Chlorpyrifos pesticides are endocrine disruptors, inhibitors of acetyl cholinesterase, used to control pests and prime contributors to indoor pollution in retail stores. Seven selected locally sourced adsorbents; Bone charcoal (BCA), corncobs, cotton seed, kokoli, sawdust, coconut shell (CSA) and Muruchi were evaluated. Only BCA and CSA shows peaks and were further examined at adsorptive temperatures of 283, 293, 303 and 313K. Adsorbents physical properties that is, micro pore surface area, total pore volume; micro pore volume, particle density and true density were measured and compared. Results from gas chromatography and surface characterization revealed that the adsorptive capacities of carbon (CSA) at various temperatures were higher than that of carbon (BCA). The plots of Langmuir and Freundlich Isotherms were well fitted by the measured adsorption data. The parameters of adsorption equation for both Langmuir and Freundlich were determined for the two adsorbents, which indicates increased values of adsorptive capacity at low temperature and decreases at high temperature. This study shows that activated carbon made from coconut shell has high surface area, micro porous structure, high degree of surface reactivity and higher heterogeneous properties that suggest it to be a better adsorbent sufficient for the adsorption of chlorpyrifos vapour in an indoor environment.
Dr. A. J. Hotton
National Agency for Food and Drug Administration and Control, P.M.B. 1018, Jalingo, Taraba State, Nigeria.