A interação de elementos potencialmente tóxicos com solos e a caracterização quanto à mobilidade e potencial de liberação ao ambiente são importantes para avaliação de risco ambiental. No caso de solos altamente intemperizados, como os Latossolos, a interação pode ser diferenciada devido à elevada acidez, baixa densidade de cargas negativas, maiores quantidades de minerais de argila 1:1 e de (hidr)óxidos de Fe, Al e Mn, em que predominam cargas negativas variáveis com o pH. O objetivo nesta tese foi caracterizar a capacidade de sorção, a distribuição entre as frações do solo, a especiação temporal, a predição da capacidade de sorção e a dessorção com método dinâmico de extração de Cd(II) em seis solos tropicais, incluindo três Latossolos. Amostras dos seis solos foram utilizadas para avaliação da interação com Cd(II), utilizando extração sequencial e especiação por espectroscopia de absorção de raios-X próximo à estrutura da borda (XANES) para avaliação da cinética de sorção. Dados de 29 solos foram utilizados para desenvolvimento de modelo de regressão linear para predição das capacidades de sorção de Cd(II). A caracterização da dessorção de Cd por extração convencional e dinâmica foi feita em solos de textura médio-arenosa, argilosa e em um solo de referência certificado. Os resultados de sorção foram ajustados ao modelo de Langmuir. As capacidades de sorção e as energias livres padrão de Gibbs variaram de 37 à 1296 mg kg-1 e de -16,6 até -27,0 kJ mol-1, respectivamente. A sorção foi fraca e reversível, e mais de 90% do Cd estava sorvido como espécies disponíveis. A especiação temporal indicou evidências fracas e variáveis para as alterações químicas do Cd no solo, sugerindo que o elemento liberado nessas amostras se ligou à matéria orgânica do solo e aos óxidos minerais ou permaneceu dissolvido, com pequenas alterações na especiação nos meses seguintes. O modelo linear representou 98% dos resultados empíricos apenas em função de uma variável, que foi o ensaio de sorção simplificado com apenas uma concentração de Cd(II). Apesar de a capacidade de sorção prevista com o modelo ter apresentado variação de cerca de 20% em relação ao empírico, o modelo de predição apresenta potencialidade de aplicação para avaliações iniciais e rápidas. A dessorção avaliada em batelada e em fluxo indicou dessorção próxima de 100% nas frações que representam disponibilidade no ambiente, enquanto o sistema desenvolvido para extração dinâmica foi adequado na mistura das soluções com a amostra de solo e propiciou rápida troca de extratores. De modo geral os atributos do solo, bem como a classe, influenciaram, mas não definiram a interação do Cd(II) com o solo. Por sua vez, o Cd(II) incorporado ao solo apresenta grande risco ambiental e de interação com a biota / The interaction of potentially toxic elements in soils and characterization as mobility and potential of environmental release are important for environmental risk assessment. In the case of highly weathered soils, as Oxisols, interaction can be differentiated, due to the high acidity, low density of negative charges, and higher amounts of 1:1 clay minerals and Fe, Al and Mn (hidr)oxides, in which negative charges are variables with pH. The objectives in this thesis was to characterize the Cd(II) sorption capacity, distribution between soil fractions, temporal speciation, prediction of sorption capacity and desorption with dynamic extraction method in six tropical soils, including three Oxisols. Samples of the six soils were used to assess the interaction with Cd(II) using sequential extraction and the speciation with X-ray absorption near edge structure spectroscopy (XANES) to evaluate the adsorption kinetics. Data of 29 soils were used to develop a linear regression model for prediction of Cd(II) sorption capacity. The Cd desorption characterization trough conventional and dynamics extractions was performed in a medium-sandy, a clayey and a certified reference soils. The sorption results were fitted to the Langmuir model. Sorption capacities and standard Gibbs free energy ranged from 37 to 1296 mg kg-1 and from -16.6 to -27.0 kJ mol-1, respectively. Sorption was weak and reversible, and more 90% Cd was sorbed as available species. The temporal speciation indicated weak and variables evidence of chemical changes of Cd in the soil, suggesting that this element released in these soils bound to the soil organic matter and to mineral oxides or remained dissolved, with minor changes in speciation in the following months. The linear model accounted for 98% of empirical results only on the basis of a single variable, which was the sorption simplified experiment with only one Cd(II) concentration. Although the sorption capacity predicted with the model ranged about 20% of the empirical, prediction model has potential of application for initial and rapid assessments. The desorption evaluated in batch and flow indicated desorption of about 100% in the fractions representing availability in the environment, meanwhile the system developed for dynamic extraction was adequate to mix the solutions with the soil sample and provided rapid exchange of extractants. Overall, the soil characteristics and the class had influence, but did not define the interaction of Cd(II) with the soil. On the other hand, the Cd(II) incorporated into the soil has a great environmental risk and to interact with the biota

