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Microporous walled micro-capillary films (MMCFs) are porous polymer films with embedded capillaries. MMCFs have been found to be suitable low-cost chromatography substrates capable of tolerating high flowrates, which suggested they might be a solution to the growing bottleneck in the downstream purification of biopharmaceuticals. However, MMCFs have been mainly tested for binary separations of model proteins and broader capabilities of this technology remain largely unknown. The experimental work presented in this thesis focused on developing MMCFs functionalised with different ligands and their subsequent testing as chromatography media for bioseparations. MMCFs were functionalised to form weak anion (MMCF-DEAE) and weak cation-exchangers (MMCF-gCM and MMCF-CA). Emphasis was placed on low-cost functionalisation methods amenable to single-use applications. To confirm the addition of functional groups on the membranes, a comprehensive characterisation routine was implemented. This included the use of spectroscopy, electron microscopy, elemental analysis and pH titration. The binding performance of these weak ion-exchangers was further assessed by static and dynamic adsorption of model proteins. Next, the functionalised MMCFs were tested for bioseparations with binary and complex mixtures, the latter being more relevant for industrial applications. It was found that MMCFs could selectively separate similarly charged biomolecules using optimised elution strategies. Further, it was observed that MMCF-gCM could capture lysozyme from chicken egg white at a near twenty-fold purity increase compared to the feed. Similarly, this weak cation-exchanger could recover antibodies from unfiltered mammalian cell lysate. The recovered biomolecules were then injected onto MMCF-DEAE to remove nucleic acid impurities in subtractive chromatography mode. Finally, MMCFs were explored for the first time as affinity chromatography supports. Bovine serum albumin (BSA) and Protein A were covalently coupled to the substrate and tested for the capture of relevant analytes. Indeed, it was found that MMCF-BSA could bind bilirubin and MMCF-ProtA could be used to recover antibodies. Given the high cost of Protein A, a cheaper synthetic ligand was coupled onto MMCFs and observed to successfully bind antibodies. Overall, this work has furthered the applications of MMCFs for bioseparations, demonstrating their great versatility and robustness. Furthermore, it opened the field for affinity-based MMCFs, which could have numerous applications in both research and industry. Extensive characterisation methods presented here will greatly simplify future studies with these membranes. While the binding capacity of the developed ion-exchangers was typically two orders of magnitude higher than non-porous MCFs (NMCFs), the low yield achieved with MMCFs currently precludes them from commercial applications. However, optimisation of MMCFs, as outlined in the future work, could make this support more commercially viable and leverage the numerous advantages offered by its unique geometry.

The major concern of this work is the development of hierarchically porous structured zeolite composites for ion-exchange applications by deposition of a thin layer of zeolite on inexpensive porous supports which offers better efficiency in separation processes. The merits of utilization of zeolite composites in industrial applications are generally reducing mass transfer resistance and pressure drop. In addition to this they have advantages in the removal of metal ions from wastewater such as increasing the metals uptake and minimizing the volume of waste disposed especially after vitrification. This thesis presents results from a combination of experimental work and simulation study of experimental data to give isotherm and kinetic models. The experimental work shed light on the preparation of zeolite composites using zeolite X (Si/Al ~ 1.35) and clinoptilolite (Si/Al ~ 4.3), studying the performance of these composites on the removal of the Sr2+ and Mn2+ ions and then stabilization of waste materials resulting from the ion-exchange process. Clinoptilolite was hydrothermally synthesized to show the effect of non-framework cations on the removal process. The porous supports were diatomite which is naturally occurring silica and carbon which is obtained from Iraqi date stones by a thermal treatment conducted at 900°C. Coating the support surface with zeolites crystals was conducted in two different ways. The layer by layer approach, which has not previously been used, was used to prepare monolithic carbon clinoptilolite composite using a combination of sucrose/citric acid and zeolite. The other approach was modifying the support surface by ultrasonication in the presence of nanoparticles suspension prepared using ball mill to create nucleation sites and enhance the crystal attachment during hydrothermal treatment. Characterisation was implemented in each case using XRD, SEM, EDAX, TGA and BET method. Ion-exchange experimental results showed higher ion-exchange capacity obtained when the composites were used in comparison to pure zeolites, when a comparison is based on actual weight of zeolite used for removal of Sr2+ and Mn2+ ions. A study of encapsulation of ions showed that it is feasible to solidify the waste materials by vitrification and/or geopolymerization to eliminate leaching of ions to the environment. The simulation studies showed that the ion-exchange kinetic followed the pseudo second order kinetic model. This fitting indicates that the rate of ion-exchange process is controlled by a chemical reaction related to valence forces. The overall ion-exchange process is controlled by a combination of ion-exchange reaction, film diffusion and intra-particle diffusion. Moreover, the thermodynamic studies which were conducted under different temperatures revealed that the ion-exchange of Sr2+ and Mn2+ ions is practicable, spontaneous and endothermic.

