Removal of dispersant-stabilized carbon nanotubes by regular coagulants

Coagulation followed by sedimentation, as a conventional technique in the water treatment plant, can be the first line of defense against exposures of carbon nanotubes (CNTs) to aquatic organisms and human beings, which has been rarely documented. This study investigated the removal of dispersant-stabilized CNT suspensions by poly aluminum chloride (PACl) and KAl(SO₄)₂. 12H₂O (alum), with a focus on the effects of dispersant type, coagulant type and dosage. PACl performed better than alum in the removal of tannic acid-, humic acid-, and sodium dodecyl benzenesulfonate-stabilized CNTs, but worse for polyethylene glycol octylphenyl ether (TX100)-stabilized CNTs. Neither coagulant could effectively precipitate cetyltrimethyl ammonium bromide-stabilized CNTs. The removal by PACl first increased up to a plateau and then decreased with the continued increase of coagulant dosage. However, the removal rates leveled off but did not decrease after achieving their highest level with the continued addition of alum. The coagulation and flocculation of the CNT suspensions by PACl could be regulated mainly by the mechanism of adsorption charge neutralization, whereas the coagulation by alum mainly involved electrical double-layer compression.     

Selection of magnetic anion exchange resins for the removal of dissolved organic and inorganic matters

Four magnetic anion exchange resins (MAERs) were used as adsorbents to purify drinking water. The effect of water quality (pH, temperature, ionic strength, etc.) on the performance of MAER for the removal of dissolved organic matter (DOM) was also investigated. Among the four studied MAERs, the strong base resin named NDMP-1 with high water content and enhanced exchange capacity exhibited the highest removal rate of dissolved organic carbon (DOC) (48.9% removal rate) and UV-absorbing substances (82.4% removal rate) with a resin dose of 10 mL/L after 30 min of contact time. The MAERs could also effectively remove inorganic matter such as sulfate, nitrate and fluoride. Because of the higher specific UV absorbance (SUVA) value, the DOM in the raw water was found to be removed more effectively than that in the clarified water by NDMP resin. The temperature showed a weak influence on the removal of DOC from 6 to 26℃, while a relatively strong one at 36℃. The removal of DOM by NDMP was also affected to some extent by the pH value. Moreover, increasing the sulfate concentration in the raw water could decrease the removal rates of DOC and UV-absorbing substances.     

Impacts of continuously regenerating trap and particle oxidation catalyst on the NO2 and particulate matter emissions emitted from diesel engine

Two continuously regenerating diesel particulate filter (CRDPF) with different configurations and one particles oxidation catalyst (POC) were employed to perform experiments in a controlled laboratory setting to evaluate their effects on NO₂, smoke and particle number emissions. The results showed that the application of the after-treatments increased the emission ratios of NO₂/NO_x significantly. The results of smoke emissions and particle number (PN) emissions indicated that both CRDPFs had sufficient capacity to remove more than 90% of total particulate matter (PM) and more than 97% of solid particles. However, the POC was able to remove the organic components of total PM, and only partially to remove the carbonaceous particles with size less than 30 nm. The negligible effects of POC on larger particles were observed due to its honeycomb structure leads to an inadequate residence time to oxidize the solid particles or trap them. The particles removal efficiencies of CRDPFs had high degree of correlations with the emission ratio of NO₂/NO_x. The PN emission results from two CRDPFs indicated that more NO₂ generating in diesel oxidation catalyst section could obtain the higher removal efficiency of solid particles. However this also increased the risk of NO₂ exposure in atmosphere.     

模糊物元模型在湿地水体污染评价中的应用

物元分析是用来处理在某些条件下用通常的方法无法解释的不相容问题的一种分析方法。文章以扎龙湿地水体中重金属污染评估为例,针对8个监测断面的5种重金属指标(锰、锌、铜、铬、砷)污染现状,用熵权法来确定指标的权重,构建模糊物元模型,用以实现水质的等级评价和监测样点排序,结果表明:扎龙湿地不同监测位点污染程度从重到轻递减顺序如下:东升水库>林甸排污口>核心区仙鹤湖>翁海排干>克钦湖>龙湖>特勒桥>龙安桥。湿地水源入口和核心区污染重金属污染严重,湿地的功能分区未能起到实质效果,湿地核心区未得到合理的保护。     

矿物质对污水污泥微波热解过程中NOx前驱物的影响研究

以酸洗脱灰污泥、原污泥及添加矿物质的污泥作为研究对象,考察了污泥中内在矿物质和添加矿物质对污水污泥微波热解过程中形成的NOx前驱物(NH3、HCN)释放的影响。结果表明:污水污泥中的内在矿物质和添加物在污水污泥微波热解过程中,对NH3和HCN的释放均有抑制作用:添加Fe2O3对NH3的抑制平均值为45%,添加CaO对HCN的抑制平均值可达79%。     

