Abstract More than 900 papers related to organosolv pulping have been reviewed in this thesis. From the information included in those papers it can be concluded that organosolv pulping processes are still in a developing stage and are not yet ready to seriously threat the position of the kraft process as the main pulp manufacturing process in the world. Distillation seems to be the main alternative as the process for recovering the solvent in organosolv pulping. A good reason for this is that using simple distillation no potentially harmful components are introduced to the process. The effect of feed composition on the operation of a separation sequence in an organosolv process using aqueous formic and acetic acids and corresponding peroxyacids was studied. When simple distillation was used as the separation method the effect was found to be significant. The no ideal nature of the formic acid-acetic acid-water mixture, which separation was studied, makes the ternary composition space to divide into four distillation regions. Which region the feed is located in, obviously determines the economy of the distillation sequence. Shortcut calculation methods cannot be recommended to be used for designing a distillation sequence for the ternary mixture studied, but they give useful information for the comparison of such sequences. They were used to choose a limited number of alternatives for studies with rigorous calculation methods. Minimum work of separation can also be used to make a satisfying estimate for the relative easiness of separation of the formic acid-acetic acid-water mixture. Thermal integration using pinch technology was also tested and found very useful for decreasing the thermal energy consumption of distillation processes. Thermodynamic efficiencies for separating the formic acid-acetic acid-water mixture by simple distillation were estimated. They were found to be lower than the average value for distillation presented in literature.

Bidentate imidazole-based extractants, 1-octylimidazole-2-aldoxime (OIMOX) and 1-octyl-2-(2′-pyridyl)imidazole (OPIM), along with dinonylnaphthalene sulfonic acid (DNNSA) as a synergist, were investigated as potential selective extractants for Cu²⁺and Ni²⁺ respectively from base metals in a solvent extraction system. The study was extended to evaluate the sorption and separation of Ni²⁺ from other base metals in a solid-solution system using microspherical Merrifield resins and nanofibers functionalized with 2,2′-pyridylimidazole. Copper was effectively separated with OIMOX and DNNSA as extractants from nickel with ΔpH½ ≈1.05 and the extraction order of Cu²⁺ > Ni²⁺ > Zn²⁺ > Cd²⁺> Co²⁺ was achieved as a function of pH. At pH 1.65 the extracted copper, from a synthetic mixture of the base metals reached 90.13(±0.90)%, and through a two-step extraction process 98.22(±0.29)% copper was recovered with negligible nickel and cobalt impurities. Stripping of the copper from the loaded organic phase using TraceSelect sulphuric acid at pH 0.35 yielded 96.60(±0.44)% of the loaded quantity after the second stage of stripping. The separation of Ni²⁺ from the borderline and hard acids; Co²⁺, Cu²⁺, Zn²⁺, Fe2²⁺, Fe²⁺, Mn²⁺, Mg2²⁺ and Ca²⁺ at a pH range of 0.5-3.5 with OPIM and DNNSA was acvieved to the tune of a ΔpH½≈ 1.6 with respect to cobalt from a sulfate and sulfate/chloride media. A three-stage counter-current extraction of Ni²⁺, at the optimized pH of 1.89, from a synthetic mixture of Ni²⁺, Co²⁺ and Cu²⁺, yielded 99.01(±1.79)%. The total co-extracted Cu²⁺ was 48.72(±0.24)% of the original quantity in the mixture, and it was 19.85(±0.28%) for Co²⁺. The co-extracted Cu²⁺ was scrubbed off from the loaded organic phase at pH≈8.5 by using an ammonium buffer, while co-extracted Co²⁺ was selectively and quantitatively stripped with H₂SO₄ at pH 1.64. The total recovery of Ni²⁺ by stripping at pH 0.32 was 94.05(±1.70)%. In the solid-liquid system, Ni²⁺ was separated from Co²⁺, Cu²⁺, and Fe²⁺ with the microspherical resins funtionalised with 2,2′-pyridylimidazole by a separation factor (β) in the range 22-45. Electrospun nanofibers as sorbents yielded high sorption capacity in the range of 0.97 - 1.45 mmol.g⁻¹ for the same metals ions. Thus, 1-octylimidazole-2-aldoxime (OIMOX), and1-octyl-2-(2′-pyridyl)imidazole (OPIM) can be effectively utilized alongside DNNSA as a co-extractant in the separation of Cu²⁺ and Ni²⁺ respectively from base metals in acidic sulfate medium in a solvent extraction process, and the latter as a selective ligand in the solid-liquid separation of Ni²⁺ from Co²⁺, Cu²⁺, and Fe²⁺.

