报废汽车内饰件塑料浮选技术研究

报废汽车内饰件塑料品种复杂、难以分选,为此,以分离汽车内饰件中4种主体塑料——PP(聚丙烯)、ABS(丙烯腈-丁二烯-苯乙烯)、PC(聚碳酸酯)、PVC(聚氯乙烯)为目标,利用实验室自制浮选设备,考察了浮选液流量、溶气罐压力、润湿液浓度等因素对浮选效果的影响. 结果表明:当溶气罐压力为0.22 MPa、浮选液流量为10 L/min、润湿液中ρ(单宁酸)为15 mg/L时,一级浮选PP、ABS、PC、PVC效果达到最佳,其中PP和ABS为上浮料,二者上浮率分别为100%和98.63%;PC和PVC为下沉料,二者下沉率分别为98.95%和100%. 当溶气罐压力为0 MPa、浮选液流量为6 L/min、润湿液中ρ(单宁酸)为10 mg/L时,二级浮选完全分离PP/ABS;当溶气罐压力为0.24 MPa、浮选液流量为10 L/min、润湿液采用10 mg/L单宁酸和10 mmol/L癸二酸二丁酯时,二级浮选分离PC/PVC效果达到最佳,PC上浮率为92.87%,PVC下沉率为91.41%. 通过二级浮选分离,PP、ABS、PC、PVC的最终分离率分别达到100%、98.63%、92.87%和91.41%,显示出该二级浮选工艺在报废汽车内饰件塑料分选方面具有较为广阔的应用前景.      

河源城南污水处理厂尾水深度处理效果的研究

河源市城南污水处理厂利用垂直流人工湿地对该厂A2-O工艺处理的尾水进行深度处理,研究了人工湿地对尾水中TN、NH4+-N、TP、COD、BOD5的去除效果。结果表明:人工湿地对污水处理厂尾水具有较好的深度处理效果,垂直流人工湿地处理系统对尾水中TN、NH4+-N、TP、COD和BOD5平均去除率分别达到97.4%、97.8%、95.06%、91.87%和95.87%以上,其出水水质基本达GB 18918—2002《城镇污水处理厂污染物排放标准》一级A标准,地表水Ⅲ类标准。     

智能化系统在自燃温度测试中的设计和应用

为降低液体自燃温度测试过程中的操作危险,准确判定自燃现象发生及温度,减少繁琐的手工操作,参照ASTME659—78（2005）、GB/T21791-2008及GB／T21860-2008标准,设计了一套智能自燃温度测试系统。采用操作微机软件控制炉体升降温、自动进样泵进样、温度采集、自燃现象拍摄、尾气抽滤等过程,实现自燃温度测试从开始进样到吹扫尾气全流程的自动化;利用设计系统测试乙醇、丙酮等5种常见物质的自燃温度,测试结果与文献值的相对标准偏差不超过2．0％。结果表明所设计系统操作方便快捷、安全实用、结果准确。     

Distribution of heavy metals in sediments of the Pearl River Estuary, Southern China: Implications for sources and historical changes

The distribution of heavy metals (Pb, Zn, Cd and As) in sediments of the Pearl River Estuary was investigated. The spatial distribution of heavy metals displayed a decreasing pattern from the turbidity maxima to both upstream and downstream of the estuary, which suggested that suspended sediments played an important role in the trace metal distribution in the Pearl River Estuary. In addition, metal concentrations were higher in the west part of the estuary which received most of the pollutants from the Pearl River. In the sediment cores, fluxes of heavy metals were consistent with a predominant anthropogenic input in the period 1970-1990. From the mid-1990s to the 2000s, there was a significant decline in heavy metal pollution. The observed decline has shown the result of pollution control in the Pearl River Delta. However, it is noteworthy that the metal concentrations in the most recent sediment still remained considerably high. Taken together, the enrichment of heavy metals in sediments was largely controlled by anthropogenic pollution.     

