电子废弃物机械–物理协同强化资源化利用的研究进展

电子废弃物组成复杂,含有金属相、有机物、氧化物材料等;其结合方式复杂,有黏结、螺丝连接、焊锡固定和卡扣连接等。在这些复杂的成分之中不仅含有多种稀贵金属而且还包含像铅、镉等多种有毒的重金属和各种溴化阻燃剂等有毒的有机物。这些电子废弃物如果不能进行有效回收,将会对环境造成巨大的危害,同时电子废弃物中稀贵金属的含量远高于自然矿物,因此回收电子废弃物中稀贵金属将能有效地缓解自然资源日益紧张的局面。与传统的化学回收方法相比,机械物理的回收方法具有操作简单、经济效益好、环境污染小等优点,被广泛应用于电子废弃物的回收过程。本工作概述了近年来电子废弃物机械物理资源化利用的研究进展,对机械物理回收的各个过程进行了系统地总结,包括前期的拆解和破碎过程以及最重要的物理分选技术,通过对不同分选技术优缺点的比较,指出对破碎产物进行形态调控将极大地提高机械物理处理的回收效率。     

The gasification recycling technology of plastics WEEE containing brominated flame retardants

The recycling of WEEE (waste electrical and electronic equipment) became a requirement in April 2001 in Japan under the Home Appliance Recycling Law. By 2008 the criterion for the recycling ratio will be raised to 80%–90%, and at that time plastic must also be recycled. For this work, gasification processes (feedstock recycling technology) were selected for plastics WEEE recycling. After high temperature treatment, at over 1200°C, shock cooling of the gases to a temperature of roughly under 200°C was done by this process. The generated ‘thin’ gas could then be used as raw materials for chemical industries or for electric power generation. The effect of the high temperature treatment and the shock cooling suppresses the emission of brominated dioxins to a very low level, just as for chlorinated dioxins. Copyright © 2003 John Wiley & Sons, Ltd.     

电子废料中的贵金属回收技术进展

电子工业的迅猛发展产生了大量电子废料,既破坏环境又浪费金属资源。详细介绍了火法冶金、湿法冶金等传统处理电子废料的化学方法,以及近几年发展起来的物理法和生物法,并进一步介绍了各技术对环境的影响。同时简要介绍国外电子废料回收领域的新发展,并对我国电子废料回收业的发展提出了建议。     

Impact strength elastomer composites based on polystyrene components separated from waste electrical and electronic equipment

The reuse of plastic components of waste electrical and electronic equipment (WEEE) is an important concern both for environmental issues and to preserve the material resources, with minimum energy consumption. Considering that polystyrene fraction was reported as approximate 80% of the total amount of WEEE plastic, this article aims to evaluate the recycling of this fraction, without separation by components, by melt compounding with styrene-butadiene block-copolymer (SBS) and hydrogenated and maleinized SBS, the blend of the two elastomers acting both as an impact modifier and compatibilizer. The composites are characterized by mechanical analysis, impact tests, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction. The recycling conditions of the polystyrene fraction as composites without eliminating the WEEE additives for improved UV and flame resistance, with physical mechanical properties comparable to those of high-impact polystyrene resulted from the study. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48329.     

Towards a Structured Framework for Techno-Economic Analyses of Chemical Recycling Technologies

The role of chemical recycling (CR) as a valuable complementary strategy to mechanical recycling in closing the carbon cycle for carbon-containing waste is currently being discussed in political, economic, and social spheres. However, CR deployment is hindered by uncertainties regarding its environmental impacts and costs compared to conventional waste treatment and chemical production routes. While methods for assessing CR's environmental impacts are the focus of socio-political debates and investigations, techno-economic analyses (TEA) to evaluate costs of CR remain scarce. To contribute to a standardized framework for assessing the economic viability of CR technologies, this article draws on life cycle assessment and TEA literature to develop a six-stage TEA process for CR. A checklist is also presented to support transparent and comprehensive analyses.     

The biological and chemical desulfurization of crumb rubber for the rubber compounding

The disposal of used car tires has become a major environmental problem, especially in densely populated countries that use motor vehicles as the principle means of transportation. Widespread recycling of waste tires has not taken place because it has not proven to be cost effective. Although there are obvious environmental reasons for recycling waste tires, to date it has not proven to be economically valuable. The aim of this study is to find a more economical way of recycling used car tires. This was done by the “unvulcanization” of vulcanized crumb rubber by two different treatments; chemical treatment with di‐(cobenzanidophenyl)disulfide, and microbial treatment with T. peromatabolis. The experimental results indicate that the processing of crumb rubber, as well as the end‐product properties, were enhanced by both these treatments, with the microbial treatment being the most effective. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1543–1549, 1999     

