Karmosin gıda boyasının bozunması için Ag/AgVO3@g-C3N4 nanokompozit fotokatalizörlerin geliştirilmesi
Investıgatıon of Ag/AgVO3@rGO@g-C3N4 nanocomposıtephotocatalysts for the degradatıon of carmoısıne fooddye
- Tez No: 996172
- Danışmanlar: PROF. DR. MAHMUT ÖZACAR
- Tez Türü: Yüksek Lisans
- Konular: Kimya, Chemistry
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2026
- Dil: Türkçe
- Üniversite: Sakarya Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Kimya Ana Bilim Dalı
- Bilim Dalı: Fizikokimya Bilim Dalı
- Sayfa Sayısı: Belirtilmemiş.
Özet
Bu çalışmada, görünür ışık bölgesinde yüksek fotokatalitik etkinlik göstermesi amacıyla Ag-AgVO3@rGO@g-C3N4 üçlü nanokompoziti sentezlenmiş ve yapısal, optik ile fotokatalitik özellikleri kapsamlı olarak incelenmiştir. Ag/AgVO3 yapısı ile g-C3N4 ve rGO bileşenleri kontrollü sentez adımları ile hazırlanmış; ardından Ag-AgVO3@rGO@g-C3N kompozit fotokatalizör elde edilmiştir. XRD, FTIR, UV-Vis DRS ve SEM analizleri, nanokompozitin güçlü ışık soğurma kapasitesine, iyi dağılmış Ag nanoparçacıklarına ve rGO'nun sağladığı gelişmiş elektron iletim özelliklerine sahip olduğunu ortaya koymuştur. Fotokatalitik performans değerlendirmeleri, dörtlü Ag-AgVO3@rGO@g-C3N4 nanokompozitinin görünür ışık altında karmosin boyasının degradasyonunda diğer iki ve üç bileşenli fotokatalizörlere göre belirgin şekilde üstün performans sergilediğini göstermiştir. Kinetik çalışmalar, fotodegradasyon sürecinin birinci dereceden kinetiğe uyduğu ve dörtlü nanokompozit fotokatalizörün hız sabitinin (k) (0,01251 dk-1) ikili Ag/AgVO3 (0,00237 dk-1), üçlü Ag/AgVO3@rGO (0,00241 dk-1) ve Ag/AgVO3@g-C3N4 (0,00478 dk-1) nanokompozit fotokatalizörlerine kıyasla sırasıyla yaklaşık 5,3 kat, 5,2 kat ve 2,6 kat daha yüksek olduğu bulunmuştur. Bu gelişmiş kinetik davranış; rGO'nun elektron iletimindeki rolü, Ag nanoparçacıklarının yüzey plazmon rezonansı etkisi ve Ag/AgVO3@g-C3N4 ara yüzeyinde oluşan etkin heteroeklem yapısının yük taşıyıcı ayrımını artırması ile ilişkilendirilmiştir. İkili ve üçlü fotokatalizörler, sınırlı yük ayrımı veya kısıtlı optik soğurma nedeniyle orta düzeyde bozunma performansı gösterirken, dörtlü kompozitteki kombinasyonlar, nispeten kısa bir ışınlama süresi içinde karmosini %93 oranında bozundurabilen son derece verimli bir sistem oluşturmuştur. Bu bulgular, çok işlevli fotokatalizörlerde arayüzey yük transferinin ve bileşenler arasındaki sinerjik etkileşimlerin önemini vurgulamaktadır. Önerilen fotokatalitik mekanizma, kompozitin ışık ile uyarılması sonucu elektron- boşluk çiftlerinin daha verimli ayrılması, rekombinasyon oranının azalması ve buna bağlı olarak •OH ve •O₂⁻ gibi oksidatif radikal türlerinin daha yüksek verimle üretilmesine dayanmaktadır. Bu aktif oksidan türler, karmosin molekülünün kromofor yapısını ve azo bağlarını hedef alarak hızlı bir parçalanma ve mineralizasyon sürecini mümkün kılmaktadır. Elde edilen sonuçlar, Ag-AgVO3@rGO@g-C3N4 nanokompozitinin görünür ışık altında etkin fotokatalitik performans sergileyen, yüksek radikal üretim kapasitesine ve gelişmiş yük taşıyıcı dinamiklerine sahip umut vadeden bir fotokatalizör olduğunu göstermektedir. Bu nitelikleriyle, özellikle gıda boyaları, tekstil boyar maddeleri ve organik kirleticilerin giderilmesine yönelik çevresel uygulamalarda güçlü bir alternatif oluşturmaktadır.
