity gradient flocculation (Gf) by time of flocculation (Tf), GT is also defined as Camp number (NC), according to the particle size distribution (PSD). In this case, the technique of image treatment was used to obtain the PSD and the others representatives parameters. Wete investigated different values of NC (18000, 24000, 36000, 54000 e 72000) for evaluation of the sedimentation efficiency in different associated velocities (0,5;, 1,5; 2,5; 3,5 e 5.0 cm/min). The results show that NC is fundamental for the sedimentation performance in all velocities. For the same NC the average of the velocity gradient was determinant, being one of the best results for Gf= 20 s. If the velocity of sedimentation is constant (2,5 cm/min) is possible to conclude that the turbidity removal efficiency maintain 70% fir Cam numbers around 24000, 36000 and 54000. In the order hand, for extrem values 18 and 72 thousand exist a reduction of efficiency. In relation with PSD, is possible to analyze your characteristic parameter β that is sensible according with the provided energy. In conclusion, the case of study show that the increase of provided energy during flocculation results in reduction of dynamic alteration about particle size distribution, establishing inverse proportion between energy and variation of the chaacteristic parameter β. This happens due to flocs action of rupture that contributes to reach the equilibrium state of the flocculent particles in less time of flocculation. Moreover,high values of Gf and NC imply high values... / Mestre

Resumo: Utilizando-se um floculador mecanizado com quatro câmaras foram realizados ensaios hidrodinâmicos com o traçador cloreto de sódio obtendo-se curvas de distribuição dos tempos de residência (DTR) e os tempos de residência médios para os tempos de residência teórico de 29,54 min, 22,15 min e 14,77 min respectivamente para o floculador operando com 04, 03 e 02 câmaras. Entre as câmaras de floculação havia quatro diferentes posições de passagens, sendo duas em cima "D" e "E" (respectivamente Direita superior e Esquerda superior) e duas embaixo "d" e "e" (respectivamente direita inferior e esquerda inferior). Levando-se em consideração que a entrada de água era realizada na passagem "e", foram combinadas quatro configurações de passagem para floculador de 04 câmaras (eEeEe , eDeDe , edede e eeeee) e uma quinta empregando-se anteparos (e/e/e/e/e). As mesmas configurações foram estendidas ao floculador operando com 03 e 02 câmaras. Procurou-se avaliar nos floculadores, operando sob as diferentes configurações de passagem apresentadas acima, a magnitude dos efeitos dos curtos-circuitos de acordo com os estudos pré- definidos. Tais estudos combinaram o sentido de rotação dos agitadores (sentido alternado e mesmo sentido de rotação ao longo das câmaras) com a constância ou a variação do gradiente de floculação, além de um estudo com os agitadores desligados. Observou-se, após a análise das curvas DTR, que as configurações edede e e/e/e/e/e para floculador de 04 câmaras, estendidas aos floculadores de 03 e 02 câmaras, apresentaram menor incidência de curtos-circuitos que a configuração eEeEe. A colocação do anteparo que gerou a configuração e/e/e/e/e para floculador de 04 câmaras, estendida aos floculadores de 03 e 02 câmaras, mostrou-se uma alternativa... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Using a mechanical flocculator with four flocculation chambers, hydrodynamic tests were conducted using sodium chloride as a tracer resulting in curves of the residence time distribution (RTD) and the mean residence times for the theoretical residence time of 29.54 min, 22.15 min and 14.77 minutes, respectively for the flocculator with 04, 03 and 02 chambers. Between the flocculation chambers had four different positions of passages, two on top "D" and "E" (respectively upper right and upper left) and two down "d" and "e" (respectively lower right and lower left). Taking into account that the entry of water has always been held in the lower left passage "e" for the flocculator with 04 chambers, four different configurations were combined (eEeEe, eDeDe, edede and eeeee) and a fifth employing shields (e/e/e/e/e). The same settings were extended to the flocculator operating with three and two chambers. Was evaluated in flocculation unit, operating under the different configurations of passage, the magnitude of the effects of short circuits according to the studies previously defined. These studies combined the direction of rotation of the agitator with the velocity gradient and a study of the rioters off. Was observed after analysis of the curves RTD, that the settings edede and e/e/e/e/e to flocculators of 04, 03 and 02 chambers, showed a lower incidence of short-circuits that configuration eEeEe. The placement of the bulkhead, which generated the configuration e/e/e/e/e, showcases itself as an efficient alternative only in the absence of agitation, promoted by agitators. Flocculator with 04 chambers, one does not notice the influence of parameters direction of the agitator and the constancy or variation of velocity gradient on the RTD / Orientador: Marcelo Libânio / Coorientador: Tsunao Matsumoto / Banca: Milton Dall'Aglio Sobrinho / Banca: Luiz Di Bernardo / Mestre

