Over the last decade, immobilization of proteins onto inorganic materials is becoming more crucial to extend a deep understanding of interaction between proteins and nanoparticles. With understanding of the real interaction lying under the protein-nanoparticle relations, it is possible to organize the conformation and orientation of surface and framework species of nanoparticles to generate ideal surfaces for potential biotechnological applications. Due to their unique properties such as large clean surface, tunable surface properties, adjustable surface charge, and dispersibility in aqueous solutions, zeolite and zeo-type materials are one of the remarkable classes of inorganic materials that are widely studied in the literature. These properties make zeolites promising alternative candidates for the immobilization of enzymes and incorporation into biosensing devices. In the current study, a new approach was developed for direct determination of urea, glucose, and butyrylcholine where zeolites were incorporated to the electrode surfaces of a conductometric biosensor and Ion Sensitive Field Effect Transistors were used to immobilize the enzymes. Biosensor responses, operational stabilities, and storage stabilities of the new approach were compared with results obtained from the standard membrane methods for the same measurements. For this purpose, different surface modification technique, which are simply named as Zeolite Modified Transducers (ZMTs) were compared with Standard Membrane Transducers (SMTs). During the conductometric measurements ZMT electrodes were used, which allowed the direct evaluation of the effect of zeolite morphology on the biosensor responses for the first time. It was seen that silicalite added electrodes lead to increased performances with respect to SMTs. As a result, the zeolite modified urea and glucose biosensors were successfully applied for detecting urea and glucose, which can offer improved possibilities to design biosensors. The results obtained show that zeolites could be used as alternatives for enzyme immobilization in conductometric biosensors development. Furthermore, the sensitivities of urease and butyrylcholinesterase biosensors, prepared by the incorporation of zeolite Beta crystals with varying acidity on the surface of pH-sensitive

Because of the growing concerns over the depletion of fossil fuel supplies, environmental pollution and global warming caused by a steep increase in carbon dioxide and other greenhouse gases in the atmosphere, much attention has been given to the development of renewable energy sources that are the only long-term solution to the energy requirements of the world&rsquo / s population, on the way towards a sustainable energy future. Hydrogen has been considered as a clean and environmentally benign new energy carrier for heating, transportation, mechanical power and electricity generation. However, the lack of effective, safe, and low-cost hydrogen storage materials for mobile, portable, and stationary applications is one of the major hurdles to be overcome for the implementation of hydrogen economy. Among various solid state hydrogen storage materials, chemical hydrogen storage materials such as sodium borohydride (NaBH4) and ammonia borane (H3NBH3) have received much attention as promising candidates for fuel cell applications under ambient conditions due to their high gravimetric and volumetric hydrogen storage capacities. Both sodium borohydride and ammonia borane generate hydrogen upon hydrolysis in the presence of suitable metal catalysts. Transition metal nanoclusters can be used as active catalysts to catalyze the hydrolysis reactions of sodium borohydride and ammonia borane for hydrogen generation since they exhibit unique properties that differ from their bulk counterparts. Although the catalytic activity of metal nanoclusters increases with decreasing particle size, they are unstable with respect to agglomeration into the bulk metal leading to a significant decrease in activity in their catalytic applications. Therefore, the exploitation of microporous and mesoporous materials with ordered porous structures as hosts to encapsulate metal nanoclusters has attracted great interest since the pore size restriction of these host materials could limit the growth of nanoclusters leading to an increase in the percentage of the catalytically active surface atoms. In this dissertation, we report the preparation, characterization and the investigation of the catalytic activities of zeolite confined cobalt(0) nanoclusters in the hydrolysis of sodium borohydride and ammonia borane. The zeolite confined cobalt(0) nanoclusters were prepared by the reduction of cobalt(II)-exchanged zeolite-Y by sodium borohydride in aqueous solution at room temperature with no alteration in the framework lattice or loss in the crystallinity. The characterization of zeolite confined cobalt(0) nanoclusters were done by using inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV-visible spectroscopy (DR-UV-Vis), infrared spectroscopy (IR), Raman spectroscopy, and N2 adsorption-desorption technique. The catalytic activity of zeolite confined cobalt(0) nanoclusters and the kinetics of hydrogen generation from the hydrolysis of sodium borohydride and ammonia borane were studied depending on catalyst concentration, substrate concentration and temperature. The rate laws and the activation parameters (Arrhenius activation energy, Ea / activation enthalpy, &Delta / H# / and activation entropy, &Delta / S#) for both catalytic hydrolysis reactions were calculated from the obtained kinetic data.

