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Research of Photodegradation of Phenanthrene, Pyrene And RESEARCH OF PHOTODEGRADATION OF PHENANTHRENE, PYRENE AND CHRYSENE ADHERING TO POLYETHYLENE IN THE WATER A Thesis Presented By ZHIPIN MAO To The Department of Civil and Environmental Engineering in partial fulfillment of the requirement for the degree of Master of Science in the field of CIVIL ENGINEERING Northeastern University Boston, Massachusetts April 2018 II ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) play an important role in the manufacturing industry. However, some PAHs are carcinogenic or mutagenic. Aqueous PAH contamination is widespread. Due to the low solubility in the water, they are likely to be absorbed in plastics. Phenanthrene, pyrene, and chrysene are three PAHs with different structures. In this project, there are two existing states of phenanthrene, pyrene, and chrysene: dissolved in water and adsorb on PE circle. Each existence state of phenanthrene, pyrene, and chrysene was irradiated using a UV lamp for 2 hours respectively. The total mass of irradiated PAHs was detected by GC-MS to identify the photodegradation ratio of each chemical. The sorption of pyrene on the PE circles increases the photodegradation. However, obvious photodegradation ratio cannot be detected on chrysene. III ACKNOWLEDGEMENT I would like to thank my advisor, Loretta A. Fernandez, for providing me the opportunity to work in her group. I have a deep gratitude to her for her patience, encouragement, guidance, help and advice for my master’s research, coursework and my future career development. Thanks to Professor Philip Larese-Casanova providing me UV lamp to finish the research. Thank you to all my thesis readers and your precious advice and encouragement. Besides, this project would not be possible without the support of Northeastern University to provide me facilities for conduction experiment. Thanks to all my lab friends: Magdalena, Yuwei, Yumeng and Wenjie who gave me support in experiment. Thanks to my parents, my fiancé, and my friends, who always be my supporter to encourage me when I met the problems. IV TABLE OF CONTENT ABSTRACT .................................................................................................................................................. II ACKNOWLEDGEMENT ........................................................................................................................... III CHAPTER 1 INTRODUCTION ....................................................................................................................... 1 1.1 Characteristics of Polycyclic Aromatic Hydrocarbons ............................................................................ 1 1.2 Environmental Hazards of PAHs ............................................................................................................. 2 1.3 PAHs and PE ........................................................................................................................................... 2 1.4 Phenanthrene, pyrene and chrysene ......................................................................................................... 3 1.5 GC-MS method detect trace organic compound ...................................................................................... 4 1.6 Objectives and hypothesis ........................................................................................................................ 5 CHAPTER2 EXPERIMENTAL METHOD ...................................................................................................... 6 2.1 Chemicals and reagents ............................................................................................................................ 6 2.2 Methanol-PAHs Samples Preparation ..................................................................................................... 6 2.3 Photo-irradiation ...................................................................................................................................... 6 2.4 Samples extraction ................................................................................................................................... 7 2.5 GC-MS sample preparation ..................................................................................................................... 7 2.6 Standard samples preparation .................................................................................................................. 7 2.7 GC-MS setting ......................................................................................................................................... 8 CHAPTER 3 RESULTS AND DISCUSSION .................................................................................................. 9 3.1 Pyrene results ........................................................................................................................................... 9 3.2 Chrysene results ..................................................................................................................................... 13 3.3 Discussion .............................................................................................................................................. 14 CHAPER 4 CONCLUSION ............................................................................................................................ 16 REFERENCES ................................................................................................................................................ 17 1 CHAPTER 1 INTRODUCTION 1.1 Characteristics of Polycyclic Aromatic Hydrocarbons Polycyclic aromatic hydrocarbons, abbreviated as PAHs, refers to hydrocarbons which contain two or more benzene rings in the molecule. PAHs can be classified into aromatic fused rings and aromatic non-fused rings. The aromatic fused ring refers to the hydrocarbon compound in which at least two carbon atoms are shared by adjacent benzene rings in one molecule, such as naphthalene, anthracene, phenanthrene, pyrene, etc.; the aromatic non-fused ring refers to that the hydrocarbon compound in which only one carbon atoms connected adjacent benzene rings in one molecule, such as biphenyl and terphenyl. The natural source of polycyclic aromatic hydrocarbons in the environment is mainly synthesized by microorganisms and higher plants, which can promote plant growth. Besides, a certain amount of PAHs are also produced along with the volcanic activity, forest fires, and grassland fires. While present naturally in the environment in low concentrations, they are primarily produced by anthropogenic activities such as incomplete combustion of organic materials (Rubio-Clemente et al. 2013). The major sources of PAHs in the environment are man-made, which are mainly caused by the incomplete combustion of coal, petroleum, wood, and organic polymer compounds, most of them come from the chemical industry, transportation, and daily life. The PAHs in water can be in three states: adsorbed on suspended solids; dissolved in water, or emulsified. The pentacyclic or higher polycyclic aromatic hydrocarbons are mainly colorless or yellowish crystals, some of which have a dark color. Those polycyclic aromatic hydrocarbons have high melting point and boiling point, which means the vapor pressures of PAHs are low. Polycyclic aromatic hydrocarbons are mostly insoluble in water, and the octanol-water partition coefficient is relatively high. Most PAHs have a large conjugation system, so their solution has some fluorescence. Its chemical properties are stable and difficult to hydrolyze. The most prominent characteristics of PAHs are carcinogenic, teratogenic and mutagenic. When PAHs interact with –OH、-NH2、-NO2, they would produce more carcinogenic derivatives. In addition, 2 PAHs easily absorb light in the visible (400-760mm) and ultraviolet (290-400mm) regions of sunlight, and are particularly sensitive to photochemical reactions caused by UV radiation. 1.2 Environmental Hazards of PAHs Although the presence of PAHs in the environment is trace, it is continuously generated, migrated, transformed and degraded, and enters humans and other organisms through the respiratory tract, skin, and digestive tract. Chemical carcinogenesis refers to the process by which chemical substances cause normal cells to transform and develop into tumors. Chemical carcinogenesis can be divided into direct carcinogens and indirect carcinogens, and polycyclic aromatic hydrocarbons belong to the latter. The carcinogenic effects of polycyclic aromatic hydrocarbons have seriously affected human health. In recent years, the incidence of lung cancer and mortality have risen significantly in various countries. The facts indicate that PAHs are an important cause of the increase in the incidence of lung cancer. Due to its high toxicity, PAHs have a strong effect on the central nervous system and blood, especially polycyclic aromatic hydrocarbons with alkyl side chains, which are highly irritating to the mucosa and highly anaesthetic. Therefore, PAHs have mainly been studied in the past concentrated on the body's metabolic active productions working on the organism's toxic effects and carcinogenic activity. However, more and more studies have shown that the real danger of PAHs is their phototoxic effects when they are exposed to UV light in sunlight. Scientists defined the phototoxic effect of PAHs as a significant effect of UV irradiation on the toxicity of PAHs. Experiments have shown that simultaneous exposure to PAHs and UV irradiation accelerates free radicals that have the ability to damage cells.
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