Photodegradation of FeDTPA in nutrient solutions. I. Effects of irradiance, wavelength, and temperature

Irradiation of FeDTPA-containing nutrient solutions by a fluorescent plus i ncandescent light source resulted in the loss of both Fe-chelate and solubl e Fe, the formation of a precipitate that was composed mostly of Fe, and a rise in pH. The rate of Fe-chelate photodegradation in solution increased w ith irradiance intensity and with solution temperature under irradiation, b ut irradiance had the greater effect. Fe-chelates absorb in the blue and UV regions of the spectrum. Removal of these wavelengths with a spectral filt er eliminated photodegradation. Chemical name used: ferric diethylenetriami nepentaacetic acid (FeDTPA).