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Removal of Dyes and Antibiotics by Adsorption and Photocatalytic Degradation Using Zn-Based Composites
(01. Izmir Institute of Technology, 2023) Saygı, Gizem; Çakıcıoğlu Özkan, Seher Fehime
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.
An Experimental and Theoretical Study on the Improvement of Adsorption Heat Pump Performance
(Izmir Institute of Technology, 2008) Demir, Hasan; Ülkü, Semra
Adsorption heat pumps, which have considerably sparked attentions in recent years, have the advantage of being environmentally friendly and operating with heat sources such as waste heat, solar and geothermal energies as well as storing the energy.The present investigation covers working principle of adsorption heat pumps, a detailed literature survey on the performed studies, information about adsorption phenomena, experimental results of two differently designed and constructed systems, numerical simulation of heat and mass transfer in an annular adsorbent bed, and microcalorimetric study for obtaining isosteric heat of adsorption for water vapor-silica gel pair. The two intermittent adsorption heat pumps can operate without any leakage. The silica gelwater was employed as the adsorbent-adsorbate pair in both of the systems. The temperature and pressure in the evaporator, condenser and adsorbent bed were measured and the coefficients of performance, total entropy generation, the second law efficiency, specific heating and cooling power values were calculated based on these measured values for all of the representative cycles. The heat transfer area of the second designed adsorption heat pump is 550% greater than the first designed adsorption heat pump and this increase resulted in 170% and 200% of improvements in specific heating power (SHP) and specific cooling power (SCP) values respectively. The silica gel granules were mixed with small size metal pieces in order to accelerate heat transfer in the bed. Experiments were performed to measure the thermal diffusivity through the adsorbent bed in which adsorbent is mixed with metal pieces. It was observed that the mixing of silica gel grains with 10wt% of small size aluminum pieces increases the SHP and SCP values of the second heat pump by 250%.

Phd Degree / Doktora

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