Recent Developments in the Chemical Recycling of PET

Titanate Nanotubes as New Nanostrutured Catalyst for Depolymerization of PET by Glycolysis Reaction

“…Among the various possibilities to mitigate this problem, the chemical recycling process would be the best alternative for this material. This process is in accordance with the principles of sustainable development because it leads to the formation of raw materials (monomers) used for producing PET 3 . Chemical recycling by glycolysis is one of de most used recycling types.…”

“…It can be described as a depolymerization process by transesterification between PET ester groups and a diol (generally ethylene glycol, EG) 4,5 , allowing obtaining of bis(hydroxyethyl) terephthalate (BHET) 6 as main depolymerization product ( Figure 1). This reaction depends on some variables such as temperature, molar ratio EG/PET, glycolysis time and amount of catalyst 3 . Among these variables, the catalyst type can dramatically influence the reaction conditions such as low temperature and reaction time.…”

“…Recently various transition metal-based catalysts with good catalytic activities on PET glycolysis have been described in literature, the most used among them being zinc acetate 7,8 , but they have limitations such as difficult synthesis of the catalyst 1,9 or catalyst toxicity or corrosivity, resulting in pollution 10 . Thus, the search for new highly selective catalysts under mild conditions is required 3 . Among the materials with potential application for catalysis are nanomaterials, such as nanotubes, nanoribbons, nanowires that exhibit unique properties, such as, changes in chemical reactivity and electrical conductivity 11,12 , which, combined, are not found in conventional materials 13 .…”

Reactive Extrusion of Polyethylene Terephthalate Waste and Investigation of Its Thermal and Mechanical Properties after Treatment

“…Although PET is not hazardous, many factors contribute to the accumulation of PET in the environment and this necessitates serious attention to recycling as the accumulation has become a global environmental issue [2,13,14]. The recycling of PET through chemical methods [10,[15][16][17][18], especially depolymerization or lysis of PET using 2 International Journal of Chemical Engineering solvents and ionic liquids, has gained considerable interest as it can help in the synthesis of different kinds of end products. Depolymerization of PET can be achieved by hydrolysis using water [19] or lysis using alcohol [20] (methanolysis using methanol) [21,22] or amines [23] or acids [24].…”

Influence of Immersion Conditions on The Tensile Strength of Recycled Kevlar®/Polyester/Low-Melting-Point Polyester Nonwoven Geotextiles through Applying Statistical Analyses

“…Strong alkali results in the decrease in the tensile strength of the experimental group because PET fibers undergo hydrolysis. Similarly, Mathur et al state that PET is subjected to a hydrolysis as a result of being exposed to an acid or an alkali environment [15], while Bartolome et al points out that a combination of water and an acid, alkali, or neutral environment renders PET with a hydrolysis that involves the depolymerization of PET to terephthalic acid (TPA), and that can be aggravated by applying a high temperature [24]. FT-IR analysis indicates that the characteristic absorption peak of PET's ester bond is C=O at a frequency of 1750-1735 cm´1 and C-O at 1300-1000 cm´1, and the same characteristic peak is absent after the immersion in an alkali solution, as indicated in Figure 7, which shows that the ester bonds exhibit bond breaking.…”