Cette étude vise à développer un système de dépollution d'eau et de sédiments viticoles. Le glyphosate, diuron et 3,4-dichloroaniline (3,4-DCA) sont considérés, en tenant compte de la charge en cuivre. L'augmentation du temps de séjour des polluants dans le système et le choix de la bioaugmentation couplée à la phytoremédiation est la stratégie retenue. Chaque composante d'un triplet « sorbant-inoculum bactérien-plante » a été sélectionnée en laboratoire et le triplet mis en oeuvre en microcosmes en conditions partiellement contrôlées.La sélection de matériaux sorbants dans différentes matrices liquides en présence des polluants seuls ou en mélange montre que les capacités de sorption des différents matériaux testés varient selon le polluant, sa formulation (seul ou en mélange) et la matrice liquide. Le sédiment se révèle être le meilleur sorbant pour le glyphosate ; le sable pour le diuron et le 3,4-DCA.Les performances de dissipation des colonies tolérantes isolées varient fortement selon le polluant. Le consortium sélectionné pour le procédé dissipe le glyphosate, le diuron et le 3,4-DCA en milieu liquide et complexe par ailleurs le cuivre.L'expérience en microcosmes montre que le temps de rétention hydraulique influe sur l'efficacité du système et que les matériaux sorbants sont efficaces. De plus les performances de dissipation atteintes sont bonnes. L'effet de la bioaugmentation sur les performances de dissipation n'est pas significatif pour le glyphosate et le 3,4-DCA, mais améliore en moyenne la dissipation du diuron. Un temps d'action prolongé dans la matrice solide s'avère nécessaire pour obtenir une bonne efficacité du procédé. / This study aims at developing a depollution system for vineyard sediments and passing water. Glyphosate, diuron and 3,4-dichloroaniline (3,4-DCA) have been chosen, taking a copper load into account. Strategical choices are increased pollutant hydraulic retention time and the use of bioaugmentation together with phytoextraction. Each item on this « sorbent-bacterial inoculum-plant » triplet has been beforehand selected in the laboratory and implemented in microcosm experiments under semi-controlled conditions.Sorbent material selection in different liquid matrices with pollutants alone or in combination shows that material sorption capacities change with the type of pollutant. It has also been shown that these capacities vary with formulation (alone or in combination) and liquid matrix chosen. Sediment is awarded the best sorbent for glyphosate, sand the best sorbent for diuron and 3,4-DCA.Dissipation performances from isolated colonies are strongly related to the nature of the compound. Elected consortium degrades glyphosate, diuron and 3,4-dichloroaniline (3,4-DCA) in liquid culture as well as it complexes copper.Microcosm experiments show that hydraulic retention time weighs on pollutant concentration in water at the system outlet. Sorbents prove to be efficient. Dissipation performances are satisfactory. Bioaugmentation does not impact on glyphosate and 3,4-DCA dissipation performances significantly, but enhances diuron dissipation in average. Suitable process efficiency requires increased action time within the solid matrix.

The aim of this research is to understand the solid state physical properties of inulin in regards to the spray-drying treatments. In this context, inulin powders were produced by pilot spray-drying a commercial inulin dispersion under various feed (Tfeed) and inlet air (Tin) temperatures. More particularly, the amorphous and crystalline properties of the powders were studied by developing different fine characterization tools, such as modulated differential scanning calorimetry or powder X-ray diffraction. When the temperature of the inulin water systems increased, the crystallinity of the powder decreased. To a smaller extent, this tendency is also observed with the increase of the inlet air temperature of the spray drier. For example, an amorphous powder is obtained with a Tfeed of 90°C whatever the Tin (comprised between 120 and 230°C); whereas for a Tfeed of 80°C, a Tin of 230°C is necessary to obtain the same result. Adsorption isotherms were established on four powders covering a large range of crystallinity (crystallinity index from 0 to 92). The Guggenheim Anderson de Boer model was fitted to the experimental data. As the water content of the powders increased, the glass transition of inulin decreased. When the Tg droped below the storage temperature (20°C for example), the powders crystallized and underwent clumping phenomenon. Under these conditions, a continuous hard mass was observed for the amorphous powders; while their semi-crystalline counterparts were agglomerated but friable. To understand these changes, a kinetic study of the physical properties evolution and stability of an amorphous powder as a function of its water content was realized. These results allowed to correlate the Tg water content relationship to the evolution of the powders behaviour, such as stickiness or hardening during storage.