The necessity of reprocessing spent nuclear fuel has arisen from increasing awareness and concern for the environment, in addition to the potential of minimising proliferation. A number of different reprocessing techniques are currently being developed around the world to allow useful spent nuclear fuel (SNF) to be recycled and reused and the remaining waste to be treated. One such technique, currently being developed in the USA is the TALSPEAK process, an advanced reprocessing method for the separation of trivalent lanthanide (Ln3+) and minor actinide (MA3+) components. This process, developed in the 1960s at Oak Ridge National Laboratory, uses DTPA to act as a holdback reagent for MA3+, in a lactate buffered aqueous phase at pH 3.6, allowing Ln3+ to be selectively extracted by organophosphate HDEHP into an organic phase of DIPB or dodecane. TALSPEAK is one of the most promising techniques being researched due to its numerous advantages, particularly its relative resistance to radiolysis and its ability to be carried out without the need for high reagent concentrations. Additionally it gives high separation factors, in the region of ~50-100, comparable to other advanced reprocessing methods under development. The chemistry of the process is very complex and not particularly well understood so it would be advantageous to simplify the process by removing the need for a separate holdback reagent and buffer. In collaboration with colleagues at the Idaho National Lab, the use of amino acids as a potential combined buffer and soft donor was investigated. Although it was found that amino acids do not act as holdback reagents in their own right, optimisation of an L-alanine buffered TALSPEAK system with DTPA was found to allow the process to be carried out effectively at a lower pH of 2, which is more preferable for industrial application. As an extension of this, separation studies were carried out using the tripeptide L-glutathione (GSH) to determine its potential for use as a combined buffer and soft-donor. As with the studies with amino acids, it was found that GSH also does not act as a holdback reagent in its own right, however it does interact with Ln-DTPA complexes at pH 4. When optimised at this pH, separation factors of up to 1200 were achieved for Eu3+/Am3+, whilst still maintaining low MA3+ partitioning. However, further studies by ICP-MS and luminescence spectroscopy showed that a GSH buffered system was not effective for extraction of heavier lanthanides, although the results show the potential for further investigation into other short and longer chain peptide buffered systems and possibly lanthanide-lanthanide separations. Further studies were carried on amino acid appended DTPA ligands which were synthesised in a one step reaction in order to create a combined buffer and soft donor. The ligands were found to self-buffer at around pH 2 and allow successful separation of Eu3+/Am3+ (SF ~ 100). The results from initial investigations by luminescence spectroscopy and solvent extraction are promising and are presented here. Further work is needed on these systems in order to optimise their extraction capability and minimise Am3+ partitioning. In the future this work could promote studies for better understanding of TALSPEAK chemistry that could be used in industrial partitioning processes.

