Waste Electrical And Electronic Equipment Plastics Research Articles

Improving the accuracy of hand-held X-ray fluorescence spectrometers as a tool for monitoring brominated flame retardants in waste polymers

An optimised method for Br quantification as a metric of brominated flame retardant (BFR) concentrations present in Waste Electrical and Electronic Equipment (WEEE) polymers is proposed as an alternative to the sophisticated, yet time consuming GC-MS methods currently preferred. A hand-held X-ray fluorescence (XRF) spectrometer was validated with Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Customized standard materials of specific BFRs in a styrenic polymer were used to perform an external calibration for hand-held XRF ranging from 0.08 to 12 wt% of Br, and cross-checking with LA-ICP-MS having similar LODs (0.0004 wt% for LA-ICP-MS and 0.0011 wt% for XRF). The “thickness calibration” developed here for hand-held XRF and the resulting correction, was applied to 28 real samples and showed excellent (R2 = 0.9926) accordance with measurements obtained via LA-ICP-MS. This confirms the validity of hand-held XRF as an accurate technique for the determination of Br in WEEE plastics. This is the first use of solid standards to develop a thickness-corrected quantitative XRF measurement of Br in polymers using LA-ICP-MS for method evaluation. Thermal desorption gas chromatography mass spectrometry (TD-GC-MS) was used to confirm the presence of specific BFRs in WEEE polymer samples. We propose that expressing limit values for BFRs in waste materials in terms of Br rather than BFR concentration (based on a conservative assumption about the BFR present), presents a practical solution to the need for an accurate, yet rapid and inexpensive technique capable of monitoring compliance with limit values in situ.

The Influence of Compatibilizer Addition and Gamma Irradiation on Mechanical and Rheological Properties of a Recycled WEEE Plastics Blend

Waste electrical and electronic equipment (WEEE) is growing rapidly, and the plastics within WEEE have an important role in fulfilling the recovery and recycling targets defined in the European WEEE Directive. This study considers recycling of WEEE plastics by making a blend of the different plastics instead of separating them. The mechanical and thermal properties can be enhanced by adding a compatibilizer. It was found that one compatibilizer, a styrene-b(ethylene-co-butylene)-b-styrene (SEBS) copolymer named Kraton® G1652 E, had a large impact on the ductility of the recycled WEEE plastics blend. By adding 2.5 weight % (wt%) of this copolymer, the elongation at break increased by more than five times compared with the non-compatibilized samples, with only a small decrease in stiffness and strength. The storage modulus (G’) decreased slightly with increasing compatibilizer amounts while the impact strength increased with increasing amounts of compatibilizer, from 2.1 kJ/m2 (reference material) to 3.6 kJ/m2 (5 weight % (wt%) compatibilizer). It was found that Kraton® FG1901 E (styrene-b(ethylene-co-butylene)-b-styrene (SEBS) grafted with maleic anhydride (MAH)), Royaltuf® 372P20 (styrene acrylonitrile (SAN) modified with ethylene-propylene-diene elastomers (EPDM)) and Fusabond® P353 (polypropylene (PP) with a high degree of grafted MAH) were ineffective as compatibilizers to the blend. Gamma irradiation (50 kGy) did not improve the mechanical properties however: the impact strength of the gamma-irradiated samples was lower than that of the non-irradiated samples.

Catalytic pyrolysis of waste plastic from electrical and electronic equipment

Plastic waste collected from waste electrical and electronic equipment (WEEE) was pyrolysed in the presence of zeolite catalysts to produce a gasoline range aromatic oil. The plastic was from equipment containing cathode ray tubes (CRTs) and also plastic waste from refrigeration equipment. In addition, for comparison the main plastics contained in the WEEE, in the form of high impact polystyrene (HIPS) and acrylonitrile-butadiene-styrene (ABS) were also pyrolysed in the presence of the zeolite catalysts. Two zeolite catalysts; Y zeolite and ZSM-5 were used. Catalytic pyrolysis took place in a two stage fixed bed, batch reactor with the plastic pyrolysed in the first stage and the evolved pyrolysis gases catalysed in the second stage reactor. The quantity of oil produced from uncatalysed pyrolysis of plastics from CRTs and refrigerators was more than 80wt%. The gases consisted of hydrogen, methane and C2–C4 hydrocarbons. When the zeolite catalysts were introduced there was a decrease of between 5 and 10wt% in oil yield and a corresponding increase in gas yield. The composition of the oils derived from the uncatalysed pyrolysis of WEEE plastics were mainly aromatic with high concentrations of styrene, derived from the HIPS and ABS present in the plastic waste. Addition of the zeolite ZSM-5 and Y zeolite to the pyrolysis process resulted in significant concentrations of benzene, toluene and ethylbenzene in the product oil but reduced concentrations of styrene. The oils from both thermal and catalysed pyrolysis also contained significant concentrations of polycyclic aromatic hydrocarbons for example, naphthalene, phenanthrene and pyrene.

