The Effect Of Copper And Irom On The Pohotodegradation Of Atrazine In Water Environment

Humic acids(HA) is the most widespread organic substances in natural waters. Copper and Iron are ubiquitous elements in natural water. All of them own optical activity. The Cu(II)-HA complex and Fe(III)-HA complex could affect the photodegradation of persistent toxic substances significantly. In this work, the degradation mechanism of atrazine with Cu(II),Fe(III), HA and their complex are explored under simulated sunlight. Activity species produced from these actions are detected by electron paramagnetic resonance(ESR). The work are helpful in understanding the potential mechanism of PTS photodegradation in natural waters and getting more insights into photosensitizing properties of Cu(II)-HA and Fe(III)-HA complex. The main results are as following.(1) Atrazine photodegradated directly under the mercury lamp irradiation. Low concentration of HA promoted the degradation of atrazine. And the reaction followed the level dynamics equation. The photodegradation rate of atrazine was enhanced when irradiated by strong intensity of Xe lamp. HA restrained the photodegradation of atrazine, the more the obviously. Atrazine degradated both directly and indirectly under weak intensity of Xe lamp irradation. Low concentration of HA promoted the photodegradation while high concentration restraint the photodegradation. Atrazine almost didn't degradate under the simulated sunlight. And HA didn't behave any promotion.(2) Cu(II) solution could generated active oxygen radicals(ROS) under the Xe lamp irradation. Copper element recycled between Cu(I) and Cu(II). ROS could react with dissolved oxygen and produce strong oxidizer·OH. Cu(II) co-existing with HA could generate stronger 1O2 than HA alone. Both of the radicals could promote the degradation of atrazine and were detected by electron paramagnetic resonance(ESR).(3) The Xe lamp in combination with a special glass filter restricting the transmission of wavelengths below 290 nm was used for sunlight simulation. The photodegradation of atrazine was promoted by both Fe(III) and HA after 120 h irradiation. The promotion was obvious as the concentration raised. And their was a proper concentration of Fe(III) and HA. The complextion of Fe(III) and HA was reflected on UV-Vis spectra. The absorption of the complextion in visible region enhanced, which would be of great benefit to degradating pollutions surviving in natural environment. The fluorescence spectra of HA was quenched by Fe(III), which confirmed functional groups on HA were complexed by Fe(III).In summary, this study is about the effect of three important factors in environment on the photodegradation of atrazine under differdent light sources. The study would provide valuable insights into the different role of humic materials on pollutants fate in natural surface waters.