Além do interesse intrínseco pelos seus aspectos mecanísticos, as reações de hidrólise de compostos carbonílicos apresentam também a interessante particularidade da reação pelo próprio solvente, a água. Dentre estas reações, conhecidas como \"reações de água\" (Robertson, 1967; Johnson, 1967), estudou-se neste trabalho a hidrólise de carbonatos, através do cálculo das energias de transferência da fase gasosa para o solvente, de reagentes (R), estado de transição (ET) e produtos (P). O estudo da solvatação de modelos moleculares para R e ET indica uma correlação entre reatividade e estrutura molecular. Os resultados usando o enfoque de \"super-molécula\" mostram maior concordância com os dados experimentais do que o cálculo de solvatação da molécula simples e indicam que a solvatação dos modelos de ET é mais eficiente que para R e, portanto, há um aumento da reatividade. O estudo mais detalhado das estruturas de R, ET e P, em misturas água/acetonitrila para carbonatos de difenila e bis(2,4-dinitrofenila), sugere a existência de duas ligações de hidrogênio: entre o oxigênio da água do \"cluster\" e um dos hidrogênios dos anéis aromáticos (CF e CDNF), e entre o hidrogênio da água e o oxigênio do grupo nitro do outro anel aromático (CDNF). A consequente diminuição da liberdade conformacional em relação à fase gasosa, provocada por estas ligações de hidrogênio (CF e CDNF), expõe um dos hemisférios da carbonila ao ataque da água, provocando então uma aceleração entrópica do processo. Os efeitos eletrônicos, devidos às ligações de hidrogênio, estão de acordo com a maior acidez esperada dos hidrogênios dos anéis do CDNF em relação ao CF. Também mostram uma compensação no CDNF, pouco contribuindo para alterar a densidade eletrônica no seu carbono carbonílico, enquanto que indica uma soma de efeitos no CF, contribuindo então para um aumento desta densidade eletrônica no CF, de acordo com sua conhecida baixa reatividade. O trabalho permite ainda concluir sobre o relativo sucesso do uso de método semi-empírico PM3 e modelo relativamente simples de solvatação (Cramer & Truhlar, 1991), para o cálculo de energia de transferência em misturas de água/acetonitrila, na faixa de fração molar da água (0,40 a 1,00) onde o método apresenta resultados concordantes com os valores experimentais. / In addition to their intrinsic mechanistic interest, hydrolysis reactions of carbonyl compounds in aqueous media exhibit the interesting peculiarity of direct reaction with the solvent itself, i.e., water. In the present work, we have investigated a representative example of one of these \"water reactions\" (Robertson, 1967; Johnson, 1967), the hydrolysis of carbonates, via quantum chemical ca1culation of the free energies of transfer of the reagents (R), the transition state (TS) and the products (P) from the gas phase to water. A model study of the solvation of R and TS points to a correlation between reactivity and molecular structure. Results using the \"super-molecule\" approach show greater agreement with experiment than solvation ca1culations on the isolated molecule and imply that the solvation of the TS is more effective than that of R in increasing reactivity. A more detailed study of the structures of R, TS and P for diphenyl- (DPC) and bis(2,4-dinitrophenyl)carbonates (DNPC) in acetonitrile/water mixtures suggests the existence of two possible types of hydrogen bonds, i.e., between oxygen of the water c1uster and an aromatic ring hydrogen (DPC and DNPC) or, in the case of DNPC, between the protons of water and the oxygens of the nitro group of the second aromatic ring. The decrease in conformational degrees of freedom reI ative to the gas phase provoked by these hydrogen bonds exposes one of the hemispheres of the carbonyl group to attack by water, resulting in an entropic acceleration of the reaction. The electronic effects on the hydrogen bonds are in line with the greater acidity of the aromatic ring hydrogens of DNPC relative to those of DNP. In DNPC, there is a compensation effect, with very little alteration of the electron density on the carbonyl carbon, while in DPC a sum of effects increases the electron density on the carbonyl carbon, in line with the known lower reactivity of the latter. This work points to the relative success of the semi-empirical PM3 method combined with relatively simple solvation models (Cramer & Truhlar, 1991) for ca1culating free energies of transfer involving acetonitrile/water mixtures in the water mole fraction range from 0.40-1.00.