Characterizing plastics originating from WEEE: A case study in France

Two studies, TRIPLE (For Analyse des gisements DEEE et optimisation des technologies de TRI des PLastiques DEEE (analysis of WEEE and optimization of sorting technologies for WEEE plastics).) and VALEEE (For VALorisation des composants, matières et substances issus du gisement DEEE (Recovery of components, materials and substances from WEEE).), supported by the French State, the Greater Lyon area (Grand-Lyon), the Rhône-Alpes Region and the French eco-organization “Eco-systèmes”, and involving laboratories, recycled material users and recycler partners, were conducted concerning the characterization, sorting and recovery of French WEEE (Waste Electrical and Electronic Equipment).To determine the heterogeneity of a 10-ton batch, the WEEE was sorted into families before grinding. Specimens were dismantled and plastic particles were analyzed to estimate their composition. The batch was then crushed and the metals extracted.The residue containing plastics was sampled at the outlet of the plant and analyzed. The detailed characterization of the plastics sample was used to calculate the estimated sampling error and the overall measurement error. The sample size was determined so as to achieve satisfactory accuracy for the most represented polymers likely to be recovered after recycling.A simple characterization methodology for use by recycling plants was proposed in order to determine the plastic composition of this waste. The procedure was validated on a second 10-ton batch of sWEEE collected from another location and treated by a different recycling facility.This article presents the sampling protocol design methodology, then the characterization protocol and its usage limitations.

Monitoring of WEEE plastics in regards to brominated flame retardants using handheld XRF

This contribution is focused on the on-site determination of the bromine content in waste electrical and electronic equipment (WEEE), in particular waste plastics from television sets (TV) and personal computer monitors (PC) using a handheld X-ray fluorescence (XRF) device. The described approach allows the examination of samples in regards to the compliance with legal specifications for polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) directly after disassembling and facilitates the sorting out of plastics with high contents of brominated flame retardants (BFRs). In all, over 3000 pieces of black (TV) and 1600 pieces of grey (PC) plastic waste were analysed with handheld XRF technique for this study. Especially noticeable was the high percentage of pieces with a bromine content of over 50,000ppm for TV (7%) and PC (39%) waste plastics. The applied method was validated by comparing the data of handheld XRF with results obtained by GC–MS. The results showed the expected and sufficiently accurate correlation between these two methods. It is shown that handheld XRF technique is an effective tool for fast monitoring of large volumes of WEEE plastics in regards to BFRs for on-site measurements.

A Mini-Review on Disposal of WEEE Plastics Containing PBDEs with a Special Focus on China

Polybrominated diphenyl ethers (PBDEs), especially pentaBDE and decaBDE have been extensively used as flame retardants in plastics of most electronic equipment. However, PBDE congeners have been found in the environment, in wildlife and in human body worldwide with evidences that they pose risks both to human health and to the entire ecosystem. China has become an important pentaBDE and decaBDE production country because of the increasing domestic demand due to rapid development of electronic industry in recent years. Although pentaBDE was phased out in 2004, decaBDE still remains in production and is used in electrical industry. Additionally, large amounts of plastics containing these pollutants from waste electrical and electronic equipment (WEEE) are generated in China each year and their disposal has been a vital environmental challenge. Machaniclal recycling, fedlock recycling and landfilling are three main means of disposal of WEEE plastics. This article reviews the production of PBDEs, the amounts of WEEE and the disposal of WEEE plastics worldwide, with a special focus on China. The state of the emission of PBDEs and highly toxic polybrominated dibenzo dioxins/furans in the process of disposal is summed up based on previous studies. This article recommends that mechanical recycling should be the main means of disposal of WEEE recycling with regards to the summaries, the current practices and the status in China.

