Master of Science in Chemical Engineering (MSChE)
Polycyclic aromatic hydrocarbons (PAHs) form a major class of air pollutants. Naphthalene is a commonly found PAH in the atmosphere. Atmospheric fog water contains naphthalene absorbed from surrounding air. The partition coefficient of naphthalene is defined as the ratio of total naphthalene concentration in fog water to total naphthalene concentration in air. The purpose of this research was to determine the partition coefficients of naphthalene for varying reactor temperature. Fog was artificially formed in a predesigned reactor. NaCl aerosols were used as condensation nuclei for fog formation. Fog droplets were exposed to naphthalene vapors in the reactor. The reactor provided 62 seconds residence time for fog droplets. Fog was then condensed using a heat exchanger at the reactor outlet. Compressed air was used as a carrier gas for the experiment. Naphthalene concentration in the collected condensate and exit gas was determined using High Performance Liquid Chromatography (HPLC). Partition coefficients were calculated at 334K, 346.5K, 361.5K and 371.5K. The experimental results indicated a decrease in partition coefficient with increasing temperature. Earlier work has demonstrated presence of products of naphthalene photooxidation as 1-naphthol, naphthoquinones, benzoquinones, phthalide and 1,3-indandione. The aim of this research was also to determine products of naphthalene photooxidation reaction within the fog condensate containing water, naphthalene and NaCl under UV light. The fog condensate was exposed to UV light for time intervals between 0 to 5 hours. Experimental observations showed a decrease in naphthalene concentration with time. Overall reaction rate constant k for naphthalene was determined to be 0.00567/min and detected reaction products were phthalide and benzaldehyde. Same experiment was performed using a reaction mixture which consisted only of water and naphthalene with compete absence of NaCl which showed that the value of k was decreased to 0.00147/min with complete absence of benzaldehyde in the reaction products. Along with phthalide, 1-3 indiandione was also observed as a product of the reaction. It was concluded from both the experiments that presence of NaCl changed product formation and reaction rate of naphthalene photooxidation and also lowered the value of partition coefficient at 298K as compared to pure water.
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Damle, Neha Shrikant, "Fog-smog reactor and photooxidation of naphthalene within the fog condensate in a UV light setup" (2008). LSU Master's Theses. 3999.
Kalliat T. Valsaraj