Abstract Water contamination is a global problem and the growing utilization of limited water resources creates a need for efficient purification methods. Industrial effluents are polluting the natural waters, e.g. uncontrolled mining activities in developing countries have created numerous environmental hazards and different types of pollutants. This study focuses on novel adsorbents and photocatalytic materials in order to reach the aim of more efficient and affordable water treatment. This thesis aimed at making active, efficient, and viable adsorbents out of waste materials, as well as using photocatalysis in water treatment for organic pollutants originating from different types of industries. Local Peruvian agro-waste was used as a precursor for activated carbon that was used in adsorption studies for single (As(V) and methylene blue, MB), and multicomponent mixtures (As(V)/Pb/Cd), and real polluted river water. An industrial intermediate product, hydrous TiO2, was used for As(III)/As(V) removal. Photocatalytic materials included a commercial photoactive TiO2 (P25), and tailor-made TiO2 based nanofibers (NF) decorated with Pt/Pd. The results show that the agro-waste based activated carbons show high potential as adsorbents (e.g. ~100% As(V) removal in 2 h). With the multicomponent solution there is evidently competition for the adsorption sites; Pb was removed most efficiently. The specific surface area and pore size distribution play an important role in MB adsorption, as with As(V) the ash content is the most influential parameter. The industrial intermediate product has a high adsorption capacity towards both As(III) and As(V) (over 96% removals in 4 h), and is promising for use in natural and wastewater treatment due to its adsorption properties, availability, low cost, and non-toxicity. Photocatalysis was found to be an efficient removal method for the pollutants tested, also in the diluted industrial wastewater matrix, e.g. diuron was removed 99% in 1 h. The NFs are promising for the efficient photocatalytic degradation of organic effluents in aqueous streams such as wastewaters originating from e.g. biofuel production or fine chemicals and pharmaceutical industry. This study provides new and valuable knowledge for the purification of waters, especially when aiming at developing inexpensive water treatment materials and methods for different applications. / Tiivistelmä Puhtaan veden puute on maailman laajuinen ongelma, ja raskasmetallien ja orgaanisten haitta-aineiden päätymistä ympäristöön ja luonnonvesiin voidaan vähentää hyvällä ja tehokkaalla teollisuuden jätevesien käsittelyllä. Uusia ja tehokkaita, ympäristön kannalta suotuisia ja kestäviä vedenpuhdistustekniikoita tarvitaan erityisesti kehitysmaissa, joissa esim. kontrolloimaton kaivostoiminta aiheuttaa ympäristö- ja terveyshaittoja. Työn kokeellisessa osassa valmistettiin perulaisesta maatalousjätteistä aktiivihiiltä kemiallisella aktivoinnilla, ja seurattiin niiden kykyä adsorboida haitta-aineita (As(V), Pb, Cd, metyleenisini) yksi- ja monikomponenttiliuoksista ja saastuneesta luonnonvedestä (Puyango-Tumbesjoki, Peru). Lisäksi tutkittiin teollisuuden välituotteen (TiO2) aktiivisuutta arseenin, As(III) ja As(V), adsorptiossa. Viimeisessä osiossa tutkittiin valokatalyysiä orgaanisten haitta-aineiden poistossa vesiliuoksista sekä kaupallisella TiO2 P25 -katalyytillä että kokeellisilla Pd/Pt-dopatuilla TiO2 -nanokuiduilla. Tulokset osoittavat, että paikallisesta raaka-aineesta valmistetut aktiivihiilet ovat hyvin potentiaalisia vedenpuhdistusmateriaaleja saavuttaen jopa 100% As(V) poistuman (2h). Adsorboitavien ionien välillä on nähtävissä kilpailua monikomponettiadsorptiossa; lyijyn havaittiin poistuvan tehokkaimmin tutkituissa olosuhteissa. Adsorbentin ominaispinta-ala ja huokoskokojakauma ovat tärkeitä tekijöitä metyleenisinin adsorptiossa, kun taas tuhkapitoisuudella on arseenin adsorptioon suurempi vaikutus. Teollisuuden TiO2-välituotteella havaittiin olevan korkea adsorptiokapasiteetti sekä As(III)- että As(V)-spesieksiä kohtaan saavuttaen yli 96% poistumat (4h). Se on lupaava materiaali edelleen kehitettäväksi ja käytettäväksi esimerkiksi luonnonvesien ja jätevesien puhdistuksessa johtuen sen hyvistä adsorptio-ominaisuuksista, saatavuudesta, edullisuudesta ja myrkyttömyydestä. Valokatalyysin havaittiin olevan toimiva menetelmä orgaanisten molekyylien hajottamiseen, myös laimeasta teollisuuden jätevesimatriisista, esim. diuroni poistui 99% tunnissa. Nanokuitujen tapauksessa aktiivinen metalli vaikutti merkittävämmin reaktion tehokkuuteen kuin ominaispinta-ala. Tämä työ tarjoaa uutta ja tärkeää tietoa vesien puhdistukseen kun tavoitteena on löytää tehokas ja edullinen menetelmä erityyppisiin sovelluksiin.