La plupart des sites de liaisons des cibles thérapeutiques sont hydrophobes. La majorité des molécules actives sont donc hydrophobes et difficilement soluble dans l'eau. Pour remédier à ce problème lors des test in vitro, un cosolvant est ajouté dans le milieu de réaction pour augmenter la solubilité des molécules. Le plus commun est le diméthylsulfoxyde (DMSO). Cependant, peu d'études ont regardé l'effet du DMSO sur l'affinité des ligand hydrophobes pour leurs cibles, mais toutes ont montré une modification de l'affinité induite par le DMSO. Pour mieux comprendre l'effet du DMSO il est nécessaire d'étudier un grand nombres de système ligand/récepteur différents. Dans cette étude, nous avons étudié l'effet d'une concentration de 5% de DMSO sur la liaison d'un ligand hydrophobe l'acide adamantane-1-carboxylique (ADA) dans deux cavités hydrophobes la beta et la gamma cyclodextrines (CD). Les deux CD diffèrent par la largeur de leur cavité. Les mesures d'affinités ont été réalisées par mesure de vélocité ultrasonore, résonance magnétique nucléaire et par des simulations moléculaires (MS). Toutes les techniques ont montré que le DMSO n'a pas d'effet sur l'affinité de l'ADA pour la gamma-CD alors qu'il diminue fortement l'affinité de l'ADA pour la beta-CD. L'analyse des MS a montré que le DMSO entre en compétition avec l'ADA pour la petite cavité de la beta-CD alors que pour la large cavité de la gamma-CD cette compétition n'est pas présente. L'effet du DMSO semble plus important lorsque le volume du ligand est parfaitement adapté au volume de la cible. / Most therapeutic targets are proteins whose binding sites are hydrophobic cavities. For this reason, the majority of drugs under development are hydrophobic molecules exhibiting low solubility in water. To tackle this issue, a few percent of cosolvent, such as dimethyl sulfoxide (DMSO), is usually employed to increase drug solubility during the drug screening process. However, the few published studies dealing with the effect of adding DMSO showed that the affinity of hydrophobic ligands is systematically underestimated. To better understand the effect of DMSO, there is a need of studying its effect on a large range of systems. In this work, we used beta and gamma-cyclodextrins (CD) as models of hydrophobic cavities to investigate the effect of the addition 5% DMSO on the affinity of 1-adamantane carboxylic acid (ADA) to these CD. The two systems differ by the size of the CD cavity. The evaluation of binding constants was performed using ultrasound velocimetry, nuclear magnetic resonance spectroscopy, and molecular simulations (MS). All techniques show that the presence of 5% DMSO does not significantly modify the affinity of ADA for gamma-CD, while the affinity is dramatically reduced for beta-CD. MS analysis show a competition between DMSO and ADA for the small cavity of beta-CD, which is not present for the large cavity of gamma-CD. The bias induced by the presence of DMSO is thus more important when the ligand volume better fits the CD cavity.

Glucokinase (GK) is an enzyme that catalyzes the ATP-dependent phosphorylation of glucose to form glucose-6-phosphate, and it is a tightly regulated checkpoint in glucose homeostasis. The monomeric enzyme possesses a highly exotic kinetic profile, with a sigmoidal dependence on glucose, which has been the source of vigorous investigation and debate in the last several decades. This unique regulatory behavior can be thought of as a remarkable glucose sensor, which may result in hyperglycemia when it is not active enough and hypoglycemia when it is too active. This interdisciplinary study, which draws on small angle X-ray scattering (SAXS) integrated with atomistic molecular dynamics simulations and experimental glucose binding thermodynamics, I reveal the critical regulation of the glucose sensor is due to a solvent controlled switch. Moreover, this solvent controlled switch manifests a regulatory mechanism of GK; a specific local conformational change that leads to an enzyme structure that has a much more favorable solvation energy than most of the protein ensemble. These findings have direct implications for the design of small molecule GK activators as anti- diabetes therapeutics as well as for understanding how proteins can be designed to have built-in regulatory functions via solvation energy dynamics.

