Enhanced herbicide "imazapyr" adsorption from water by thermo- modified bentonite

This study deals with the development of thermally modified bentonite as an effective adsorbent for the removal of imazapyr herbicide from aqueous solution. XRD, SEM, and TGA analyses were used to characterize the material. Bentonite was calcined at 350-550°C for 3 and 12 h. Calcination at 350-500°C for 12 h increased the specific surface area strongly. Sample calcined at 500°C shows the highest surface area of 43.6 m2/g (BET) and 750 m2/g (BM). The calcined bentonite-500°C adsorbed approximately 65 % of imazapyr at an initial concentration of 30 mg/L, while bentonite adsorbed only 33 % under the same conditions. The effects of various factors on the adsorption, such as contact time, pH of the solution and amount of adsorbent, were studied. For both bentonite and bentonite-500°C the adsorption isotherm has been determined and data have been analysed according to the Freundlich model and found to be favourable. © by PSP 2007.