Solar photovoltaic modules provide clean electricity from sunlight but will not be able to compete on an open market until the cost of the electricity they produce is comparable to that produced by traditional methods. At present, modules based on crystalline silicon wafer solar cells account for nearly 90% of photovoltaic production capacity. However, it is anticipated that the ultimate cost reduction achievable for crystalline silicon solar cell production will be somewhat limited and that thin film solar cells may offer a cheaper alternative in the long term. The highest energy conversion efficiencies reported for thin film solar cells have been for devices based around chalcopyrite Cu(In, Ga)(Se, S)2 photovoltaic absorbers. The most efficient Cu(In, Ga)(Se, S)2 solar cells contain absorber layers deposited by vacuum co-evaporation of the elements. However, the cost of ownership of large area vacuum evaporation technology is high and may be a limiting factor in the cost reductions achievable for Cu(In, Ga)(Se, S)2 based solar cells. Therefore, many alternative deposition methods are under investigation. Despite almost thirty companies being in the process of commercialising these technologies there is no consensus as to which deposition method will lead to the most cost effective product. Non-vacuum deposition techniques involving powders and chemical solutions potentially offer significant reductions in the cost of Cu(In, Ga)(Se, S)2 absorber layer deposition as compared to their vacuum counterparts. A wide range of such approaches has been investigated for thirty years and the gap between the world record Cu(In, Ga)(Se, S)2 solar cell and the best devices containing non-vacuum deposited absorber layers has closed significantly in recent years. Nevertheless, no one technique has demonstrated its superiority and the best results are still achieved with some of the most complex approaches. The work presented here involved the development and investigation of a new process for performing one of the stages of non-vacuum deposition of Cu(In, Ga)(Se, S)2 absorber layers. The new process incorporates copper into an initial Group III-VI precursor layer, e.g. indium gallium selenide, through an ion exchange reaction performed in solution. The ion exchange reaction requires only very simple, low-cost equipment and proceeds at temperatures over 1000°C lower than required for the evaporation of Cu under vacuum. In the new process, indium (gallium) selenide initial precursor layers are immersed in solutions containing Cu ions. During immersion an exchange reaction occurs and Cu ions from the solution exchange places with Group III ions in the layer. This leads to the formation of an intimately bonded, laterally homogeneous copper selenide – indium (gallium) selenide modified precursor layer with the same morphology as the initial precursor. These modified precursor layers were converted to single phase chalcopyrite CuInSe2 and Cu(In, Ga)Se2 by annealing with Se in a tube furnace system. Investigation of the annealing treatment revealed that a series of phase transformations, beginning at low temperature, lead to chalcopyrite formation. Control of the timing of the Se supply was demonstrated to prevent reactions that were deemed detrimental to the morphology of the resulting chalcopyrite layers. When vacuum evaporated indium (gallium) selenide layers were used as initial precursors, solar cells produced from the absorber layers exhibited energy conversion efficiencies of up to 4%. While these results are considered promising, the devices were characterised by very low open circuit voltages and parallel resistances. Rapid thermal processing was applied to the modified precursor layers in an attempt to further improve their conversion into chalcopyrite material. Despite only a small number of solar cells being fabricated using rapid thermal processing, improvements in open circuit voltage of close to 150mV were