of Polychlorinated Biphenyls (PCBs) from Oils

Transcription

1 JUNBA 2009 January 13, 2009 Marriott San Francisco Airport, Burlingame A Technique for Efficient i Removal and Recovery of Polychlorinated Biphenyls (PCBs) from ils Mitsuru Akashi Graduate School of Engineering, g saka University

2 Polychlorinated Biphenyls(PCBs) in Japan m n Polychlorinated Biphenyls (PCBs) Excellent Insulating Capacity Non-flammability High Chemical Stability PCBs were widely used as insulating fluids in transformers and capacitors. Transformer Capacitor High toxicity to the human body and the environment was revealed (Yusho incident in 1968). Large amounts of PCBs have been stored by the holders for more than 30 years without treatment. PCB Treatment Law (2001) Total Abolition of PCBs until 2016 In 1972 Prohibition of PCB Production and Use by Administrative Direction In 1974 Prohibition of PCB Production, Imports, and Use by Law In 1998 Permission of Chemical Destruction Methods to Render PCB Harmless by Law Large amounts of oils contaminated with trace amounts of PCBs (1-100 ppm) are still stored! 1

3 Treatment of PCB-contaminated ils in Japan Various chemical destruction methods for PCB-contaminated oils have been developed. Supercritical Water xidation 1 Dechlorination with Alkalines 2 H 2 2 PCB C 2 + H 2 + H PCB 30 MPa 400 C supercritical water t-buk 250 C biphenyl 1 Hatakeda K et al. Chem. Eng. Sci. 1999, 54, hno M et al. rganohalogen Compounds 1997, 31, 415. Disadvantage High reaction temperature and/or prolonged reaction times were required. Development of a New Technique for Efficient Treatment of Large Amounts of PCB-contaminated ils (More than 500,000 t) 2

4 PCB Waste Treatment Facilities of Japan Environmental Safety Corporation (JESC) Hokkaido Facility Kitakyushu Facility saka Facility Toyota Facility Tokyo Facility JESC s Tokyo Facility for PCB Waste Treatment Table. Capacity for PCB-Contaminated Contaminated il Treatment in JESC s Five Facilities Kitakyushu saka Toyota Tokyo Hokkaido Capaciy 1.3 t/day 2.0 t/day 1.6 t/day 2.0 t/day 1.8 t/day Prolonged reaction times will be required for the treatment of more than 500,000 t of PCB-contaminated oils. 3

5 Stockholm Convention on Persistent rganic Pollutants (PPs) Global treaty to protect human health and the environment from chemicals (PPs), including PCBs, that remain intact in the environment for long periods, become widely distributed geographically, and accumulate in the fatty tissue of humans and wildlife. Adopted in 2001 and entered into force in More than 150 countries have agreed to destroy PCBs until Efficient and safe treatment of PCB-contaminated ils is also a crucial problem from a global l viewpoint. i 4

6 ur Strategy for Treatment of PCB-Contaminated ils Cyclodextrin polymer (adsorbent) Pump PCB-contaminated oils (more than 500,000 t) PCB Wash with small amounts of organic solvents Adsorbent-loaded column Highly concentrated PCB solution Reuse or Incineration Environmental protection Pure oils Chemical treatment with low energy Energy saving 5

7 Cyclodextrins (CDs) H H H H H H H H H H H H n H H H H α-cd (n = 1) β-cd (n = 2) γ-cd (n = 3) H H nm 0.5 ~ 0.9 nm H H H H H H Prepared by transglucosidation of starch using a cyclodextrin glucanotransferase (CGTase). Have a hydrophobic cavity into which an organic compound of an appropriate size and shape can be incorporated (inclusion). 6

8 Inclusion Complex Formation Using CDs Inclusion Complex Formation with Guest Compounds in Aqueous Media Guest Inclusion Release H H H H H H CD Guest Inclusion Complex Guest Solubilization of Guest Compounds into Water Stabilization of Incorporated Guest compounds Selective Separation of a Target Compound Controlled Release of Incorporated Guest Compounds Inclusion Complex Formation with Guest Compounds in il Inclusion Release Guest H H H H Guest In il H H CD Guest Inclusion Complex 7

