Complex utilization of polyethyleneterephthalate wastes
G.P. Panasyuk, Doctor of Chemical Science, professor, head of chemical laboratory N. S. Kurnakov Institute of General and Inorganic Chemistry Russian Academy of Sciences (IONH RAN)
Utilization the used articles made of polyethyleneterephthalate (PET) wastes is now one of the most important ecological problems. Its solution is connected mainly with the difficulty of the collection of these articles which is determined, in particular, by their low weight (weight of a bottle is about tens of grams). This leads to the low profitability of the majority of the existing processes. The solution of this problem seems to be in the creation of remunerative processes, for which used of articles of PET are used as a source material. Were developed the following highly profitable processes of utilization of PET articles. 1. PET decomposition to its consisting components terephthalic acid (TA) and ethylene glycol (EG) Process of PET decomposition  was achieved in the autoclave in temperature interval of 180-200oC in different media. The most perspective here are: - methods that enable to obtain directly ammonium terephthalate with its subsequent transformation into TA - or the direct decomposition of PET wastes leading to the formation of macrocrystalline TA. We succeed to obtain TA of high purity with the required dimension of crystals in the range 1-500 microns. 2. Transformation of PET into the crispy state with subsequent splitting and using the powders. Conditions under which the conversion of PET items to crystalline crispy state are determined. This material easily yields to splitting to the size of the crystals of 1-20 microns and can be successfully used filler for polyester resins, rubber, paints and many other fields. 3. Obtaining of TA salts and their using. Terephthalic acid from PET waste items can be used to obtain terephthalates of various metals. It is known that such salts have a wide range of utilities. Methods of synthesis of sodium, potassium, magnesium, calcium, aluminum, zirconium, copper terephthales as well as terephthalates of other elements. On the basis of terephthalates we develop methods of synthesis of high-purified fine-crystalline oxides of magnesium, calcium, aluminum and zirconium in the range of the sizes of crystals 5-300 microns. These powders can be used for obtaining the special ceramics, fire retardant materials, abrasives and in many other cases. Application of the developed methods to make it possible to accomplish processing the used articles made of PETF on the basis of highly profitable processes.