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Novel use of Nano Materials for degradation of PCB
Citation:
Al-Abed, S. AND J. McKernan. Novel use of Nano Materials for degradation of PCB . Presented at 42nd International Symposium on Halogenated POPs - Dioxin 2022, New Orleans, LA, October 09 - 14, 2022.
Impact/Purpose:
Polychlorinated biphenyls (PCBs) are recalcitrant contaminants and their pollution in water and sediments is still present in many countries. The remediation of PCB-contaminated sites is difficult and expensive. Incineration is currently the most used PCB remediation technology. Solvent extraction and soil washing are also recommended. These technologies and several others generate residuals that need treatment prior to disposal. We investigated the catalytic hydrodechlorination of PCBs as a remediation technology using reactive nanomaterials (nanoscale Zero Valent Iron and ZVI/Pd/carbon nanosystems) in contaminated sediments. We investigated different methods to generate the nanoparticles using green chemistry concepts. We also investigated the efficiency of the hydrodechlorination and its kinetics. The better understanding of the adsorption and hydrodechlorination mechanisms will allow the optimization of PCBs removal and will allow to minimize the environmental impact of PCB-laden waste disposal. With the data and conclusions generated in this study, the scientific community, academia, consulting firms, regulatory agents, and other involved parties in PCBs remediation and in nanoparticles applications will gain practical knowledge of this novel technology. The exposure of these principles in the conference will motivate further discussion and research that will improve PCB remediation technologies.
Description:
Persistent organic pollutants (POPs) such as Polychlorinated biphenyls (PCBs) are notorious for their widespread prevalence in aquatic and sedimentary ecosystems, recalcitrance, and carcinogenicity. Dredging and land-filling are still commonly used for treating PCB contaminated matrices but are often prohibitively expensive. Incinerating PCBs produces toxic dioxins. PCBs resist oxidative degradation, especially in higher chlorinated homologues where reductive methods are more effective and safer because dioxins are not formed. Catalytic hydrodechlorination using bimetallic systems is a reduction technique where enhanced galvanic corrosion of a reactive metal at the bimetallic interface combined with the catalytic hydrogenation of a noble metal to drive the reduction of PCBs. We present a recent approach to using reactive nanomaterials, such as Fe0 (nZVI) nanoparticles (NPs) or bimetallic (ZVI/Pd/carbon) nanosystems, offer the potential for highly efficient targeted delivery of remedial agents to contain and degrade PCBs in situ. The primary challenge is to select appropriate synthesis method of the nano particles, composition (monometallic vs bimetallic NPs), support (e.g. carbon, silica) and surface modification agents that enable emplacement in the contamination zone, but do not adversely impact the particle’s reactivity with the contaminant, diminish environmental impact and overall risks. Concomitant optimization of mobility, reactivity, while minimizing toxicity requires a fundamental molecular level understanding of the surface modifiers properties and how they affect nanoparticle deposition. Our presentation will include all relevant results illustrating the potential of this approach in remediating contaminated sites.