Üçlü ZnO-SnO2-Zn2SnO4 nanokompozitlerinin sentezlenmesi ve fotokatalitik aktivitelerinin belirlenmesi

Abstract

Son yıllarda özellikle yarı kurak ve kurak bölgelerdeki hızlı nüfus artışı, çarpık kentleşme ve endüstrileşmenin muazzam bir hızla gelişimi nedenleriyle temiz su kaynaklarına olan talep nedeniyle su kaynaklarının kirlilik derecesi de giderek artmaktadır. Günümüzde, organik boyar madde içeren endüstriyel atık sulara uygulanan arıtma/temizleme işlemlerinde düşük maliyetle temizleme işlemlerine ihtiyaç duyulmaktadır. Fotokatalitik yöntem bu amaca yönelik etkili çözüm sunabilecek seçeneklerden biridir. Fotokatalitik yöntem ile su atıklarında bulunan organik boyar maddelerin ultraviyole (UV) ve/veya güneş ışığından faydalanarak direk olarak yok edilmesine imkân veren yarı iletken malzemeler kullanılmaktadır. İki bileşenli çinko oksit (ZnO), kalay oksit (SnO2) ve üç bileşenli çinko kalay oksit (Zn2SnO4, ZTO) n-tipi yarı iletken metal oksitler ve bu bileşenlerle oluşturulan ikili - üçlü nanokompozit yapıların (ZTO:ZnO, ZTO:SnO2, ZTO:SnO2:ZnO) sentezi ve fotokatalitik aktivitesinin incelenmesi önemli bir araştırma konusu olmuştur. Fotokatalizör sentezinde istenilen şekil ve boyutlarda üretim yapılabilmesi seçilen sentez metoduna göre değişkenlik gösterebilmektedir. Bu tez çalışmasında istenilen boyut ve morfolojide nanokompozit üretimi yapılabilen ve karmaşık bir deney düzeneği gerektirmeyen elektro-eğirme yöntemi sentez metodu olarak seçilmiştir. Bu tez çalışmasında ilk olarak üçlü ZTO:SnO2:ZnO nanokompozit yapıları elektro-eğirme yöntemi ile sentezlenmiştir. Nanofiberlerin optik özelliklerinin optimum olması amacıyla, sentezlenen fiberlere fiber yapısından polimerik malzemenin uzaklaştırılması amacıyla 400°C ile 1200 °C arasında değişen farklı sıcaklıklarda ısıl işlem uygulanarak ısıl işlem sıcaklığının nanofiberlerin fotokatalitik özelliklerine etkileri araştırılmıştır. XRD sonuçlarına göre yüksek kristallikte ZTO:SnO2:ZnO sentezlenmesi için en uygun ısıl işlem sıcaklığının 1150 ? olduğu anlaşılmıştır. Daha sonra ZTO:SnO2:ZnO nanokompozit yapıların fotokatalitik aktivitesinin belirlenmesi amacıyla Rodamin B (RhB) organik boyar maddesinin UV ışık altındaki davranışları incelenmiştir. Nanokompozitlerin en iyi fotokatalitik aktiviteye sahip olması amacıyla, farklı ısıl işlem sıcaklıkları uygulanan fiberlerin boya çözeltisindeki konsantrasyonları, boya çözeltisinin pH değeri, boya çözeltisinin ışığa maruz kalma suresinin incelendiği çalışmalar yapılmıştır. Sonuç olarak yapılan tez çalışması kapsamında ZTO:SnO2:ZnO nanokompozit yapıların elektro-eğirme yöntemi ile sentezi ayrıca UV/görünür ışık altında sergilediği fotokatalitik aktiviteleri detaylı bir şekilde incelenmiş ve en uygun sentez/fotokatalitik parametreleri belirlenmiştir. Tez kapsamında yapılan çalışmalardan elde edilen sonuçlara göre 1150 °C ısıl isleme maruz bırakılarak üretilen üçlü ZTO:SnO2:ZnO nanokompozit fiberlerin 40 mg olacak şekilde pH değeri 2.03 olan 100 mL RhB boya çözeltisine eklenmesi sonucunda UV ışık altında 180 dakikada % 97.8 bozunum değerine ulaştığı gözlemlenmiştir. Bu sonuca göre üretilen üçlü nanokompozit fiber yapısı oldukça etkin fotokatalitik özellik sergilemektedir.

