Yazar "Koyuncu, İsmail" ile LEE- Çevre Bilimleri Mühendisliği ve Yönetimi-Doktora'a göz atma
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ÖgeFabrication of thin film nanocomposite pressure retarded osmosis (PRO) membranes using cellulose nanocrystal (CNC) and evaluation of performances in the processes(Graduate School, 2021-02-02) Paşaoğlu, Mehmet Emin ; Koyuncu, İsmail ; 659118 ; Environmental EngineeringNowadays, owing to quick world population growth and abrupt economy, high water demands desire innovative technologies in order to ensure clean and safe water with lower energy use. Severe environmental emissions arising by the consumption of fossil fuels often needs us to build energy harvesting technology which are environmentally sustainable. As an advanced technology, osmotic membrane processes consisting of forward and pressure-retarded osmosis, are conceived to be conspicuous technologies for the treatment, recycling and reuse of wastewaters and the harvesting of salinity gradient energy which is called "Blue Energy". Nevertheless, forward osmosis (FO) and pressure retarded osmosis (PRO) are at the level of growth yet. It is difficult piece of work to fabricate osmotic membranes obtaine high water permeability and perfect ion retention. The ideal osmotic membrane candidate can be a thin film composite membrane satisfy the conditions which has high water permeation and as soon as low reverse salt flux ratio. Furthermore, for the membrane to endure relatively high hydraulic pressures in PRO systems, certain mechanical properties are vital. Thankfully, membranes that are fabricated with electrospinning method have an excellent capability to overcome all specifications of the perfect support layer in consequence of porous structure characteristics and simplicity with that nanomaterials may be integrated to enhance the nanofibers mechanical strength. Apart from this, interfacial polymerization (IP) may be accomplished to electrospun nanofiber membrane to achieve a very thin selective polyamide coating. TFN membranes may show tremendous potential in osmotically driven membrane processes after integrating nano additives into their support layer. The aim of this thesis to carry out and design a comprehensive study on the development of reinforced pressure retarded osmosis membranes. Specifically, this thesis presents the development of novel nanofiber supported thin film composite membranes with high water permeability and excellent selectivity for solvents, while showing an excellent mechanical strength for PRO processes. Interfacial polymerization reactions were used to construct very thin polyamide selective layer on the support, and electrospinning process was used to fabricate a number of support layers. Initially, we investigated the potential to use flat sheet electrospun polyacrylonitrile nanofibers as support support layer to fabricate PRO membranes. Polyamide TFCs were successfully applied on five different substrate containing 0,1,2,5,10% crystal nanocellulose (CNC) in 16% PAN polymer solution. PRO membranes successfully fabricated via tailor-made flat sheet fabrication unit. It is concluded that PAN and CNC generated a complete mixture according to SEM, FTIR, DMA & contact angle analysis findings.The addition of CNC improved the mechanical strength of PAN support layers which is the main phenomenon in PRO applications. The newly developed membrane can achieve a higher PRO water flux of 300 LMH, using a 1 M NaCl draw solution and deionized water feed solution. The corresponding salt flux is only 1.5 gMH. The reverse flux selectivity represented by the ratio of water flux to reverse salt flux (Jw/Js) was able to be kept as high as 200 L/g for PRO operation. Following the success of flat-sheet TFN PRO membrane fabrication, improvements need to be done to increase packing density of fabricated final membrane modules. In this point, we used a novel technique to fabricate tubular membranes for PRO applications. The newly fabricated membrane achieves a higher PRO water flux of 405.38 LMH with using a 1 M NaCl and a DI as feed water. The corresponding salt flux is found as 2.10 gMH which is higher than flat sheet membranes. The selectivity of the reversed flux represented by the ratio of the water flow to the reversed salt flux (Jw/ Js) was able to be kept as high as 193.03 L/g for PRO operation.As far as we know, the performance of the work developed membrane in this study has shown better performance than all PRO membranes reported in the literature previously.
ÖgeRecovery of water and chemicals from textile wastewater with ceramic membranes(Graduate School, 2021-12-17) Ağtaş, Meltem ; Koyuncu, İsmail ; 501142702 ; Environmental Sciences Engineering and ManagementDecreased water resources in our world necessitate the treatment and reuse of polluted water. Water recovery is of vital importance, both in terms of sustainability and economy, especially in industries that consume large amounts of water. One of the industries that consume a high amount of water is the textile industry. In the textile industry, 0.06-0.40 m3 water/kg product is used according to literature. In parallel with the amount of water used in the processes in the textile industry, a high amount of wastewater is generated. These wastewaters are known to contain high COD, different dyes, heavy metals, etc. For this reason, it is not possible to discharge these wastewaters into the environment without proper treatment. Many traditional methods for the treatment of textile wastewater such as coagulation flocculation, activated carbon adsorption, ozonation and biological treatment are used. However, these methods cannot meet strict discharge limits or are not economically viable. Therefore, membrane processes come to the fore in textile wastewater treatment since they are recommended for textile wastewater treatment in the BAT (Best Available Techniques) reference document. As a result of textile wastewater treatment with membrane processes, high-efficiency treatment is provided and the treated wastewater can have the potential to be reused. Polymeric membranes are generally preferred in treatment processes. However, since textile wastewaters have high temperatures and extreme pH values, the use of polymeric membranes is not suitable. The textile industry produces wastewater with temperatures that can go up to 90-95 °C. Generally, wastewater must be cooled down before membrane treatment. For efficient treatment, membranes have to be thermally stable; most polymeric membranes tend to degrade at high temperatures and therefore, they are not suitable for hot wastewater treatment.Therefore, the use of ceramic membranes in the treatment of textile wastewater is a viable method. Besides, when ceramic and polymeric membranes are compared, it can be said that ceramic membranes are having more advantageous in terms of high thermal, mechanical, and chemical stability, well-defined pore size distribution, and high flux. In this thesis, a comprehensive study was carried out on the pilot-scale water and chemical recovery using ceramic membranes from real textile wastewater and the development of halloysite nanotube doped membranes for the treatment and recovery of real textile wastewater. First, a pilot-scale ceramic ultrafiltration/nanofiltration system was operated for hot water recovery by treating real textile wastewater in a selected textile factory. Later, in the same facility, real textile wastewater with caustic content was used in order to make chemical recovery. Based on the successful results of these studies, after it was proven that water and chemical recovery can be made with ceramic membranes, halloysite nanoclay added membranes were produced in order to make this process more economical, and treatment trials were carried out with real wastewater from the same facility and important results were obtained.