Thesis (Master)--İzmir Institute Of Technology, İzmir, 2005. / Keywords: Natural zeolite, clinoptilolite, aqueous media, ion exchange, adsorption. Includes bibliographical references (leaves . 70-73).

Thesis (Master)--İzmir Institute of Technology, İzmir, 2005 / Keywords: Citral hydrogenation, clinoptilolite, zeolite Y, zeolite beta. Includes bibliographical references (leaves. 92-94).

Thesis (Master)--İzmir Institute of Technology, İzmir, 2004 / Includes bibliographical references (leaves. 96).

Thesis (Master)--İzmir Institute of Technology, İzmir, 2002. / Includes bibliographical references (leaves. 92-96).

M.Tech. / Clinoptilolite possesses acid and base properties, and is hydrothermally stable at high temperatures. It can be reactivated by simple oxidation, and is highly selective due to its unique-shape selectivity. It is also not harmful to the environment and it has shown benefits to soil as well (Mumpton,1977). An initial study of the reactions of methanol amination was done using both natural local and synthetic clinoptilolites. Characterization of each was done before and after modification using XRD, TPD and BET analysis. The BET analysis showed an increase in the surface area and pore diameter of both the natural and synthetic types after acid treatment and calcination. Most interesting of all was the large increase in surface area, where the natural type increased from 16 to 36.7 m 2/g after acid treatment and the synthetic type increased almost 13 times, from 2 to 27.7 m2/g after acid treatment. This effect had a strong influence on the selectivity of methylamines by allowing a larger surface area to be in contact with the feed reagents. The XRD of the treated and untreated natural and synthetic clinoptilolite were compared and discussed. The catalytic properties of zeolites depend on the treatment of clinoptilolite, and the characteristic peaks of natural and the acid treated form can be identified in the XRD plots.The TPD analyses showed that there were two acid sites associated with the clinoptilolite; one weak and one strong. The synthetic clinoptilolite weak acid site also showed a much lower ammonia uptake, than the natural clinoptilolite weak acid site. Clinoptilolite was shown to be successful as a catalyst for the production of dimethylamine with high selectivity. This was attributed to a transition state shape selectivity associated with the clinoptilolite channels. The natural clinoptilolite displayed good selectivities at 400°C and a 5:1 ratio of methanol to ammonia, and gave a high conversion of > 90% ammonia to amines. The synthetic clinoptilolite gave better conversions and lower TMA selectivity than the natural clinoptilolite over a large range of feed ratios and temperatures. This included conversions of over 90% for most ratios (at 400 and 450°C). The natural clinoptilolite gave better results than those obtained using the amorphous clinoptilolite, which is currently used in industry. For example, low TMA selectivity was observed when a ratio of 5:1 or greater (methanol to ammonia) was used. The TMA selectivity is still far lower than the thermodynamic equilibrium selectivities obtained without a catalyst (62%). The catalyst lifetime has been shown to deteriorate with time.

The aim of this study was to establish whether samples of South African-mined clinoptilolite could be used to remove selected metal cations from aqueous solution. The clinoptilolite samples supplied, (by Pratley SA) were in four different particle sizes. Batch study results revealed a decrease in the initial metal concentration in samples that were in contact with clinoptilolite. The finer particle size clinoptilolite had a greater capacity to remove metal cations from aqueous solution. However, ion-exchange results from atomic absorption analysis showed that the larger particle sizes, removed more magnesium ions. Magnesium was the only ion investigated in this study that was present as an exchangeable ion in the Pratley clinoptilolite chemical formula, (MgCaNa2K2)2.5(AlO2)7(SiO2)30.21H2O. Results from the ion-exchange studies showed that the decreasing order of percentage metal removal at pH 3.00 was as follows: Pb > Ni > Cu > Fe > Mg. The mass of metal ions that accumulated on one gram of clinoptilolite as determined from the isotherms was calculated to be 6.16 mg/g for lead and 0.74 mg/g for copper. Data from the lead equilibrium studies were fitted into Langmuir and Freundlich equations and linear regression was used to calculate linearity coefficients for the isotherms. The results showed that the removal of lead ions by clinoptilolite is complex as both monolayer and multilayer adsorption occurs on a heterogeneous surface.

Thesis MSc Faculty of Engineering and the Built Environment,School of Chemical and Metallurgical Engineering, University of the Witwatersrand / This research concerns the further characterisation and establishment of adsorption behaviour of the South African clinoptilolite. Synthetic single- and multi-component wastewaters were used, and experiments conducted in both batch and column systems at 25oC ± 2. Wastewaters containing heavy metals ions Cu2+, Co2+, Ni2+ and Cr3+, were used at different feed concentrations (50 - 500 mg/L), and adsorbed onto natural and homoionic (Na+, K+, Ca2+, NH+ 4) forms of the zeolite. The Na+-form clinoptilolite had an improved cation exchange capacity over the natural one, and the selectivity series of metal ions by these two forms varied. Brunauer Emmett Teller surface area analysis carried out also confirms that preconditioning clinoptilolite with Na+ ions results in an increase in pore diameter, allowing for easier diffusion of ions and more adsorption. An atomic adsorption spectrophotometer (AAS) was used to analyse metal ions in solution. Adsorption efficiencies with over 75% of metal ions adsorbed in the first hour of contact were recorded, and complete adsorption equilibrium being reached in 4 hrs. Regeneration of Na+-form and natural clinoptilolite (using 0.5M NaCl stripping solution) initially showed an increase in loading capacities, then a decrease with the subsequent cycles. A comparison between two particle sizes revealed that smaller particle sized clinoptilolite have slightly higher adsorption capacities. The equilibrium data also fitted well with the linear form of the Langmuir and Freundlich isotherms at lower concentrations of 50 mg/L.

