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排序方式: 共有1365条查询结果,搜索用时 125 毫秒
381.
Jiangping Li Chen Song Yixin Su Hai Long Ta Huang Trokon Omarley Yeabah Wei Wu 《Environmental science and pollution research international》2013,20(8):5397-5404
A combined treatment of electrocoagulation and ultrasound was proposed to solve some problems which exist in the phosphorus removal processes in fine chemical industry. The intermittently discharged wastewater has the features of high initial phosphorus concentration and wide initial pH variation. The electrocoagulation–ultrasound effective performance for the removal of phosphorus was investigated. The results obtained from synthetic wastewater showed that the total phosphorus (TP) decreased from 86 to about 0.4 mg/L, and the removal efficiency reached about 99.6 %, when ultrasound was applied to the electrocoagulation cell under the optimum working conditions in 10 min. Comparatively, the TP removal efficiency of electrocoagulation group was 81.3 % and the ultrasound group has almost no change. Therefore, we can conclude that the electrocoagulation and ultrasound synergistic effect can effectively degrade high-phosphorus wastewater. We have discussed the impact of various parameters on the electrocoagulation–ultrasound based on the phosphorus removal efficiency. The results obtained from synthetic wastewater showed that the optimum working pH was found to be 6, allowing the effluent to be met the emission standards without pH adjustment. An increased current enhanced the speed of treatment significance, but higher current (>40 mA/cm2) enhanced ultrasonic cavitation effect causing flocculation ineffective. In addition, it was found that the optimum ultrasonic power was 4 W/cm2 and the frequency was 20 kHz. The best ultrasound intervention and ultrasonic irradiation time were processed with electrocoagulation simultaneously. The results indicated that the electrocoagulation–ultrasound could be utilized as an attractive technique for removal of phosphate in the real wastewater. 相似文献
382.
383.
Joseph F. Walling Gary Evans Thomas A. Hinners Joseph P. Lambert Sharon J. Long Frank W. Wilshire 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1134-1136
A comparison was made of over 300 pairs of arsenic results from instrumental neutron activation and flameless atomic absorption analyses of atmospheric particulates collected on glass fiber filters. Atomic absorption analyses involved low temperature ashing of filters at high power levels. No matrix modification chemicals were added to the acid extract which was analyzed. Neutron activation results are on the average 9% higher than those obtained by atomic absorption and the difference is statistically significant. This small difference is probably due to the analytical techniques or acid extraction and not in any important way to losses during low temperature ashing. This conclusion is in sharp contrast to other recently reported situations where low temperature ashing losses in analyzing atmospheric particulate were sizable. Although the atmospheres sampled differed somewhat between these situations the most obvious difference was in the combustibility of the filters used in sampling. 相似文献
384.
B. I. Chevone Y. S. Yang W. E. Winner I. Storks-Cotter S. J. Long 《Journal of the Air & Waste Management Association (1995)》2013,63(4):355-359
A rainfall simulator, developed on the principle of droplet formation from needle tips, is described. The simulator is designed for laboratory experimentation to examine the effects of acidic precipitation on terrestrial plants. Droplet diameter can be varied from 2.5 to 3.4 mm with different gauge needles, and rainfall intensities from 0.50 to 1.25 cm h-1 can be attained by a variable speed peristaltic pump. Uniform distribution of rainfall was achieved by rotating the target area and by spacing needles, using an empirical cumulative probability distribution function, along eight radial tubular arms. Variation in rainfall distribution across a 1.2 m diameter circular target area was < 5 % . Integrity of solution chemistry was maintained upon passage through the simulator with variations in cation concentrations <10%, anion concentrations <5 % and pH <0.2. The system offers sufficient flexibility to simulate a range of rainfall characteristics by varying needle diameter, changing pump speed and/or altering the number of radial arms on each unit. 相似文献
385.
R.Q. Long R.T. Yang K.D. Zammit 《Journal of the Air & Waste Management Association (1995)》2013,63(3):436-442
ABSTRACT Fe3+-, Cr3+-, Cu2+-, Mn2+-, Co2+-, and Ni2+-exchanged Al2O3-pillared interlayer clay (PILC) or TiO2-PILC catalysts are investigated for the selective catalytic reduction (SCR) of nitric oxide by ammonia in the presence of excess oxygen. Fe3+-exchanged pillared clay is found to be the most active. The catalytic activity of Fe-TiO2-PILC could be further improved by the addition of a small amount of cerium ions or cerium oxide. H2O and SO2 increase both the activity and the product selectivity to N2. The maximum activity on the Ce-Fe-TiO2-PILC is more than 3 times as active as that on a vanadium catalyst. Moreover, compared to the V2O5-WO3/TiO2 catalyst, the Fe-TiO2-PILC catalysts show higher N2/N2O product selectivities and substantially lower activities (by ~85%) for SO2 oxidation to SO3 under the same reaction conditions. A 100-hr run in the presence of H2O and SO2 for the CeO2/Fe-TiO2-PILC catalyst showed no decrease in activity. 相似文献
386.