In recent years, especially in semi-arid and arid regions, due to rapid population growth, unplanned urbanization and rapid development of industrialization, in addition to the increase in the demand for clean water resources, the degree of pollution of water resources is also increasing. Nowadays, low cost cleaning processes are needed in the treatment/cleaning processes applied to industrial wastewater containing organic dyestuffs. Photocatalytic method is one of the options that can offer an effective solution for this purpose. With the photocatalytic method, semiconductor materials are used that allow the organic dyestuffs in water waste to be directly destroyed by making use of ultraviolet (UV) and/or sunlight. Two-component zinc oxide (ZnO), tin oxide (SnO2) and three-component zinc tin oxide (Zn2SnO4, ZTO) n-type semiconductor metal oxides and the synthesis and examination of photocatalytic activity of binary - ternary nanocomposite structures (ZTO:ZnO, ZTO:SnO2, ZTO:SnO2:ZnO) formed with these components has been an important research topic. Production of desired shapes and sizes in photocatalyst synthesis may vary depending on the synthesis method chosen. In this thesis, the electro-spinning method, which can produce nanocomposites in the desired size and morphology and does not require a complex experimental setup, has been chosen as the synthesis method. In this thesis, firstly, ternary ZTO:SnO2:ZnO nanocomposite structures were synthesized by electro-spinning method. In order to optimize the optical properties of nanofibers, the effects of heat treatment temperature on the photocatalytic properties of nanofibers were investigated by applying heat treatment at different temperatures ranging from 400°C to 1200°C in order to remove the polymeric material from the fiber structure. According to the XRD results, it was understood that the most suitable heat treatment temperature for the synthesis of high crystallinity ZTO:SnO2:ZnO is 1150 ?. Then, the behavior of Rhodamine B (RhB) organic dyestuff under UV light was investigated in order to determine the photocatalytic activity of ZTO:SnO2:ZnO nanocomposite structures. In order for nanocomposites to have the best photocatalytic activity, studies were carried out to examine the concentrations of the fibers applied at different heat treatment temperatures in the dye solution, the pH value of the dye solution, and the exposure time of the dye solution to light. As a result, within the scope of the thesis study, the synthesis of ZTO:SnO2:ZnO nanocomposite structures by electro-spinning method and their photocatalytic activities under UV/visible light were examined in detail and the most suitable synthesis/photocatalytic parameters were determined. According to the results obtained from the studies carried out within the scope of the thesis, it was observed that the ternary ZTO:SnO2:ZnO nanocomposite fibers produced by heat treatment at 1150 °C were added to a In recent years, especially in semi-arid and arid regions, due to rapid population growth, unplanned urbanization and rapid development of industrialization, in addition to the increase in the demand for clean water resources, the degree of pollution of water resources is also increasing. Nowadays, low cost cleaning processes are needed in the treatment/cleaning processes applied to industrial wastewater containing organic dyestuffs. Photocatalytic method is one of the options that can offer an effective solution for this purpose. With the photocatalytic method, semiconductor materials are used that allow the organic dyestuffs in water waste to be directly destroyed by making use of ultraviolet (UV) and/or sunlight. Two-component zinc oxide (ZnO), tin oxide (SnO2) and three-component zinc tin oxide (Zn2SnO4, ZTO) n-type semiconductor metal oxides and the synthesis and examination of photocatalytic activity of binary - ternary nanocomposite structures (ZTO:ZnO, ZTO:SnO2, ZTO:SnO2:ZnO) formed with these components has been an important research topic. Production of desired shapes and sizes in photocatalyst synthesis may vary depending on the synthesis method chosen. In this thesis, the electro-spinning method, which can produce nanocomposites in the desired size and morphology and does not require a complex experimental setup, has been chosen as the synthesis method. In this thesis, firstly, ternary ZTO:SnO2:ZnO nanocomposite structures were synthesized by electro-spinning method. In order to optimize the optical properties of nanofibers, the effects of heat treatment temperature on the photocatalytic properties of nanofibers were investigated by applying heat treatment at different temperatures ranging from 400°C to 1200°C in order to remove the