Pyrolysis and dehalogenation of plastics from waste electrical and electronic equipment (WEEE): A review

Plastics from waste electrical and electronic equipment (WEEE) have been an important environmental problem because these plastics commonly contain toxic halogenated flame retardants which may cause serious environmental pollution, especially the formation of carcinogenic substances polybrominated dibenzo dioxins/furans (PBDD/Fs), during treat process of these plastics. Pyrolysis has been proposed as a viable processing route for recycling the organic compounds in WEEE plastics into fuels and chemical feedstock. However, dehalogenation procedures are also necessary during treat process, because the oils collected in single pyrolysis process may contain numerous halogenated organic compounds, which would detrimentally impact the reuse of these pyrolysis oils. Currently, dehalogenation has become a significant topic in recycling of WEEE plastics by pyrolysis. In order to fulfill the better resource utilization of the WEEE plastics, the compositions, characteristics and dehalogenation methods during the pyrolysis recycling process of WEEE plastics were reviewed in this paper. Dehalogenation and the decomposition or pyrolysis of WEEE plastics can be carried out simultaneously or successively. It could be ‘dehalogenating prior to pyrolysing plastics’, ‘performing dehalogenation and pyrolysis at the same time’ or ‘pyrolysing plastics first then upgrading pyrolysis oils’. The first strategy essentially is the two-stage pyrolysis with the release of halogen hydrides at low pyrolysis temperature region which is separate from the decomposition of polymer matrixes, thus obtaining halogenated free oil products. The second strategy is the most common method. Zeolite or other type of catalyst can be used in the pyrolysis process for removing organohalogens. The third strategy separate pyrolysis and dehalogenation of WEEE plastics, which can, to some degree, avoid the problem of oil value decline due to the use of catalyst, but obviously, this strategy may increase the cost of whole recycling process.

Brominated Flame Retardants (BFRs) in Waste Electrical and Electronic Equipment (WEEE) Plastics and Printed Circuit Boards (PCBs)

Two kinds of BFRs in three WEEE plastics(cell phone shells, computer housings and TV housings) and PCBs were detected with GC/MS. The results showed the plastics used as mobile phone shells had no BFRs. TBBPA was only found in computer housings. Among PBDEs, congeners of heptabromodiphenyl ether, octabromodiphenyl ether and nonabromodiphenyl ether were frequent ones, and detected in both TV housings and computer housings. But the contents of N9BDE were lower than the other two, only 180 mg/kg and 5.3 mg/kg in computer housings and TV housings respectively, while pentabromodiphenyl ether and hexabromodiphenyl ether were determined in PCBs.

Environmental Impact of Pyrolysis of Mixed WEEE Plastics Part 2: Life Cycle Assessment

Waste electrical and electronic equipment (WEEE) contains up to 25% plastics. Extraction of higher quality fractions for recycling leaves a mix of plastic types contaminated with other materials, requiring the least environmentally harmful disposal route. Data from trials of pyrolysis, described in part 1 of this paper set, were used in a life cycle assessment of the treatment of WEEE plastics. Various levels of recycling of the sorted fraction were considered, and pyrolysis was compared with incineration (with energy recovery) and landfill for disposal of the remainder. Increased recycling gave reduced environmental impact in almost all categories considered, although inefficient recycling decreased that benefit. Significant differences between pyrolysis, incineration and landfill were seen in climate change impacts, carbon sent to landfill, resources saved, and radiation. There was no overall "best" option. Landfill had the least short-term impact on climate change so could be a temporary means of sequestering carbon. Incineration left almost no carbon to landfill, but produced the most greenhouse gases. Pyrolysis or incineration saved most resources, with the balance depending on the source of electricity replaced by incineration. Pyrolysis emerged as a strong compromise candidate since the gases and oils produced could be used as fuels and so provided significant resource saving without high impact on climate change or landfill space.

Environmental Impact of Pyrolysis of Mixed WEEE Plastics Part 1: Experimental Pyrolysis Data

Growth in waste electrical and electronic equipment (WEEE) is posing increasing problems of waste management, partly resulting from its plastic content. WEEE plastics include a range of polymers, some of which can be sorted and extracted for recycling. However a nonrecyclable fraction remains containing a mixture of polymers contaminated with other materials, and pyrolysis is a potential means of recovering the energy content of this. In preparation for a life cycle assessment of this option, described in part 2 of this paper set, data were collected from trials using experimental pyrolysis equipment representative of a continuous commercial process operated at 800 °C. The feedstock contained acrylonitrile-butadiene-styrene and high impact polystyrene with high levels of additives, and dense polymers including polyvinylchloride, polycarbonate, polyphenylene oxide, and polymethyl methacrylate. On average 39% was converted to gases, 36% to oils, and 25% remained as residue. About 35% of the gas was methane and 42% carbon monoxide, plus other hydrocarbons, oxygen and carbon dioxide. The oils were almost all aromatic, forming a similar mixture to fuel oil. The residue was mainly carbon with inorganic compounds from the plastic additives and most of the chlorine from the feedstock. The results showed that the process produced around 70% of the original plastic weight as potential fuel.