Abstract Protecting human skin against harmful UV radiation from the sun is an acute problem nowadays. Due to decreased thickness of the ozone layer, more UV light reaches the ground surface. This is one of the reasons of increased frequency of skin diseases. Titanium dioxide (TiO2) nanoparticles are embedded with sunscreens into the skin to attenuate UV radiation through absorption and scattering. The effectiveness of the interaction between particles and UV light depends on nanoparticle sizes. The aim of the study is to predict how the optical properties of the superficial layer of the human skin (stratum corneum) can be modified by means of nanoparticles, assuming that these particles are spheres and do not aggregate (this is achieved by application of some modern treatment techniques). In-depth distribution of TiO2 particles embedded into the skin after multiple applications of sunscreens was determined experimentally using the tape-stripping technique. A computer code implementing the Monte Carlo method was developed to simulate photon migration within the 20-μm thick horny layer partially filled with nano-sized TiO2 spheres, 35–200 nm in diameter. Dependencies of UV radiation of two wavelengths (310 and 400 nm) absorbed by and totally reflected from, as well as transmitted through the horny layer on the size of TiO2 particles were obtained and analyzed. Silicon nanoparticles of the same diameters were considered for comparison. The most attenuating particles were found for both cases. The harmful side-effect of UV light absorption by TiO2 particles is the generation of free radicals. Study of this phenomenon, using an electron paramagnetic resonance technique, was also carried out in this thesis. Comparison of the strength of the effect was done for two particle sizes administered onto either glass slides or porcine ear skin.

Ce mémoire rapporte la préparation et l'étude de matériaux hybrides organiques-inorganiques à base de titane où les deux réseaux sont liés par des liaisons titane-carbone stables. Différents précurseurs dans lesquels deux groupes cyclopentadienyltitane sont reliés par des espaceurs variés ont été préparés. Ces espaceurs comprennent des groupes aromatiques et hétéroaromatiques linéaires ainsi que des groupes aromatiques disubstitués par des chaînes alkyle. Ces complexes dimétalliques, où le titane est aussi lié à trois groupes labiles, ont été ensuite hydrolysés dans les conditions du procédé sol-gel pour conduire à des hybrides de classe II. Le réseau organique y est lié au réseau inorganique par des liaisons stables titane-carbone. Ces matériaux sont organisés et leur mode d'organisation dépend de la nature de l'espaceur reliant les groupes cyclopentadienyle. Les espaceurs linéaires conduisent à des matériaux à structure en escalier dans lesquels les ligands sont associés par des liaisons p. La longueur des espaceurs n'a pas d'effet sur cette organisation. Par contre, les matériaux à espaceurs substitués latéralement sont organisés par les chaînes alkyle. La calcination de ces matériaux hybrides sous oxygène conduit à la formation de dioxyde de titane nanoporeux sous forme d'anatase dont la cristallinité et la surface spécifique dépendent de la température de calcination. D'une façon similaire des films de dioxyde de titane de même type sont obtenus par la calcination de films minces d'hybrides préparés par spin-coating. / This work aimed to the preparation of titanium-based organic-inorganic hybrid materials where both networks are linked through stable titanium-carbon bonds. The preparation of various di(cyclopentadienyltitanium) precursors in which various organic groups serve as a bridge between the two cyclopentadienyl groups while each titanium atom is equipped with three hydrolysable groups was first achieved. Then, these complexes were hydrolyzed in a sol-gel process that led to new self-assembled titanium-based class II hybrid materials in which the inorganic network is connected to the organic network through stable titanium-carbon bonds. The mode of organization of the nanostructures depends on the spacer bridging the cyclopentadienyl groups. Linear aromatic spacers led to materials having a stair-like structure in which the organic ligands are arranged via p-stacking. The length of the spacer has a little effect on the organization of the nanostructures. The structure of the materials obtained with spacers endowed with long lateral chains is governed by the side chains. The calcination of these materials under oxygen led to the formation of nanoporous anatase titanium dioxide the crystallinity and surface area of which depend on the calcination temperature. Similarly titanium dioxide thin films were prepared by the calcination of hybrid thin films prepared by spin coating.