The polyolefins production is the largest among all types of plastics given their thermal and chemical stability and low cost, which allows them to be used in a wide variety of products worldwide, including polypropylene (PP) and polyethylene (PE) membranes. However, the small percentage of polyolefins being recycled compared to the enormous amount produced has led to severe environmental pollution issues. In addition, the traditional polyolefin membrane fabrication methods utilize mostly toxic non-renewable solvents such as xylenes at high temperatures, causing further negative environmental impact. The objective of this study is to propose a greener alternative for polyolefins in general and in particular for membrane fabrication. For this, two bio-based solvents (α-pinene and Dlimonene) were proposed to dissolve PP and LDPE, and the resulting films and membrane properties were studied. Hydrophobic PP microporous membranes were obtained by thermally induced phase separation from pristine commercial polymers and plastic waste. They were applied for water-in-toluene emulsion separation. The water rejection was above 95% for membranes fabricated from dope solutions containing 25% pristine PP and 30% waste PP heated at 130°C, suggesting that they could be used in oil spill recovery operations. This work aims to contribute to the implementation of more sustainable practices in the membrane industry.

One of the more attractive attributes of calixarenes is their wide variety of possible conformations and hence cavity shapes. However, the flexibility that allows this long-range benefit gives rise to major synthetic challenges when working with the larger members of the family. O-alkylations have proven to be the most widely employed synthetic routes to "functionalization" of the calixarenes, and these have shown a dependence upon both solvent and the metal ions present. Surprisingly, there have been no structural data presented concerning the complexes between the simple unsubstituted calix[6]arenes and the metal ions of groups 1 and 2. The structures of four complexes, containing cesium, rubidium, and calcium are reported as determined by X-ray crystallography. The solution behavior of the complexes for both representative groups is also discussed, in particular with regard to conformational stabilization of the calix[6]arenes and the role of solvent upon this stabilization. These complexes are also investigated as starting materials for the selective functionalization of the calix[6]arenes.

Mass transfer in a porous solid, partially saturated with asingle solvent and multicomponent liquid mixtures, has beenexperimentally and theoretically studied. A porous materialcontaining single liquids and mixtures of organic solvents wasisothermally dried. Experiments were performed using a jacketedwind tunnel, through which a humidity andtemperature-controlled air stream flowed. The wetted porousmaterial was placed in a cylindrical vessel, whose top isexposed to the air stream until the material became dried to acertain extent. Drying experiments with the single solventswater, methanol, ethanol and 2-propanol, were performed atdifferent temperatures and transient liquid content profileswere determined. In isothermal drying experiments with liquidmixtures,the transient concentration profiles of thecomponents along the cylindrical sample as well as the totalliquid content were determined. The liquid mixtures examinedwere water-methanolethanol and isopropanol-methanol-ethanol.Two different temperatures and initial compositions were usedin the experiments. Mathematical models that describe nonsteadystate isothermal drying of a solid containing single liquidsand multicomponent liquid mixtures were developed. In the solidwetted with a single liquid, capillary movement of the liquidwas the main mechanism responsible for mass transfer. In thesolid containing liquid mixtures, interactive diffusion inliquid phase was superimposed to the capillary movement of theliquid mixture. In addition, interactive diffusion of thevapours in empty pores was considered. The parameters todescribe the retention properties of the solid and thecapillary movement of the liquid were determined by comparingtheoretical and experimental liquid content profiles obtainedduring drying of the solid wetted with single liquids. Tosimulate the transport of the liquid mixtures these parameterswhere weighed according to liquid composition. A fairly goodagreement between theoretical and experimental liquidcomposition profiles was obtained if axial dispersion isincluded in the model when the moisture consists of amixture. Keywords:Internal mass transfer, capillary flow,multicomponent, diffusion, solvent mixtures

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