基于循环特性的镍氢和锂离子电池环境影响机制分析

为了了解镍氢电池和锂离子电池在生产、使用、废弃或回收过程中的环境影响,建立了一种简单快速的二次电池环境影响机制分析方法。通过生命周期评价(LCA)方法,采用Eco-indicator99体系,综合考虑电池循环容量衰减和循环次数的影响,建立了二次电池环境影响机制分析模型,并运用此模型对两种实验用二次电池(镍氢电池和锂离子电池)的环境影响机制进行了研究。结果表明:1)在所选取的两种二次电池当中,锂离子(Li-ion)电池的环境影响明显比镍氢(Ni-MH)电池的低;2)随着循环次数的增加Li-ion电池环境影响衰减比Ni-MH电池的明显,即随着使用循环次数的增加,Li-ion电池对环境的影响会降低到更多。综合来说,所选取的Li-ion电池比Ni-MH电池更具环境可持续性。文中所提出的环境影响机制分析模型同样可以应用于其他二次电池,以期为环境友好型二次电池的开发提供帮助。     

改性粉煤灰处理含铬(Ⅵ)地下水的实验研究

用硫酸改性的粉煤灰作为吸附剂,处理含铬(Ⅵ)为5mg/L地下水,最佳条件为:pH=2,液固比10000:3,25℃下反应3h。处理后水样铬(VI)浓度0.03mg/L,满足(GB/T 14848-93)《地下水环境质量标准》。在不改变原水pH条件下,增加粉煤灰用量,水样中铬(VI)浓度也可由5mg/L降至0.05mg/L。同时,吸附剂对铬(VI)的吸附符合Freundlich和Langmuir等温线。     

真空吸尘系统应用于散货码头的积尘清扫

描述了散货码头粉尘污染现状,分析比较了几种常用的积尘清扫方法。为了有效清扫散货码头的积尘,提出采用集中式真空吸尘系统。文章从系统形式、水力计算方法和工程实例等方面简单介绍了集中式真空吸尘系统。印尼Paiton燃煤电厂码头工程设计采用了集中式真空吸尘系统进行积尘清扫,工程建成投产一年多来,积尘清扫效果明显,有效地降低了粉尘污染。实例说明,真空吸尘是解决散货码头积尘清扫问题较为有效的方式。     

排放和气象对疫情前后武汉不同类型点位大气污染物的影响

采用随机森林算法剥离了排放和气象对6种大气污染物(SO₂、 NO₂、 CO、 PM₁₀、 PM_2.5和O₃)浓度的贡献,识别了疫情前后武汉市中心城区、郊区、工业区、三环线交通点和城市背景点这5种类型点位的大气污染物浓度变化.结果表明,与管控前相比,管控期间PM_2.5/CO、 PM₁₀/CO和NO₂/CO分别减小了10.8～21.7、 9.34～24.7和14.4～22.1倍,表明排放对PM_2.5、 PM₁₀和NO₂贡献减小;O₃/CO增加了50.1～61.5倍,表明二次生成增加明显.解除管控后排放对各类污染物的贡献均增加.管控期间,受一些不可间断工序的运行影响,工业区PM_2.5降幅最小(20.5%).与管控期间相比,解除管控后居民生活、交通出行和工业生产等基本恢复,使5种类型站点PM_2.5     

城市聚乙烯燃气管道漏气案例统计与原因分析

目的 分析影响聚乙烯燃气管道漏气的薄弱部位及原因,为建立聚乙烯燃气管道安全服役评价方法可行性分析提供实际数据支撑。方法 收集、归纳某城市聚乙烯燃气管道实际应用中的290例漏气案例,从失效薄弱部位、服役年限、月份等多方面进行统计分析,并讨论聚乙烯燃气管道发生漏气的主要原因。结果 PE燃气管道安全服役的钢塑转换、套袖、焊接位置等连接位置是聚乙烯燃气管道服役的薄弱部位,服役年限与漏气案例比例成正比,且各部位的敏感月份相差较大。影响管道服役的主要因素是环境/应力长期耦合作用和外力突发作用。结论 土壤环境中存在的有机酸介质会加速管道老化,特别是对于施工等带来的固有薄弱缺陷、外界因素带来的表面损伤、应力集中等,在土壤服役环境中化学介质、温度、运行压力的耦合作用下,管道性能大大下降,产生漏气事故,给安全运行带来极大威胁。     

Selective sorption of perfluorooctane sulfonate on molecularly imprinted polymer adsorbents

Perfluorooctane sulfonate (PFOS), as a potential persistent organic pollutant, has been widely detected in water environments, and has become a great concern in recent years. PFOS is very stable and difficult to decompose using conventional techniques. Sorption may be an attractive method to remove it from water. In this study, the molecularly imprinted polymer (MIP) adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate (PFOS) from water. The MIP adsorbents using perfluorooctanoic acid (PFOA) as the template had good imprinting effects and could selectively remove PFOS from aqueous solution. The sorption behaviors including sorption kinetics, isotherms, and effect of pH, salt, and competitive anions were investigated. Experimental results showed that the sorption of PFOS on the MIP adsorbents was very fast, pH-dependent, and highly selective. The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents. The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations, which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface. The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS. The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.