Effect of pollutant gases on chlorophyll a multilayer

Abstract

The aim of this paper is to examine the direct effect of polluting gases on chlorophyll a (chl a) multilayer arrays. The pollutants studied are CO, CO2, SO2, H2S, NO, and NO2. Electronic and infrared spectroscopies were used to monitor the time effect of the polluting gases on chl a molecules. TLC, atomic absorption, and electronic spectroscopies were used to characterise the reaction products. The results show that neither CO nor CO2 affect the chl a molecules in the multilayer arrays. Upon exposure to SO2, we notice many modifications on the electronic and ir spectra. All the evidence confirms that one of the reaction products is pheophytin a. A mechanism is presented to explain the reaction of SO2 with chl a. The effect of H2S on chl a is less pronounced than that of SO2, but the end products are the same. NO and NO2 have exactly the same effect on the chl a multilayer. The reaction is much more drastic than the reaction of chl a with either SO2 or H2S. There is opening of the cycle and nitration of the chl a molecule.