以季铵盐阳离子表面活性剂CTMAB及阴离子表面活性剂SDS对粉末状天然沸石进行复合改性,制备得到了CTMAB/SDS改性沸石。对改性沸石及天然沸石进行红外吸收光谱及XRD衍射表征,并研究了PAEs在天然沸石和CT-MAB/SDS改性沸石上的吸附机制。结果表明,阴阳离子表面活性剂没有对层状结构的键型造成较大的影响;PAEs在天然沸石和CTMAB/SDS改性沸石上的吸附更符合表面吸附一分配作用复合模型;PAEs的表面吸附和分配作用对吸附作用的贡献主要受吸附剂中有机质含量及吸附物质大小、极性及溶解度的影响。 相似文献
387.
采用PDMDAAC改性方法对油页岩灰渣进行改性,确定最佳改性方案,并研究了环境因素对改性油页岩灰渣吸附DNBP的影响。实验研究结果表明,油页岩灰渣经20 g/L 的PDMDAAC处理时,对DNBP的吸附能力最强。在吸附温度为30℃,初始溶液pH值为4的条件下,0.3 g 的改性油页岩灰渣对30.0 mg/L DNBP溶液50 mL,吸附120 min时,其吸附率达到94.48%以上。在实验条件下,改性油页岩灰渣对DNBP的吸附符合Langmuir和Freundlich等温吸附方程,相关系数分别为0.9985和0.9776,其对DNBP的理论饱和吸附量达到6.196 mg/g。改性油页岩灰渣对DNBP的吸附主要归因于离子交换和表面吸附作用。 相似文献
388.
Study on the Effect of Dicumyl Peroxide on Structure and Properties of Poly(Lactic Acid)/Natural Rubber Blend 总被引:1,自引:0,他引:1
Yun Huang Chunmei Zhang Yonghao Pan Weiwei Wang Long Jiang Yi Dan 《Journal of Polymers and the Environment》2013,21(2):375-387
In attempt to enhance the compatibility of NR in PLA matrix, and furthermore to enhance mechanical properties of PLA, PLA/NR blends with strong interaction were prepared in Haake internal mixer, using dicumyl peroxide (DCP) as cross-linker. The effects of dicumyl peroxide on morphology, thermal properties, mechanical properties and rheological properties of PLA and PLA/NR blends were studied. The results indicated that dicumyl peroxide could increase the compatibility of poly(lactic acid) and natural rubber. With small amount of dicumyl peroxide, the effect on NR toughening PLA was enhanced and the tensile toughness of PLA/NR blends was improved. When the DCP content was up to 0.2 wt%, the PLA/NR blend reached the maximum elongation at break (26.21 %) which was 2.5 times of that of neat PLA (the elongation at break of neat PLA was 10.7 %). Meanwhile, with introducing 2 wt% DCP into PLA/NR blend, the maximum Charpy impact strength (7.36 kJ/m2) could be achieved which was 1.8 times of that of neat PLA (4.18 kJ/m2). Moreover, adding adequate amount of DCP could improve the processing properties of blends: the viscosity of PLA/NR blend decreased significantly and the lowest viscosity of the blends could be achieved when the DCP content was 0.5 wt%. 相似文献
389.
390.
Yabusaki SB Fang Y Williams KH Murray CJ Ward AL Dayvault RD Waichler SR Newcomer DR Spane FA Long PE 《Journal of contaminant hydrology》2011,126(3-4):271-290
Three-dimensional, coupled variably saturated flow and biogeochemical reactive transport modeling of a 2008 in situ uranium bioremediation field experiment is used to better understand the interplay of transport and biogeochemical reactions controlling uranium behavior under pulsed acetate amendment, seasonal water table variation, spatially variable physical (hydraulic conductivity, porosity) and geochemical (reactive surface area) material properties. While the simulation of the 2008 Big Rusty acetate biostimulation field experiment in Rifle, Colorado was generally consistent with behaviors identified in previous field experiments at the Rifle IFRC site, the additional process and property detail provided several new insights. A principal conclusion from this work is that uranium bioreduction is most effective when acetate, in excess of the sulfate-reducing bacteria demand, is available to the metal-reducing bacteria. The inclusion of an initially small population of slow growing sulfate-reducing bacteria identified in proteomic analyses led to an additional source of Fe(II) from the dissolution of Fe(III) minerals promoted by biogenic sulfide. The falling water table during the experiment significantly reduced the saturated thickness of the aquifer and resulted in reactants and products, as well as unmitigated uranium, in the newly unsaturated vadose zone. High permeability sandy gravel structures resulted in locally high flow rates in the vicinity of injection wells that increased acetate dilution. In downgradient locations, these structures created preferential flow paths for acetate delivery that enhanced local zones of TEAP reactivity and subsidiary reactions. Conversely, smaller transport rates associated with the lower permeability lithofacies (e.g., fine) and vadose zone were shown to limit acetate access and reaction. Once accessed by acetate, however, these same zones limited subsequent acetate dilution and provided longer residence times that resulted in higher concentrations of TEAP reaction products when terminal electron donors and acceptors were not limiting. Finally, facies-based porosity and reactive surface area variations were shown to affect aqueous uranium concentration distributions with localized effects of the fine lithofacies having the largest impact on U(VI) surface complexation. The ability to model the comprehensive biogeochemical reaction network, and spatially and temporally variable processes, properties, and conditions controlling uranium behavior during engineered bioremediation in the naturally complex Rifle IFRC subsurface system required a subsurface simulator that could use the large memory and computational performance of a massively parallel computer. In this case, the eSTOMP simulator, operating on 128 processor cores for 12h, was used to simulate the 110-day field experiment and 50 days of post-biostimulation behavior. 相似文献