Bisfenol A'nın katalitik, fotokatalitik ve ozonlama yöntemleri ile arıtılabilirliğinin incelenmesi = Investigation of Bisphenol A's improvement by catalytic, photocatalytic and ozonation methods

Abstract

Bisfenol A (BFA) kimyasal olarak bir köprü ile bağlı iki fenol halkasından ve köprüye bağlı iki metil fonksiyonel grubundan oluşan organik bir bileşiktir. En yaygın kullanılan endüstriyel kimyasal olan Bisfenol A'nın çevreye ve insan sağlığına olumsuz etkileri belirlenmiştir. Endokrin bozucu olarak bilinen Bisfenol A günlük yaşantımızda sıkça kullanılan malzemelerin ham maddesi olarak kullanılmaktadır. Plastik şişe ve kaplarda, metal konserve kutularının iç tabakalarında, elektronik eşyalarda, ev eşyalarında (halı, koltuk, perde, vb), oyuncaklar, kozmetik malzemeler, kişisel temizlik ürünleri, ev temizlik ürünleri, plastik borular ve pestisitler gibi ürünlerin bileşiminde bulunuyor. Ortamda çok az miktarda olsalar da etkilerinin fazla olduğu muhtemeldir. Günlük yaşantımızda sıkça kullandığımız bu ürünler yüzünden çevreye çok fazla endokrin bozucu Bisfenol A kimyasalı karışmış olmaktadır. Bu sebeple yüzey akış sularında, atıksu arıtma tesisleri çıkış sularında ve katı atık depolama alanlarından çıkan çöp sızıntı sularında görülmüştür. Bu çalışmada BFA'nın giderimi için yüksek verime sahip olan ileri arıtma proseslerinden ozonlama, katalitik ozonlama ve fotokatalitik ozonlama prosesleri kullanılmıştır. Laboratuvar ortamında sentetik olarak üretilen 50 mg/L BFA atıksuyu kullanılmıştır. Deneylerde proseslere etki eden pH, ozon dozu, ZnO dozu, ışık gücü ve reaksiyon süresi parametreleri incelenmiştir. İncelenen parametrelerde, parametre aralıkları geniş tutularak en iyi değeri aldığımız durumlar optimum koşulları sağlamıştır. Deneyler sonucunda ozonlama prosesinde optimum şartlar pH 6,32, ozon dozu 2400 mg/L ve 45 dk. reaksiyon süresi bulunmuş ve arıtım verimi %93,37 olarak belirlemiştir. Katalitik ozonlama prosesinde ise pH 6,32, 10 mg/L ZnO dozu, 1800 mg/L ozon dozu ve 45 dk. reaksiyon süresi bulunmuş ve arıtım verimi %95,55 olarak hesaplanmıştır. Üçüncü ve son prosesimiz olan fotokatalitik ozonlamada ise pH 6, 10mg/L ZnO dozu, 3000 mg/L ozon dozu, 18 Watt ışık gücü ve 45 dk. reaksiyon süresi belirlenmiş olup arıtım verimi %98,92 olarak bulunarak çıkan sonuçlar karşılaştırılmıştır. Her üç proses için kinetik modeller incelenmiş ve her üç proses için ikinci mertebe kinetik model en uygun model olarak bulunmuştur.