基于QAA算法的巢湖悬浮物浓度反演研究

QAA(quasi-analytical algorithm)算法基于辐射传输原理,估算水体后向散射系数,是目前较为成熟的半分析模型方法.2009年6月对巢湖水体进行野外实测,在获得遥感反射率、吸收衰减系数、悬浮物浓度(cTSM)等数据的基础上,构建了巢湖水体cTSM的近红外双波段反演模型,并将QAA算法计算得到的后向散射概率作为输入,以期提高cTSM的反演精度.结果表明,①对巢湖水体而言,807 nm和834 nm是构建近红外双波段模型的最佳波段,807 nm处的单位散射系数为0.411 m2.g-1,834 nm处的单位散射系数为0.395 m2.g-1;②利用QAA算法计算得到的巢湖水体的后向散射概率为0.029,将该值输入反演模型后,cTSM的反演精度与输入其他经验值相比得到明显提高,反演值与实测值的均方根误差RMSE和平均相对误差绝对值MAPE分别达到12.143 mg.L-1和24.378%;③在cTSM较高的站点(近似高于30 mg.L-1),利用近红外双波段模型反演的悬浮物浓度结果更为稳定和可靠.     

柳州市空气可吸入颗粒物中重金属污染特征分析

用TEOM 1405大气颗粒物监测仪于2011年2—6月在柳州市3个空气质量监测点进行了PM10的监测,样品用AAS进行重金属元素分析,得到了空气PM10中的重金属元素的浓度。研究结果表明,九中点位污染最大,市监测站次之,三门江相对较好。     

堆肥过程水溶性有机物组成和结构演化研究

基于Leenheer的分组方法,用XAD-8树脂将鸡粪不同堆肥阶段样品提取出的水溶性有机物(DOM)按极性和电荷特性分为疏水酸性组分(HOA)、疏水碱性组分(HOB)、疏水中性组分(HON)、酸不溶组分(AIM)及亲水性组分(HIM),采用元素分析、核磁共振(~1H-NMR)及红外光谱(FTIR),对各组分的组成和结构特征进行了研究.结果表明,堆肥DOM中HIM和HOA组分的含量分别为32%~44%和35%~47%,而HOB、AIM及HON组分之和不到25%,经堆肥后HIM组分含量下降,而疏水性组分含量增加.元素分析显示,堆肥过程N、C、S含量呈增加趋势,经堆肥后有机质H/C比降低,腐殖化率提高;~1H-NMR分析表明:HIM组分中烷基链烃的含量最少,支链最短,分支较多,碳水化合物含量高,而HON组分的组成恰好与之相反,AIM组分结构类似胡敏酸,HOB富含含氮化合物.FTIR分析表明,HOA和HOB组分富含羧基、酯基和醇羟基官能团,而AIM和HIM除上述官能团外,还含有大量苯环官能团,HON组分富含脂肪族官能团,该组分官能团种类最多,经堆肥后,脂族官能团含量降低,苯环官能团增加.     

Characterising the performance of a tapered scrubber for controlling particulate emission

The performance of a modified tapered scrubber using water is presented in this article. The column is fabricated with internals so as to improve the performance of a simple tapered bubble scrubber. Experimentation indicates that the system developed can obtain almost 100% particulate (fly ash) removal efficiency under certain hydrodynamical conditions and the removal efficiency has been found to be higher than the existing similar systems. An empirical correlation is put forward for the prediction of removal efficiency as a function of relevant variables of the system. Experimental results agree very well with the correlation.     

机动车制动磨损颗粒物及挥发性有机物的组分特征

利用制动惯性实验台测试了6套制动系统,分别采集了制动磨损颗粒物（BWPs）和制动过程中排放的挥发性有机物（VOCs）样品,提取并检测了颗粒物中39种元素、12种水溶性离子、7种碳组分和18种多环芳烃（PAHs）的含量,分析了气体样品中74种VOCs的浓度.含量较高的12种无机元素（即Sb、Mg、Cu、Zn、Ti、Ca、Si、Zr、K、Ba、Al和Fe）在PM_2.5和PM₁₀中的质量分数平均值分别为43.4%和40.3%,其中Fe的质量分数最高,在PM_2.5和PM₁₀中分别为16.6%和13.1%.元素的粒径分布与BWPs质量分布一致.12种水溶性离子在PM_2.5和PM₁₀中的质量分数平均值分别为16.5%和12.6%,其中NO₃^-、SO₄^2-和Ca²⁺的质量分数平均值较高.总碳（TC）在PM_2.5和PM₁₀中的质量分数平均值分别为21.9%和18.1%,有机碳（OC）的质量分数平均值是元素碳（EC）的5倍左右.检出率大于50%的PAHs共有6种,其中萘（Nap）含量最为丰富.74种VOCs的浓度平均值为316.04 μg ·m^-3,其中芳香烃的浓度最高.6套制动系统排放的BWPs组分和VOCs构成的差异较大,主要是由刹车片的品牌和制造使用的材料决定的.