Polyethylene terephthalate (PET) is a very stable polymer widely used in the modern world. Due to its stability, this polymer can remain in the environment for several years before its complete degradation. The glycolysis reaction of PET has emerged as a green approach to obtain the PET monomer, thus avoiding such environmental problems and adding value to this waste. In this work, PET waste was depolymerized by glycolysis using ultrasmall cobalt nanoparticles (1.5 wt %) as the catalyst for the production of bis-2-hydroxyethyl terephthalate (BHET). A capping agent (tannic acid, TA) and a borohydride reduction approach were used to obtain such ultrasmall cobalt nanoparticles (∼3 nm). A PET depolymerization yield of 96% was achieved within 3 h at 180 °C. The precipitation of 77% of pure BHET was achieved without the need for water. The remaining ethylene glycol solution containing the ultrasmall cobalt nanoparticle catalyst was reused five times for this glycolysis process, demonstrating the feasibility of solvent reuse without the need for any treatment. A reaction mechanism is proposed in order to explain the high BHET yield obtained by this ultrasmall cobalt nanoparticle catalyst stabilized with TA.

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A hybrid material on the carbon paste electrode exhibited a greater electroactivity for the determination of an endocrine disruptor.

Stimuli-resposive hydrogels, such as poly(acrylamide), are smart materials that can be loaded with gold nanoparticles to explore the localized surface plasmon resonance effect to develop an optical device. Here we used electropolymerized poly(acrylamide) hydrogel for entrapped gold nanoparticles into gel structure (composite) to prepare a plasmonic device. Sensing tests were performed; for this bovine serum albumin molecules were placed into the composite by diffusion from an aqueous solution. The presence of the molecules alters the refractive index around the gold nanoparticles, changing its resonance conditions. The plasmonic band shifted 3.8 nm when the composite was incubated at the 20 mg/mL bovine serum albumin solution, which is a result comparable to reports elsewhere using gold nanoparticles on glass substrates. The device showed that it was possible to detect significantly low concentrations up to 10 ng/mL of protein in aqueous solution.

New recycling alternative for multilayer films was successfully presented. Food packaging formed from different materials is difficult to recycle. The use of aluminum, glass, paper, paints, varnishes, and other materials in the rolling processes from plastic packaging is intended to optimize the efficiency of packaging. Nevertheless, these materials prevent the recycling of packaging because they become contaminants to the recycling process. Food multilayered packaging containing poly (ethylene terephthalate) PET, poly (ethylene) PE and aluminum was used as filler in the preparation of composites with post-consumer high density polyethylene matrix. Composites containing up to 50 wt% of filler were feasible to prepare, allowing the obtention of a material with varied mechanical and thermal properties. This feature allows the preparation of composites suitable for specific application. The addition of multilayer matter in the polyethylene matrix provided a material with excellent mechanical properties such as higher tensile impact strength (148 J/m) and elasticity (350 MPa) as compared to pure polyethylene (40 J/m and 450 MPa).

The X/A zeolite crystal mixtures were synthesized using sugar cane bagasse ash (SCBA) as a silicon source and multilayer food packing (MFP) as an aluminum source under hydrothermal conditions at 80 °C for 79–296 hours.

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