9 Removal of 1,2,4-TrCBz from il by Si-β-CD Insulating il (240 mg) Including 1,2,4-TrCBz (90 ppm) (%) 2,4-TrCBz emoved 1, R ,2,4-TrCBz was completely removed from oil Amount of added Si-β-CD (mg) Figure. Relationship between removal percentage of 1,2,4-TrCBz and the amount of added Si-β-CD. H H H H Me Me : Si C Me Me Me Si-β-CD Shaking 20 C Filtration Measurement of 1,2,4- TrCBz Concentration by GC-MS 24 h Heptakis(6--tert-butyldimethylsilyl)- β-cyclodextrin Si-β-CD 1,2,4-TrCBz 8

10 Inclusion Complex Formation between CD Derivatives and PCBs in il Inclusion Complex Formation with PCBs in il Inclusion (Adsorption) Release (Desorption) nm m PCB in il H H H H CD Derivative-PCB Complex PCB : nm Me Me Si C Me Me Me PCB n Size and Shape of CD Cavity Suitable for PCBs Inclusion Appropriate Modification of CDs Selective Removal of PCBs from il Efficient Recovery of Adsorbed PCBs 9

11 Cyclodextrin Adsorbents Examined H H H H : Me Si Me Me C Me Me Si-β-CD Channel-type γ-cd CD polymer 10

12 Adsorption Experiments Insulating il (300 mg) Including Chlorinated Aromatics (90 or 100 ppm) CD derivative (solid) Shaking 20 CC Filtration Measurement of Chlorinated Aromatics Concentration by GC-MS 24 h Chlorinated Aromatic Compounds 1,2,4-TCBz 1,3,5-TCBz 4-MCB 2-MCB 4,4 -DCB 3,4,4 -TrCB 3,4,5-TrCB 3,3,5,5 -TeCB 2,3,4,5,5 -PeCB 2,2,4,4,5,5 -HeCB 11

13 lorinated aromatics Re emoved ch (% %) Removal of Chlorinated Aromatics from Insulating il by Si-β-CDβ ,2,4-1,3,5-4-MCB 2-MCB 4,4 -DCB 3,4,4 -TCB TCBz TCBz H H H H Si-β-CD : Me Me Si C Me Me Me Initial concentration of chlorinated aromatics: 90 ppm (in 240 mg of insulating oil) Si-β-CD: 20 mg 12

14 Removal of Chlorinated Aromatics from Insulating il by Channel-type γ-cd 100 matics 80 oved chlor rinated aro Remo (%) ,4,4 - TrCB 2-MCB 4-MCB 4,4 - DiCB 3,3,5,5 - TeCB Channel-type γ-cdγ Initial concentration of chlorinated aromatics: 100 ppm (in 300 mg of insulating oil) Channel-type γ-cd: 180 mg 13

15 Removal of PCBs from Insulating il by CD Polymer Remo oved PCBs (%) PCBs were perfectly removed from insulating oil 20 CD polymer (adsorbent) 0 PCBs-contaminated oils (20 ppm) Initial concentration ti of PCB: 100 ppm (in 400 mg of insulating oil) Amount of CD polymer: 200 mg 14

16 Photograph of CD Adsorbent and Column 15

17 Quick and Energy-Saving Treatment of PCB-Contaminated ils Pump Cyclodextrin polymer (adsorbent) PCB-contaminated oils (more than 500,000 t) Reuse or PCB Wash with small amounts of organic solvents Adsorbent-loaded column Highly concentrated PCB solution Incineration Chemical treatment t t with low energy Pure oils Environmental protection Energy saving 16

18 Conclusions We developed cyclodextrin adsorbents that were highly useful for the removal and recovery of polychlorinated biphenyls (PCBs) from oils. By passing PCBs-contaminated oils through a column of the cyclodextrin adsorbent, the efficient i and complete removal of PCBs from oils is accomplished. This technique for PCBs removal and recovery will contribute to the quick and energy-saving treatment of large amounts of PCBs-contaminated oils that are kept in many countries, including Japan. We are now working toward practical use of this technique with NES Company, Ltd. (supported by Japan Science and Technology Agency, JST). 17

19 Acknowledgments saka University NES Company, Ltd. Assoc. Prof. Toshiyuki Kida Mr. Yoshinori Fujino Dr. Eiichi Kato, Dr. Kazuhiro Miyawaki Funds: A Grant for Promotion of Environmental Technology and Development from the Ministry of the Environment of Japan (2007) A Fund for Technology Development from Japan Science and Technology Agency (JST) ( ) 18