Dentre as características desejáveis em leveduras fermentadoras alcóolicas estão a capacidade de floculação, a não produção de H2S e o caráter "killer". Neste trabalho foram selecionadas sete linhagens de Saccharomyces cerevisiae com algumas destas características, que passaram por testes confirmativos e pela cariotipagem eletroforética resultando na escolha de duas linhagens: ATCC 26602 (altamente floculante) e K1 (H2S - e possuidoras do caráter "killer"). Estas linhagens foram utilizadas em um cruzamento via fusão de protoplasto para se obter um produto de fusão estável com as características de interesse tecnológico. Na seleção das linhagens híbridas com base em caracteres naturais foram isolados 1291 híbridos em meio seletivo e entre essas colônias somente 1,5% foram inicialmente consideradas híbriadas. Após três subcultivos em YEPD líquido, estes produtos de fusão não se mostraram estáveis. / Flocculative and "killer" skills and lack in production of H2S are desirable characteristics of the ethanolic fermentative yeasts. Seven selected strains of Saccharomyces cerevisiae with some of these characteristics were evaluated for confirmation of these habilities and their genetic characterization was undertaken by eletrophoretic kariotyping. The strain ATCC 26602 had flocculant hability and the strain K1 was H2S - and "killer". The strains were selected for protoplast fusion aiming to obtain a stable fusion strain with these desirable technologyc characteristics. The selection of the hybrid strains were based on natural characters and have shown 1291 hybrids (frequency of 1,5%) in the medium for the isolation of the fusionants (protoplasts). The protoplast stability were monitored by three continuous growth in the YEPD liquid midium and the stable fusion products were not obtained.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22763号 / 工博第4762号 / 新制||工||1745(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 高岡 昌輝, 教授 清水 芳久, 准教授 大下 和徹 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The adsorption of cationic polyacrylamide (C-PAM) and silicananoparticles onto a model surface of silicon oxide wascompared with the adsorption of C-PAM to fibres and theirinfluence on flocculation of a fibre suspension. An increase inionic strength affects the polyelectrolyte adsorption indifferent ways for these two systems. With the silica surface,an increase in the ionic strength leads to a continuousincrease in the adsorption. However, on a cellulose fibre, theadsorption increases at low ionic strength (1 to 10 mM NaCl)and then decreases at higher ionic strength (10 to 100 mMNaCl). It was shown that the adsorption of nanoparticles ontopolyelectrolyte-covered surfaces has a great effect on both theadsorbed amount and the thickness of the adsorbed layer. Theresults showed that electrostatic interactions were thedominating force for the interaction between both the fibresand the polyelectrolytes, and between the polyelectrolytes andthe silica particles. Furthermore, at higher NaClconcentrations, a significant non-ionic interaction between thesilicon oxide surface/particles and the C-PAM was observed. The adsorption rate of C-PAM onto fibres was rapid andquantitative adsorption was detected in the time range between1 and 8 s at polyelectrolyte addition levels below 0.4 mg/g.Conversely, an increase in the amount of added polymer leads toan increased polymer adsorption up to a quasi-static saturationlevel. However, after a few seconds this quasi-staticsaturation level was significantly lower than the level reachedat electrostatic“equilibrium”. The adsorbed amountof charges at full surface coverage after 1 to 8 s contact timecorresponded to only 2 % of the total fibre charge, whereasafter 30 minutes it corresponded to 15 % of the total fibrecharge. This shows that a full surface coverage at shortcontact times is not controlled by surface charge. Based onthese results, it is suggested that a combination of anon-equilibrium charge barrier against adsorption and ageometric restriction can explain the difference between theadsorption during 1 to 8 s and the adsorption after 30 minutes.With increasing time, the cationic groups are neutralised bythe charges on the fibre as the polyelectrolyte reconforms to aflat conformation on the surface. The addition of a high concentration of C-PAM to a fibresuspension resulted in dispersion rather than flocculation.This behaviour is most likely due to an electrostericstabilisation of the fibres when the polyelectrolyte isadsorbed. Flocculation of the fibre suspension occurred at lowadditions of C-PAM. A maximum in flocculation was found ataround 50 % surface coverage and dispersion occurred above 100% surface coverage. It was also shown that for a given level ofadsorbed polymer, a difference in adsorption time between 1 and2 seconds influenced the flocculation behaviour. An optimum inflocculation at 50 % surface coverage in combination with theimportance of polymer reconformation time at these shortcontact times showed that the C-PAM induced fibre flocculationagrees with La Mer and Healy’s description of bridgingflocculation. A greater degree of flocculation was observed with theaddition of silica nanoparticles to the fibre suspension thanin the