Facile characterization of polymer fractions from waste electrical and electronic equipment (WEEE) for mechanical recycling

In view of the environmental problem involved in the management of WEEE, and then in the recycling of post-consumer plastic of WEEE there is a pressing need for rapid measurement technologies for simple identification of the various commercial plastic materials and of the several contaminants, to improve the recycling of such wastes. This research is focused on the characterization and recycling of two types of plastics, namely plastic from personal computer (grey plastic) and plastic from television (black plastic). Various analytical techniques were used to monitor the compositions of WEEE. Initially, the chemical structure of each plastic material was identified by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). Polymeric contaminants of these plastics, in particular brominated flame retardants (BFRs) were detected in grey plastics only using different techniques. These techniques are useful for a rapid, correct and economics identification of a large volumes of WEEE plastics.

Thermal Processing of Toxic Flame-Retarded Polymers Using a Waste Fluidized Catalytic Cracker (FCC) Catalyst

Waste electrical and electronic equipment (WEEE) plastics are particularly problematic to recycle because they contain a variety of brominated flame retardants, some of which are extremely toxic. Pyrolysis has been proposed as a viable processing route for toxic WEEE plastics, but it has been found that the volatile pyrolysis products contain toxic brominated compounds. In this work, we have built on previous work where we reported that zeolite catalysts were capable of destroying toxic organobromines during pyrolysis (Hall, W. J.; Williams, P. T. J. Anal. Appl. Pyrolysis 2008, 81, 139—147). We have investigated the pyrolysis of brominated high-impact polystyrene and acrylonitrile—butadiene—styrene in the presence of a waste fluidized catalytic cracker (FCC) catalyst. It is reported that, unlike Y-zeolite, the FCC catalyst did not completely destroy the organobromine compounds; however, the catalyst did lower the yield of bromine found in the liquid pyrolysis products by a mechanism that is as yet unclear. The waste FCC catalyst did not greatly alter the composition of the nonbrominated pyrolysis products, and valuable single-ring aromatics were present in the pyrolysis oil.

Small WEEE: Determining recyclables and hazardous substances in plastics

An examination regarding the determination of recyclables and hazardous substances in small waste electrical and electronic equipment (WEEE) found in the residual household waste stream of the city of Dresden, Germany, is described. Firstly, attitudes towards the disposal of small WEEE in the latter are assessed, and product types and categories which mostly contribute to its composition are identified. Physical parameters which could be used as mechanical sorting criteria are measured, and the material composition of the small WEEE found is determined. The hazardous substances’ “base” charge in the residual waste is established by means of atomic absorption spectrometry and ionic chromatography, as a first step in estimating the contribution of small WEEE to its pollutant load. Consequently, the content of small WEEE plastics in key heavy metals and halogens is determined. Key conclusions are drawn concerning the future strategic development and practical implementation of the 2002/96/EC Directive, in relation to small WEEE management and recycling.

Characterisation of polymer fractions from waste electrical and electronic equipment (WEEE) and implications for waste management

There is an increasing interest in the end-of-life management of polymers present in waste electrical and electronic equipment (WEEE). This is mainly due to high recycling and recovery quotas set by the European WEEE directive, which can only be fulfilled by including the plastic fraction in recycling and recovery approaches. Previous studies identified a high material diversity and various contaminants in WEEE plastics, including heavy metals, polybrominated biphenyls (PBB), diphenyl ethers (PBDE), as well as polybrominated dibenzodioxins and dibenzofurans (PBDD/F). These substances are regulated by European directives that limit their levels in marketable products. Consequently, both material diversity and contaminants are strong arguments against material recycling and point to hazardous waste treatment. However, recent developments in the production of flame retardants and electrical and electronic goods aimed to reduce contaminants and material diversity. Thus, the present study summarises updated contaminant levels of plastic fractions of European WEEE, as well as data on materials in waste housing polymers. Material characterisation revealed housing fractions to be interesting sources for polymer recycling, which however has to implement potent material separation and/or bromine elimination techniques. With respect to contaminants, our data indicate an effective phase-out of PBB, but still high levels of PBDE and PBDD/F are found. Sources and implications for the material recycling and thermal recovery approaches are discussed in detail.