Used PET Bottles Decomposed to Raw Materials in Microwave Oven

Dr. Kazutoshi Ikenaga, Associate Professor of the Department of Applied Chemistry at Sojo University (formerly Kumamoto Institute of Technology), has focused his attention on microwave heating, the same technology used in the household microwave oven, and has developed a chemical reaction that completely decomposes used PET (polyethylene terephthalate) bottles to raw materials within two minutes in a microwave reactor vessel. This reaction is the fastest of its type in the world, and a patent application was filed in 2006.

The reaction needs potassium hydroxide, lithium hydroxide, sodium carbonate and sodium hydrogen carbonate (baking soda) as base catalysts, and produced excellent results. The results of a study examining the reaction conditions also suggest that this reaction is a simple and safe chemical decomposition reaction. Moreover, the alcohols used as reaction solvents can be reused repeatedly.

Since 45 percent of total plastic waste is unutilized, establishing a simple and easy recycling method has been a critical issue in dealing with the enormous amounts of waste plastic. At present, thermal recycling is the major means for waste utilization, and this accounts for 37 percent of the total, while material recycling accounts for 15 percent, and chemical recycling accounts for three percent. However, progress in the latter two methods has been slow due to sorting and equipment costs (Note: these figures are as of 2002).

In conventional methods, PET has to be decomposed under long periods of heating or high pressure. If the microwave method is established, it will contribute to substantially reducing the energy costs associated with recycling.



Posted: 2007/01/20 10:57:34 PM
Japanese version