Removal of dissolved organic matter from water by adsorption-flocculation using organobentonite

Bentonite modified with short chain cationic surfactant might be the basis of a new approach to removing dissolved organic matter (DOM) from water. The treatment process involves dispersing bentonite to the DOM-containing water and then adding a small cationic surfactant to result in flocs which are agglomerates of organobentonite and bound DOM. The flocs are then removed from the solution by sedimentation. Experimental results indicate that Benzyltrimethylammonium bromide (BTMA)-bentonite displays a high affinity for DOM, most likely due to aromatic groups in the DOM molecule interacting with the benzene ring in the BTMA ion through increased pi-pi type interactions. Under appropriate operating conditions, 75% DOM removal and nearly 100% bentonite recovery could be achieved by the adsorption-flocculation process using BTMA-bentonite. Additionally, the rapid adsorption kinetics made adsorption-flocculation with BTMA-bentonite attractive for continuous treatment of large volumes of raw water. The bentonite may function as a recyclable surfactant medium for the adsorption and subsequent combustion of organic pollutants.