废弃PET化学回收及制备不饱和聚酯树脂的研究进展

随着聚对苯二甲酸乙二醇酯（PET）材料用量的大幅增长,大量废弃PET制品堆积造成的环境污染问题日益突出,其回收利用技术也随之广受关注。在不同的PET回收方法中,将PET降解为单体或低聚物的化学回收是效率最高、产物利用价值最大的方法,但也存在反应条件苛刻、产物收率低等问题。本文详细梳理了水解法、甲醇醇解法、二元醇醇解法、胺解法和氨解法等化学回收方法的主要特点以及微波加热、离子液体、纳米技术等新兴技术在PET化学回收过程中的应用概况。通过对各种化学回收工艺的比较,文中得出二元醇醇解法是最具商业应用价值方法的结论。在此基础上,文中重点介绍了PET的二元醇解以及进一步制备不饱和聚酯树脂的化学过程、发展现状、制约因素和改进措施。分析表明,由PET二元醇解产物制备不饱和聚酯树脂是提高废弃PET资源化效率、丰富原料供给、推动产品升级的重要途径,开发高效、廉价、环保的新型催化剂或酶催化技术是废弃PET回收领域今后主要的发展方向。     

Statistical Evaluation of Factors Affecting the Leaching Process of Waste Electrical and Electronic Equipment using Sodium Persulfate

Recycling of waste electrical and electronic equipment (WEEE) is important not only to reduce the amount of waste requiring treatment, but also to promote the recovery of valuable materials. Implementation of the European Directive on WEEE and recycling targets imposed in the European Union will require new processes to be developed and applied to recover metals from WEEE. This study aims to provide an alternative process for the dissolution of metals from WEEE which contains Cu and Zn based on our previous research. The effects of leaching parameters, such as temperature, Na₂S₂O₈ concentration, and leaching time, were separately investigated on leaching of copper, zinc, and brass (alloy composition ?35% zinc and 65% copper) in Na₂S₂O₈ solution (0.1, 0.2 and 0.3 M). Box–Behnken experimental design (BBD) method was used to determine the number and the condition of necessary leaching experiments. Statistical analysis of variance (ANOVA) was performed to see whether process parameters such as leaching time, temperature, and oxidant concentration are statistically significant or not on the leaching performance. Results show leaching time as the most influential factor in the dissolution process, for the first six models. Two extended models have been developed to optimize the parameters of the investigated process. In these models, we consider the metal composition as a model input next to the earlier investigated parameters. Optimal condition for maximum copper and zinc dissolution in Na₂S₂O₈ environment can be found for parameter values: temperature 45°C, oxidant concentration 0.1 M and leaching time 35 min.     

Chemical recycling of polymers from Waste Electric and Electronic Equipment

This research is focused on the recycling of three types of polymers, namely polycarbonate (PC), poly(acrylonitrile‐butadiene‐styrene) (PABS), and polystyrene (PS) from Waste Electric and Electronic Equipment (WEEE). Initially, the chemical structure of each polymeric material in a variety of WEEE was identified by Fourier Transform Infra Red (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC). The potential recycling of these polymers from these wastes was examined by employing two different approaches, the dissolution/reprecipitation method and the more challenging technique of pyrolysis. During the first, the polymer is separated and recycled through a solvent/non‐solvent system. It is a simple and economic technique leading to high recovery of pure polymer. Both, model polymers and plastic parts from WEEEs were studied and optimum experimental conditions, including dissolution temperature and time, polymer concentration and type of solvent were proposed to achieve significant recovery of the polymer (>90 wt %). Furthermore, pyrolysis of waste Compact Disks (CD) was investigated and compared with model poly(bisphenol A carbonate) (PC) through a laboratory‐scale fixed bed reactor. The appropriate pyrolysis temperature was selected after measuring the thermal degradation of model PC by Thermogravimetric analysis (TGA). A large amount of oil was measured, together with a smaller amount of gaseous product, leaving also a solid residue. For both samples, the gaseous fraction consisted mainly of CO₂ and CO whereas in the liquid fraction a large amount of different phenolic compounds, including the monomer bisphenol A, was measured. It seems that recycling of used CDs by pyrolysis is a very promising technique having the potential of producing useful high‐value chemicals, which may find applications in the petrochemical industry. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Recycling of GaN,a Refractory eWaste Material: Understanding the Chemical Thermodynamics

