(25b) Hydrophobically Modified Biopolymer As Enhanced Carrier for in Situ Groundwater Remediation

Carbon submicrospheres as a carrier for nanoscale zerovalent iron particles are of much potential in the remediation of chlorinated compounds. Effective in situ groundwater remediation requires the successful delivery of these reactive systems through soil without aggregation. Here, we show that hydrophobically modified chitosan(HMC),  with C12 alkyl groups stabilize carbon submicrospheres through hydropobic interactions. Detailed NMR characterizations indicate attachment of the alkyl groups onto the microspheres. The coating of the environmentally benign biopolymer therefore leads to suspension stability of these submicrospheres through electrostatic and steric repulsion. Compared with pristine chitosan and commonly used sodium carboxymethyl cellulose (CMC), HMC is more effective in stabilizing carbon submicrospheres, and this is even enhanced under normal groundwater iron strength condition. Our results indicate that this system has optimal transport characteristics in groundwater saturated sediments with carbon submicrospheres attachment efficiency of 0.04 calculated from breakthrough data of capillary transport experiments. The fundamental concepts will be detailed in the talk.