Fate and behaviour of isopropyl N-(3- chlorophenyl) carbamate (chlorpropham) herbicide in the environment
Chapter two investigates the adsorption of chlorpropham on six different absorbents including three soil types; the adsorption-desorption of chlorpropham from soil including the development of an analytical method suitable for the analysis of chlorpropham residues in drinking water. The analytical method involved preconcentration of chlorpropham residues on a solid sorbent (C18) followed by elution with a suitable solvent to achieve an environmentally safe and sensitive method for the detection and quantification of chlorpropham. Octaedecyl silylbonded silica cartridges (C18) proved to be very efficient for the determination of chlorpropham residues with a high recovery and reproducibility of 97%. The adsorption study of chlorpropham was carried out on six different adsorbents including three soil types in an effort to find out their efficacy for the purification of chlorpropham polluted water. The studies were carried out using three types of soils - Downholland (peat), Midelney (clay), and Dreghorn (sand) - and charcoal, bark, wheat straw, at three different temperatures and concentrations. The results showed generally, that charcoal had the greater adsorption efficacy followed by tree bark, wheat straw, Downholland (peat), Midelney (clay), and Dreghorn (sand) soil under all investigated temperatures and concentrations. The desorption study was carried out to determine the extent of reversibility of the adsorption process for all the adsorbents under the same conditions of temperatures and concentrations. The results of the assessment indicated that desorption, in general, was more at higher temperature for all the studied adsorbents. However, for charcoal, adsorption was irreversible except at zero time at higher concentrations. For Downholland (peat), Midelney (clay) and tree bark, there was zero desorption at lower concentration levels.