South Korea is a major producer of light‐emitting diode (LED) material, contributing 31% of total LED demand worldwide, and also a major consumer of electronic devices. During manufacturing and after end of life (EOL) of the consumer electronics, significant amount of GaN‐bearing waste is being generated. As the Republic of Korea depends upon the import of all mineral commodities, under the national policy of securing a stable supply, much attention has been paid to the notion of “urban mining.” The stringent international environmental directive for recycling of waste electrical and electronic equipment (WEEE), United Nations Environment Programme (UNEP) E‐Waste Management goal, restriction of the use of hazardous substances in EEE (RoHS), and extended producer responsibility (EPR) have made recycling an important responsibility. Recovery of the gallium from GaN‐bearing waste can be a promising feasible option; simultaneously from the waste, the wealth can be generated. As GaN is a refractory material, which is hard to leach in the recovery process, hence, needs a chemical pretreatment. In this study, thermodynamics of GaN oxidation and oxidative roasting using Na₂CO₃ has been studied. Thermodynamic feasibility for leaching of oxidized GaN either through acidic leaching or through alkali leaching has been explored.     

废旧反渗透膜循环再利用研究现状与进展

随着反渗透（RO）技术在水处理领域的广泛应用,全球每年有数百万计的废旧RO膜组件作为垃圾被处理处置,由此造成了环境污染与资源浪费。本文首先综述了废旧RO膜可能的循环再利用方案和相关的应用案例,为了比较不同循环方式对环境的影响,概述了通过全生命周期分析（LCA）的方法评价不同循环利用方式的环境效益和物质投入的研究进展。文章指出研究结果表明：回收利用废旧RO膜是研究RO膜末端处理的方法之一,其中包括通过使用清洗后的RO膜作为新生RO膜直接再利用、通过化学转化为其他多孔膜材料再循环使用、通过清洗RO膜拆解回收RO膜。另外,LCA在膜工艺中的分析仍以评估使用过程为主,而缺少在膜设计、膜改造和膜回收等关键过程的分析研究。     

煤化工废水的深度处回用工艺和运行状况分析

煤化工企业污水的再生利用可有效地减轻环境污染,又可解决当前的水资源短缺问题,具有广泛的社会效益、环境效益和经济效益。文章介绍了宁东煤化工的污水深度处理回用工艺,并对其运行状况进行了分析,运行结果表明,该工艺处理效果稳定,工艺组合合理。     

Chemical Recycling of Polymer Materials

After the first life cycle of plastics various recycling processes are available for further utilization of these valuable materials. For an ecologically and economically satisfying solution the most suitable process has to be chosen. In chemical recycling polymers are degraded to basic chemical substances which can be reused in the petrochemical industry. For soiled waste plastics or waste plastics which could not be recycled until now, chemical recycling plays a key role. The pyrolysis of acrylic polymers provides a good example for comparing a fluidized-bed reactor and a tubular reactor on the basis of reactor modelling evaluations. The used tubular reactor with internal mass transport is a simplified model for a rotary kiln. Relevant parameters for reactor design and scale-up are presented.     

Cost effective recovery of lithium from lithium ion battery by reverse osmosis and precipitation: a perspective

Production of lithium from primary resources is lagging behind demand (12% versus 16% in 2016), cost of lithium is increasing (between 40 and 60% in 2016), battery energy density rapidly increasing versus declining cost, and estimated lithium ion battery (LIB) markets size ($77.42 billion by 2024) driven by projected demands for plug‐in electric vehicles (PEVs) clearly justifies recycling. PEV technology and projected demand raise several challenges, including lithium demand/scarcity and future technology to recover lithium from LIB waste. To address the circular economy, steady supply chain security, self‐reliance, environment safety, environment directive, energy security, resources conservation, futuristic carbon footprint, WEEE directives and waste crime, recycling of LIB is an absolute essential. During the last decade, LIB recycling research and industrial recycling of LIB have attracted the interest of researchers, industrialists, and environmentalists. All have reported progress in the recovery of valuable metals like Co, but have rarely focused on lithium recovery. Hence, this paper addresses logical hypothesis and application of available technology in a fashion where lithium recycling from LIB can be addressed. © 2017 Society of Chemical Industry     

Carpet Recycling: Determining the Reverse Production System Design

Roughly 4 billion pounds of carpet are disposed of in the United States each year. This carpet is composed of a significant fraction of nylon, polypropylene, and polyester fiber. A key limiting factor to recycling is effective design and development of the reverse production system to collect and reprocess this large volume of valuable material. A reverse production system is composed of material and chemical recycling functional elements interconnected by transportation steps. In this article, we develop a mixed-integer programming model to support decision-making in reverse production system design. To illustrate its use and applicability, we apply the model to a representative U.S. carpet recycling industrial case study. The overall economic feasibility of recycling is strongly dependent on the volumes that can be expected from investments in collection infrastructure. The geographic location of processing centers influences the network economics, and the subdivision of recycling tasks to avoid the shipment of low value material is proposed as an effective strategy for carpet recycling.     

