Cyclodextrin Polymers as Highly Effective Adsorbents for Removal and Recovery of Polychlorobiphenyl (PCB) Contaminants in Insulating Oil

• Published in: Environmental science & technology Vol. 48; no. 14; pp. 8094 - 8100
• Main Authors: Kawano, Shintaro, Kida, Toshiyuki, Miyawaki, Kazuhiro, Noguchi, Yuki, Kato, Eiichi, Nakano, Takeshi, Akashi, Mitsuru
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.07.2014
• Subjects: acetone; Adsorbents; Adsorption; Applied sciences; Cellulose - chemical synthesis; Cellulose - chemistry; Contamination; crosslinking; Cyclodextrins - chemical synthesis; Cyclodextrins - chemistry; Environmental Pollutants - isolation & purification; esterification; Exact sciences and technology; gamma-cyclodextrin; gamma-Cyclodextrins - chemistry; Global environmental pollution; Natural polymers; oils; Oils - chemistry; oligosaccharides; PCB; persistent organic pollutants; Physicochemistry of polymers; Pollutants; Pollution; Polychlorinated biphenyls; Polychlorinated Biphenyls - chemistry; Polychlorinated Biphenyls - isolation & purification; Polymers; Recycling; Starch and polysaccharides; Temperature; washing; Organic adsorbate; Oligoholoside; Polychlorobiphenyls; Organic chlorine compounds; Organic adsorbent; Organic halogen compounds; Macrocycle; Persistent organic pollutant; Cyclodextrin; Insulating oil; Halogenated hydrocarbon; Adsorption; Decontamination; Chlorocarbon; Crosslinked polymer; Poison; Aromatic compound; Inclusion compound; Organic compounds
• ISSN: 0013-936X; 1520-5851; 1520-5851
• DOI: 10.1021/es501243v

A total of 179 countries (parties) ratified the Stockholm Convention on persistent organic pollutants (POPs) and agreed to destroy polychlorobiphenyls (PCBs) and develop a sound management plan by 2028. Currently, still 3 million tons of PCB-contaminated oil and equipment need to be managed under the Stockholm Convention. Thus, the development of a facile and environmentally benign method to treat large amounts of oil stockpiles contaminated with PCBs is a crucial subject. Herein, we report that cyclodextrin (CD) polymers, which are easily prepared by cross-linking the renewable cyclic oligosaccharide γ-cyclodextrin (γ-CD) with dibasic acid dichlorides, are a new selective and powerful adsorbent to remove PCB contaminants in oil. When PCB (100 ppm)-contaminated oil was passed through a column packed with the terephthaloyl-cross-linked γ-CD polymer (TP-γ-CD polymer) at 80–110 °C, the PCB contaminants were completely removed from the oil. Additionally, methyl esterification of the free carboxylic groups of the TP-γ-CD polymer enabled the complete recovery of the PCBs adsorbed on the polymer (with >99.9% recovery efficiency) by simply washing with acetone. The methyl-esterified TP-γ-CD polymer could be recycled at least 10 times for PCB adsorption without any loss in the adsorption capability. These results revealed that the γ-CD polymers can function as highly effective and powerful adsorbents for the removal and recovery of PCBs from PCB-contaminated oil and, thus, significantly contribute to the protection of the global environment.