achieved. However, due to increases in series resistance and reductions in current collection only small increases in solar cell efficiency were recorded. Rapid thermal processing was also used to demonstrate synthesis of single phase CuInS2 from modified precursor layers based on non-vacuum deposited indium sulphide. Non-vacuum deposition methods provide many opportunities for the incorporation of undesirable impurities into the deposited layers. Analysis of the precursor layers developed during this work revealed that alkali atoms from the complexant used in the ion exchange baths are incorporated into the precursor layers alongside the Cu. Alkali atoms exhibit pronounced electronic and structural effects on Cu(In, Ga)Se2 layers and are beneficial in low concentrations. However, excess alkali atoms are detrimental to Cu(In, Ga)Se2 solar cell performance and the problems encountered with cells produced here are consistent with the effects reported in the literature for excess alkali incorporation. It is therefore expected that further improvements in solar cell efficiency might be achieved following reformulation of the ion exchange bath chemistry.

Tire particles (TP) are the largest source of microplastics in nature. However, theadsorption behavior of TP needs to be better understood. TP used in this study weregenerated from cryo-milling and aged with 30% nitric acid. Single and competitiveadsorption isotherm experiments were conducted to investigate the potential of TP ascarriers of heavy metals. Langmuir and Freundlich models were used to analyzeadsorption data. Competitive adsorption demonstrated a reduction in the adsorptioncapacity of TP. The preference for lead to copper by TP was explained by the physicaland chemical properties of the metals. The adsorption capacity was maximum at the pHrange of 6-12 for lead, and for copper, it was pH 10. pH, zeta potential, FT-IR, and XPSresults indicated that electrostatic attraction and surface complexation were involved inthe heavy metal adsorption on TP.

The microphase separation of diblock polymers allows for excellent control over the nanostructuring of polymer-based materials. Polymers are also readily functionalized and chemically manipulated to alter their chemical properties. Therefore, block polymers represent an important tool in the preparation of precision nanostructured functional materials. Polymerization-induced microphase separation (PIMS) is a convenient and powerful strategy towards the development of such materials. In PIMS, the diblock polymer is simultaneously grown while one block is crosslinked. This captures a non-equilibrium percolating morphology. In this thesis, the morphology is used as a host for photochromic dyes, diluted with solvent to increase the possible porosity, and prepared in suspension to give uniform mesoporous beads.Chapter 1 is a brief overview of key topics relevant to the entire thesis. Chapter 2 describes the incorporation of photochromic dye molecules into a variety of materials from liquid solvent to rigid polymer. PIMS thermosets were created using a liquid-like polycaprolactone derivative and crosslinked polymethylmethacrylate. The liquid-like domains provide an environment for the dye where fast structural relaxation allows for fast dye decoloration while being encased in a rigid matrix. Chapter 3 shifts focus to porous PIMS derivatives. In particular, the effect on the pore size distribution of diluting the monomer solution with solvent to create an organogel is explored. Chapter 4 presents a new synthetic method to prepare beads from PIMS thermosets by performing the chain-growth and cross-linking steps in aqueous suspension. The size of the particles is tuned independently from the size of the pores. Also, functionality is incorporated into the pore walls using a diblock precursor. Chapter 5 provides general conclusions and possible future directions for research relating to disordered diblock thermoset materials.

