Removal of PCB and other halogenated organic contaminants found in ex situ structures

Emulsified systems of a surfactant-stabilized, biodegradable water-in-solvent emulsion with bimetallic particles contained with the emulsion droplets are useful at removing PCBs from ex situ structures. The hydrophobic emulsion system draws PCBs through the solvent/surfactant membrane. Once inside the membrane, the PCBs diffuse into the bimetallic particles and undergo degradation. The PCBs continue to enter, diffuse, degrade, and biphenyl will exit the particle maintaining a concentration gradient across the membrane and maintaining a driving force of the reaction

Kinetic Studies Of Nano-Scale And Micro-Scale Zero Valent Iron Emulsions

Nano-scale and micro-scale iron were tested for their efficiency in dehalogenating dense non-aqueous phase liquids (DNAPL) (trichloroethylene, TCE) and its ability to challenge the DNAPL (TCE) pool. The by-products of the dehydrogenation reaction, primarily ethylene, diffused out of the emulsion droplet. Ethylene production proved that the DNAPL has sorbed into the emulsion droplet where the dehalogenation reactions take place. Ethylene had a lower solubility than water allowing the gaseous compound to exit through the droplet wall and into the headspace. By comparing the rates of ethylene production in emulsions made with nano-scale iron or micro-scale iron, it could be shown which type of iron would yield a more reactive emulsion. Nano-scale iron emulsions degraded TCE more effectively than micro-scale iron emulsions. Headspace kinetic studies showed the rate of ethylene production in most nano-scale iron emulsions is significantly larger than the production rate in micro-scale iron emulsions. Emulsions mixed with Span 85 expressed this phenomenon most effectively. Degradation kinetics also prove emulsions dehalogenated DNAPL TCE more effectively than nano Fe alone. This is an abstract of a paper presented at the 223rd ACS National Meeting (Orlando, FL 4/7-11/2002)