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211.
Preparations of organobentonite using nonionic surfactants 总被引:12,自引:0,他引:12
Shen YH 《Chemosphere》2001,44(5):989-995
Due to hydrophilic environment at its surface, natural bentonite is an ineffective sorbent for nonpolar nonionic organic compounds in water even though it has high surface area. The surface properties of natural bentonite can be greatly modified by simple ion-exchange reactions with large organic cations (cationic surfactants) and this organobentonite is highly effective in removing nonionic organic compounds from water. Cationic surfactant derived organobentonites have been investigated extensively for a wide variety of environmental applications. In this study, the preparation of organobentonite using nonionic surfactants has been investigated for the first time. Results indicate that nonionic surfactants intercalates into the interlamellar space of bentonite and may demonstrate higher sorption capacity than cationic surfactant. It is possible to create large interlayer spacing and high organic carbon content organobentonite by use of nonionic surfactants with suitable balance between the hydrocarbon and ethylene oxide chain lengths. In addition, nonionic surfactant derived organobentonites are more chemically stable than cationic surfactant derived organobentonites. 相似文献
212.
213.
Leaching and uptake of heavy metals by ten different species of plants during an EDTA-assisted phytoextraction process 总被引:10,自引:0,他引:10
In a pot experiment, the potential use of 10 plant species, including six dicotyledon species and four monocotyledon species, was investigated for the EDTA-enhanced phytoextraction of Pb from contaminated soil. Mung bean and buckwheat had a higher sensitivity to the EDTA treatment in soils. In the 2.5 and 5.0 mmol kg(-1) EDTA treatments, the Pb concentrations in the shoots of the six dicotyledon species ranged from 1,000 to 3,000 mg kg(-1) of dry matter, which were higher than those of the monocotyledon species. The highest amount of phytoextracted Pb (2.9 mg Pb pot(-1)) was achieved in sunflowers, due to the high concentration of Pb in their shoots and large biomass, followed by corns (1.8 mg Pb pot(-1)) and peas (1.1 mg Pb pot(-1)). The leaching behavior of heavy metals as a result of applying EDTA to the surface of the soil was also investigated using short soil-leaching columns (9.0-cm diameter, 20-cm height) by the percolation of artificial rainfall. About 3.5%, 15.8%, 13.7% and 20.6% of soil Pb, Cu, Zn and Cd, respectively, were leached from the soil columns after the application of 5.0 mmol kg(-1) of EDTA. The growth of sunflowers in the soil columns had little effect on the amount of metals that were leached out. This was probably due to the shallowness of the layer of soil, the short time-span of the uptake of metals by the plant and the plant's simple root systems. 相似文献
214.
The parameters affecting the electron spin resonance (ESR) detection of hydroxyl free radical in water are studied and optimized. The hydroxyl radical is generated by the Fenton reaction with iron (II) ammonium sulfate and hydrogen peroxide reacting in a phosphate buffer using N-tert-butyl-alpha-phenylnitron as the spin trap. The concentrations of Fe2+, H2O2, and phosphate buffer are the parameters studied. The Taguchi method and the orthogonal experiment design were used to evaluate the effects of these parameters on the ESR signal intensity. By the analysis of the signal-to-noise ratio and the analysis of variance, the order of importance of the various parameters on the hydroxyl radical formation is determined for optimal ESR detection of hydroxyl radical. The results will help the development of water purification technologies using hydroxyl free radical as a green oxidant. 相似文献
215.
216.
Shen YH 《Chemosphere》2002,48(10):1075-1079
This study investigates the feasibility of using ethylene oxide chain adsorption to determine the surface area of an expandable clay, montmorillonite. Experimental results indicate that high molecular weight poly(ethylene oxide) or nonionic surfactant with long ethylene oxide chain should be used to provide reasonable estimations for monolayer capacity. The method has advantages over Brunauer, Emmett, and Teller method in that it is readily applicable to a wide range of areas, particularly to 2:1 layer silicates under aqueous conditions. 相似文献
217.
按GB11890—89顶空气相色谱法分析苯系物时,发现重复性和分割水平样品平行性较差,经仔细分析,是由于使用普通玻璃注射器造成的。为避免此类误差,建议顶空气相色谱法分析时,使用带特氟龙顶端推杆的气密性注射器。 相似文献
218.
在SBR反应器中对DO和pH值在短程硝化和半亚硝化过程中的作用进行试验研究,结果表明,控制低DO和适宜的pH值在短程硝化过程中起着重要的作用.本试验条件下,当DO为0.5~1.0 mg/L、pH值为7.5~8.0时,在SBR反应器中很容易实现短程硝化;当DO>0.3 mg/L时,DO越低,出水NO2--N积累率越高;当pH值>6.8时,不会影响系统NO2--N积累的稳定性.另外,研究结果还表明,通过控制DO和pH值可以实现半亚硝化.本试验条件下,当进水氨氮浓度为120 mg/L时,控制DO为0.3~0.4 mg/L可实现出水半亚硝化;当进水氨氮浓度为200 mg/L时,控制DO为0.5~0.6 mg/L或pH值为6.8也可以实现出水半亚硝化. 相似文献
219.
各种影响因子对电解法预处理医药废水的影响研究 总被引:2,自引:0,他引:2
探讨了电解法预处理医药废水时停留时间、电解电压、废水初始浓度、温度和废水pH值等影响因子对去除色度、COD和提高废水可生化性等处理效果的影响,并考察了其应用于工业实际废水处理的可行性。实验结果表明:电解法更适合高浓度医药废水的处理,色度的去除率可达到90%以上;电解时间宜控制在40-60min;电解电压越高,废水COD和色度去除效果越好;在实验温度范围内,温度对色度和COD去除率的影响不大;废水pH值为7.5时电解效果最佳,工程运用宜控制在6—9之间。 相似文献
220.
应用由城市污水处理厂序批式间歇反应器(SBR)中筛选得到的4株特殊氨氧化菌,分别在SBR和有回流的生物膜与A/O工艺耦合体系培养中,考察其降解低碳高氨氮废水的功能。结果表明,自养硝化与异养氨氧化菌的混合菌群较单一自养硝化菌株降解氨氮速率快;在生物膜与A/O工艺耦合系统中,自养硝化与异养氨氧化菌协同代谢加速氨氮氧化脱除,氨氮脱除速率远比SBR系统快。对生物膜与A/O工艺耦合系统中氨氮脱除动力学进行了研究,模拟了NH4^+、NO2^-;质量浓度与氨氮脱除比速率之间的关系,模型得到了较好的验证。 相似文献