Photodegradation Kinetics of Rimsulfuron in Senegalese Surface and Groundwater, and Determination of Its Herbicidal Activity

Abstract

The objective of this study was to examine the photodegradation of rimsulfuron in natural waters from the Niayes agricultural zone in Senegal. This was conducted in both the presence and absence of oxalic acid, which acts as a photosensitiser. The photodegradation values of rimsulfuron in distilled water and natural waters were found to be 15.52% and 6.3% to 7.19%, respectively. The results demonstrate that rimsulfuron is relatively stable in natural waters under solar radiation in the absence of photosensitiser. The photodegradation percentage in distilled water was 68.57%, while the range in natural water was from 16.98% to 40.32%. The results clearly show that oxalic acid significantly accelerates the photodegradation of the herbicide rimsulfuron. The photodegradation reaction half-life time varies considerably, from 144.41 to 693.15 minutes, with the highest value observed in surface water (runoff water), which generally contains a greater quantity of dissolved organic matter. We then examined the herbicidal activity of the compound in question. The results of this study indicate that the herbicidal activity of rimsulfuron may be attributed to either the initial product or a combination of the initial product and its photoproduct.