Nous présentons dans ce manuscrit l'élaboration par électrofilage (ES) de nanofibres hybrides métal/oxyde métallique (HMMOC) et leurs caractérisations physico-chimiques. Leurs utilisations dans le cadre d’applications de type « énergie » et « environnement » ont été évaluées. En particulier, la photocatalyse de nanofibres TiO2-Au pour la dégradation en solution aqueuse du bleu de méthylène et l’utilisation de nanofibres WO3-Au comme capteurs de gaz (VOCs) ont été examinées. En lien étroit avec les résultats obtenus sur l'évaluation des performances comme photocatalyseurs ou capteurs à gaz de ces nouvelles structures HMMOC, l'influence de nombreux paramètres a été étudiée : la concentration en ions aurique, la méthode utilisée pour introduire ces derniers à l’intérieur ou les déposer à la surface des nanofibres d’oxydes et finalement le traitement thermique. En effet, on peut soit mélanger directement, avant la procédure d’électrofilage, la solution contenant les ions aurique à la solution polymérique (composée de PVP, PAN, ou PVA contenant le précurseur d'oxyde métallique), soit déposer sous forme de goutte cette solution d’ions Au à la surface des nanofibres d’oxyde métallique une fois la procédure d’électrofilage effectuée. Quant au traitement thermique, il joue un rôle multiple puisqu’il permet à la fois, d’éliminer les composés organiques des solutions polymériques, participant ainsi à la structuration de la partie oxyde du HMMOC, mais aussi de réduire les ions Au sous forme de nanoparticules.Des résultats prometteurs en photocatalyse ont été obtenus sur des fibres optimisées de TiO2 contenant des nanoparticules d’Au de 10 nm (concentration en Au : 4 wt%). En effet, pour cet échantillon, on montre une dégradation 3 fois plus rapide du bleu de méthylène en solution aqueuse que celle obtenue sur les nanofibres de TiO2 de références et sur le catalyseur commercial P25. De la même manière, des nanofibres de WO3 décorées de nanoparticules d’Au de 10 nm, utilisées comme capteurs de gaz, permettent d’obtenir une réponse 60 fois plus importante que dans le cas de nanofibres de WO3 pure et en améliorant grandement la sélectivité par rapport au n-butanol / We present in this manuscript the elaboration by Electrospinning (ES) process of hybrid metal-metallic oxide composite (HMMOC) nanofibers (NFs), and their physical-chemical characterizations. Their applications, especially the photocatalysis of TiO2-Au composite NFs for photocatalytic degradation for methylene blue (MB) in an aqueous solution and WO3-Au composite NFs for gas sensing of the volatile organic compounds (VOCs) have been investigated. According to the performance evaluation results as photocatalyst or gas sensors, the influence of many parameters have been studied: gold ions concentration, the way to introduce them into or at the NFs surface, typically by mixing them into the polymeric solution (composed of PVP, PAN, or PVA with the metallic oxide precursor) before the ES process or by simple droplet deposition onto the NFs after ES process, and finally the annealing treatment. This latter plays an important role since it both removes the organic components of the polymeric solution, thus forming the metal oxide and in-situ participates to the Au reduction.Concerning the photocatalytic properties, an optimized HMMOC material based on TiO2 NFs including 10 nm Au nanoparticles (NPs) has been obtained and shows 3 times significantly improvement of MB degradation compared to pure TiO2 NFs and the commercial catalyst P25. For gas sensing elaboration, we have shown that a HMMOC material based on WO3 NFs decorated at their surface with 10 nm Au NPs can exhibit 60 times higher response and significantly improved selectivity toward n-butanol compared with pure WO3 NFs