Titanium dioxide (TiO2) attracts extensive attention due to its widespread technological and environmental applications. This study seeks to investigate the surface charging behavior of the two TiO2 polymorphs, anatase and rutile, using Flow Adsorption Microcalorimetry (FAMC). FAMC allows direct quantitative measurement of the heat of a surface reaction; these calorimetric heats are directly proportional to the surface charge. Determining the magnitude of positive and negative charges at the surface over a range of pHs allows for the determination of the point of zero net charge (PZNC) via a unique calorimetric method that removes many of the shortcomings related to the other analytical techniques used for such measurements.

Abstract: Recently, considerable research has been conducted into solid-acid catalyzed carbonylation of dimethyl ether (DME) to methyl acetate (MeOAc), which can be further used for the iodine-free production of ethanol or acetic acid. The zeolite mordenite (H-MOR) is known as a potential catalyst but is subject to a rapid deactivation that so far hinders the process commercialization. The objective of the current study is to find a simple and effective means by which H-MOR can be stabilized for DME carbonylation. The bimetallic liquid-based ion-exchange (IE) of Cu2+ and Zn2+ onto MOR was used to enhance its stability. Compared to the original H-MOR (Si/Al ratio of 6.5), 1Cu-4Zn/H-MOR (Cu:Zn ratio of 0.25) had 3 times the lifetime and produced 4 times the total MeOAc before deactivation at 438 K. High selectivity to MeOAc was also maintained on catalyst deactivation. Cu and Zn occupied around 55% of the acid sites on MOR but there was no decrease in activity compared to the H-MOR. Despite Cu being a known carbonylation catalyst, it did not enhance the catalyst activity. It was determined that, due to the competitive IE of Cu2+ and Zn2+ over MOR, the two metals were forced into blocking different unselective acid sites that would normally have contributed to coking reactions. This was shown by quantum chemical modeling of the potential IE locations for Cu2+ and Zn2+, which was in agreement with catalyst characterization results. Specifically, competitive IE at the T1 acid site was responsible for the unique behaviour of the 1Cu-4Zn/H-MOR. The use of Zn also stabilized Cu in its monovalent state and prevented any sintering from occurring. Thus, it is shown that the selectivity and stability of H-MOR can be substantially improved by selective poisoning of acid sites. This has important implications for Cu/H-MOR catalysts that have found increasing use, such as in methane-to-methanol processes. Dealumination of MOR via acid leaching was also used in an attempt to increase its stability and to understand the relative contributions of different acid sites. Gradual dealumination from the original Si/Al ratio of 6.5 resulted in activity loss, but also increased H-MOR’s selectivity to MeOAc during deactivation. At a Si/Al ratio of 15.4, the H-MOR was substantially deactivated by the dealumination. The catalyst characterization showed that the acid leaching was preferably removing the T3 acid site. This acid site had been previously theorized to be the only site at which DME carbonylation selectively occurred. This work provided substantial experimental evidence supporting this theory. Mild dealumination to a Si/Al ratio of 8.6 did improve H-MOR performance and it was determined that, while the other acid sites may contribute to coking, they were not solely responsible for the catalyst deactivation. Too high an acid site density near to the T3 acid site is also detrimental to the performance of the catalyst. Applying the principle of selective site poisoning derived from the bimetallic Cu2+-Zn2+ IE study, Fe2+ was placed onto MOR via oxidative solid-state IE (Fe(II)/H-MOR). The resultant catalyst had 2 times the lifetime and produced over 3 times the MeOAc compared to acidic MOR. High selectivity to MeOAc was maintained even with catalyst deactivation. The use of monometallic Fe2+ on MOR is preferable to the use of monometallic Cu2+ or Zn2+ placed onto mordenite via IE. When combined with Zn2+, the bimetallic 3Fe(II)-1Zn/H- MOR catalyst (Fe:Zn ratio of 3) had very similar performance to the bimetallic 1Cu-4Zn/H-MOR catalyst. Thus, three potential catalysts were identified for possible use in industrial DME carbonylation: Fe(II)/H-MOR, 1Cu-4Zn/H-MOR, and 3Fe(II)-1Zn/H-MOR. All of these catalysts have high peak activity levels and maintain high selectivity to MeOAc for the entirety of the catalyst lifetime, and are significant improvements over H-MOR alone. It is still required that the reaction conditions be optimized as well as suitable regeneration procedures put in place to restore the catalysts after deactivation.

