Selective flotation separation of plastics by chemical conditioning with methyl cellulose

The floatability of seven plastics (POM, PVC, PET, PMMA, PC, PS and ABS) in the presence of methyl cellulose (MC) and separation of plastics mixtures were investigated in this paper. It was found that the seven plastics can be separated into three groups by using the wetting agent MC. Group one includes POM and PVC. They are depressed at very low MC concentrations. Group two, including PET, PMMA and PC, has an intermediate floatability. Group three (ABS and PS) has a high floatability. They are almost not depressed within the given MC concentration range. In order to understand the mechanism of selective flotation of plastics and the chemical conditioning process, surface chemical factors, such as wettability of plastics and surface tension of flotation medium, and gravity factors, such as particle density and shape, were studied. It was found that the depressing effect of MC on plastics is ascribed mainly to its adsorption on the plastics surfaces. The MC molecules absorbed on plastics expose some of their polar groups oriented towards the aqueous phase, hence making the plastics surfaces hydrophilic. In addition, flotation selectivity for the plastics is dominated not only by wettability of plastics, but also by particle size, density and shape.     

电子废弃物拆解地水体多溴联苯醚分布特征

为了解和比较广东贵屿电子废弃物拆解地和珠三角城市地区水体中多溴联苯醚的种类、含量及分布特征,于2011年9月在广东贵屿周边地区和广州采集了20个地下水、7个地表水和4个珠江水,用反相C18萃取小柱提取净化后,利用气相色谱-质谱法测定了样品中的8种多溴联苯醚（PBDEs）。研究结果表明：贵屿地区地下水中PBDEs浓度总体上较高,总质量浓度范围为2.54~71.74 ng·L-1,平均为22.97 ng·L-1,各类PBDEs的检出率为25%~95%。三溴联苯醚（BDE28）、四溴联苯醚（BDE47）、五溴联苯醚（BDE99和BDE100之和）、六溴联苯醚（BDE153和BDE154之和）、七溴联苯醚（BDE183）和十溴联苯醚（BDE209）的质量浓度分布分别为nd~0.64、nd~18.43、nd~25.26、nd~13.92、nd~9.06和nd~15.60 ng·L-1。从物种上来看,分别源于四溴、五溴和十溴联苯醚产品的BDE47、BDE99和BDE209是贵屿地区地下水样中的优势同系物。通过比率P=（BDE47＋BDE99）/BDE209研究发现：低溴代联苯醚比高溴代联苯醚更易被地表径流迁移转换进入到地下水中。贵屿地区地表水中PBDEs的质量浓度范围为3.41~63.83 ng·L-1,平均总质量浓度为19.38 ng·L-1,稍低于当地地下水中PBDEs的平均总质量浓度,PBDEs的组成以高溴代的BDE209为特征,与世界其他水体研究结果相比,可以发现贵屿地区的地表水中PBDEs的平均总质量浓度明显偏高,说明该地区的地表水受到较严重的PBDEs污染,必须引起足够的重视。珠江水中PBDEs的总质量浓度范围为3.48~20.84 ng·L-1,平均为10.39 ng·L-1,表明近年来珠江水体中PBDEs污染有逐渐恶化的趋势。     

Bio-based materials for high-end electronics applications

During the past decade, a shift of focus onto greener alternatives to petroleum-based plastics has spurred the development of bio-based resins for plastic development. This has led to a positive marketing image for companies making the switch to resins from renewable resources. This shift of focus is further reinforced by corporations, which are committed to a reduction in their greenhouse gas emissions and product environmental footprints. Here, we present a perspective on the use of renewable materials in durable goods applications and the challenges and advantages associated with the use of renewable materials. Replacement of petroleum-based acoustic foam with that derived from sustainable resources and qualification of thermoplastic polylactic acid blends for enclosure covers has been demonstrated. The technical details of the materials development required for use in durable goods, and their characterization is also discussed.     

非溶剂型热介质法消泡回收聚苯乙烯泡沫塑料

回收利用聚苯乙烯泡沫塑料可用不同的消泡减容方法。非溶剂型热介质法分别采用20%氯化钙水溶液作水性介质,液体石蜡和固体石蜡混合物作油性介质,消泡操作温度110℃～130℃,可减容30倍,回收物料密度达到0.9g/cm3,适于下游产品加工应用。     

综合环境社会经济指标的优先污染物筛选方法研究:以电子废物拆解为例

电子信息技术的快速更新迭代以及日常生活中的正常使用造成的磨损,导致众多电器电子产品被淘汰,产生了大量的电子废物,因此电子废物拆解量逐年增加.针对当前我国电子废物拆解污染现状和监测评价的需求,提出利用层次分析法和系统聚类方法相结合的筛选模型.在对电子废物拆解评价因子进行赋值和评分的基础上进行层次分析,得出污染物综合评分并进行聚类分析,将聚类结果中潜在危险优先等级最高的一类,即二（口恶）英类和多环芳烃（PAHs）作为优先控制污染物,为中国电子废物治理提供了有参考意义的指标体系.     

日中构建办公设备废塑料的跨境循环

介绍了日本理光公司生产的办公设备废塑料的原料再生利用,及其在中国跨境循环利用的背景程和流程,指出将国内处理完结型局部再生利用系统和国际循环完结型全面再生利用系统融合驱动是促进资源环境可持续性发展的有效途径。     

日本容器包装废塑料再生利用现状及对我国的启示

介绍了日本“容器包装再生法”的相关规定和实施过程,以及日本容器包装废塑料的回收、再生利用状况,并借鉴其先进经验,结合我国实际情况,指出发展我国废塑料循环利用的重要性,并提出具体建议措施。     

进口废塑料清洁程度定量化合格评定方法的探讨

目前国内对进口废塑料清洁程度的合格评定,长期以来一直采取感官检验的定性方法,引起了较多争议。以《进口可用作原料的固体废物环境保护控制标准——废塑料》（GB16487,12）为依据,分析了GB16487．12对进口废塑料清洁程度进行规定的原因,并在此基础上探讨了对进口废塑料清洁程度采取定量化的合格评定原理,提出参照《一般工业固体废物贮存、处置场污染控制标准》（GB18599）和《生活垃圾填埋污染控制标准》（GB16889）对进口废塑料清洁程度制定定量化限量要求,并建议尽快修订现行国家标准《进口可用作原料的固体废物环境保护控制标准——废塑料》。     

Recycling of electronic displays: Analysis of pre-processing and potential ecodesign improvements

This article analyses the current and future end-of-life management of electronic displays (flat screen televisions and monitors), and identifies and discusses possible ecodesign recommendations to improve it. Based on an investigation of the treatment of displays in two typical European recycling plants, key aspects and criticalities of the recycling methods (sorting, dismantling and pre-processing) are identified. Disaggregated data concerning on-site measurements of the time needed to manually dismantle different displays are presented. The article also discusses the potential evolution of end-of-life scenarios for electronic displays and suggests possible recommendations for recyclers, producers and policy-makers to promote resource efficiency in the recycling of such waste products. Data on time for dismantling the displays can be used to build measurers for voluntary and mandatory policies, to stimulate design innovations for products improvement, and to assess possible alternative treatments of the waste during the pre-processing at the recycling plants. Some quantitative product measures (based on the time thresholds for dismantling some key components) are also discussed, including an assessment of their economic viability. These measures can potentially be enforced through mandatory and voluntary European product policies, and could also be extended to other product groups.