The present thesis deals with the beneficial influence of nanostructuring on electrochemical performance of certain promising electrode and electrolyte materials for lithium-ion batteries (LIBs). Electrochemical performances of chosen electrodes and electrolytes have been presented in a systematic and detailed manner via studies related to both transport and lithium storage. Titanium dioxide (TiO2) or titania, a promising non-carbonaceous anode material for LIBs was chosen for the study. As part of the study, variety of nanostructured titania were synthesized. In general, all materials exhibited high lithium storage ( theoretical value for lithium storage in titania) and some of them showed exemplary rate capability, typically desired for modern lithium-ion batteries. Studies related to performance of these materials and mechanistics of lithium storage and kinetics are presented in Chapters 2-5. “Soggy sand” electrolyte, a promising soft matter electrolyte for LIBs was studied on the electrolyte side. Ion transport, mechanical strength and electrochemical properties of “soggy sand” electrolytes synthesized via dispersion of various surface chemically functionalized silica particles dispersed in model as well as LIB relevant electrolytes were studied in this thesis. Extensive physico-chemical and battery performance studies of “soggy sand” electrolytes are discussed in Chapters 6-8. A brief discussion of the contents and highlights of the individual chapters are described below: Chapter 1 briefly discusses the importance of electrochemical power sources as a viable green alternative to the combustion engine. Various facets of rechargeable LIBs, one of the most important electrochemical storage devices, are presented following the general discussion on electrochemical power devices. The importance of nanostructuring of electrodes with special emphasis on anodes for high lithium storage capacities and rate capabilities are also discussed in the opening chapter. The various advantages and disadvantages of the most commonly used electrolytes in LIB i.e. the liquid electrolytes are also discussed in Chapter 1. Suggestions for improvement of the physico-chemical properties of liquid electrolytes especially via nanostructuring (demonstrated via dispersions of fine oxide particles in liquid electrolytes in Chapters 6-8) using the concept of Heterogeneous doping are discussed in detail. A brief description on the importance of rheology for comprehension of soft matter microstructure is also provided in this chapter. Chapter 2 discusses composite of anatase titania (TiO2) nanospheres and carbon grown and self-assembled into micron-sized mesoporous spheres via a solvothermal synthesis route as prospective anode for rechargeable lithium-ion battery. The morphology and carbon content and hence the electrochemical performance are observed to be significantly influenced by the synthesis parameters. Synthesis conditions resulting in a mesoporous arrangement of an optimized amount of carbon and TiO2 exhibited the best lithium battery performance. The first discharge cycle capacity of carbon-titania mesoporous spheres (solvothermal reaction at 150 oC at 6 h, calcination at 500 oC under air, BET surface area 80 m2g-1) was 334 mAhg-1 (approximately 1 Li) at current rate of 66 mAg-1. High storage capacity and good cyclability is attributed to the nanostructuring (i.e. mesoporosity) of TiO2 as well as due to formation of a percolation network of carbon around the TiO2 nanoparticles. The micron-sized mesoporous spheres of carbon-titania composite nanoparticles also show good rate cyclability in the range (0.066-6.67) Ag-1. The electrochemical performance of the mesoporous carbon-TiO2 spheres has been compared with nonporous TiO2 spheres, normal mesoporous TiO2 and bulk TiO2. Implications of nanostructuring and conductive carbon interface on lithium insertion/removal capacity and insertion kinetics in nanoparticles of anatase polymorph of titania is discussed in Chapter 3. Sol-gel synthesized nanoparticles of titania (particle size ~ 6 nm) were hydrothermally coated ex situ with a thin layer of amorphous carbon (layer thickness: 2-5 nm) and calcined at a temperature much higher than the sol-gel synthesis temperature. The carbon-titania composite particles (resulting size  10 nm) displayed immensely superior cyclability and rate capability (higher current rates  4 Ag-1) compared to unmodified calcined anatase titania. The conductive carbon interface around titania nanocrystals enhances