Polyethylene terephthalate (PET) is one of the most widely used materials for food packaging and fishing nets. After use it become waste and, due to poor collection, most will be found floating in marine waters. This paper presents the results of a study of PET depolymerization by hydrolysis. We observed that marine water is a perfect reactant because it contains a multitude of metal ions that act as catalysts. A first-order kinetic model was developed and experimental data fitted to it. An activation energy of 73.5 kJ/mole and a pre-exponential factor of 5.33 × 107 h–1 were obtained. Considering that the global ocean is a huge batch reactor operating under isothermal conditions, the solution of the mathematical model shows that in tropical regions only 72 years is needed for total and only 4.5 years for 50% PET conversion.
Background: This paper aims to evaluate the sustainability of biodiesel, a renewable fuel used as a blending component in diesel fuel. This study describes the current situation in Romania where the European Union (EU) settlement regarding the blending ratio of biodiesel and compliance with environmental protection specifications are applied. The evaluation covers the whole biodiesel value chain, from rapeseed production through biodiesel synthesis and combustion.Results: Our evaluation process takes into account three elements of sustainability: economic, environmental, and social. The overall result of this research is that, despite Romania’s high potential for biodiesel production and use, the sustainability of biodiesel is low as a result of the Romania’s government strategy, combined with biodiesel prices on the international market and the interests of Romanian refinery owners.Conclusions: Our prediction is that the current situation will remain over the next decade, owing to economic factors such as the decline in rapeseed crops, a key raw material for biodiesel manufacturing, and the higher cost of biodiesel produced in Romania. Another factor could be Romania's implementation of EU regulations aimed at replacing diesel engines with electric ones. If this decision is implemented, diesel fuel and, implicitly, biodiesel will be phased out of the vehicle fuel market.
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