Perfluorosulfonate ionomers, such as Nafion® have been shown to demonstrate a profound affinity for large cationic complexes, and the study of polymer-bound cations may provide insight regarding Nafion® morphology by contrasting molecular size with existing models. The trimetallic complex, [{(bpy)2Ru(dpp)}2RhBr2] 5+, is readily absorbed by ion exchange into Na+ -form Nafion® membranes under ambient conditions. The dimensions of three different isomers of the trimetallic complex are estimated to be: 23.6 Å × 13.3 Å × 10.8 Å, 18.9 Å × 18.0 Å × 13.7 Å, and 23.1 Å × 12.0 Å × 11.4 Å, yielding an average molecular volume of 1.2×103 Å3 . At equilibrium, the partition coefficient for the ion-exchange of the trimetallic complex into Nafion® from a DMF solution is 5.7 × 103 . Furthermore, the total cationic charge of the exchanged trimetallic complexes counterbalances 86 ± 2% of the anionic SO3 − sites in Nafion®. The characteristic dimensions of morphological models for the ionic domains in Nafion® are comparable to the molecular dimensions of the large mixedmetal complexes. Surprisingly, SAXS analysis indicates that the complexes absorb into the ionic domains of Nafion® without significantly changing the ionomer morphology. Given the profound affinity for absorption of these large cationic molecules, a more open-channel model for the morphology of perfluorosulfonate ionomers is more reasonable, in agreement with recent experimental findings. In contrast to smaller monometallic complexes, the time- v dependent uptake of the large trimetallic cations is biexponential. This behavior is attributed to a fast initial ion-exchange process on the surface of the membrane, accompanied by a slower, transport-limited ion-exchange for sites in the interior of the ionomer matrix. The development of Nafion®/[{(bpy)2Ru(dpp)}2RhBr2] 5+ modified electrodes is also described for both FTO electrodes and materials made from electrospun carbon mats. The [{(bpy)2Ru(dpp)}2RhBr2] 5+ complexes behave as photocatalytic hydrogen production catalysts in the Nafion® membrane. Furthermore, a second bulk photoelectrolysis experiment with the Nafion®/[{(bpy)2Ru(dpp)}2RhBr2] 5+/FTO electrodes shows an enhancement of catalytic activity compared to the first photoelectrolysis experiment. This enhancement is attributed to halide loss following the first reduction process. Lastly, electrospun carbon nanofiber mats behave as electron donor materials for [{(bpy)2Ru(dpp)}2RhBr2] 5+/Nafion® membranes.

Global demand for clean water is becoming a persistent concern and this has stimulated research into efficient and effective desalination and water treatment processes. Ion-exchange (IEX) resins have been used for water purification, but are limited by the continuous depletion of the resins and the need for large volumes of acid and base solutions for their regeneration. This Thesis presents a new chemical/thermal regeneration method and the novel use of mixed-bead and mixed-bed IEX resins for future desalination purposes. Mixed-bead resins composed of weak-acid and weak-base groups were synthesized and used for sorption studies with saline, followed by regeneration with ammonium bicarbonate (AB) and heating at 80°C. It was found that AB followed by heating provides 100% regeneration of these resins. Unfortunately, the low IEX capacities of polyampholytic resins restrict their commercial applications. However, a novel process was developed for increasing their IEX capacity by exposing Ni²⁺ and Ca²⁺ saturated resins to concentrated AB solutions, followed by heating. This was found to increase the IEX capacity by 4−5× with a corresponding increase in observable pore size and Brunauer-Emmett-Teller surface area. Although these mixed-bead resins could be completely regenerated using AB and heating, this also causes their thermal degradation, so the exhausted resins were also regenerated using AB washing but without heating. This was highly effective and showed an increased IEX capacity when in AB form, with higher selectivity for Na⁺ and HCO3‾ ions. It was also discovered that mixed-bed resin systems of strong-acid and strong-base resins, can be used to desalt 0.1M NaCl solution, producing about 6× the resin mass of drinking quality water, and this system can also be regenerated using concentrated AB in situ. In general, regeneration processes using AB could be applied for mixed-bead and mixed-bed systems in a continuous process, minimizing chemical waste, environmental impact, and costs. Lastly, a polystyrene based zwitterionic latex was synthesized with a particle size of about 110 nm to study the IEX behaviour of the polyampholytic resins. It was found that Na⁺, NH4⁺, Cl‾ and HCO3‾ ions readily exchanged with the surface groups following the Law of Mass Action.

