Hidrólise básica de resíduos poliméricos de pet pós-consumo e degradação catalítica dos monômeros de partida

Abstract

The growing use and application of plastic materials have raised the index of residues of these materials in the great cities, mainly poli(ethylene tereftalate) (PET). Amongst the recycling techniques proposals to minimize the accumulation of these polymeric residues, the chemical recycling, has intensified the interest, on the part of the scientific community, a time that products of a high aggregate value can be achieved, that they can be used in new industrial processes. Of this form, the present work had as objective, to investigate the solubility of the PET postconsumer in different chemical agents, to promote the depolymerization chemical of the PET by hydrolysis basic and to carry preliminary study of the degradation of monomers post-hydrolysis through heterogeneous Fenton reaction using pure and Co- and Mn-doped magnetites catalysts, as source of Fe2+ in H2O2 having as molecule of reference for the study, the methylene blue (MB). The hydrolysis reaction was carried in reflux system under temperature of 110 oC for three hours using NaOH 7.5 mol L-1 as catalytic and the gotten products had been characterized by spectroscopic method in the region of the IV. The reactions of heterogeneous Fenton had been monitored by UV-visible measurements. Between the gotten results, it could be verified (i) PET solubility in phenol concentrated solution of about 40 oC; (ii) the chemical recycling of the PET presented yield of 99.72 % with recovery of monomers terephthalic acid (AT) and ethylene glycol (EG) monomers which were characterized by IV; (iii) the study of degradation of the methylene blue (MB) 20 mg L-1 was monitored by UV-visible measurements in λmax = 663 nm thus the kinetic model that better described the process was of the pseudo first-order, disclosing bigger capacity of degradation for the doped magnetite catalysers with Co and Mn, respectively; (iv) degradation of AT, was observed in λmax = 283 nm and had a similar behavior to the reference molecule; (v) the loss of the organic load of the solution afterhydrolysis of the PET was bottle was analyzed qualitatively by comparison of the spectrums obtained by FT-IV/ATR before and after of the heterogeneous Fenton reaction. Thus the results gotten in this work are considered satisfactory and promising for news studies future.