The migration behavior of actinides and other radioactive contaminants in the environment is controlled by prominent molecular phenomena such as hydrolysis and complexation reactions in aqueous solutions as well as the diffusion and sorption onto minerals present along groundwater flow paths. These reactions significantly influence the mobility and bioavailability of the metal ions in the environment, in particular at liquid-solid interfaces. Hence, for the assessment of migration processes the knowledge of the mechanisms occurring at interfaces is crucial. The required structural information can be obtained using various spectroscopic techniques. In the present study, the speciation of uranium(VI) and neptunium(V) at environmentally relevant mineral – water interfaces of oxides of titania, alumina, silica, zinc, and alumosilicates has been investigated by the application of attenuated total reflection Fouriertransform infrared (ATR FT-IR) spectroscopy. Moreover, the distribution of the hydrolysis products in micromolar aqueous solutions of U(VI) and Np(V/VI) at ambient atmosphere has been characterized for the first time, by a combination of ATR FT-IR spectroscopy, near infrared (NIR) absorption spectroscopy, and speciation modeling applying updated thermodynamic databases. From the infrared spectra, a significant change of the U(VI) speciation is derived upon lowering the U(VI) concentration from the milli- to the micromolar range, strongly suggesting the dominance of monomeric U(VI) hydrolysis products in the micromolar solutions. In contradiction to the predicted speciation, monomeric hydroxo species are already present at pH ≥ 2.5 and become dominant at pH 3. At higher pH levels (> 6), a complex speciation is evidenced including carbonate containing complexes. For the first time, spectroscopic results of Np(VI) hydrolysis reactions are provided in the submillimolar concentration range and at pH values up to 5.3, and they are comparatively discussed with U(VI). For both actinides, the formation of similar species is suggested at pH ≤ 4, whereas at higher pH, the infrared spectra evidence structurally different species. At pH 5, the formation of a carbonate-containing dimeric complex, that is (NpO2)2CO3(OH)3^-, is strongly suggested, whereas carbonate complexation occurs only under more alkaline conditions in the U(VI) system. The results from the experiments of the sorption processes clearly demonstrate the formation of stable U(VI) surface complexes at all investigated mineral phases. This includes several metal oxides, namely TiO2, Al2O3, and SiO2, serving as model systems for the elucidation of more complex mineral systems, and several alumosilicates, such as kaolinite, muscovite and biotite. From a multiplicity of in situ experiments, the impact of sorbent characteristics and variations in the aqueous U(VI) system on the sorption processes was considered. A preferential formation of an inner-sphere complex is derived from the spectra of the TiO2 and SiO2 phases. In addition, since the in situ FT-IR experiments provide an online monitoring of the absorption changes of the sorption processes, the course of the formation of the U(VI) surface complexes can be observed spectroscopically. It is shown that after prolonged sorption time on TiO2, resulting in a highly covered surface, outer-sphere complexation predominates the sorption processes. The prevailing crystallographic modification, namely anatase and rutile, does not significantly contribute to the spectra, whereas surface specific parameters, e.g. surface area or porosity are important. A significant different surface complexation is observed for Al2O3. The formation of innerspheric species is assumed at low U(VI) surface coverage which is fostered at low pH, high ionic strength and short contact times. At proceeded sorption the surface complexation changes. From the spectra, an outer-spheric coordination followed by surface precipitation or polymerization is deduced. Moreover, in contrast to TiO2, the appearance of ternary U(VI) carbonate complexes on the γ-Al2O3 surface is suggested. The first results of the surface reactions on more complex, naturally occurring minerals (kaolinite, muscovite and biotite) show the formation of U(VI) inner-sphere sorption complexes. These findings are supported by the spectral information of the metal oxide surfaces. In this work, first spectroscopic results from sorption of aqueous Np(V) on solid mineral phases are provided. It is shown that stable inner-sphere surface species of NpO2 ^+ are formed on TiO2. Outer-sphere complexation is found to play a minor role due to the pH independence of the sorption species throughout the pH range 4 – 7.6. The comparative spectroscopic experiments of Np(V) sorption onto TiO2, SiO2, and ZnO indicate structurally similar bidentate surface complexes. The multiplicity of IR spectroscopic experiments carried out within this study yields a profound collection of spectroscopic data which will be used as references for future investigations of more complex sorption systems in aqueous solution. Furthermore, from a methodological point of view, this study comprehensively extends the application of ATR FT-IR spectroscopic experiments to a wide range in the field of radioecology. The results obtained in this work contribute to a better understanding of the geochemical interactions of actinides, in particular U(VI) and Np(V/VI), in the environment. Consequently, more reliable predictions of actinides migration which are essential for the safety assessment of nuclear waste repositories can be performed.

