Environmentally benign chemical recycling of polycarbonate wastes: comparison of micro- and nano-TiO2 solid support efficiencies

Abstract

Polycarbonate (PC) wastes, including optical discs (CDs) and digital optical discs (DVDs), were chemically recycled into valuable materials such as 4,4′-(propane-2,2-diyl)diphenol (BPA) and etherified derivatives of BPA using sodium hydroxide (NaOH) as the alkali metal catalyst and nanostructured titanium dioxide (nano-TiO2) and microstructured titanium dioxide (micro-TiO2) as the solid supports in the binary green system consisting of water and 2,2′-oxydi(ethan-1-ol) (DEG) under conventional heating method, and data were compared. In this study, the effects of various parameters, such as solvent composition, concentration of NaOH, and solid support, were studied on the reaction progress. In these reactions, the importance of water as the green solvent was investigated in achieving pure BPA as the valuable material. When used with 20% aqueous DEG (pbw), a pure BPA can be obtained at 70% yield in the presence of nano-TiO2 and micro-TiO2 as the solid supports. According to the results, the use of nano-TiO2 in comparison with micro-TiO2 accelerates the chemical recycling of PC wastes. The nano-TiO2 catalyst recovery shows that the recovered solid support is applicable for four cycles. The obtained products were characterized using spectroscopic methods, namely, 1H NMR, 13C NMR, and Fourier transform infrared spectroscopy as well as gas chromatography-mass spectrometry.

Comprehensive Analysis of E478 Single-Component Epoxy Resin and Tungsten-E478 Interface for Metallic-Polymer Composite Electron Source Applications

“…Finally, the peak at 1.6 ppm is related to the CH 3 in the Bisphenol A. This shows high consistency with the XPS and Raman results about the existence and the source of the aromatic rings, which is mainly from the cured epoxy resin structure. − …”

Synthesis of calcium carbonate microcapsules as self-healing containers

“…Thus, the NMR data are in good agreement with the FTIR results. 8,44,45 Self-healing of EPX composite coatings Scratch tests were performed on the EPX composite coatings of the metal substrate by varying the loading concentration as 10 wt%, 20 wt%, and 50 wt% with both types of CC microcapsules. The composite coatings were applied on metal substrates to investigate the releasing ability of the loaded CC microcapsules aer 24 h of manually fracturing the coatings.…”

Recyclable Nanomagnetic Fe3O4@APTES catalyst role on the Hydrolysis of Polycarbonate Wastes

“…Recently our research group, depolymerization of PC wastes was carried out to recover bis (4-hydroxybutyl hydrogen carbonate) of BPA (DHB-BPA), mono (4-hydroxybutyl hydrogen carbonate) of BPA (MHB-BPA) and BPA itself in the presence of (1,4-butanediol and water) as the solvent composition, nanoparticles TiO2 (NPs-TiO2) and microparticles TiO2 (MPs-TiO2) as the recyclable solid supports and NaOH as the homogeneous catalyst under simple heating method [37]. In addition, we recovery of pure BPA has been studied using hydroglycolysis of PC wastes in diethylene glycol (DEG) and water as the green solvent composition, NPs-TiO2 and MPs-TiO2 as the recyclable solid supports and NaOH as the homogeneous catalyst conditions [38]. Finally, we investigated the performance of magnetite nanomaterials coated with amine modified silica nanoshell (Fe3O4/SiO2/NH2) as an available, efficient, reusable heterocatalyst and inexpensive for recovering of BPA with yield 100% from hydrolysis of PC wastes at atmospheric pressure using water and DEG mixture without the disadvantages of traditional techniques [39].…”