Cu-MOF katkılı montmorillonit (Cu-MOF/MMT) adsorbanı ile atık sulardan ilaç giderimi
Drug removal from wastewater by using Cu-MOF added montmorillonite (Cu-MOF/MMT) adsorbent
Yazar: ELÇİN TUTUŞ
Danışman: DOÇ. DR. NALAN ERDÖL AYDIN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Kimya Mühendisliği Ana Bilim Dalı / Kimya Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: Kimya Mühendisliği = Chemical Engineering

Özet:
Su, yaşamın temel taşıdır ve varlığımızı sürdürmemiz için kritik bir öneme sahiptir. Su, doğal ve antropojenik kaynaklardan kaynaklanan su kirliliği nedeniyle çeşitli kirleticilerle karşılaşmaktadır. Bu kirleticiler arasında farmasötikler ve kişisel bakım ürünleri (PPCP'ler), insanların ve hayvanların sağlık ihtiyaçlarını karşılayan ürünleri içerir ve su ortamında sürekli varlıklarını sürdürdükleri için yeni tür kirleticiler olarak kabul edilmektedir. Antibiyotikler, dünya genelinde yaygın olarak kullanılan ilaçlar arasında öne çıkar. Özellikle tetrasiklinlerin artan kullanımı, su kaynaklarında çevresel sorunlara yol açmaktadır. Tetrasiklinlerin su ortamında birikimi, besin zinciri aracılığıyla insan ve hayvan sağlığına zarar verebilen düşük konsantrasyonlarda bile gerçekleşebilir. Ayrıca, tetrasiklinlerin su kaynaklarındaki varlığı, antibiyotiklere dirençli bakterilerin ortaya çıkmasına neden olarak ciddi tehditlere yol açabilir. Kil mineralleri, uygun fiyatlı ve çevre dostu olmaları nedeniyle tercih edilmekte ve smektit grubu kil minerallerinden biri olan montmorillonit, özellikle adsorpsiyon ve iyon değişimi performansı ile dikkat çekmektedir. Metal iyonları veya kümeleri ile organik ligandların birleştirilmesiyle oluşturulan yüksek kaliteli metal-organik çerçeveler (MOF'lar), spesifik yüzey alanı, tasarlanabilir çerçeve yapısı, kontrol edilebilir gözenek boyutu, metal doymamışlık bölgeleri ve modifikasyon kolaylığı gibi avantajlara sahiptir ve adsorpsiyon kapasitesi ve kinetiği açısından geleneksel adsorbanlara göre üstün performans sergileyebilirler. Ortaya çıkan kirleticilerin su ortamından uzaklaştırılması için çeşitli yöntemler araştırılmıştır. Adsorpsiyon, bu kirleticilerin atık su ortamından etkili, ekonomik, hızlı, kolay ölçeklenebilir ve çevre dostu bir şekilde uzaklaştırılmasını sağlayan bir teknoloji olarak öne çıkmaktadır.
Bu tez çalışması, Cu-MOF katkılı montmorillonit adsorbanının, adsorpsiyon yoluyla sulu ortamdan tetrasiklin giderimini sağlamak amacıyla gerçekleştirilmiştir. Bu çalışmanın ilk aşamasında, farklı oranlarda Cu-MOF kullanılarak sentezlenen kompozitler, FTIR, XRD, BET, SEM ve zeta potansiyel ölçümleri ile karakterize edilmiş ve başarılı bir şekilde sentezlendiği doğrulanmıştır. Sonraki aşamada, başlangıç konsantrasyon, temas süresi, çözelti pH'ı ve sıcaklık gibi parametrelerin adsorpsiyona etkisi değerlendirilmiştir. Yapılan deneyler sonucunda TC'nin sulu ortamdan gideriminde %10Cu-MOF/MMT kompoziti en uygun adsorban olarak seçilmiştir. TC adsorpsiyonu için 240 dakika temas süresinde, pH 7.32'de (çözeltinin kendi pH değerinde), 45 °C sıcaklıkta en yüksek adsorpsiyon kapasitesi 319,57 mg g-1 olarak elde edilmiştir. İzoterm modellemeleri sonucunda TC adsorpsiyonunun Langmuir modeliyle uyumlu olduğu ve adsorpsiyon kinetiğinin yalancı ikinci derece modelini takip ettiği gözlemlenmiştir. Termodinamik analizler sonucunda, TC adsorpsiyonunun endotermik olduğu ve kendiliğinden gerçekleştiği tespit edilmiştir. Bu çalışma, atıksulardan adsorpsiyonla TC giderimi için %10Cu-MOF/MMT adsorbanının umut vaat edici nitelikte olduğunu göstermiştir.

Abstract:
Water is the basic element of all life and one of the most critical elements of the environment. Extensive urbanization, industrialization, and uncontrolled population growth have increased the pressure on available water resources. This has resulted in decreasing water quantity and deteriorating water quality, making water pollution a serious global concern.
Water pollution is caused by natural and anthropogenic sources, resulting in the emergence of different water pollutants. Emerging contaminants show adverse ecological and human health effects in case of continuous long-term exposure. Emerging contaminants are produced from different sources and are classified as pharmaceuticals and personal care products (PPCPs), pesticides, veterinary products, industrial by-products, food additives and engineering nanomaterials. Pharmaceuticals and personal care products (PPCPs) often combine products that meet the health-related needs of humans or animals. Pharmaceuticals and personal care products (PPCPs) often combine products that meet the health-related needs of humans or animals. PPCPs have recently been identified as emerging new types of pollutants as they are continuously present in the aquatic environment. There is an increase in the use of pharmaceuticals every year and drug abuse is becoming an increasingly important problem, resulting in the formation of drug residues in the environment. 
