In situ Treatment Systems for Remediation of Polychlorinated Biphenyl-contaminated Building Materials
Polychlorinated Biphenyls (PCBs) are a family of synthetic organohalides comprising 209 congeners which were used historically as additives in paint and caulking materials over a span of many years. Even though the production of PCBs in the USA has been banned since the late 1970s, their former prevalence and widespread use means many structures are still coated with PCB-laden paints. In addition, the presence of PCBs in elastic sealants has resulted in transport of PCBs into concrete structures and has caused soil contamination around buildings. PCB-contaminated building materials have become a significant concern for the environment and building occupants due to their carcinogenic nature and potential indoor contamination. This results in an urgent need for development of a cost-effective method to extract and degrade PCBs from contaminated materials. Experiments employing reductive dehalogenation through the use of zero-valent magnesium (ZVMg) ball-milled with activated carbon (AC) in an acidified solvent system have shown that PCBs can be broken down even in the presence of water. This research describes the development of two delivery systems for effective deployment of this treatment reaction to field samples. Two treatment systems formulated in this process, the Non-Metal Treatment System (NTMS) and the Activated Metal Treatment System (AMTS), are capable of extracting or extracting and degrading, respectively, trapped PCBs within a variety of building materials. In the development of NMTS and AMTS, an acidified dual system of ethanol/ethyl lactate was used as solvent while ZVMg over activated carbon is used in the AMTS. After development, applications of the systems extended to laboratory prepared PCB-laden paint as well as field samples received from Seattle. A marked successful on PCB remediation was observed. The green solvent 2-butoxyethanol is approved by both the EPA and the FDA, and is an interesting alternative for the dechlorination of PCBs. Novel versions of NMTS and AMTS were developed by substituting 2-butoxyethanol for ethanol/EL and used on a set of paint chips and building materials from the same field site. PCBs were degraded significantly below their starting concentrations with removal efficiency greater than 99% for all samples after two weeks of treatment. The use of acidified 2-butoxyethanol and ZVMg permitted the extraction and destruction of PCBs from contaminated building materials in a one-step treatment. Additional studies were conducted on laboratory-prepared concrete where transport of the organic solvents (used in development of NMTS/AMTS) into the concrete structure was studied. PCB concentrations in concrete after treatment were reduced to below the limit of detection.
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Doctor of Philosophy (Ph.D.)
College of Sciences
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Almutairi, Adibah, "In situ Treatment Systems for Remediation of Polychlorinated Biphenyl-contaminated Building Materials" (2018). Electronic Theses and Dissertations. 6228.