共查询到20条相似文献,搜索用时 15 毫秒
1.
Yan He Jian Xu Yuan Zhang Changsheng Guo Lei Li Yuqiu Wang 《Environmental science and pollution research international》2012,19(9):4206-4213
This study presents oxidative transformation of carbamazepine by synthetic manganese oxide (??-MnO2) as well as impact of variables including initial MnO2 loading, pH, coexisting metal ions, and humic acid (HA) on transformation. Manganese oxide (??-MnO2) was synthesized and stored in the form of suspension. The oxidative reactions were conducted in 50?mL polyethylene (PE) centrifuge tubes with constant pH maintained by buffers. The kinetic experiment was carried out in the solution of pH 2.72 containing 5.0?mg/L of carbamazepine and 130.5?mg/L of MnO2. Effects of initial MnO2 loading (0?C130.5?mg/L), pH (2.72?C8.58) and 0.01?M of coexisting solutes (metal ions and HA) on carbamazepine oxidation were also determined. Reaction kinetics indicated that carbamazepine was rapidly degraded in the first 5?min, and approximately 95?% of carbamazepine was eliminated within 60?min. The reaction exhibited pronounced pH dependence and increased with decreasing pH values. The transformation of carbamazepine was also accelerated with increasing MnO2 loadings. Coexisting metal ions competed with carbamazepine for reactive sites leading to reduced carbamazepine removal, and the inhibitive capacity followed the order of Mn2+?>?Fe3+?>?Ca2+????Mg2+. Presence of HA in aqueous solution caused a significant reduction on the magnitude of carbamazepine transformation. This study indicated that carbamazepine can be effectively degraded by ??-MnO2, and transformation efficiency was strongly dependent on reaction conditions. It suggests that amendment of soil with MnO2 be a potential alternative to solve carbamazepine pollution. 相似文献
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采用水热法和化学浴沉积法制备了ZnO/CdS/Au异质结光催化剂,用于可见光下室温去除低浓度甲醛。通过XRD、SEM、TEM、XPS、UV、PL、PEC、EIS等手段对ZnO/CdS/Au异质结光催化剂的光学性能、光电性能进行表征。结果表明,Au负载的ZnO/CdS纳米棒组成的微米花状结构中,异质结和金属等离子体效应能拓宽光谱吸收范围,抑制半导体缺陷发光,促进光吸收以及光生电子空穴的分离和迁移;所制备的ZnO/CdS/Au异质结光催化剂对甲醛的去除具有优异性能,室温下2 h即可将反应舱内低质量浓度甲醛(1.25 mg·m−3)降至0.025 mg·m−3以下,且经过8次重复使用后催化剂活性没有明显下降。此外,影响甲醛去除的因素,如催化剂种类、光照波长、甲醛初始质量浓度、相对湿度也进行了研究和探讨。该研究结果对低浓度甲醛的室温去除具有理论指导意义。 相似文献
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Colored N-containing MOx-ZnO (M = W, V) composite powders with high surface area were synthesized by spray pyrolysis. The nitrogen content was controlled from 600 to 3000 ppm by changing the powder ingredients and the spray pyrolysis temperature. Ultraviolet-visible spectra indicated that the N-containing MOx-ZnO powders absorbed not only ultraviolet light like pure ZnO powder, but also some visible-light. Acetaldehyde decomposition was used as a probe reaction to evaluate the photocatalysis of these MOx-ZnO powders. The photocatalytic activity of the N-containing ZnO powder was pronouncedly enhanced by the WO3 or V2O5 addition under both UV and visible-light irradiation. This enhancement was ascribed to the MOx acting as a sink for photogenerated electrons in the UV case, and to a synergistic effect of N-doping and MOx-ZnO coupling in the case of visible-light. 相似文献
5.
Hsu JN Tsai CJ Chiang C Li SN 《Journal of the Air & Waste Management Association (1995)》2007,57(2):204-210
Copper, zinc, and cerium oxide adsorbents supported on alumina were used to remove silane gas (SiH4). The adsorbents were prepared using a coprecipitation method and characterized by the inductively coupled plasma mass spectrometry, X-ray powder diffractometer, and Brunauer-Emmett-Teller method (BET). The silane removal efficiency and adsorption capacity of the adsorbents were investigated in this study. Test results showed that the adsorbents containing active species had a removal efficiency >99.9% for SiH4 before breakthrough. Adsorbents containing mixed oxides (CuO-CeO2/ Al2O3 and CuO-ZnO/Al2O3), which showed well-dispersed active species and high BET surface areas, had a greater adsorption capacity than the adsorbents containing single metal oxide. However, when the CuO-ZnO/ Al2O3 adsorbents contain >40 wt% of active metal oxides, the increase of active species lowered the BET surface area leading to a decrease of the adsorption capacity. Additionally, when the content of the active metal oxides was between 20% and 40%, the CuO-ZnO/Al2O3 adsorbents demonstrated higher adsorption capacity. 相似文献
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Tsai CH Huang YJ Chen JC Liao WT Fang GC 《Journal of the Air & Waste Management Association (1995)》2003,53(10):1225-1232
The traditional technologies for odor removal of thiol usually create either secondary pollution for scrubbing, adsorption, and absorption processes, or sulfur (S) poisoning for catalytic incineration. This study applied a laboratory-scale radio-frequency plasma reactor to destructive percentage-grade concentrations of odorous dimethyl sulfide (CH3SCH3, or DMS). Odor was diminished effectively via reforming DMS into mainly carbon disulfide (CS2) or sulfur dioxide (SO2). The removal efficiencies of DMS elevated significantly with a lower feeding concentration of DMS or a higher applied rf power. A greater inlet oxygen (O2)/DMS molar ratio slightly improved the removal efficiency. In an O2-free environment, DMS was converted primarily to CS2, methane (CH4), acetylene (C2H2), ethylene (C2H4), and hydrogen (H2), with traces of hydrogen sulfide (H2S), methyl mercaptan (CH3SH), and dimethyl disulfide. In an O2-containing environment, the species detected were SO2, CS2, carbonyl sulfide, carbon dioxide (CO2), CH4, C2H4, C2H2, H2, formaldehyde, and methanol. Differences in yield of products were functions of the amounts of added O2 and the applied power. This study provided useful information for gaining insight into the reaction pathways for the DMS dissociation and the formation of products in the plasmolysis and conversion processes. 相似文献
8.
