Université de Kinshasa, Faculté des Sciences et Technologies, Département de Chimie et Industrie, Laboratoire de Chimie Organique et d’Energétique, BP 190, Kinshasa XI, RD Congo
The present study aimed to improve the solar water disinfection by the photosensitization of coumarin extracts of some plants of the Rutaceae family (Citrus reticulata, Citrus aurantium and Citrus maxima). The results found in this work show an inhibition of around 7% of faecal coliforms after 15 minutes of exposure for solar disinfection. An inhibition of 17 % is noticed after 30 minutes of exposure. On the other hand, for water treated and exposed to the sun, an inhibition of around 90% is noticed for all the extracts after 30 minutes of exposure. Complete inhibition is recorded after 60 minutes of exposure. These results show that the plant extracts used improve significantly the solar disinfection of water. The photosensitizing activity observed in these extracts is due to the presence of coumarins. These molecules, in the presence of light, absorb energy and pass from the ground state to the excited state. Returning to the ground state, the stored energy is transferred to the oxygen, which then passes from the ground state, triplet, to the excited state, singlet, and inhibits the microorganisms present in the water.
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