PET Recycling – Contributions of Crystallization to Sustainability

Polyethylene terephthalate (PET) is one of the most common thermoplastic polymers and its durability has become a major environmental concern. The current public debate on plastic debris also triggered the revision of PET recycling technologies. This Research Article focuses on the chemical recycling of PET by means of methanolysis. The process degrades PET into two main reaction products, dimethyl terephthalate (DMT) and ethylene glycol (EG). Subsequent separation by distillation combined with crystallization removes critical impurities and non-PET components from co-polymers, providing monomers of high purity needed for re-polymerization purposes.     

废旧塑料摩擦荷电机理及摩擦电选技术研究进展

塑料由于材质轻、化学性质稳定、成本低、耐磨性及耐腐蚀性好等优点被广泛应用于工程建设、食品安全、交通运输以及医疗等领域,如果处理不当会对环境造成严重的污染,废塑料污染防治已成为全球关注的环境问题。目前处理废旧塑料的常用方法有风选法、浮选法、静电分离法和光选法等,摩擦电选作为一种新型干式分选方法越来越受到研究者们的重视,其具有工艺简单、污染小、投资少、成本低等优点。本工作针对废旧塑料的分选回收利用,详细介绍了摩擦电选的荷电机理、影响因素、荷电装置和分选设备的研究现状,指出了目前通过摩擦电选回收废旧塑料的技术问题,并对摩擦电选技术未来的发展趋势和应用进行了展望。     

Evaluating and improving environmental performance of HC's recovery system: A case study of distillation unit

Waste solvents/valuable products in the effluent stream are one of the major environmental problems in the chemical industry if not properly controlled. Separation processes are vital for the recovery of waste solvent/valuable product from the effluent stream to reduce the pollution along with improvement in economic performance. Among the various separation processes, distillation is most widely used. A number of environmental indicators, each satisfying researchers own need, and methodologies such as life cycle assessment (LCA), minimum environmental impact assessment (MEIM), waste reduction algorithm (WAR) and environmental fate and risk assessment (EFRAT) are available for evaluation of environmental performance of chemical processes. In this article, a systematic procedure, introducing an environmental performance index (EPI) based on potential environmental impact (computed from waste reduction algorithm (WAR)), energy consumption, resource conservation and fugitive emission, for evaluating environmental performance is presented. Analytical hierarchy process (AHP) is used at two levels for the determination of weighting of individual categories. The procedure is applied for the study of environmental performance of distillation column (steam stripping column) from a real chemical plant for the recovery of acetone and HC's from the off gases of the distillation fraction (DF) plant. Alternatives are compared using environmental performance index and best alternative is selected.     

化工废催化剂污染特征及资源化途径

全世界化工行业每年会置换出大量的废催化剂,如处置不当,不仅污染环境,而且浪费了资源。本文对化工行业废催化剂的现状进行了初步调查分析,综述了其来源、类别及特点。基于废催化剂中有价金属的含量远远高于矿藏中所含有的相应组分的特点,建议将其作为二次资源进行利用;分析了化工废催化剂潜在的环境风险并提出了开展环境风险评价的流程,建议建立废催化剂环境风险信息数据库;概括论述了废催化剂减量化、资源化、无害化等的控制手段及存在的问题。文中提出：对于化工废催化剂的处理处置应从清洁生产的角度考虑,不局限于单纯的末端污染控制;建议开展废催化剂减量化、资源化及无害化处理的绿色新技术,达到减少污染、资源综合回收利用的目的。     

A novel strategy of lithium recycling from spent lithium-ion batteries using imidazolium ionic liquid

In light of the increasing demand for environmental protection and energy conservation,the recovery of highly valuable metals,such as Li,Co,and Ni,from spent lithium-ion batteries (LIBs) has attracted wide-spread attention.Most conventional recycling strategies,however,suffer from a lack of lithium recycling,although they display high efficiency in the recovery of Co and Ni.In this work,we report an efficient extraction process of lithium from the spent LIBs by using a functional imidazolium ionic liquid.The extraction efficiency can be reached to 92.5％ after a three-stage extraction,while the extraction effi-ciency of Ni-Co-Mn is less than 4.0％.The new process shows a high selectivity of lithium ion.FTIR spec-troscopy and ultraviolet are utilized to characterize the variations in the functional groups during extraction to reveal that the possible extraction mechanism is cation exchange.The results of this work provide an effective and sustainable strategy of lithium recycling from spent LIBs.