This doctoral research focuses on the design, development and characterization of advanced ion-exchange membranes and their performance evaluation as process chromatography media for downstream bioseparations. Chromatography is a widely used unit operation in the biopharmaceutical industry for the downstream purification of protein therapeutics. The rapid developments in biotechnology and the pharmaceutical potential of biomolecules have increased the worldwide demand for protein therapeutics dramatically. Considering that 50−90% of the total cost of bioprocesses is due to the downstream recovery and purification, high-productivity and high-resolution separation techniques that will enable cost-effective production are essential to the biopharmaceutical industry. In recent years, membrane chromatography has been promoted as a promising alternative to more conventional packed-bed resin chromatography. Although the potential for membrane chromatography is great, the historically lower binding capacity of membranes compared to resin media has limited its broad implementation. Therefore, primary objectives of this dissertation were to prepare advanced weak and strong anion-exchange membranes with ultrahigh and completely reversible protein binding capacities and to demonstrate the high-throughput and high resolution that these membranes enable in the separation of a target protein from a complex media (cell lysate). The research presented here pertains to the use of atom transfer radical polymerization (ATRP) to prepare surface-modified weak and strong anion-exchange membranes for chromatographic bioseparations. Surface-initiated atom transfer radical polymerization (ATRP) was used to graft poly(2-dimethylaminoethyl methacrylate), (poly(DMAEMA)), and poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride), (poly(MAETMAC)), nanolayers from the internal pore surfaces of commercial regenerated microporous membranes. Characterization of physicochemical and performance properties of newly designed, surface-modified membranes was performed using various analytical techniques. The central theme of my research was to investigate how polymer architecture influences the separation performance properties of surface-modified ion-exchange membranes. In one study, the grafting density and average molecular weight of polymer chains grown from the membrane pore surfaces were varied independently and optimized to prepare weak anion-exchange membranes with ultra-high and completely reversible dynamic binding capacity. The effects of polymer grafting density, average molar mass of polymer and linear flow velocity on the dynamic binding capacity were studied. This study yielded weak anion-exchange membranes with very high volumetric protein binding capacities (static binding capacity∼140 mg BSA/mL and dynamic capacity ∼130 mg/mL) at high linear flow velocities (>350 cm/h) and relatively low transmembrane pressure drop (190 cm/h) and relatively low transmembrane pressure drop ( Finally, I evaluated the protein separation performance of my newly designed anion-exchange membrane adsorber and compared it to a commercial membrane adsorber and resin column. One aspect of this study was to compare the protein separation performance of membrane chromatography with resin column chromatography. Anion-exchange chromatography was used under salt-gradient and pH-gradient elution to separate anthrax protective antigen protein from periplasmic Escherichia coli lysate. Overall, this part of the work demonstrates that membrane chromatography is a high-capacity, high-throughput, high-resolution separation technique, and that resolution in membrane chromatography can be higher than resin column chromatography under preparative conditions and at much higher (15 times higher than widely used resin column) volumetric throughput.