Antibiotics are among the most widely used drugs worldwide. The increasing use of Tetracyclines, which are widely used among antibiotics and have different application areas, has brought environmental problems. In recent years, Tetracyclines have been observed especially in groundwater and surface waters. Tetracyclines can accumulate in human and animal bodies through the food chain and can harm human and animal health even at low concentrations. In addition, the presence of these antibiotics in water resources poses a serious threat to human and animal health by causing the emergence of antibiotic-resistant bacteria. 
Antibiotics have long been difficult to remove from aqueous media because of their special physicochemical characteristics, low concentrations in environmental matrices, stable chemical structures, and non-biodegradable nature.
Researches have been carried out on various methods for the removal of antibiotics, which are included in the emerging pollutants group, from the aqueous media. Among these methods, adsorption is considered as a suitable, economical, fast, easily scalable, operationally feasible and generally environmentally friendly technology for the effective removal of antibiotics from wastewater. 
In recent years, the use of clay minerals and metal-organic frameworks as adsorbents for drug removal by adsorption from aqueous media has become quite popular. The fact that clay minerals, which have large reserves in nature, have good adsorption and ion exchange performances, are cheap and environmentally friendly, and serve a function in a promising high-quality adsorbent has led to their widespread use in wastewater treatment. Monmorillonite, a smectite group clay mineral, is a Food and Drug Administration-approved material, as well as being stable under acidic conditions, having high chemical resistance, large specific surface area and high potential for ion exchange. 
Metal-organic frameworks (MOFs) formed by combining organic ligands with metal ions or clusters are high quality materials with significant specific surface area, designable framework structure, controllable pore size, metal unsaturation sites and ease of modification. When the studies in the literature are examined, MOFs have shown better adsorption capacity and kinetics than conventional adsorbents in the removal of pollutants from wastewater. Among metal oranic frameworks, copper-metal organic frameworks (MOFs) are remarkable for their different pore sizes, large surface area and ease of synthesis.
There is no study in the literature on the removal of Tetracycline from wastewater by adsorption with Cu-MOF/MMT structure. For this reason, this study is an innovative study that has led the way in obtaining alternative structures for the removal of tetracycline from wastewater by adsorption.
The thesis study was carried out in order to provide the removal of Tetracycline from aqueous media by adsorption of Cu-MOF doped Montmorillonite adsorbent synthesized in line with the study. In the first stage of the study, Cu-MOF doped Montmorillonite composites (5%Cu-MOF/MMT, 10%Cu-MOF/MMT, and 20%Cu-MOF/MMT) were synthesized using three different ratios of Cu-MOF and these composites were characterized by FTIR, XRD, BET, SEM, and zeta potential measurements and it was confirmed that the composite was successfully synthesized.
In the next step, the effect of antibiotic initial concentration, contact time, solution pH, and temperature parameters on adsorption was evaluated, and adsorption isotherms, adsorption kinetics, and adsorption thermodynamics were analyzed.  
As a result of the experiments performed with varying TC initial concentrations (10-60 ppm) to determine the adsorbent with the most favourable Cu-MOF ratio to be used in TC adsorption experiments, 10%Cu-MOF/MMT adsorbent was determined as the most suitable adsorbent for the removal of TC from aqueous media, and the maximum adsorption capacity for TC was determined as 280,55 mg g-1. It was found that the adsorption capacity increased with increasing initial concentration of TC, but no significant increase in adsorption capacity was observed when the initial concentration of TC increased above 50 ppm.
Adsorption experiments were carried out to evaluate the effect of the contact time. The adsorption capacities of 10%Cu-MOF/MMT adsorbent for TC adsorption from aqueous media were evaluated for certain time intervals. As a result of contact time studies, the equilibrium time of the system was determined as 240 minutes and the adsorption capacity obtained at 240 minutes was determined as 247,56 mg g-1. 
Adsorption experiments were carried out to evaluate the effect of pH for TC adsorption. The adsorption capacities of 10%Cu-MOF/MMT adsorbent for TC adsorption from aqueous media for different pH values (2-12) were investigated. As a result of pH experiments, similar results were obtained in the adsorption capacity in the acidic and neutral pH range for TC removal from aqueous media with 10%Cu-MOF/MMT adsorbent, while a relative decrease in adsorption capacity was observed at high basic pH (pH=12). The maximum adsorption capacity of 10%Cu-MOF/MMT adsorbent for TC was obtained at its own pH of aqueous solution (pH=7.32) and was determined as 247,56 mg g-1. 
The thermodynamics of adsorption was evaluated. The enthalpy value of 11,09 kJ mol-1 indicates that TC adsorption is physical adsorption. When the change in free Gibbs energy was analysed, the ∆G° values obtained for each temperature were negative and decreased with increasing temperature. This indicates a spontaneous adsorption process and spontaneity increased with increasing temperature. Positive ∆S° values indicate randomisation at the solid-solution interface during adsorption. 
As a result of the isotherm studies, it was found that TC adsorption of 10%Cu-MOF/MMT adsorbent from aqueous media occurred according to the Langmuir isotherm model, and it was observed that the adsorption kinetics conformed to the pseudo-second-order kinetic model. Finally, the thermodynamics of adsorption was evaluated and it was found that the adsorption of Tetracycline was endothermic and spontaneous. 
As a result of the experiments, the highest adsorption capacity of 10%Cu-MOF/MMT adsorbent for Tetracycline removal from aqueous media was obtained as 319,57 mg g-1 at a contact time of 240 minutes, pH of 7.32 (pH value of the solution), temperature of 45 °C and optimum conditions for adsorption experiments were determined.
In conclusion, it was concluded that 10%Cu-MOF/MMT composite is a promising adsorbent for Tetracycline removal from wastewater by adsorption.