The long-lived fission product 126Sn (105 years) (Weast (1972)) is of substantial interest in the context of nuclear waste disposal in deep underground repositories. However, the prevalent redox state, the aqueous speciation as well as the reactions at the mineral-water interface under the expected anoxic conditions are a matter of debate. Therefore, in this PhD thesis I present work on the reactions of SnII with three Fe-bearing minerals as a function of pH, time, and SnII loading under anoxic condition with O2 level < 2 ppmv. The first mineral, goethite, contains only trivalent Fe (FeIIIOOH), the second, magnetite, contains both FeII and FeIII (FeIIFeIII2O4), and the third, mackinawite (FeIIS), contains only divalent Fe. The uptake behavior of the three mineral surfaces was investigated by batch sorption studies. Tin redox state was investigated by Sn-K X-ray absorption near-edge structure (XANES) spectroscopy, and the local, molecular structure of the expected Sn surface complexes and precipitates was studied by extended X-ray absorption fine-structure (EXAFS) spectroscopy. Selected samples were also investigated by transmission electron microscopy (TEM) to elucidate the existence and nature of secondary, Fe- and /or Sn containing solids, and by Mössbauer spectroscopy to study FeII and FeIII in the minerals. Based on the such-obtained molecular-level information, surface complexation models (SCM) were fitted to the batch sorption data to derive surface complexation constants. In the presence of the FeIII-bearing minerals magnetite and goethite, I observed a rapid uptake and oxidation of SnII to SnIV. The local structure determined by EXAFS showed two Sn-Fe distances of about 3.15 and 3.60 Å in line with edge and corner sharing arrangements between octahedrally coordinated SnIV and the Fe(O,OH)6 octahedra at the magnetite and goethite surfaces. While the respective coordination numbers suggested formation of tetradentate inner-sphere complexes between pH 3 and 9 for magnetite, bidentate inner-sphere complexes (single edge-sharing (1E) and corner-sharing (2C)) prevail at the goethite surface at pH > 3, with the relative amount of 2C increasing with Sn loading. The interfacial electron transfer between sorbed SnII and structural FeIII potentially leads to dissolution of FeII and transformation to secondary FeII/FeIII oxide minerals. There is no clear evidence to confirm the reductive dissolution in the Sn/ magnetite system, Rietveld refinement of XRD patterns, however, indicates an increase of FeII/FeIII ratio in the magnetite structure. For the Sn/goethite system, dissolved FeII increased with SnII loading at the lowest pH investigated, indicative of reductive dissolution. At pH >5, spherical and cubic particles of magnetite were observed by TEM, and their number increased with SnII loading. Based on previous finding, this secondary mineral transformation of goethite should proceed via dissolution and recrystallization. The molecular structure and oxidation state of sorbed Sn were then used to fit the batch sorption data of magnetite and goethite with SCM. The sorption data on magnetite were fit with the diffuse double layer model (DLM) employing two different complexes, the first ( = -14.97±0.35) prevailing from pH 2 to 9, and the second ( = -17.72±0.50), which forms at pH > 9 by co-adsorption of FeII, thereby increasing sorption at this high pH. The sorption data on goethite were fitted with the charge distribution–multisite complexation model (CD-MUSIC). Based on the EXAFS-derived presence of two different bidentate inner-sphere complexes ((≡FeOH)(≡Fe3O)Sn(OH)3 (1E) and (≡FeOH)2Sn(OH)3) (2C)), sorption affinity constants of 15.5 ±1.4 for the 1E complex and of 19.2 ±0.6 for the 2C complex were obtained. The model is not only able to predict sorption across the observed pH range, but also the transition from a roughly 50/50 distribution of the two complexes at 12.5 µmol/g Sn loading, to the prevalence of the 2C complex at higher loading, in line with the EXAFS data. The retention mechanism of SnII by mackinawite is significantly dependent on the solution pH, reflecting the transient changes of the mackinawite surface in the sorption process. At pH <7, SnII is retained in its original oxidation state. It forms a surface complex, which is characterized by two short (2.38 Å) Sn-S bonds, which can be interpreted as the bonds towards the S-terminated surface of mackinawite, and two longer Sn-S bonds (2.59 Å), which point most likely towards the solution phase, completing the tetragonal SnS4 innersphere sorption complex. Precipitation of SnS or formation of a solid solution with mackinawite could be excluded. At pH > 9, SnII is completely oxidized by an FeII/FeIII (hydr)oxide, most likely green rust, forming on the surface of mackinawite. Six O atoms at 2.04 Å and 6 Fe atoms at 3.29 Å demonstrate a structural incorporation by green rust, where SnIV substitutes for Fe in the crystal structure. The transition between SnII and SnIV and between sulfur and oxygen coordination takes place between pH 7 and 8, in accordance with the transition from the mackinawite stability field to more oxidized Fe-bearing minerals. The uptake processes of SnII by mackinawite are largely in line with the uptake processes of divalent cations of other soft Lewis-acid metals like Cd, Hg and Pb. Very different Sn retention mechanisms were hence active, including oxidation to SnIV and formation of tetradentate and bidentate surface complexes of the SnIV hydroxo moieties on goethite and magnetite, and in the case of mackinawite a SnII sulfide species forming a bidentate surface complex at low pH, and structural incorporation of SnIV by an oxidation product, green rust, at high pH. In all three mineral systems and largely independent on the retention mechanisms, inorganic SnII was strongly retained, with Rd values always exceeding 5, across the relatively wide pH range relevant for the near and far-field of nuclear waste respositories. For the goethite and magnetite systems, the retention could be well modeled with surface complexation models based on the molecular structural data. This is an important contribution to the safety case for future nuclear waste repositories, since such SCMs provide reliable means for predicting the radioactive dose released by 126Sn from nuclear waste into the biosphere across a wide range of physicochemical conditions typical for the engineered as well as natural barriers.

