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排序方式: 共有160条查询结果,搜索用时 234 毫秒
71.
城市绿地对空气负离子的影响 总被引:2,自引:0,他引:2
在南昌市选择有典型特征的城市绿地,对其在不同环境状况下的空气正、负离子浓度进行监测。研究结果表明:(1)城市绿地能有效提高空气负离子数量;(2)乔、灌、草3种不同类型的绿地中,以乔木林对提高空气负离子浓度和改善空气质量的作用最为显著;(3)在城市环境下,不同林分结构类型的乔木片林对空气负离子水平以及空气质量指数(CI)的影响差异不显著;(4)天气条件对绿地的空气负离子水平存在显著影响;(5)喷泉对空气负离子有显著影响。喷泉周围空气负离子浓度节律性振荡周期与喷泉的喷水变化周期相吻合。喷泉对空气负离子浓度以及CI的影响随着距离的增加而迅速减小。 相似文献
72.
73.
水中微量甲基膦酸类化合物的树脂富集与GC/MS分析 总被引:3,自引:0,他引:3
本文使用三种阴离子交换树脂(即大孔弱碱型D-301-R,强碱型D-296,201X7)柱对水中微量甲基膦酸类化合物的富集方法进行了研究。含磷毒剂降解产物的水样用气相色谱/质谱法进行定性定量分析。结果表明,D-301-R阴离子交换树脂柱对甲基膦酸的富集回收率高于60%。 相似文献
74.
采用吸附-Fenton氧化-絮凝法处理对硝基苯胺生产废水(简称废水),研究了吸附剂、脱附温度、絮凝剂等因素对处理效果的影响.经实验确定的最佳工艺条件为:DM301大孔树脂加入量5.0 g/L,吸附时间20 h,Fenton氧化pH 3.0,H_20_2加入量0.3 moL/L,m(Fe):m(H_20_2)=6,絮凝阴离子型聚丙烯酰胺加入量20 mg/L.在此条件下对COD为2 780 mg/L、色度为185倍和pH为12.2的废水进行处理,出水的COD、色度和pH分别为169 mg/L、10倍和6.5,COD去除率和色度去除率分别达到93.9%和94.5%.DM301树脂在10~25次重复使用后对硝基苯胺的平均总去除率为47.7%,对硝基苯胺的平均回收率为37.9%. 相似文献
75.
The mesoporous Cu/Mg/Fe layered double hydroxide(Cu/Mg/Fe-LDH) with carbonate intercalation was synthesized and used for the removal of arsenate from aqueous solutions.The Cu/Mg/Fe-LDH was characterized by Fourier transform infrared spectrometry,X-ray diffraction crystallography,scanning electron microscopy,X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller.Effects of various physico-chemical parameters such as pH,adsorbent dosage,contact time and initial arsenate concentration on the adsorption of arsenate onto Cu/Mg/Fe-LDH were investigated.Results showed that it was efficient for the removal of arsenate,and the removal efficiency of arsenate increased with the increment of the adsorbent dosage,while the arsenate adsorption capacity decreased with increase of initial pH from 3 to 11.The adsorption isotherms can be well described by the Langmuir model with R 2 > 0.99.Its adsorption kinetics followed the pseudo second-order kinetic model.Coexisting ions such as HPO42-,CO32-,SO42and NO3could compete with arsenate for adsorption sites on the Cu/Mg/Fe-LDH.The adsorption of arsenate on the adsorbent can be mainly attributed to the ion exchange process.It was found that the synthesized Cu/Mg/Fe-LDH can reduce the arsenate concentration down to a final level of < 10 μg/L under the experimental conditions,and makes it a potential material for the decontamination of arsenate polluted water. 相似文献
76.