Ce travail étudie les matériaux composites zéolithes surfactifs, principes actifs pour des applications pharmaceutiques. D'abord sont identifiées les principales propriétés physiques, chimiques et biologiques des matériaux, requises pour des applications en tant que supports médicamenteux ciblant certaines formes de cancer. Par la suite sont décrits les différentes étapes de formulation des supports médicamenteux à base des zéolithes naturelles, les caractéristiques des matériaux intermédiaires ainsi obtenus, ainsi que les mécanismes des phénomènes interfaciaux à l'origine de l'action de ces matériaux. La dernière partie est consacrée à l'étude d'un relargage contrôlé des principes actifs de l'interface jusque dans un milieu aqueux modèle. / This work studies the composite zeolites surfactants, active principles for pharmaceutical applications. First identified the main physical, chemical and biological materials, required for applications as drug carriers targeting some cancers. Subsequently described the various stages of formulation of drug carriers based on natural zeolites, the characteristics of intermediate materials obtained, and the mechanisms of interfacial phenomena at the origin of the action of these materials. The last part is devoted to the study of controlled release of active ingredients of the interface into a model aqueous medium.

The aim of the work described in this thesis was to study the removal of ammonium ions from water by ion exchange. The classical technique is to use biological nitrification and denitrification to convert ammonia into nitrogen gas. Removal by ion exchange offers a number of advantages, such as the ability to handle shock loadings and to polish water to a very high specification. The ion exchanger used in this project was clinoptilolite, a naturally occurring zeolite. Previous research has included characterisation of clinoptilolite, the effect of other common cations on uptake, biological regeneration, and a few other studies. A comparison with other exchangers was also conducted. Much of the available literature is concerned with clinoptilolite and occasionally with mordenite, however modern ion exchangers are polymer based. Two polymeric ion exchangers (Dowex 50w-x8, and Purolite MN500) were evaluated in this project. The main scope of this thesis was to look at the effect that organic pollutants has on ammonium ion removal during ion exchange. The results of batch equilibrations of NH4+ and the three exchanger resins can be seen in chapter 4.0. They show that the presence of an organic compound enhanced the uptake of NH4+ in most cases onto clinoptilolite and Purolite MN500. There was no apparent uptake onto Dowex 50w-x8. Further experiments with a sample of real industrial wastewater (woolscour wastewater) showed varied results, showing that each site should carry out its own pilot scale testing during plant design. Other experimental work showed that the exchanger resins adsorb little or none of the organic compounds in solution. These results can be seen in chapter 5.0. ii Removal of ammonia from wastewater by ion exchange in the presence of organics. Studies in a packed column showed that the presence of organic compounds had little or no effect on NH4+ removal. There was however an increase in capacity after each regeneration of the bed and continued removal after breakthrough. The same results were achieved in the control experiment with no organic compounds present, hence these results are not related to the presence of an organic compound. The presence of NH4+ and various compounds did however provide micro-organisms with substrates from which to grow causing hydraulic difficulties in the column. See chapter 6.0 for these results. The final section of experimental work studied whether the presence of organic compounds changed the rate of uptake of NH4+. The results in chapter 7.0 show that there was no effect on the rate of NH4+ uptake.

Clinoptilolite is a zeolite and an aluminosilicate that can be fed to swine in order to reduce nutrients being excreted because of their molecular sieving properties, high cation exchange capacities, and a high affinity for the ammonium ion (NH4+). Preliminary research has been carried out on utilizing zeolite's unique characteristics for dietary supplementation for livestock, however much of this research is limited and is still in its infancy. / The results from this study show that the zeolite with a particle size distribution either >250 mum or mixed (50% particles greater and smaller than 250 mum) adsorbed the most NH4+. Macro mineral and heavy metal release was similar among all particle size distributions tested, but varied between sources of zeolite. Handling properties of zeolite were not affected by moisture content or particle size. The feed trial indicated that zeolite supplementation, combined with a low crude protein and energy diet and at an inclusion level of 4%, showed potential as a feed additive in swine diets for the purposes of nutrient reduction. Nevertheless, zeolite seemed to have a greater impact on energy ingestion, as compared to crude protein. Even at 6% zeolite inclusion in the feed, hog muscle, kidney and liver tissues showed no significant increase in heavy metal contents, as compared to those fed any zeolite.