the electronic conductivity and inhibits crystallite growth during electrochemical insertion/removal thus preventing detrimental kinetic effects observed in case of un-modified anatase titania. The carbon coating of the nanoparticles also stabilized the titania crystallographic structure via reduction in the accessibility of lithium ions to the trapping sites. This resulted in decrease in the irreversible capacity observed in case of nanoparticles without any carbon coating. Chapter 4 discusses the morphology and electrochemical performance of mixed crystallographic phase titania nanotubes and nanosheets for prospective application as anode in rechargeable lithium-ion batteries. Hydrothermally grown nanotubes/nanosheets of titania (TiO2) and carbon/silver-titania (C/Ag-TiO2) comprise a mixture of both anatase and TiO2(B) crystallographic phases. The first cycle capacity (at current rate = 10 mAg-1) for bare TiO2 nanotubes was 355 mAhg-1 (approximately 1.06 Li), which is higher than both the theoretical capacity (335 mAhg-1) as well as reported values for pure anatase and TiO2(B) nanotubes. Higher capacity is attributed to a combination of presence of mixed crystallographic phases of titania as well as trivial size effects. The surface area of bare TiO2 nanotubes was very high being equal to 340 m2g-1. Surface modification of the TiO2 nanotubes via amorphous carbon and Ag nanoparticles resulted in significant improvement in battery performance. The first cycle irreversible capacity loss can be minimized via effective coating of the surface. Carbon coated TiO2 nanotubes showed superior performance than Ag nanoparticle coated TiO2 nanotubes in terms of long term cyclability. Unlike Ag nanoparticles which are randomly distributed over the TiO2 nanotubes, the effective homogeneous carbon coating forms an efficient percolation network for the conducting species thus exhibiting better battery performance. The C-TiO2 and Ag-TiO2 nanotubes showed a better rate capability i.e. higher capacities compared to bare TiO2 nanotubes in the current range 0.055-2 Ag-1. Although titania nanosheets retains mixed crystallographic phases, the lithium battery performance (first cycle capacity = 225 mAhg-1) is poor compared to TiO2 nanotubes. It is attributed to lower surface area (22 m2g-1) which resulted in lesser electrode/electrolyte contact area and inefficient transport pathways for Li+ and e-. Implications of iron on electrochemical lithium insertion/removal capacity of iron (Fe3+) doped anatase TiO2 is discussed in Chapter 5. Iron doped anatase TiO2 nanoparticles with different doping concentrations were synthesized by simple sol-gel method. The electrochemistry of anatase TiO2 is observed to be a strong function of concentration of iron (Fe3+). A high 1st cycle discharge capacity of 704 mAhg−1 (2.1 mol of Li) and 272 mAhg−1 (0.81 mol of Li) at the 30th discharge cycle with Coulombic efficiency greater than 96% has been observed for 5% iron (Fe3+) doped TiO2 at a current density of 75 mAg−1. Additional increase in the iron (Fe3+) concentrations deteriorates the lithium storage of TiO2. An improvement in lithium storage of more than 50% is noticed for 5% iron (Fe3+) doped TiO2 compared to pure anatase TiO2 which shows an initial discharge capacity of 279 mAhg−1. The anomalous lithium storage behavior in all the iron (Fe3+) doped TiO2 has been accounted, in addition to homogeneous Li insertion in the octahedral sites, on the basis of formation of metallic Fe and Li2O during initial lithiation process and subsequent heterogeneous interfacial storage between Fe and Li2O interface. Chapter 6 discusses in a systematic manner the crucial role of oxide surface chemical composition on ion transport in “soggy sand” electrolytes. A “soggy sand” electrolytic system comprising of aerosil silica functionalized with various hydrophilic and hydrophobic moeities dispersed in lithium perchlorate ethylene glycol solution ( = 37.7) was used for the study. Detailed rheology studies show that the attractive particle network in case of the composite with unmodified aerosil silica (with surface silanol groups) is most favorable