In this study binary and ternary ion exchange on Zeolite NaA using silver and cadmium ions were investigated. Ion exchange were conducted at constant temperature (25oC) and normality (0.1N) in a batch system for both binary and ternary experiments. Zeolite weights were varied between 0.1 and 1 g for binary experiments. Thermodynamic analysis of binary ion exchange between Cd2+-Na+ and Ag+-Na+ were examined and thermodynamic equilibrium constant and Gibbs free energy were calculated. Thermodynamic equilibrium constants were found as respectively 28.2 and 300.4 for Cd2+-Na+ and Ag+-Na+ binary system. Standart free energy of Cd2+-Na+ and Ag+-Na+ binary exchange were calculated as -4.1 kJ/mol and -14.1 kJ/mol respectively. In literature Ay (2008) calculated the Gibbs free energy for Ag+-Na+ binary system as -14.4 kJ/mol and Biskup and Subotic (2010) and Gal et al. (1970) calculated the Gibbs free energy for Cd2+-Na+ binary system as -3.7 kJ/mol and -4.4 kJ/mol respectively. It is concluded Zeolite 4A has higher affinity to silver than cadmium and selectivity sequence was found as / Ag+&gt / Cd2+&gt / Na+. Langmuir and Freundlich isotherms were drawn to describe experimental data. As compared the R2 of isotherms, it is clearly seen that Freundlich isotherm provides better fit for Cd2+-Na+ binary ion exchange and Ag+-Na+ binary ion exchange. The ternary ion exchange isotherms were plotted using equivalent fraction of three ions (Ag+,Na+,Cd2+) which participated in ion exchange experiments to determine selectivity of zeolite 4A for cadmium and silver. Selectivity sequence was determined as Ag+ &gt / Cd2+ &gt / Na+ for ternary ion exchange.

In this thesis, firstly, the equilibrium adsorption capacity of water on a natural zeolite at several zeolite temperatures and water vapor pressures has been experimentally determined for adsorption and desorption processes. Additionally, the modified Dubinin-Astakhov adsorption equilibrium model has been fitted to experimental data and separate correlations are obtained for adsorption and desorption processes as well as a single correlation to model both processes. Experimental results show that the maximum adsorption capacity of natural zeolite is nearly 0.12 kgw/kgad for zeolite temperatures and water vapor pressures in the range 40-150 C and 0.87-7.38 kPa. Secondly, a thermally driven adsorption cooling prototype using natural zeolite-water as working pair has been built and its performance investigated experimentally at various evaporator temperatures. Under the experimental conditions of 45 C adsorption, 150 C desorption, 30 C condenser and 22:5 C, 15 C and 10 C evaporator temperatures, the COP of the adsorption cooling unit is approximately 0.25 and the maximum average volumetric specific cooling power density (SCPv) and mass specific cooling power density (SCP) of the cooling unit are 5.2 kWm-3 and 7 Wkg-1, respectively. Thirdly, in order to investigate the dynamic heat and mass transfer behavior of the adsorbent bed of an adsorption cooling unit, a transient local thermal non equilibrium model that accounts for both internal and external mass transfer resistances has been developed using the local volume averaging method. Finally, the influence of several design parameters on the transient distributions of temperature, pressure and amount adsorbed inside the cylindrical adsorbent bed of an adsorption cooling unit using silica-gel/water have been numerically investigated for the one and two dimensional computational domains. Moreover, validity of the thermal equilibrium model assumption has been shown under the given boundary and design conditions. Generally, for the conditions investigated, the validity of the local thermal equilibrium and spatially isobaric bed assumptions have been confirmed. To improve the performance of the bed considered, eorts should be focused on reducing heat transfer resistances and intra-particle mass transfer resistances but not inter-particle mass transfer resistances.