Özet (Çeviri)
The present research focuses on the synthesis, structural characterization, and photocatalytic performance evaluation of Ag/AgVO3-, g-C3N4-, and rGO-based nanocomposites designed for the visible-light-driven degradation of the azo dye Carmoisine. Increasing concerns about the ecological impact of synthetic dyes, particularly azo compounds that persist in the environment due to their complex aromatic structures and high chemical stability, have made advanced photocatalytic materials essential for sustainable wastewater treatment. In this context, engineering semiconductor heterostructures with enhanced optical absorption, improved charge separation capacity, and high surface activity is a promising approach. The current study aims to contribute to this field by developing a quaternary photocatalyst integrating Ag/AgVO3, g-C3N4, and reduced graphene oxide (rGO), each selected for its unique physicochemical features. To fabricate these photocatalysts, Ag/AgVO3 nanostructures were first synthesized by a hydrothermal method, ensuring well-defined crystalline phases and controlled particle morphology. Subsequently, these nanostructures were combined with g-C3N4, a metal-free polymeric semiconductor known for its structural stability and visible-light activity, and with rGO, which serves as a conductive support that facilitates rapid electron transfer. The synthesis strategy was designed to maximize interfacial contact between the components, thereby enabling effective heterojunction formation. Such heterojunctions are crucial in photocatalysis because they promote the separation of photogenerated electron–hole pairs, reduce recombination, and enhance the formation of reactive oxygen species. Extensive characterization techniques were employed to evaluate the structural, morphological, chemical, and optical properties of the synthesized materials. X-ray diffraction (XRD) analysis revealed well-defined diffraction peaks corresponding to both AgVO3 and metallic Ag, confirming the successful formation of the composite structure. The absence of secondary impurity phases and the consistency of peak positions indicated the materials' purity and crystallinity. Application of the Debye–Scherrer equation enabled estimation of crystallite sizes and microstrain values, which correlated well with SEM observations. The calculated crystallite sizes further validated the nanoscale structure, confirming that the synthesis route effectively controlled crystal growth. Field emission scanning electron microscopy (FE-SEM) provided critical insights into the surface morphology of the materials. The Ag/AgVO3 particles exhibited a nanoscale morphology, with particle sizes typically ranging from 30 to 100 nm. The incorporation of g-C3N4 resulted in a layered, plate-like structure, while the rGO component introduced wrinkled, sheet-like formations that served as a conductive network. The SEM micrographs demonstrated that Ag/AgVO3 nanoparticles were uniformly distributed on the g-C3N4 and rGO surfaces, suggesting effective interaction among the components. This structural integrity is crucial for photocatalytic efficiency, as uniform distribution enhances interfacial charge transfer and increases the number of active sites. Energy-dispersive X-ray spectroscopy (EDS) confirmed the homogeneous presence of Ag, V, O, C, and N across the surface, providing strong evidence of successful composite formation. No unexpected elemental signals were detected, indicating that the synthesis method yielded chemically pure structures. Fourier-transform infrared spectroscopy (FTIR) was used to analyze the chemical bonding and structural integrity of the nanocomposites. The characteristic heptazine units of g-C3N4 were preserved, as evidenced by the presence of stretching vibrations associated with C–N and C=N bonds. The vibrational bands corresponding to Ag-O-V linkages provided further confirmation of the AgVO3 phase. The absence of foreign functional groups indicated that the synthesis and combination procedures did not alter the intrinsic chemical framework of the constituent materials. The optical properties, which play a central role in photocatalytic applications, were evaluated using diffuse reflectance spectroscopy (DRS). Kubelka–Munk transformations were applied to determine the band gap energies. Pure g-C3N4 exhibited a typical band gap of approximately 2.7 eV, while AgVO3 showed stronger absorption in the visible-light region. Notably, the integration of rGO and metallic Ag nanoparticles led to a significant red-shift in the absorption edge, indicating improved light harvesting capability and narrowing of the effective band gap. These optical enhancements are attributed to the surface plasmon resonance (SPR) of metallic Ag and the high conductivity of rGO, both of which facilitate electron excitation under visible-light irradiation. The photocatalytic activity of the nanocomposites was evaluated measuring the degradation of the carmoisine dye under visible light. The time-dependent absorbance spectra clearly demonstrated a substantial reduction in dye concentration, particularly for the quaternary composite