Bisphenol A (BPA) is an organic compound consisting of two phenol rings chemically linked by a bridge and two methyl functional groups attached to the bridge. Bisphenols have emerged as contaminants of concern in recent years due to common human exposures and toxicities, including estrogenicity, cytotoxicity, genotoxicity and carcinogenicity. The negative effects of Bisphenol A, the most widely used industrial chemical, on the environment and human health have been determined. Bisphenol A, known as an endocrine disruptor, is used as a raw material for frequently used materials in our daily life. BPA is found in plastic bottles and containers, the inner layers of metal cans, electronics, household goods (carpets, armchairs, curtains, etc.), toys, cosmetics, personal cleaning products, household cleaning products, plastic pipes and pesticides. Although they are in very small amounts in the environment, their effects are likely to be high. Due to these products, which we frequently use in our daily lives, Bisphenol A chemical, which is an endocrine disruptor, is mixed with the environment. For this reason, it has been seen in surface runoff waters, wastewater treatment plant effluent, and garbage leachate from solid waste landfills. Although the removal of BPA is done biologically, it has been found in the effluent of efficiently modeled domestic and industrial wastewater treatment plants. Many studies have documented the adverse effects of BFA, known as an endocrine disruptor chemical, on human health. Accordingly, many countries have restricted the use of BFA and actively encouraged scientists and industries to seek alternative substances. BFA is considered dangerous to human health due to its well-known estrogenic activity. Other adverse effects related to metabolism disruption, neuroendocrine defects and behavioural changes in children have been reported recently. Potential health concerns have led to banning the use of BPA in bottles and baby food packaging. According to the latest developments in toxicology, the European Food Safety Authority reduced the safe level of BFA from 50 μg/kg body weight/day to 4 μg/kg body weight/day in 2015. Human BFA exposure has recently received appropriate attention due to the fact that it is related to adverse effects on male reproductive function, impairing thyroid function. In the past half-century, plastics have become indispensable for human life. For this reason, the role of plastic is widely used in many branches of industry due to its ease of processing and low cost compared to other materials. One of the most produced chemicals in the world is Bisphenol-A. In 2015, its global use reached 7.7 million metric tons. Bisphenol A is a synthetic compound that is a pioneer in the manufacture of plastics widely used in the manufacture of water bottles and food storage containers. Adult foods, and especially canned foods, are considered an important source of BFA exposure. BFA concentrations in non-canned foods are lower compared to canned foods. It has been observed that the negative effects of endocrine disrupting compounds on the environment and animal health have increased over the past years. As a result of the discharge of wastewater generated from the use of BFA in industrial processes, it is inevitable that it mixes with sewage waters and groundwater and affects the aquatic ecosystem. Once released during production and use, BFA can be converted or degraded through abiotic and biological processes in the aquatic ecosystem. Abiotic processes, including photodegradation and advanced oxidation, can effectively remove BFA with the main conversion products of 4-isopropenylphenol and 4-hydroxycumyl alcohol. The increasing popularity of ozone applications in recent years is mainly due to two factors. The costs associated with ozone production have decreased significantly over the last decade and ozone offers environmental advantages over chlorine. Ozone is an unstable gas; Therefore, its production must be done on-site. Commercially available technology for ozone production is based on the corona discharge process, which involves applying a high-voltage discharge in a cooled/dried gas phase containing oxygen (O2). Ozonation is an effective alternative to treating wastewater containing complex organic metals. AOPs are among the most effective methods for removing organic pollutants. Recently, studies on catalytic ozonation processes (COP) among the methods of AOPs stand out. Adding a catalyst to the ozonation process effectively improves ozone utilisation efficiency and enhances the decomposition of ozone to form hydroxyl radicals (OH•) with oxidative solid stability. The simultaneous combination of ozone and a photocatalyst in the presence of UV radiation, called photocatalytic ozonation, generates hydroxyl radicals from ozone molecules on the catalyst surface, forming ozonide radicals. The rapid reaction of the ozonite radical with H+ yields HO.3, followed by hydroxyl radicals. Therefore, surface reactions of UV irradiation with a semiconductor catalyst can play a major role in photocatalytic ozonation for removing Bisphenol-A from aqueous solutions. In the presence of ZnO and UV radiation, the adsorbed ozone acts as a powerful electrophilic agent generating ozonide radicals. At the same time, other reactions eventually produce hydroxyl radicals in the adsorption layer. To our knowledge, no research has been conducted on photocatalytic ozonation using the O3/ZnO/UV combination of Bisphenol-A. The main objective of this study is the combined effect of UV/Ozone/ZnO on the degradation of aqueous solutions of Bisphenol-A. In this study, ozonation, catalytic ozonation and photocatalytic ozonation processes, which are advanced treatment processes with high efficiency for the removal of BPA. Experiments have been used 50 mg/L BPA wastewater produced synthetically in the laboratory. In the experiments, the parameters of pH, ozone dose, ZnO dose, light power and reaction time, which affect the processes, have been investigated in the experiments. In the parameters examined, the parameter ranges were kept wide, and the conditions where we got the best value provided the optimum conditions. In the catalytic ozonation process, pH 6.32, 10 mg/L ZnO dose, 1800 mg/L ozone dose and 45 min reaction time have been found as the optimum conditions and the treatment efficiency has been achieved as 95.55%. In our third and last process, photocatalytic ozonation, pH 6, 10 mg/L ZnO dose, 3000 mg/L ozone dose, 18 Watt light power and 45 min reaction time have been determined and the BPA removal efficiency has been obtained as 98.92%. The kinetic models for all three processes have been examined and the second-order kinetic model has been found to be the most suitable model for all three processes.