Zeolites are crystalline aluminosilicates which have highly ordered pore structures and high surface area. Also the tailorable surface properties, high ion-exchange capability, high chemical, thermal, and mechanical strength make these particles an important candidate for various application such as sensors, catalysis, dielectric materials, separation, and membrane technologies. Although zeolites have these unique properties, applications where zeolites are integrated into devices according to their application areas, are limited due to the powder form of the material. The purpose of the current study was to investigate the effect of zeolite nanoparticles on conductometric biosensor performance and cell viability measurements. Firstly, zeolite attachment on silicon surfaces was investigated by attaching silicalite and zeolite A nanoparticles onto the silicon substrates by direct attachment methodology in a closely packed monolayer form with perfect orientation and full coverage without using any chemical linker. Furthermore, the ability to pattern these zeolite crystals on silicon substrates with electron beam lithography and photolithography techniques was investigated. With the combination of electron beam lithography and direct attachment methodology, zeolite patterns were produced with feature sizes as small as a single silicalite nanoparticle thick line, that is approximately 500 nm. This approach has the ability of patterning very small features on silicon substrate, but the drawback is the long patterning time and lack of electron beam stability during long pattern formation process. Accordingly, it is almost impossible to form large patterns with electron beam lithography systems. Afterwards, to have full control on surfaces with differentiated areas on solid substrates, patterns of one type of zeolite crystals was formed on the monolayer of another type of zeolite layer with electron beam lithography for the first time. The same closed packed and highly oriented silicalite patterns were successfully formed on zeolite A monolayers and vice versa. Then photolithography technique was combined with direct attachment methodology to overcome the problem of the lack of total patterned area. With this technique, it was possible to pattern the whole silicon wafer in a couple of seconds, however the feature size of the zeolite patterns was limited with the infrastructures of the mask fabricated for photolithography studies. In this particular study, zeolite lines patterns with a minimum of 5 &micro / m thickness were prepared and the total patterned area was kept constant at 1 cm2. Similar to what was obtained by electron beam lithography study, zeolite A patterns were formed on silicalite monolayers with the minimum feature size of 5 &micro / m and vice versa. In the second part of the study, zeolite films were prepared on the transducers of conductometric biosensors using dip coating technique and named as Zeolite Coated Transducers (ZCT). Electrodes prepared using a mixture of zeolite and enzyme solution and then subjected to casting using glutaraldehyde were called Zeolite Membrane Transducers (ZMT). The operational and storage stabilities were determined to be in an acceptable range using ZCTs for conductometric urea biosensors. It was observed that using electrodes fabricated by the ZCT technique enhanced the biosensor signals up to two times and showed a rapid response after the addition of urea to the medium when it was compared with Standard Membrane Transducers (SMT). This enhancement can be explained by the lack of GA layer on top of the film, which acts as a diffusion barrier and inhibits the activity of the enzyme. On the second part of this conductometric biosensor study, effect of zeolite modification with methyl viologen (MV) and silver nanoparticles (Ag+ and Ag0), as well as the effect of changing Si/Al ratio was investigated with three different zeolite Beta particles which have Si/Al ratios of 40, 50, and 60. There were no significant effect of MV modification on ZMTs and there was no response observed with Ag+ and Ag0 modified zeolites. However, it was observed that conductometric responses increased with increasing Si/Al ratio for ZMTs. This behavior can be due to an increased hydrophobicity and/or the increasing acidic strength with the increasing Si/Al ratio within the zeolite crystals. Also ZCTs showed higher responses with respect to both SMTs and ZMTs. When compared with SMTs and ZMTs, ZCTs had higher reproducibility due to the controlled thickness of zeolite thin film by dip coating, and the controlled amount of enzyme adsorbed on this film. In the third part of the study, effect of zeolites on cell proliferation with MG63 osteoblast cells and NIH3T3 fibroblast cells were investigated. For that purpose, zeolite A, silicalite, and calcined forms of these zeolites were patterned with photolithography technique onto silicon wafers. Three different patterns prepared for this particular study, which has 0.125cm2, 0.08825cm2, and 0.04167cm2 zeolite patterned areas on 1 