Chemical Recovery of Useful Chemicals from Polyester (PET) Waste for Resource Conservation: A Survey of State of the Art

In this paper we present the main technologies developed over the last decades on chemical recycle of PET from a practical and economical point of view. We show details of plants used to carry out solvolitic reactions emphasising steps of purification, which are sometimes not considered when discussing chemical, recycle but which, in fact, are the key feasibility factors. The recycling or modification of PET to obtain monomers and other useful chemicals as intermediates and additives is carefully considered.     

PET-modified red mud as catalysts for oxidative desulfurization reactions

This work describes the synthesis of catalysts based on red mud/polyethylene terephthalate(PET) composites and their subsequent heat treatment under N2 atmosphere.The materials were characterized by scanning electron microscopy(SEM),temperature programmed reduction(TPR),Fourier transform infrared spectroscopy(FT–IR),X-ray diffraction(XRD),thermogravimetric(TG) analysis and N2adsorption/desorption.The catalysts were evaluated in the oxidative desulfurization reaction of dibenzothiophene(DBT) in a biphasic system.The results indicated that the PET impregnation on red mud increased the affinity of the catalyst with the nonpolar phase(fuel),in which the contaminant was dissolved,allowing a higher conversion(up to 80%) and selectivity to the corresponding dibenzothiophene sulfone.The sulfone compound is more polar than DBT and diffused into the polar solvent as indicated by the data obtained via gas chromatography–mass spectrometry(GC–MS).     

废聚酯非酸催化合成对苯二甲酸二(2-乙基己)酯的研究

介绍了以废聚酯瓶为原料,用醋酸锌与氧化镁复合催化剂合成对苯二甲酸二(2-乙基己)酯(DOTP)的方法.利用正交实验研究了醇解酯交换反应中的影响因素,并对产物进行了表征.当反应条件:n(2-EH)/n(PET)=4,m(催化剂)/m(PET)=1%,反应时间为8 h,反应最高温度为200℃时,对苯二甲酸二(2-乙基己)酯的收率为82.3%,与其他酯化催化剂相比,醋酸锌与氧化镁复合的催化活性最好.      

典型水环境因素对聚酯微塑料沉降的影响机制研究

以聚酯（聚对苯二甲酸乙二醇酯,简称PET）微塑料为主要对象,研究电解质浓度,电解质类型及pH值等典型水环境因素对其沉降行为的影响机制.结果表明：水环境中PET微塑料的沉降随电解质浓度的升高而不断增强,其悬液标准化浓度（C/C₀）最低可降至0.64;同一类型电解质对水环境中PET微塑料沉降行为的影响程度相似,而与1-1型电解质（NaCl及KCl）相比,水环境中1-2型电解质（CaCl₂及MgCl₂）的存在能够显著促进PET微塑料的沉降;水环境中PET微塑料的沉降随pH值的增加而降低,随着pH值由10降至4,PET微塑料悬液的C/C₀由最高0.98下降至最高0.76.一阶动力学沉降模型能够较好的拟合水环境中PET微塑料的沉降行为.此外,DLVO （Derjaguin-Landau-Verwey-Overbeek）理论能够反映出PET微塑料沉降行为的变化趋势,其计算结果与实验结果吻合度较高.本研究结果有助于提高对微塑料环境行为的认识程度,同时能够为评估微塑料环境风险提供理论依据.     

PET containers in Brazil: Opportunities and challenges of a logistics model for post-consumer waste recycling

The use of post-consumer materials is directly related to reducing the cost of production and extraction of natural resources. Non-recyclable materials are randomly disposed in the environment. Brazil is one of the largest consumers of PET (polyethylene terephthalate) bottles. The purpose of this paper is to describe the opportunities and challenges of the logistics model for post-consumer PET bottle recycling in Brazil, while providing knowledge of its practices along the recycling chain. The results describe the need to educate those directly and indirectly involved in the process; to reduce consumption in order to reduce the amount of waste generated; to structure the post-consumer reverse chain and engage industrial sectors and government, through public policies, to support cleaner technologies along the PET bottle production chain.     

Decomposition of mixed plastics consisting of polypropylene and polyethylene terephthalate into oils over titania/silica catalysts

The catalytic decomposition of mixed plastics consisting of polypropylene (PP) and polyethylene terephthalate (PET) has been investigated over titania/silica catalysts at 698 K. The yield of oil produced was about 70%, and the large amounts of C₁₈₊ hydrocarbons this contained was from the aromatics in PET. Gas was also produced, including C₃–C₅ hydrocarbons. The carbon-number fractions in the oil was influenced by the PET/(PP + PET) ratios and the catalyst weight. The titania/silica catalysts could be used repeatedly, and after they had been fouled, could be regenerated. From the Fourier Transform Infrared (FT–IR) spectroscopic data of adsorbed pyridine on the catalyst surface, most of the acid sites of the titania/silica catalysts were found to be Lewis sites where the hydride abstracted from PP pyrolysates react with PET pyrolysates to form oil and gas. Received: July 19, 2000 / Accepted: October 20, 2000     

关于进口废PET饮料瓶砖的探讨

从环保和经济的角度出发,我国已逐步放开废PET饮料瓶(砖)的进口。随着废PET饮料瓶(砖)的大量进口,相关问题也逐渐凸显出来。本文结合进口废PET饮料瓶(砖)监督管理工作实际,从检测指标、企业管理等方面进行探讨,提出相应意见和建议。     

高压静电分选Ag与PET的实验研究

为了提高高压静电分选Ag与聚对苯二甲酸乙二醇酯(polyethylene terephthalate,简称PET)的效率,寻求可产生较佳分选效率的电压、转速、极间距和电晕线角度。采用自制的线辊式静电分选机,通过单因素实验和部分因子实验,研究了不同条件下Ag与PET的分选效率。结果表明:将Ag与PET从二者混合物中有效分选出来的电压为25~30k V、转速为60~75 r/min、极间距为60~70 mm、电晕极角度为50~60°;当电压为30 k V、转速为75 r/min、电晕极距离为70 mm和电晕极角度为60°时,Ag的分选效率达到了最大值为99.60%,PET的分选效率也达到了最大值为99.98%,为线辊式静电分选机结构设计与参数优化提供了参考。