for percolation in ionic conductivity as well as rendering the composite with beneficial elastic mechanical properties. Though weaker in strength compared to the composite with unmodified aerosil particles, attractive particle networks are also observed in composites of aerosil particles with surfaces partially substituted with hydrophobic groups. However, ionic conductivity is observed to be dependent on the size of the hydrophobic moiety. No spanning attractive particle network was formed for aerosil particles with surfaces modified with stronger hydrophilic groups (than silanol) and as a result no percolation in ionic conductivity was observed. The composite with hydrophilic particles was a sol contrary to gels obtained in case of unmodified aerosil and partially substituted with hydrophobic groups. Chapter 7 also discusses the influence of oxide surface chemical composition but additionally the role of solvent on ion solvation and ion transport of “soggy sand” electrolytes. Compared to the liquid electrolyte in Chapter 6, a lower dielectric constant liquid electrolyte was employed for the study in this chapter. A “soggy sand” electrolyte system comprising of dispersions of hydrophilic/hydrophobic functionalized aerosil silica in lithium perchlorate-methoxy polyethylene glycol solution ( = 10.9) was employed for the study. Static and dynamic rheology measurements again showed formation of an attractive particle network in case of the composite with unmodified aerosil silica (i.e. with surface silanol groups) as well as composites with hydrophobic alkane groups. While particle network in the composite with hydrophilic aerosil silica (unmodified) were due to hydrogen bonding, hydrophobic aerosil silica particles were held together via van der Waals forces. The network strength in the latter case (i.e. for hydrophobic composites) were weaker compared with the composite with unmodified aerosil silica. Both unmodified silica as well as hydrophobic silica composites displayed solid-like mechanical strength. However, this time around no enhancement in ionic conductivity compared to the liquid electrolyte was observed in case of the unmodified silica. This is attributed to the existence of a very strong particle network which leads to the “expulsion” of all conducting entities from the interfacial region between adjacent particles. The ionic conductivity for composites with hydrophobic aerosil particles displayed ionic conductivity as a function of the size of the hydrophobic chemical moiety. No spanning attractive particle network was observed for aerosil particles with surfaces modified with stronger hydrophilic groups (than silanol). The composite resembled a sol and no percolation in ionic conductivity was observed. Chapter 8 describes the influence of dispersion of uniformly sized mono-functional or bi-functional (“Janus”) particles on ionic conductivity in lithium battery solutions and it’s implications on battery performance. Mono-functionalized (hydrophilic or hydrophobic) and bi-functionalized Janus (hydrophilic and hydrophobic) particles form physical gels of varying strength over a wide range of concentration (0.1    0.4; , oxide volume fraction). While the composites with mono-functionalized particles display shear thinning typical of gels (due to gradual breaking up spanning particle network held together by hydrogen/van der Walls force), the bi-functionalized “Janus” particles exhibit both complementary properties of gel and sol. The latter observation is interpreted in terms of existence of both hydrogen and van der Waals force arising out of the particle arrangement which get perturbed under the influence of external shear. Composites with homogeneous hydrophilic surface group show the highest ionic conductivity whereas the homogeneous hydrophobic surfaces exhibit superior electrode/electrolyte interface stability and battery cyclability. The Janus particles did not show any enhancement in ionic conductivity however, battery performance is highly satisfactory taking intermediate values between the homogeneously functionalized hydrophilic and hydrophobic particle composites.