polymeric material from the fiber structure. According to the XRD results, it was understood that the most suitable heat treatment temperature for the synthesis of high crystallinity ZTO:SnO2:ZnO is 1150 ?. Then, the behavior of Rhodamine B (RhB) organic dyestuff under UV light was investigated in order to determine the photocatalytic activity of ZTO:SnO2:ZnO nanocomposite structures. In order for nanocomposites to have the best photocatalytic activity, studies were carried out to examine the concentrations of the fibers applied at different heat treatment temperatures in the dye solution, the pH value of the dye solution, and the exposure time of the dye solution to light. As a result, within the scope of the thesis study, the synthesis of ZTO:SnO2:ZnO nanocomposite structures by electro-spinning method and their photocatalytic activities under UV/visible light were examined in detail and the most suitable synthesis/photocatalytic parameters were determined. According to the results obtained from the studies carried out within the scope of the thesis, it was observed that the ternary ZTO:SnO2:ZnO nanocomposite fibers produced by heat treatment at 1150 °C were added to a In recent years, especially in semi-arid and arid regions, due to rapid population growth, unplanned urbanization and rapid development of industrialization, in addition to the increase in the demand for clean water resources, the degree of pollution of water resources is also increasing. Nowadays, low cost cleaning processes are needed in the treatment/cleaning processes applied to industrial wastewater containing organic dyestuffs. Photocatalytic method is one of the options that can offer an effective solution for this purpose. With the photocatalytic method, semiconductor materials are used that allow the organic dyestuffs in water waste to be directly destroyed by making use of ultraviolet (UV) and/or sunlight. Two-component zinc oxide (ZnO), tin oxide (SnO2) and three-component zinc tin oxide (Zn2SnO4, ZTO) n-type semiconductor metal oxides and the synthesis and examination of photocatalytic activity of binary - ternary nanocomposite structures (ZTO:ZnO, ZTO:SnO2, ZTO:SnO2:ZnO) formed with these components has been an important research topic. Production of desired shapes and sizes in photocatalyst synthesis may vary depending on the synthesis method chosen. In this thesis, the electro-spinning method, which can produce nanocomposites in the desired size and morphology and does not require a complex experimental setup, has been chosen as the synthesis method. In this thesis, firstly, ternary ZTO:SnO2:ZnO nanocomposite structures were synthesized by electro-spinning method. In order to optimize the optical properties of nanofibers, the effects of heat treatment temperature on the photocatalytic properties of nanofibers were investigated by applying heat treatment at different temperatures ranging from 400°C to 1200°C in order to remove the polymeric material from the fiber structure. According to the XRD results, it was understood that the most suitable heat treatment temperature for the synthesis of high crystallinity ZTO:SnO2:ZnO is 1150 ?. Then, the behavior of Rhodamine B (RhB) organic dyestuff under UV light was investigated in order to determine the photocatalytic activity of ZTO:SnO2:ZnO nanocomposite structures. In order for nanocomposites to have the best photocatalytic activity, studies were carried out to examine the concentrations of the fibers applied at different heat treatment temperatures in the dye solution, the pH value of the dye solution, and the exposure time of the dye solution to light. As a result, within the scope of the thesis study, the synthesis of ZTO:SnO2:ZnO nanocomposite structures by electro-spinning method and their photocatalytic activities under UV/visible light were examined in detail and the most suitable synthesis/photocatalytic parameters were determined. According to the results obtained from the studies carried out within the scope of the thesis, it was observed that the ternary ZTO:SnO2:ZnO nanocomposite fibers produced by heat treatment at 1150 °C were added to a 100 mL RhB dye solution with a pH value of 2.03 and reached a decomposition value of 97.8% in 180 minutes under UV light. According to the results obtained from the studies carried out within the scope of the thesis, it was observed that the ternary ZTO:SnO2:ZnO nanocomposite fibers produced by heat treatment at 1150 °C were added to a 100 mL RhB dye solution with a pH value of 2.03 and reached a decomposition value of 97.8% in 180 minutes under UV light. According to this result, the ternary nanocomposite fiber structure produced exhibits very effective photocatalytic properties.