GCRIS

Now showing 1 - 2 of 2

Removal of Dyes and Antibiotics by Adsorption and Photocatalytic Degradation Using Zn-Based Composites
(01. Izmir Institute of Technology, 2023) Özkan, Seher Fehime; Çakıcıoğlu Özkan, Seher Fehime; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In this study, the ZIF-8 was synthesized and immobilized on the clinoptilolite surface (ZIF8@CLN) and doped with Ag nanoparticles, forming the Ag-ZIF8 and Ag-ZIF8@CLN composite materials. The characterization results indicated that the ZIF-8 was well-deposited on the clinoptilolite surface and doped successfully with Ag nanoparticles. The adsorption and photocatalytic activity of these adsorbents/catalysts were evaluated by the removal of the organic pollutants such as dyes and antibiotics. The target dyes were cationic Methylene blue (MB), anionic Methyl orange (MO) and Congo red (CR), and zwitterionic Rhodamine B (RhB). The target antibiotic was tetracycline (TC). The influence of various parameters on removal was investigated using different initial pH, photocatalyst amount, pollutant concentrations and ionic strength. The results showed that ZIF-8 and ZIF-8@CLN are excellent adsorbents. However, the photocatalytic activity of Ag-ZIF8 and especially Ag-ZIF8@CLN composites were much better than ZIF-8 and ZIF-8@CLN for degradation of all dyes. The Ag-ZIF8 and Ag-ZIF8@CLN composite catalysts exhibited more than 90% removal capacity under UV irradiation for 120 min with the dye concentration of 25 mg L-1 at the optimum pHs of each dye. The enhanced adsorption and photocatalytic performance of the composite photocatalysts was attributed to the synergistic effect between the ZIF-8, CLN and Ag. The adsorption data were evaluated by considering adsorption isotherms, kinetics and thermodynamics using target dyes and antibiotics. Proposed photodegradation mechanism of the dyes over Ag-ZIF8@CLN was explained detailed. This work introduced the ZIF-8-based composite photocatalysts with high efficiency, and may provide to prefer these catalysts in photocatalytic field.
Heat and Mass Transfer Characteristics of Adsorbents in Heat Pump and Refrigerator
(01. Izmir Institute of Technology, 2023) Gündoğan, Şefika Çağla; Özkan, Seher Fehime; Çakıcıoğlu Özkan, Seher Fehime; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Due to increasing drought, pandemic and climate crisis in recent years, researchers have increased their studies on environmentally friendly energy use. Although there are technological developments in the production of energy from renewable energy sources, the storage of this produced energy is still a problem that awaits a solution. At this point, adsorption heat pumps with high primary energy efficiency come to the fore as a developing technology and attract the attention of researchers. However, low heat transfer properties in the adsorbent bed reduce the performance of adsorption heat pumps and limit their applications. The aim of this thesis was to improve the performance of the adsorption heat pump by increasing the effective thermal conductivity within the adsorbent bed. Two methods have been employed to enhance the effective thermal conductivity. In the first method, which was unconsolidated adsorbent bed design, it was aimed to increase the thermal conductivity of the bed with metal additives with a continuous structure. In the second method, which is known as consolidated bed design, the effective thermal conductivity of zeolite 13X was tried to be enhance with a high conductive material, reduced graphene oxide. In the experimental studies, it was observed that the thermal conductivity increased from 0.12 W/m.K to 0.28 W/m.K in unconsolidated bed design by means of fin-shaped metal additive. In consolidated adsorbent bed design, the effective thermal conductivity of the Graphene/Zeolite 13X (1 wt% Graphene) was determined as 0.1613 W/m.K. In theoretical studies, the effect of thermal conductivity in the temperature, pressure and adsorbate concentration was investigated. The indirect and direct effects of effective thermal conductivity on specific cooling/heating power (SCP/SHP) and coefficient of performance (COP) values were examined. Although the effect of thermal conductivity on COP was ignored in most of the studies in the literature, it was observed that COP increased from 0.01 to 0.10 when thermal conductivity increased from 0.12 W/m.K to 1 W/m.K.

Phd Degree / Doktora

Browse

Filters

Settings

Sort By

Results per page

Search Results