This thesis describes the rejection efficiency and the fouling behaviour of calcium sulphate solutes in a 1 nm tubular ceramic titanium dioxide nanofiltration membrane. Calcium sulphate is considered as one of the greatest scaling potential inorganic salts that responsible for membrane fouling which represents a main challenge in the expansion of membrane processes for desalination of brackish and saline water. The surface charge type and magnitude for the composite amphoteric TiO_2 membrane were characterised using streaming potential measurements. Electrokinetic membrane experiments were conducted in a background electrolyte comprising 0.01 M (NaCl). The zeta potential was estimated from the measured streaming potential using the Helmoholtz-Smoluchowski equation and the surface charge density was subsequently calculated using the Gouy-Chapman and Graham equations. The experimental results showed that the membrane was negatively charged at neutral pH and its iso-electrical point (i.e.p) was at pH of 4.0. The rejection behaviour of calcium sulphate at three different initial concentrations (0.001, 0.005 and 0.01 M) were investigated compared to other naturally occurring minerals (NaCl, Na_2 SO_4, CaCl_2) in single salt solutions. The rejection experiments were conducted at five different applied trans-membrane pressures ranged from 1.0 to 5.0 bars. Salt retention measurements showed that the rejection sequence was R (CaSO_4) > R (Na_2 SO_4) > R (CaCl_2) > R (NaCl). This rejection sequence behaviour showed an inverse relationship with the diffusion coefficients of the four salts. The salt with the lowest diffusion coefficient (CaSO_4) showed the highest rejection (43.3%), whereas that with the highest diffusion coefficient showed the lowest rejection. The rejection of calcium sulphate solution at saturation concentration was also conducted after a suspension solution of 0.015 M (CaSO_4) was prepared and filtered. The ionic analysis for calcium sulphate permeates indicated that, for the negatively charged TiO_2 membrane, the rejection for bivalent anion (SO_4^(2-) ) was higher than that of the bivalent cation (Ca^(2+) ).The critical flux (CF) experiments were carried out at six trans-membrane pressure ranged from 1.0 to 6.0 bars to identify the form and the onset of calcium sulphate fouling (as gypsum) using different concentrations below saturation concentration (0.001, 0.005, 0.01 M) and at saturation concentration. Two different flux-pressure techniques have been applied and compared to determine the critical flux values; these are: step by step technique and standard stepping technique. The obtained critical flux results from both measuring techniques (for all the four sessions) confirmed that the critical flux was reached and exceeded. The present work indicated that the resulting critical flux values from both measuring procedures were decreased as the ionic strengths of the calcium sulphate solutes were increased. A mathematical model has been proposed to identify the key parameters that affect the transport performance inside the TiO_2 nanofiltration membrane. The original Donnan steric pore model (DSPM) was used to simulate the rejection of 0.01 M sodium chloride as a reference solution. The membrane effective pore radius was estimated using two different transport models, both of these models depend on the permeation test of uncharged solute (glucose). The Donnan potential was determined based on the membrane effective fixed charge density which was determined by supposing that the membrane surface charge was uniformly distributed in the void volume of cylindrical pores. The theoretical rejection of NaCl solute for the present DSPM model was found to be in agreement with the experimental data.

Afin d'étudier la granulo- et la morpho-dépendance des propriétés d'énergies de surface de solides divisés, plusieurs lots de TiO2 anatase ont été synthétisés. Une série de matériaux parfaitement définis avec des morphologies allant de sphéroïdale à facettée, dans des gammes de tailles allant de 4 à 20 nm a été obtenue grâce aux modifications de conditions de pH et la présence d'acides organiques. La combinaison de différentes molécules sonde a permis de déterminer l'hétérogénéité énergétique superficielle de ces matériaux, aux interfaces solide/gaz et solide/liquide. La volumétrie de quasi-équilibre à basse pression (N2/Ar) couplée à la méthode de modélisation DIS et la microcalorimétrie à écoulement de gaz (NH3) ont mis en évidence les contributions des différentes faces cristallographiques et les effets de la cristallinité. Ces mêmes propriétés ont été analysées grâce à la titration potentiométrique en milieu aqueux (H+/OH-), couplée à la procédure TDIS (détermination du PCN et des distributions d'affinité de protons). Cette stratégie a permis une étude complète des propriétés superficielles énergétiques et géométriques des nanomatériaux. / In order to study the relationships between the particle size, the morphology and the surface energy properties of divided solids, several batches of TiO2 anatase were synthesized. A series of materials with morphologies ranging from spheroidal to well faceted, with particle sizes ranging from 4 to 20 nm were obtained by adjusting the pH conditions and the presence of organic acids. The surface heterogeneity of these materials, at solid/gas and solid/liquid interfaces, was studied by combining various molecular probes. The low pressure quasi-equilibrium adsorption volumetry (N2/Ar) coupled with the DIS modeling approach and the flow adsorption microcalorimetry (NH3) have evidenced the various contributions of crystallographic faces and the effect of the crystallinity. These properties have also been analyzed using potentiometric titration in aqueous medium (H+/OH-), coupled with the TDIS procedure, to determine PZC and proton affinity distributions. Such a strategy has led to a complete study of the energetic and geometric surface properties of these nanomaterials.