Till följd av den hårda utbyggnaden av vårt samhälle åtgår en stor mängd naturresurser. Samtidigt som samhället utveckas sätts allt högre krav på att det ska hushållas med naturresurser, inte minst genom införandet av miljömålet en ”God bebyggd miljö”. Enligt detta miljömål ska användningen av såväl mark som naturresurser ske på ett så hållbart sätt som möjligt. Samtidigt med detta skapar den svenska stålindustrin över en miljon ton slagg årligen, varav en stor del deponeras. Då deponeringen är kostsam pågår i dagsläget många försök att finna användningsområden för slagg så att deponeringskostanden ska undvikas. Bland annat har slagg i vissa fall visats kunna ersätta naturmaterial i formav sten, grus och sand vid till exempel vägbyggen och deponitäckningar. Slagg har i försök även visat på en vattenrenande förmåga då föroreningar fastläggs på slaggen.Detta har lett till försök med att använda slagg som filtermaterial i reaktiva filter där sand traditionellt sett ofta används. Denna studie avsåg att undersöka om slagg från Avesta Jernverk fungerar att använda i reaktiva filter för att rena vatten som är förorenade med till exempel tungmetaller och fosfor. Detta gjordes genom att skaka tre olika slagger som produceras i Avesta med ett lakvatten från en kommunal deponi med behov att renas från bland annat fluor, fosfor, kadmium, klorider, nickel och zink. I försöken användes en EAF-slagg och två AOD-slagger. För att undersöka om upptaget av föroreningar påverkades av om slaggen hade nya ytor användes både nykrossad slagg och slagg som varit placerade utomhus under 71 dagar. Resultaten visade att slaggerna som bildas vid Avesta Jernverk har en vattenrenandeförmåga och att samtliga av de testade slaggerna sorberade aluminium, fosfor och zink. Utöver dessa ämnen sorberade flera av slaggerna även arsenik, fluor, koppar och magnesium. Resultatet visade också på ett tidsberoende hos sorptionen, då mer föroreningar togs upp om slagg och lakvatten skakades i fem dygn jämfört med om skaktiden var femton minuter eller fyra timmar. Det gick dock inte att avgöra om slagg med nygjorda ytor sorberade bättre än slaggen som stått utomhus. Beräkningar utfördes och visade att ett slaggfilter dimensionsmässigt skulle vara möjligt att bygga och att en kornstorlek som sand skulle behövas för att få rätt uppehållstid. / As a result of the harsh exploitation and development of our society, a large amount of natural resources are needed. While the society develops it becomes more and more important to economise natural resources. This is also stated as an environmental objective, called "A good built environment" by the Swedish government. According to this environmental objective, the use of both land and natural resources should be undertaken in the most sustainable way possible. At the same time the Swedish steel industry produces over one million tonnes of slag annually, which is mostly deposited. Slag is a byproduct from the steel manufacturing process. When disposal is costly, many attempts to find usage for slag are done instead. For instance, in some cases it has been as replacement for natural resources as stone, gravel and sand in road constructions and landfill covers. Slag has also been shown to have a water-purifying capacity since contamination can be sorbed by the slag. This has led to attempts to use slag as filter material in reactive filters where sand traditionally is widely used. This study aimed to investigate whether slag from Avesta Works could be used in reactivefilters to purify water that is contaminated with heavy metals and phosphorus. This was done by shaking a number of slags produced in Avesta with leachate water from amunicipal landfill, Karlslund. The leachate water needs to be purified from i.a. fluorine, phosphorus, cadmium, chloride, nickel and zinc. In the experiments an EAF slag and two AOD slags were used. To investigate if the sorption of contamination in the leachate water was affected by the age of the particle surfaces, both slags with freshly made and aged surfaces were tested. The aging of the slags was created by placing the slags outdoor for 71 days. The results showed that the slags formed at Avesta Works has a water-purifying ability and that all of the tested slags sorbed aluminum, phosphorus and zinc. Beside these substances, some of the slags also sorbed arsenic, fluorine, copper and magnesium. Theresults also showed a time-dependence of the sorption: More contaminations were sorbed after reacting slag and leachate water for five days compared with fifteen minutes or four hours. It was not possible to determine if the slags with fresh surfaces sorbed better than the slags with aged surfaces. Calculations showed that a filter containing slag should be possible to build dimensionally and that the grain size of sand would be needed to get the required retention time.

Sorption Behaviour of Selected Dairy Powder Mixtures: A Study of The Effects of Composition and Mixing Methods Abstract As water mediates physico-chemical reactions (i.e. Maillard reactions, phase changes of sugars and minerals, protein conformational changes), water-powder interactions during storage are critical for dairy powder stability. Therefore, the mechanisms of moisture adsorption from the environment and water distribution among components in the dry state need to be investigated, especially in mixed systems. In order to achieve this goal, the research reported in this thesis had two key objectives. The first was to examine the effect of the sorption properties and phase changes of individual components in relation to the sorption properties of the mixed system. This was achieved by adding three level concentrations of lactose and mineral rich dairy powder (10, 20 and 30%) to Milk Protein Concentrate containing 85% of protein (MPC-85). The second objective was to examine the effect of mixing methods on the sorption behaviour of mixed systems, by applying two different mixing methods, solution mixing and mechanical mixing (particulate mixing). In the solution mixing method, the components were mixed in the same water and then spray dried. In the mechanical mixing method, two individual powder components were physically mixed. For both mixed systems, the kinetics of moisture adsorption were determined at 4 different equilibrium relative humidity levels (22.5, 43.2, 65.4 and 84.3%) and the final equilibrium moisture contents were determined at 8 different equilibrium relative humidity levels (11.3, 22.5, 32.8, 43.2, 52.9, 65.4, 75.3 and 84.3%) at 25°C. The effect of lactose addition to the MPC powder tended to retard the moisture sorption of the mixtures. The increase of concentration level of the lactose that was introduced to the MPC system, through either solution or mechanical mixing, resulted in less moisture adsorption when compared to MPC itself (p-value<0.05). This effect tended to be greater with the increase in relative humidity. A similar effect was observed for MPC/mineral rich milk calcium powder (MC) mixtures. The application of different mixing methods modified the equilibrium moisture content of MPC/Lactose mixtures, even though both mixing methods resulted in similar monolayer moisture value. The monolayer moisture values calculated for both mixing methods were significantly lower than their theoretical values (p-value< 0.05). This suggested that a lactose-protein interaction might exist in both powders prepared by solution and mechanical mixing. Even though the interaction itself is hypothetical, the effect of interaction could be reflected by significant different adsorption rate (p-value < 0.05) of powders produced by different mixing method. A similar type of interaction might exist for the solution mixed MPC/MC system, even though different results were obtained for MPC/MC mixtures prepared by mechanical mixing. The addition of lactose to MPC tended to slow the rate of moisture adsorption. This deceleration might have been contributed to by a reduction of the protein hydration sites by the association of lactose molecules to these sites. In contrast to the MPC/lactose system, the addition of mineral rich MC powder to MPC did not significantly change the rate of adsorption (p-value<0.05). Different mixing methods were found to change the rate of moisture adsorption for the MPC/Lactose systems (p-value<0.05). Even though the mechanically mixed powder adsorbed faster than that of solution mixed powder and X-Ray measurement indicated lactose crystal formation, a drop of moisture during the sorption study was not observed. This suggests that water released during crystallisation might be adsorbed by protein. Meanwhile, the application of two different mixing methods did not modify adsorption rate of MPC/MC system, except for samples stored at RH 84.3%. At this environment, mechanically mixed MPC/MC powders were adsorbed more slowly than the solution mixed powder (p-value<0.05). It might reflect powder compaction or a collapse of the porous structure, leading to limited moisture transfer at the interface. Lactose proportions and different mixing methods influenced the glass-rubber transition temperature (Tg-r) of the MPC/Lactose mixtures. An increase in the proportion of lactose tended to depress Tg-r of the mixtures (p-value<0.05). The Tg-r of the mechanically mixed powder was lower than that of solution mixed powder, presumably on account of the Tg-r for mechanically mixed powder being dominated by phase separated sugar components. Meanwhile, the Tg-r of MPC/MC mixtures was not influenced by either MC proportion or mixing method, particularly for samples stored at below RH 65.4%. The XRD-pattern suggested that the crystal formed during storage of MPC/Lactose mixtures was α-lactose monohydrate. As confirmed by XRD, a drop in moisture for the mixture corresponded to the presence of a peak in the XRD pattern, except for mechanically mixed powder. In this type of powder, even though a peak was detected, a moisture drop was not observed. Within the sensitivity limits of XRD, a crystalline form was not observed for MPC/MC mixtures.

Sorption Behaviour of Selected Dairy Powder Mixtures: A Study of The Effects of Composition and Mixing Methods Abstract As water mediates physico-chemical reactions (i.e. Maillard reactions, phase changes of sugars and minerals, protein conformational changes), water-powder interactions during storage are critical for dairy powder stability. Therefore, the mechanisms of moisture adsorption from the environment and water distribution among components in the dry state need to be investigated, especially in mixed systems. In order to achieve this goal, the research reported in this thesis had two key objectives. The first was to examine the effect of the sorption properties and phase changes of individual components in relation to the sorption properties of the mixed system. This was achieved by adding three level concentrations of lactose and mineral rich dairy powder (10, 20 and 30%) to Milk Protein Concentrate containing 85% of protein (MPC-85). The second objective was to examine the effect of mixing methods on the sorption behaviour of mixed systems, by applying two different mixing methods, solution mixing and mechanical mixing (particulate mixing). In the solution mixing method, the components were mixed in the same water and then spray dried. In the mechanical mixing method, two individual powder components were physically mixed. For both mixed systems, the kinetics of moisture adsorption were determined at 4 different equilibrium relative humidity levels (22.5, 43.2, 65.4 and 84.3%) and the final equilibrium moisture contents were determined at 8 different equilibrium relative humidity levels (11.3, 22.5, 32.8, 43.2, 52.9, 65.4, 75.3 and 84.3%) at 25°C. The effect of lactose addition to the MPC powder tended to retard the moisture sorption of the mixtures. The increase of concentration level of the lactose that was introduced to the MPC system, through either solution or mechanical mixing, resulted in less moisture adsorption when compared to MPC itself (p-value<0.05). This effect tended to be greater with the increase in relative humidity. A similar effect was observed for MPC/mineral rich milk calcium powder (MC) mixtures. The application of different mixing methods modified the equilibrium moisture content of MPC/Lactose mixtures, even though both mixing methods resulted in similar monolayer moisture value. The monolayer moisture values calculated for both mixing methods were significantly lower than their theoretical values (p-value< 0.05). This suggested that a lactose-protein interaction might exist in both powders prepared by solution and mechanical mixing. Even though the interaction itself is hypothetical, the effect of interaction could be reflected by significant different adsorption rate (p-value < 0.05) of powders produced by different mixing method. A similar type of interaction might exist for the solution mixed MPC/MC system, even though different results were obtained for MPC/MC mixtures prepared by mechanical mixing. The addition of lactose to MPC tended to slow the rate of moisture adsorption. This deceleration might have been contributed to by a reduction of the protein hydration sites by the association of lactose molecules to these sites. In contrast to the MPC/lactose system, the addition of mineral rich MC powder to MPC did not significantly change the rate of adsorption (p-value<0.05). Different mixing methods were found to change the rate of moisture adsorption for the MPC/Lactose systems (p-value<0.05). Even though the mechanically mixed powder adsorbed faster than that of solution mixed powder and X-Ray measurement indicated