single polyelectrolyte system. Flocculation increased asa function of the concentration of added nanoparticles until0.5 mg/g. At higher additions the flocculation decreased againand this behaviour is in agreement with an extended model formicroparticle-induced flocculation. An increase in flocculationwas especially pronounced for the more extended silica-2particles. This effect is attributed to the more extendedpolyelectrolyte layer, since the adsorbed amount wasessentially the same for both silica particles. Finally it was found that fines from the wood fibres had asignificant effect on the flocculation. When fines were added,a greater degree of flocculation was detected. Furthermore, itwas also more difficult to redisperse the fibres with polymerin the presence of fines. <b>Keywords:</b>Adsorption, bridging, cationic polymers,cellulose fibres, electrosteric stabilisation flocculation,ionic strength, nanoparticle, polyelectrolyte, reconformation,retention aids and silica / NR 20140805

Thermally expandable microspheres are spherical particles around 5-­‐40 µm in size, consisting of a polymeric shell in which a blowing agent has been encapsulated. The microspheres are expanded upon heating, resulting in a particularly low density. Microspheres are therefore suitable to use as light weight filler or as foaming agent. AkzoNobel is world leading in the production of expandable microspheres, which are commercialised under the name Expancel. Sustainability is a great focus at AkzoNobel and two issues that AkzoNobel works with today is to develop products free from chlorine and Me1. The aim with this thesis has been to investigate whether it is possible to produce microspheres free from these chemicals and to see if they can be a more sustainable alternative to one of the existing Expancel grades. In this study, the microspheres have been produced through free radical suspension polymerisation and analysed by measuring mainly the particle size and expansion properties. The polymeric shell was composed of the monomers acrylonitrile, methacrylonitrile, and methyl acrylate. The main focus has been to evaluate the silica-­‐based stabilisation system, which stabilise the monomer droplets during the suspension polymerisation. The stabilisation is possible due to the formation of silica flocs that is adsorbed on the surface of the droplets. It has been investigating how different parameters, e.g. amount of stabiliser or mixing procedure, affects the formation of silica flocs and the stabilisation of monomer droplets. For the silica-­‐based system, it was found that the mixing order, stirring rate, and amount of stabilisers affect the formation of flocs. It was also seen that the amount of stabiliser affect the stabilisation of droplets, and that some stabilisers is more significant than others. Microspheres without chlorine and Me1 have successfully been produced in laboratory scale (50 mL and 1 L). The expansion and size of the microspheres produced in this study was relatively similar to one of the existing Expancel grades. However, the reproducibility of polymerisations in 1 litre reactors has been poor. / Termiskt expanderbara mikrosfärer är sfäriska partiklar, ca 5-­‐40 µm i diameter, som består av ett polymerskal som innesluter en drivgas. Mikrosfärerna expanderar när de utsätts för värme och erhåller då en mycket låg densitet. De är därför lämpliga att använda som fyllmedel då låg vikt är önskvärt eller som skummedel. AkzoNobel är världsledande inom produktion av expanderbara mikrosfärer, som marknadsförs under namnet Expancel. Hållbar utveckling är en viktig fråga för AkzoNobel och två problem som de står inför idag är att utveckla produkter fria från klor och Me1. Målet med detta examensarbete har varit att undersöka om det är möjligt att framställa mikrosfärer fria från dessa kemikalier och om de framtagna mikrosfärerna skulle kunna vare ett hållbarare alternativ till en av de befintliga Expancel-­‐ produkterna. I den här studien har mikrosfärerna framställts genom suspensionspolymerisation som initierats av fria radikaler och de har analyserats främst genom att mäta partikelstorlek och expansionsegenskaper. Polymerskalet bestod av monomererna akrylnitril, metakrylnitril och metylakrylat. I det här arbetet har det viktigaste varit att utvärdera det silikabaserade stabiliseringssystemet som stabiliserar monomerdropparna vid polymerisationen. Stabiliseringen är möjlig eftersom silika bildar flockar som adsorberar på ytan av monomerdropparna. Olika parametrar, exempelvis mängd stabiliseringsmedel och satsningsförfarande, har därför varierats för att undersöka vilken effekt det får på flockningen av silika och stabiliseringen av monomerdroppar. Satsningsordning och omrörningshastiget för stabiliseringssystemet samt mängd stabiliseringsmedel är några av de faktorer som påverkar bildningen av flockar. Det konstaterades även att mängd stabiliseringsmedel påverkar stabiliseringen utav monomerdropparna. Fulländade mikrosfärer utan klor och Me1 har framställts i laboratorieskala (50 mL och 1 L) och partikelstorleken samt expansionsegenskaper är jämförbara med en av Expancels nuvarande produkter. Dock har reproducerbarheten i 1 litersskala varit otillfredsställande.

No description available.