PROCESS AND PLANT FOR RECYCLING POLYETHYLENE TEREPHTHALATE (PET) WASTES BY SEAWATER HYDROLYSIS

The invention relates to an ecological process and to a plant for recycling polyethylene terephthalate PET wastes by hydrolysis with seawater used as a reaction medium and catalyst. According to the invention, the process consists of the hydrolysis of polyethylene terephthalate wastes in a reactor using seawater as reactant, where the catalyst is the mixture of inorganic salts itself present therein, in concentrations ranging between 0.1... 10%, the PET/seawater mass ratio ranging between 1: 5...1: 50 g/g, the process taking place at temperatures ranging between 200...270°C, under a nitrogen cushion that provides a pressure of 35 ... 60 at for maintaining the reaction mixture in the liquid phase, remaining in the reactor for a period ranging between 20...180 minutes, and, in the end, the autoclave is cooled down to temperatures of 20...80°C and depressurized, the mixture is filtered at the room temperature, the solid remained on the filter is washed and dried at temperatures ranging between 70 and 120°C, and the liquid containing catalyst and ethylene glycol is collected and recycled in the process. The claimed plant consists of a melted-PET supply vessel (1), a seawater supply vessel (2), a pump (3) for the transfer of the molten PET, a pump (4) for the transfer of seawater, a reactor (5) with countercurrent flowing, a water and monoethylene glycol collecting vessel (6), a separation column (7) for separating water from monoethylene glycol, a filter (8), an alkalizing vessel (9), a filter (10), a neutralization vessel (11) and a centrifuge (12). Invenţia se referă la un procedeu ecologic şi la o instalaţie pentru reciclarea deşeurilor de polietilentereftalat PET prin hidroliză cu apă de mare folosită ca mediu de reacţie şi catalizator. Procedeul conform invenţiei constă în hidroliza deşeurilor de polietilentereftalat într-un reactor folosind ca reactant apa de mare iar catalizatorul este chiar amestecul de săruri anorganice prezente în aceasta, în concentraţii cuprinse între 0,1...10%, raportul masic PET/apă de mare este cuprins între 1 : 5...1 : 50 g/g, procedeul având loc la temperaturi cuprinse între 200...270°C, sub o pernă de azot care va asigura o presiune de 35...60 atm pentru menţinerea amestecului reactant în fază lichidă şi un timp de şedere în reactor cuprins între 20...180 minute, iar la final autoclava este răcită până la temperaturi de 20...80°C şi depresurizată, amestecul este filtrat la temperatura camerei, solidul rămas pe filtru este spă