Porézní anodická alumina (PAA) je oxidová vrstva vytvořená anodickou oxidací hliníku, která má široké průmyslné využití. Její popularita zaznamenala exponenciální nárůst zejména v oblasti nanotechnologií, k čemu přispělo objevení jejího samouspořádání do struktury o nanorozměrech připomínající včelí plástev. Její jednoduchá příprava a laditelné vlastnosti z ní tvoří levný způsob výroby nanostruktur. Ve stejném duchu se tato disertační práce zabývá metodami přípravy funkčních nanostruktur za využití PAA. První část je zaměřena na výrobu pole nanosloupců z oxidu titaničitého (TiO2) a jejich možné použití jako fotoanody pro štěpení vody. TiO2 nanostloupce jsou tvořeny anodizací hliníkové vrstvy na titanovém substrátu, také nazývanou PAA-asistovaná anodizace. Táto studie demonstruje elektrochemické vlastnosti a fotoelektrochemickou aktivitu nano sloupců vytvořených z dusíkem obohacených substrátů, které byly následně různě termálně modifikovány. Hlavním poznatkem studie je, že špatné vlastnosti jsou způsobeny dutou morfologií nanosloupců. Tento poznatek vedl k rozsáhle studii zabývající se dopadem anodizačných podmínek na morfologii ale i stabilitu vytvořených nanosloupců, jejímž výsledkem byla nová strategie anodizace. Druhá část prezentuje výrobní proces přípravy uspořádané vrstvy zlatých nanočástic na transparentním substrátu pro jejich použití jako optického senzoru využívající efekt rezonance lokalizovaných povrchových plasmonů. Základem této multidisciplinární metody je využití kombinace samouspořádání PAA k výrobě šablony a následného procesu řízeného smáčení v pevné fázi tenké vrstvy zlata. Táto práce detailně popisuje technologické aspekty přípravy; od samotné výroby šablon z hliníku, přes vytváření zlatých nanočástic, až po jejich přenos na transparentní substrát. Na závěr této práce jsou kompozity z nanočástic charakterizovány, přičemž je porovnána jejich citlivost na změnu indexu lomu okolí a jejich stálost. Ze závěrů vyplývá, že tato poměrně velkoplošná a levná metoda je konkurence schopná i v oblasti senzorické citlivosti.

This diploma thesis deals with a plasmochemical treatment of photoanodes with an active layer containing TiO2 deposited on two different substrates by material printing. The plasmochemical treatment was performed by a low-temperature ambient-air plasma using a diffuse coplanar surface barrier discharge (DCSBD). The experimental part is focused on the investigation of DCSBD influence on the fabricated photoanodes photoelectrochemical properties, and the influence of plasma treatment time. Process optimization was achieved by height adjustment of the electrode. The processed coatings were electrochemically investigated by linear sweep voltammetry and chronoamperometry.

Nanoparticles present potential risk for environmental compartments including soil. Previous works have been focused on negative effects of nanoparticles on soil biota, however studies about the influence of nanoparticles on soil properties are still limited. This thesis investigates an impact of 20 nm titanium dioxide nanoparticles on selected water properties in soil organic matter exposed to air with various relative humidity. Indeed, at 43, 70 and 95 % dominate different water types, i.e. water adsorbed on soil organic matter, water in water molecular bridges and phase water, respectively. Differential scanning calorimetry (DSC) was used in the study. An important finding is that nanoparticles reduce the stability of water molecular bridges under 70% relative air humidity and generally reduce evaporation enthalpy of water, which represents the ability of the soil to retain water. In the next part the influence of nanoparticles on total water in soil was observed. Under low relative humidity, rutile and anatase affected soil in different ways due to their various hydrophilicity. Under higher relative humidity this effect disappeared. In the last part, ice melting and water evaporation enthalpies of nanoparticle solutions were measured to confirm the presumed effect of nanoparticles on water. The ice melting enthalpy of the solutions was higher relatively to pure water, while the evaporation enthalpy showed a reverse trend (decrease). This confirmed the effects of nanoparticles both for pure water and soil water.