lactose crystal formation, a drop of moisture during the sorption study was not observed. This suggests that water released during crystallisation might be adsorbed by protein. Meanwhile, the application of two different mixing methods did not modify adsorption rate of MPC/MC system, except for samples stored at RH 84.3%. At this environment, mechanically mixed MPC/MC powders were adsorbed more slowly than the solution mixed powder (p-value<0.05). It might reflect powder compaction or a collapse of the porous structure, leading to limited moisture transfer at the interface. Lactose proportions and different mixing methods influenced the glass-rubber transition temperature (Tg-r) of the MPC/Lactose mixtures. An increase in the proportion of lactose tended to depress Tg-r of the mixtures (p-value<0.05). The Tg-r of the mechanically mixed powder was lower than that of solution mixed powder, presumably on account of the Tg-r for mechanically mixed powder being dominated by phase separated sugar components. Meanwhile, the Tg-r of MPC/MC mixtures was not influenced by either MC proportion or mixing method, particularly for samples stored at below RH 65.4%. The XRD-pattern suggested that the crystal formed during storage of MPC/Lactose mixtures was α-lactose monohydrate. As confirmed by XRD, a drop in moisture for the mixture corresponded to the presence of a peak in the XRD pattern, except for mechanically mixed powder. In this type of powder, even though a peak was detected, a moisture drop was not observed. Within the sensitivity limits of XRD, a crystalline form was not observed for MPC/MC mixtures.

Sorption Behaviour of Selected Dairy Powder Mixtures: A Study of The Effects of Composition and Mixing Methods Abstract As water mediates physico-chemical reactions (i.e. Maillard reactions, phase changes of sugars and minerals, protein conformational changes), water-powder interactions during storage are critical for dairy powder stability. Therefore, the mechanisms of moisture adsorption from the environment and water distribution among components in the dry state need to be investigated, especially in mixed systems. In order to achieve this goal, the research reported in this thesis had two key objectives. The first was to examine the effect of the sorption properties and phase changes of individual components in relation to the sorption properties of the mixed system. This was achieved by adding three level concentrations of lactose and mineral rich dairy powder (10, 20 and 30%) to Milk Protein Concentrate containing 85% of protein (MPC-85). The second objective was to examine the effect of mixing methods on the sorption behaviour of mixed systems, by applying two different mixing methods, solution mixing and mechanical mixing (particulate mixing). In the solution mixing method, the components were mixed in the same water and then spray dried. In the mechanical mixing method, two individual powder components were physically mixed. For both mixed systems, the kinetics of moisture adsorption were determined at 4 different equilibrium relative humidity levels (22.5, 43.2, 65.4 and 84.3%) and the final equilibrium moisture contents were determined at 8 different equilibrium relative humidity levels (11.3, 22.5, 32.8, 43.2, 52.9, 65.4, 75.3 and 84.3%) at 25°C. The effect of lactose addition to the MPC powder tended to retard the moisture sorption of the mixtures. The increase of concentration level of the lactose that was introduced to the MPC system, through either solution or mechanical mixing, resulted in less moisture adsorption when compared to MPC itself (p-value<0.05). This effect tended to be greater with the increase in relative humidity. A similar effect was observed for MPC/mineral rich milk calcium powder (MC) mixtures. The application of different mixing methods modified the equilibrium moisture content of MPC/Lactose mixtures, even though both mixing methods resulted in similar monolayer moisture value. The monolayer moisture values calculated for both mixing methods were significantly lower than their theoretical values (p-value< 0.05). This suggested that a lactose-protein interaction might exist in both powders prepared by solution and mechanical mixing. Even though the interaction itself is hypothetical, the effect of interaction could be reflected by significant different adsorption rate (p-value < 0.05) of powders produced by different mixing method. A similar type of interaction might exist for the solution mixed MPC/MC system, even though different results were obtained for MPC/MC mixtures prepared by mechanical mixing. The addition of lactose to MPC tended to slow the rate of moisture adsorption. This deceleration might have been contributed to by a reduction of the protein hydration sites by the association of lactose molecules to these sites. In contrast to the MPC/lactose system, the addition of mineral rich MC powder to MPC did not significantly change the rate of adsorption (p-value<0.05). Different mixing methods were found to change the rate of moisture adsorption for the MPC/Lactose systems (p-value<0.05). Even though the mechanically mixed powder adsorbed faster than that of solution mixed powder and X-Ray measurement indicated lactose crystal formation, a drop of moisture during the sorption study was not observed. This suggests that water released during crystallisation might be adsorbed by protein. Meanwhile, the application of two different mixing methods did not modify adsorption rate of MPC/MC system, except for samples stored at RH 84.3%. At this environment, mechanically mixed MPC/MC powders were adsorbed more slowly than the solution mixed powder (p-value<0.05). It might reflect powder compaction or a collapse of the porous structure, leading to limited moisture transfer at the interface. Lactose proportions and different mixing methods influenced the glass-rubber transition temperature (Tg-r) of the MPC/Lactose mixtures. An increase in the proportion of lactose tended to depress Tg-r of the mixtures (p-value<0.05). The Tg-r of the mechanically mixed powder was lower than that of solution mixed powder, presumably on account of the Tg-r for mechanically mixed powder being dominated by phase separated sugar components. Meanwhile, the Tg-r of MPC/MC mixtures was not influenced by either MC proportion or mixing method, particularly for samples stored at below RH 65.4%. The XRD-pattern suggested that the crystal formed during storage of MPC/Lactose mixtures was α-lactose monohydrate. As confirmed by XRD, a drop in moisture for the mixture corresponded to the presence of a peak in the XRD pattern, except for mechanically mixed powder. In this type of powder, even though a peak was detected, a moisture drop was not observed. Within the sensitivity limits of XRD, a crystalline form was not observed for MPC/MC mixtures.