Haiou Song Zhijian Yao Mengqiao Wang Jinnan Wang Zhaolian Zhu Aimin Li 《环境科学学报(英文版)》2013,25(1):105-113
The effects of dissolved organic matter (DOM) on the removal of nitrate-nitrogen from the model contaminated water have been investigated utilizing the strong base anion exchange resins. With the increase of gallic acid concentration from 0 to 400 mg/L, the adsorption amount of nitrate-nitrogen on the commercial resins, including D201, Purolite A 300 (A300) and Purolite A 520E (A520E), would significantly decrease. However, the presence of tannin acid has little impact on nitrate-nitrogen adsorption on them. Compared to D201 and A300 resins, A520E resin exhibited more preferable adsorption ability toward nitrate-nitrogen in the presence of competing organic molecules, such as gallic acid and tannin acid at greater levels in aqueous solution. Attractively, the equilibrium data showed that the adsorption isotherm of nitrate-nitrogen on A520E resin was in good agreement with Langmuir and Freundlich equations. The rate parameters for the intra particle diffusion have been estimated for the different initial concentrations. In batch adsorption processes, nitrate-nitrogen diffuse in porous adsorbent and rate process usually depends on t 1/2 rather than the contact time. The pseudo first- and the second-order kinetic models fit better for nitrate-nitrogen adsorption onto A520E resin. The observations reported herein illustrated that A520E resin will be an excellent adsorbent for enhanced removal of nitrate-nitrogen from contaminated groundwater. 相似文献
77.
离子色谱法中高浓度盐基体对无机阴离子分析影响规律的研究 总被引:5,自引:0,他引:5
本文首次研究高浓度盐基体中,大量盐的存在对无机阴离子的保留时间,峰高峰面积等参数的影响规律,并对其影响机理进行了初步探讨,实验证明,在样品中离子总浓度不超过柱容量孤情况下,虽然由于某些离子的浓度过高,使待测离子的保留时间变短,峰形改变,但用峰面积和标准加入外推法计算,仍可得到较即的结果。 相似文献
78.
Qing ZHOU Mengqiao WANG Aimin LI Chendong SHUANG Mancheng ZHANG Xiaohan LIU Liuyan WU 《Frontiers of Environmental Science & Engineering》2013,7(3):412-419
A novel hyper-crosslinked resin (MENQ) modified with an anion exchange group was prepared using divinylbenzene (DVB) and methyl acrylate (MA) as comonomers via four steps: suspension polymerization, post-crosslinking, ammonolysis and alkylation reactions. The obtained resin had both a high specific surface area (793.34 m2·g-1) and a large exchange capacity (strong base anion exchange capacity, SEC: 0.74 mmol·g-1, weak base anion exchange capacity, WEC: 0.45 mmol·g-1). XAD-4 was selected as an adsorbent for comparison to investigate the adsorption behavior of tetracycline (TC) and humic acid (HA) onto the adsorbents. The results revealed that MENQ could effectively remove both TC and HA. The adsorption capacity of XAD-4 for TC was similar to that of MENQ, but XAD-4 exhibited poor performance for the adsorption of HA. The adsorption isotherms of TC and HA were well-fitted with the Freundlich model, which indicated the existence of heterogeneous adsorption through cation-π bonding and π–π interactions. The optimal solution condition for the adsorption of TC was at a pH of 5–6, whereas the adsorption of HA was enhanced with increasing pH of the solution. 相似文献
79.
利用ANSYS有限元分析软件对肋片式换热器首先进行热分析,获得温度场温度扩展分布云图,得出温度在管道周围的值最大,最大值是78.76℃;通过定义路径分析了沿着肋片径向及管道高度内壁方向上的温度分布情况,得到相应的曲线和温度分布云图;之后在热分析的基础上,利用ANSYS软件中的间接法进行热应力分析,获得热应力的分布情况,最大热应力值发生在管道外壁与蒸汽管道连接部位,其值为40.19MPa;最后根据JB4732-95《钢制压力容器分析设计标准》进行相应的应力评定后,证明该肋片换热器是安全可靠的,可以应用在实际工程生产中。 相似文献
80.
何志华 《中国特种设备安全》2012,(12):17-19,51
根据双管板换热器的结构特点,从设计、制造、监造与使用维护方面全过程要点剖析,对主要重点进行系统性进行阐述,并与业内人士全方位交流与要点探讨。 相似文献