Metal—oxide interfaces play a major role in a variety of applications, such as packaging for electronic devices, oxide-dispersion-strengthening of alloys, and thermal barrier coatings. For many of these applications, it would be a great advantage if it was possible to engineer the mechanical properties of metals—oxide interfaces. The present thesis describes experiments I have carried out on a model metal—oxide interface to understand diffusion reactions and the effect of an external electric field across the interface. I have focused on investigating the formation of a new phase, morphological changes, and redistribution of ions at the interface. These features are believed to impact the mechanical properties of a metal—oxide interface. A planar Al—MgAl2O4 interface was considered as a suitable model system due to the small lattice mismatch between aluminum and MgAl2O4 and its coherent interface. Thin film of aluminum on a planar MgAl2O4 (001) substrate was prepared by molecular beam epitaxy (MBE), electron beam evaporation, and thermal evaporation. After annealing of different polarity at 620-630deg.C for 5-40h with and without an applied voltage, the interface was investigated using conventional transmission electron microscopy (CTEM), high-resolution TEM (HRTEM), X-ray energy-dispersive spectroscopy (XEDS), electron spectroscopic imaging (ESI), and electron energy-loss spectroscopy (EELS). When Al—MgAl2O4 interfaces were annealed without an applied electric field, a - and -faceted phase formed at the interface toward the aluminum film. The reaction phase is believed to be gamma-Al2O3, which is formed by oxidation of aluminum at the interface and diffusion of oxygen into the aluminum film. It was also observed that magnesium ions at the interface were replaced by aluminum ions which diffused from the aluminum film. When Al—MgAl2O4 interfaces were annealed with an applied electric field, the results were different depending on the polarity of the applied voltage. When a positive voltage Ua>0V was applied to the aluminum film, magnesium ions migrate into the MgAl2O4 substrate from the interface, which results in a Mg-deficient layer close to the interface. In the case of (Ua-faceted MgAl2O4 form in the presence of trapped or dissolved oxygen in the aluminum film. The rate-limiting step of reaction is considered to be the lateral growth of pyramidal MgAl2O4 islands, in particular the interfacial diffusion of oxygen to the MgAl2O4 islands. The results of the present study demonstrate that the morphology, the spatial distribution of ions, and, consequently, the metal—oxide bonding can be substantially modified by annealing at elevated temperatures, and that the effect of annealing can be strongly enhanced or hindered by applying an electric field. Since metal—oxide adhesion and the fracture energy sensitively depend on the spatial distribution of atomic species and the interface morphology, the results of the present study further suggest that annealing - in particular under applied electric fields - can have profound effects on the technologically important properties of metal—oxide interfaces.

Pineapple juice of low acid content was prepared by removal of acids by using weakly basic anion exchange resin, IRA-93. The changes in the contents of titratable acid, pH and total soluble solids of model solutions that contained the principal constituents of pineapple juice (citric acid, citrate salt and sucrose) were investigated. The adsorption of individual acids and changes in composition of juice after a de-acidification process were explored. The adsorbed acids were recovered as solutions by some eluants, and studies on colour development in the recovered solutions carried out. The solutions of adsorbed acids recovered by NaOH from the resin, which had been treated by model solutions, were brown in colour. The brown colour was also found immediately when NaOH was added to the resin treated with pineapple juice but it was not found in the treated juice during acid removal treatment when its pH rose to 10. A greater amount of the dark colour was observed in the desorbed solution from the resin that had been treated with pineapple juice. The use of sulphuric acid, sodium chloride, sodium sulphate, sodium bicarbonate and phosphate buffer solution to desorb the acids from pineapple juice-treated resins reduced the intensity of the colour, measured at pH 3.5, of desorbed acid solutions. The colours of the desorbed solutions were pH dependent. Either solution of sulphuric acid or sodium chloride has a comparable desorbing power to a solution of sodium hydroxide whereas the rest has a lower desorbing power