Sorption Behaviour of Selected Dairy Powder Mixtures: A Study of The Effects of Composition and Mixing Methods Abstract As water mediates physico-chemical reactions (i.e. Maillard reactions, phase changes of sugars and minerals, protein conformational changes), water-powder interactions during storage are critical for dairy powder stability. Therefore, the mechanisms of moisture adsorption from the environment and water distribution among components in the dry state need to be investigated, especially in mixed systems. In order to achieve this goal, the research reported in this thesis had two key objectives. The first was to examine the effect of the sorption properties and phase changes of individual components in relation to the sorption properties of the mixed system. This was achieved by adding three level concentrations of lactose and mineral rich dairy powder (10, 20 and 30%) to Milk Protein Concentrate containing 85% of protein (MPC-85). The second objective was to examine the effect of mixing methods on the sorption behaviour of mixed systems, by applying two different mixing methods, solution mixing and mechanical mixing (particulate mixing). In the solution mixing method, the components were mixed in the same water and then spray dried. In the mechanical mixing method, two individual powder components were physically mixed. For both mixed systems, the kinetics of moisture adsorption were determined at 4 different equilibrium relative humidity levels (22.5, 43.2, 65.4 and 84.3%) and the final equilibrium moisture contents were determined at 8 different equilibrium relative humidity levels (11.3, 22.5, 32.8, 43.2, 52.9, 65.4, 75.3 and 84.3%) at 25°C. The effect of lactose addition to the MPC powder tended to retard the moisture sorption of the mixtures. The increase of concentration level of the lactose that was introduced to the MPC system, through either solution or mechanical mixing, resulted in less moisture adsorption when compared to MPC itself (p-value<0.05). This effect tended to be greater with the increase in relative humidity. A similar effect was observed for MPC/mineral rich milk calcium powder (MC) mixtures. The application of different mixing methods modified the equilibrium moisture content of MPC/Lactose mixtures, even though both mixing methods resulted in similar monolayer moisture value. The monolayer moisture values calculated for both mixing methods were significantly lower than their theoretical values (p-value< 0.05). This suggested that a lactose-protein interaction might exist in both powders prepared by solution and mechanical mixing. Even though the interaction itself is hypothetical, the effect of interaction could be reflected by significant different adsorption rate (p-value < 0.05) of powders produced by different mixing method. A similar type of interaction might exist for the solution mixed MPC/MC system, even though different results were obtained for MPC/MC mixtures prepared by mechanical mixing. The addition of lactose to MPC tended to slow the rate of moisture adsorption. This deceleration might have been contributed to by a reduction of the protein hydration sites by the association of lactose molecules to these sites. In contrast to the MPC/lactose system, the addition of mineral rich MC powder to MPC did not significantly change the rate of adsorption (p-value<0.05). Different mixing methods were found to change the rate of moisture adsorption for the MPC/Lactose systems (p-value<0.05). Even though the mechanically mixed powder adsorbed faster than that of solution mixed powder and X-Ray measurement indicated lactose crystal formation, a drop of moisture during the sorption study was not observed. This suggests that water released during crystallisation might be adsorbed by protein. Meanwhile, the application of two different mixing methods did not modify adsorption rate of MPC/MC system, except for samples stored at RH 84.3%. At this environment, mechanically mixed MPC/MC powders were adsorbed more slowly than the solution mixed powder (p-value<0.05). It might reflect powder compaction or a collapse of the porous structure, leading to limited moisture transfer at the interface. Lactose proportions and different mixing methods influenced the glass-rubber transition temperature (Tg-r) of the MPC/Lactose mixtures. An increase in the proportion of lactose tended to depress Tg-r of the mixtures (p-value<0.05). The Tg-r of the mechanically mixed powder was lower than that of solution mixed powder, presumably on account of the Tg-r for mechanically mixed powder being dominated by phase separated sugar components. Meanwhile, the Tg-r of MPC/MC mixtures was not influenced by either MC proportion or mixing method, particularly for samples stored at below RH 65.4%. The XRD-pattern suggested that the crystal formed during storage of MPC/Lactose mixtures was α-lactose monohydrate. As confirmed by XRD, a drop in moisture for the mixture corresponded to the presence of a peak in the XRD pattern, except for mechanically mixed powder. In this type of powder, even though a peak was detected, a moisture drop was not observed. Within the sensitivity limits of XRD, a crystalline form was not observed for MPC/MC mixtures.