cm2 samples. In that way, not only the zeolite type and effect of calcination of zeolites, but also the effect of zeolite amount on MG63 osteoblast cells and NIH3T3 fibroblast cells were investigated. Silicalite coated samples were observed to have higher amount of cells than zeolite A coated samples after 24, 48, and 72 hours of incubation. This may be referred to the hydrophilic/hydrophobic properties, surface charge, and/or particle size of zeolites. Also it is observed that higher zeolite amount on samples resulted in an increase in the number of cells attached to the samples. There was also a significant increase in the number of cells upon using calcined silicalite samples. Accordingly, it can be hypothesized that zeolite pores result in an enhancement of protein adsorption and proliferation, even if this only occurs at the pore openings. On the other hand, there was no positive effect of calcining zeolite A. This result was expected since there is no structure directing agent used in synthesis procedure of zeolite A, which again supports the fact that pores might have some role in cell attachment.

Diffusion in bulk has been well studied and our understanding may be said to be adequate if not complete. Similarly, surface diffusion has been investigated by a number of workers and a fair understanding of it has emerged. When guest particles are confined within the micropores of solids such as zeolites, the resulting phase is neither bulk nor an adsorbed phase but something in between. Properties of such a phase have not been understood sufficiently. Such phase found within these porous solids display rich variety in their property. In part, such a variety arises from the large number of factors that determine their properties. Present thesis attempts to study the relationship of some of these factors, viz., the pore size and the disorder in the pore sizes, the sorbate sizes, the role of orienta-tional motion, the inhomogeneities in temperature etc. to diffusion of the guest molecules in porous solids. Chapter 1 gives a brief overview of the literature and the present understanding in the field of diffusion of spherical atoms and small molecules in microporous materials with special attention to zeolites.,The discussion is focussed on the experimental, theoretical and computer simulation results reported in the last few years. In chapter 2 an analytic expression is derived for the diffusion coefficient of a sorbate in a crystalline porous solid with bottlenecks. This is done by assuming a situation of quasiequi-Hbrium and by applying some elementary results of kinetic theory of gases. The diffusion coefficients obtained from the analytic expression is found to agree well with the molecular dynamics results. Further, it is found to reproduce the diffusion anomaly and its temperature dependence for different zeolites such as Y, A and p. The present calculations provide a strong theoretical support for the levitation effect obtained so far purely from molecular dynamics calculations. The computational effort involved in evaluating the derived expression is at least an order of magnitude less as compared to the molecular dynamics simulations. Levitation effect is found to exist in crystalline porous solids, irrespective of the geometry and topology of the void network of the host - the zeolite. Does levitation effect exist in non-crystalline porous solids where a distribution of pore sizes is seen instead of a single size? Chapter 3 attempts to answer this question via detailed molecular dynamics simulations on zeolite Y whose perfectly crystalline pore structure has been modified by introducing disorder. A normal distribution characterized by its width <TQ of 12-ring window diameters has been generated. Investigation of motion of spherical sorbates within such a disordered host suggests that levitation effect persists although the intensity of the anomalous peak is reduced compared to crystalline faujasite. Further, there is a breakdown of the linear relationship between the self-diffusivity D and 1 /^ where a99 is the sorbate diameter in the disordered host. Comparison of similarity between the effect of temperature and that of disorder are discussed. Chapter 4 investigates the role of orientation on diffusion of methane in zeolite NaCaA during intercage and intracage migration. In this work, diffusion of a five site model of methane within porous zeolite A has been investigated by molecular dynamics simulation. Methane exhibits interesting orientational preference during its passage through the 8-membered window, the rate determining step for overall diffusion: (2+2) (or scissor) orientation is preferred to (1+3) (or inverted umbrella) orientation. This suggests strong translational-orientational coupling. This is supported by ab initio mixed basis calculations thereby suggesting that the results are not a consequence of the classical potential employed. Partial freezing of certain rotational degrees of freedom is observed during the passage of methane through the 8-ring window. Intracage