containing g-C3N4, Ag/AgVO3, and rGO. Comparative analyses showed that the quaternary system achieved over 90% degradation, outperforming binary and ternary nanocomposites. The enhanced activity is attributed to synergistic mechanisms operating within the composite. Kinetic evaluation using a pseudo-first-order model revealed a significantly higher reaction rate constant (k), confirming that the composite accelerates the photocatalytic process by enabling faster charge separation and more efficient generation of reactive oxygen species such as hydroxyl radicals (•OH) and superoxide radicals (•O2⁻). A mechanistic pathway for the photocatalytic degradation process was proposed based on the combined characterization results. Visible-light excitation generates electron–hole pairs on both g-C3N4 and AgVO3 surfaces. The metallic Ag component enhances light absorption through the SPR effect and acts as an electron mediator, rapidly transferring electrons to rGO. This prevents electron–hole recombination and promotes the formation of reactive radicals. The holes generated in the valence band of semiconductors engage in oxidation reactions that initiate cleavage of the azo bonds in Carmoisine, leading to progressive degradation and mineralization into CO2, H2O, and less harmful by-products. This multi-step mechanism highlights the importance of interfacial engineering in designing high-performance photocatalysts. In conclusion, the findings demonstrate that the Ag-AgVO3@rGO@g-C3N4 composite synthesized in this study holds strong potential as an efficient and robust visible-light- driven photocatalyst. Its superior performance arises from the complementary interactions among its components, resulting in enhanced structural stability, optical response, and charge-carrier dynamics. The integration of these features not only improves photocatalytic degradation efficiency but also supports the development of sustainable approaches for removing persistent organic pollutants. The results provide valuable insight into the design principles of advanced multi-component photocatalysts and lay the groundwork for future research aimed at large-scale environmental remediation technologies. The significance of Ag/AgVO3 hybrid materials lies in their optical activity, charge-separation ability, and potential for environmental remediation. Although the primary scope of this thesis centered on material preparation and characterization, the properties observed here are foundational for future application-oriented research. The presence of metallic Ag on the semiconductor matrix is known to enhance light absorption, create electron–hole separation sites, and improve catalytic activity. These well-established mechanisms are consistent with the structural observations obtained in this study. When the synthesis–characterization relationship is evaluated holistically, it becomes clear that the controlled hydrothermal approach successfully produced nanostructures with desirable physicochemical properties. The close agreement between different characterization techniques confirms the reproducibility and stability of the synthesized material. The outcomes also demonstrate that tuning synthesis parameters—such as precursor type, pH, and reaction duration—can strongly influence the final material quality. In conclusion, this work contributes to the growing field of research on silver-based vanadate nanostructures by providing a reproducible synthesis pathway and in-depth characterization. The fundamental data obtained here creates a solid framework for future modifications, performance evaluations, and application-driven developments in environmental and catalytic technologies.
Benzer Tezler
- Bazı gıda renklendiricilerinin Zea mays L. var. saccharata Sturt. üzerindeki genotoksik etkileri
The genotoxic effects of some food colorants on Zea mays L. var. saccharata Sturt.
SALİH DİKİLİTAŞ
- Sentetik gıda boyalarının farklı özellikteki kompozit rezinlerin renk stabilitesi üzerindeki etkilerinin incelenmesi
Investigation of the effects of synthetic food dyes on the color stability of composite resins with different properties
BURÇİN DENİZ
Diş Hekimliği Uzmanlık
Türkçe
2023
Diş HekimliğiAkdeniz ÜniversitesiRestoratif Diş Tedavisi ve Endodonti Ana Bilim Dalı
PROF. DR. OSMAN TOLGA HARORLI
- Gıdalara katılan bazı suda çözünen sentetik boyaların belirlenmesi
Determination of some water soluble synthetic dyes in foodstuffs
MİTHAT DİNÇ
Yüksek Lisans
Türkçe
2007
Gıda MühendisliğiNamık Kemal ÜniversitesiGıda Mühendisliği Ana Bilim Dalı
DOÇ. DR. MUHAMMET ARICI
- Bazı gıda ürünlerinde kullanılan renk maddelerinin yüksek performans sıvı kromatografisi ile tayini ve optimizasyonu
Determination and optimization of color materials used in some food products with high performance liquid chromatography
EVREN KOÇ
- Gıda katkı maddesi olan karmosinin zebra balığı emriyoları üzerindeki toksik etkilerinin araştırılması
Investigation of the toxic effects of carmosin, a food additive, on zebrafish embryos
TUBA KIZILTAN
Yüksek Lisans
Türkçe
2022
Su ÜrünleriAtatürk ÜniversitesiNanobilim ve Nanomühendislik Ana Bilim Dalı
PROF. DR. SALTUK BUĞRAHAN CEYHUN