motion of methane shows that methane performs a rolling motion rather than a sliding motion within the supercage. In Chapter 5, diffusion of methane and neopentane through the pores of zeolite NaY has been investigated by means of molecular dynamics simulation. Intercage motion consisting of diffusion through 12-ring window of zeolite NaY is seen to occur with strong orientational preference for (2+2) orientation in the case of neopentane but not methane. Comparison of the result with methane diffusion through the 8-ring window of zeolite NaCaA reported in chapter 4 suggests that such a preferential orientation is a typical characteristic of systems whose levitation parameter is close to unity. Temperature dependence of translational-orientational coupling during the passage through the bottleneck has been obtained. As seen earlier, partial freezing of certain rotational degrees of freedom also exists. Little or no freezing is observed around the molecular axis of symmetry parallel to the vector, ft, perpendicular to the window plane since it does the orientation of the molecule with respect to fi. Analysis of intracage motion suggests existence of rolling motion in preference to sliding motion both in methane and neopentane. It is suggested that globular molecules show a predominance of rolling motion in comparison to anisotropic molecules such as benzene. Chapter 6 reports results from molecular dynamics(MD) simulations and its comparison to the quasi-elastic neutron scattering (QENS) measurements of the diffusion of propane, NaY zeolite, at different temperatures and at a relatively high loading. The contributions to S(Q, cu) from ballistic and diffusive motions are analysed. The self-diffusivity D has been calculated from mean squared displacement (MSD) as well as from the dynamic structure factor (S(Q,cu)) computed from the MD simulation. Both the values are consistent with each other. Also, they are in reasonable agreement with the experimental QENS results. The MD results indicate a fixed jump length diffusion process, whereas, the QENS data fits well to a jump diffusion model with a Gaussian distribution of jump lengths. Diffusion is often accompanied by a reaction or sorption which in turn can induce temperature inhomogeneities. In chapter 7 Monte Carlo simulations of Lennard-Jones atoms in zeolite NaCaA are reported for the presence of a hot zone presumed to be created by a reaction. Our simulations show that the presence of localized hot regions can alter both the kinetic and transport properties such as diffusion. An enhancement in diffusion coefficient is seen in the presence of a local hot spot. Further, the enhancement of the diffusion constant is greater for systems with larger barrier height, a surprising result that may be of considerable significance to many chemical and biological processes. We find an unanticipated coupling between reaction and diffusion due to the presence of hot or cold zone in addition to that which normally exists between them via concentration. Chapter 8 explores the possibility of exploiting a judicial combination of levitation effect and blow-torch effect for the separation of mixtures. In this study, Monte Carlo simulations have been carried out for three different binary mixtures in zeolite NaCaA with hot spot placed just before the position of the window along one direction. The binary mixture consisting of two types of particles both of which are from the linear regime does not separate well while the separation achieved of the mixture with one component from the linear regime and another from the anomalous regime is excellent. The separation factors obtained in the case of the latter mixture is more than an order of magnitude larger than that of the conventional separation methods. In the case of Ne-Ar mixture in NaCaA also, where Ne is in the linear regime and Ar is in the anomalous regime, the separation attained is excellent. These results suggest that a combination of levitation and blow-torch effects can be used to obtain extraordinary separation. Here the levitation effect specifies the sign and the magnitude of the energy barrier. The blow-torch drives the component in positive or negative direction depending on the energy barrier of the guest species. An appendix describes an additional but unrelated work carried out: a Monte Carlo study of the orthorhombic(fJ), monoclinic(ct) and liquid phases of toluene in the isobaric isothermal ensemble employing variable shape simulation cell. The structure has been characterized in terms of the radial distribution functions and orientational correlation functions. The transition from the orthorhombic low temperature (3-phase to the high temperature monoclinic cc-phase has been successfully simulated. The transition is first order and lies between 140 and 145K in agreement with experiment. The reverse transition from the a-to the (3-phase does not take place in agreement with experiment. The liquid phase density and the heat of vapourization are in good agreement with the experimental values.

Thesis (Ph. D.)--Ohio State University, 2009. / Title from first page of PDF file. Includes bibliographical references (p. 268-291).

Most concrete produced today utilizes pozzolans or supplementary cementitious materials (SCMs) to promote better long term durability and resistance to deleterious chemical reactions. While other pozzolans and SCMs are available and provide many of the same benefits, Class F fly ash has become the industry standard for producing quality, durable concrete because of its low cost and wide-spread availability. With impending environmental and safety regulations threatening the availability and quality of Class F fly ash, it is becoming increasing important to find viable alternatives. This research aims to find natural, lightly processed, alternatives to fly ash that perform similarly to Class F fly ash with regards to pozzolanic reactivity and provide comparable compressive strength, workability, drying shrinkage, thermal expansion properties and resistance to alkali-silica reaction, sulfate attack, and chloride ion penetration. Eight fly ash alternatives from the US were tested for compatibility with the governing standard for pozzolans used in portland cement concrete and various fresh and hardened mortar and concrete properties. The results of this research indicate that six materials meet the requirements for natural pozzolans set by the American Society for Testing and Materials and many are comparable to Class F fly ash in durability tests. The primary concern when using these materials in concrete is the increase in water demand. The spherical particle shape of fly ash provides improved workability even at relatively low water-to-cement ratios; however, all of the materials tested for this research required grinding to achieve the appropriate particle size, resulting in an angular and rough surface area that requires more lubrication to achieve a workable consistency. So long as an appropriate water reducing admixture is used, six of the eight materials tested in this study are appropriate and beneficial for use in portland cement concrete. / text

This thesis presents the recent progress of diffusion measurements in nanoporous host systems by micro-imaging. Interference microscopy is applied as a powerful tool to record transient, intracrystalline concentration profiles of different sorbate species in the porous framework of two different zeolites, viz. ZSM-5 (MFI) and ZSM-58 (DDR). These profiles, yielding high temporal and spatial resolutions of about 10 s and 0.45 μm, follow the change of the refractive index of the host-guest system during uptake and release of certain guest molecules. With the thus accessible changes of concentration and particle fluxes, mass transport parameters, such as intracrystalline diffusivity and surface permeability, can be obtained by the use of the very fundamental equations on diffusion. Additionally, in two examples of never before performed types of experiments, further insights into challenging fields of host-guest interactions are provided: The well known phase transition in MFI type zeolites covering high benzene loadings is investigated in a single crystal study, allowing to follow the change of the sorbate phase in great detail. Furthermore, in DDR zeolites, a new way of data analysis facilitates to study the uptake and release of binary mixtures. Here, from the two-dimension profiles obtained by interference microscopy, the local concentrations of the sorbate species could be retrieved by using the so-called ideal adsorbed solution theory.

The current study investigated application of natural adsorbents in brine treatment. Brines are hypersaline waters generated in power stations and mining industries rich in Mg2+, K+, Ca2+, Na+, SO4 2- , Cl- and traces of heavy metals, thus there is a need for these brines to be treated to recover potable water and remove problematic elements. Natural adsorbents have been successfully used in waste water treatment because of their high surface area and high adsorptive properties when they are conditioned with acid or base. The investigation of pH showed that natural adsorbents did not perform well at low pH of 4 and 6. The adsorbents were able to work efficiently at the natural pH of 8.52 of the brine solution. These results show that natural adsorbents hold great potential to remove cationic major components and selected heavy metal species from industrial brine wastewater. Heterogeneity of natural adsorbents samples, even when they have the same origin, could be a problem when wastewater treatment systems utilizing natural clinoptilolite and bentonite are planned to be developed. Therefore, it is very important to characterize the reserves fully in order to make them attractive in developing treatment technologies.