This study investigates the effect of initial tetrachloroethylene (PCE) concentration, irradiation dose and dissolved metal ions such as Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+ on removal of PCE by gamma irradiation. The amount of removed PCE decreased with increase in initial PCE concentration and increased with increase in irradiation dose. PCE removal reached a maximum in the presence of Fe3+, while Cu2+ strongly hindered PCE decomposition. Except for Cu2+, the amount of removed PCE in the presence of metal ions was linearly dependent on the standard reduction potential of the metal ions. The extraordinary inhibition of Cu2+ in PCE removal was caused by the action of Cu2+ as a strong *OH scavenger, that was directly confirmed by electron paramagnetic resonance spectroscopy. 相似文献
9.
S Muramoto 《Journal of environmental science and health. Part. B》1989,24(5):559-568
The toxicity of metal oxides (CdO, ZnO, PbO) were compared with each other and the critical levels of metal uptake by rice plants were determined. The order of metal toxicity to rice plants is CdO greater than ZnO greater than PbO. The highest concentration obtained for unpolished rice was 4.97 micrograms/g at the Cd 10,000 ppm in soil. This values is higher than every other we have seen in the reports for treatment with CdO. We are able to find out that the concentration of 10,000 ppm Cd in the form of CdO in the critical one towards rice plant. By contrast, such damage was not observed at even higher levels of ZnO and PbO were considered to have low toxicity toward rice plant. Also, a negative correlation between Zn or Cu accumulation in rice plants and Cd concentration in soil was found. 相似文献
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采用厌氧氨氧化污泥,通过脱氮效能的测定,研究了常温(15±2)℃下保藏过程中基质添加与保藏时间对污泥活性的影响以及探讨长期保持污泥活性的保藏策略。结果表明,在无营养物添加的情况下,保藏的前45天厌氧氨氧化污泥氮去除速率由0.107 kg/(m3·d)下降到0.025 kg/(m3·d),其速率下降最快,但是经过6 d培养,污泥的活性可以得到恢复;当保藏365 d后,厌氧氨氧化污泥活性基本消失,即使通过11 d恢复也无明显的厌氧氨氧化特性。说明常温下保藏时间对厌氧氨氧化污泥活性影响显著,随着保藏时间的延长污泥氮去除速率会大幅降低,甚至消失。根据衰减指数模型拟合出常温状态下厌氧氨氧化污泥活性衰减模型为y=0.547×exp(-0.0109×t)。通过定期(15 d)投加营养物,经过150d和365 d保藏后的厌氧氨氧化污泥仍然保持48%和31%的活性。说明定期投加营养物可以有效缓解厌氧氨氧化污泥活性在常温保藏过程中的衰减,适用于厌氧氨氧化污泥常温下长期保藏。 相似文献
11.
复合金属氧化物的制备及其光催化性能 总被引:1,自引:0,他引:1
《环境工程学报》2016,(3)
采用溶胶-凝胶法制备了一系列钛基复合金属氧化物(Fe Ti Ox、Fe Al Ti Ox和Cu Mg Al Ti Ox),采用X射线衍射(XRD)、X射线光电子能谱(XPS)和透射电镜(TEM)等手段对材料的晶体结构、元素化学状态和结构形貌进行表征,以降解罗丹明B(Rh B)为模型反应来评价材料的光催化性能,实验考察了光源类型、催化剂用量、光照时间等因素对Rh B降解效果影响。结果表明:由于金属氧化物的协同作用,复合金属氧化物的光催化性能均优于纯二氧化钛的光催化性能,其中,以Fe Al Ti Ox催化剂的降解效果最好,Rh B的去除率高达97.5%。 相似文献
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Six 5 wt.% metal sorbents including Mn, Fe, Cu, Co, Ce and Zn supported on gamma-Al2O3, prepared by the incipient wetness impregnation method with calcination at 700 degrees C for 2 h, have been investigated for sorption of hydrogen sulfide in the temperature range of 500-700 degrees C. The sorption experiments were conducted in a fixed-bed reactor in terms of breakthrough curves and characterized by X-ray powder diffraction. The results reveal that the copper and manganese sorbents exhibit the best performance because they provide nearly 100% utilization, but the copper sorbent has a lower sulfur sorption capacity compared with the manganese sorbent. The zinc and cerium sorbents are not good candidates attributed to the vaporization of zinc and unexpected product for cerium. Effects of support materials on 5 wt.% manganese were also investigated by using gamma-Al2O3, SiO2 and TiO2 in this study. Five weight percent Mn/gamma-Al2O3 shows the best performance among support candidates. On the basis of XRPD and BET surface area analysis, TiO2 appears a huge loss in BET surface area associated with a significant formation of rutile form. 相似文献
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Lanthanum-doped anatase TiO2 thin films on glass prepared via a sol–gel process have been shown to have much higher photocatalytic activity for the degradation of gaseous benzene than pure anatase TiO2 thin film. The photodecomposition of benzene on both types of TiO2 films follows the first-order kinetics while the CO2 and CO formation followed the zero-order kinetics. GC/MS identification of the intermediates produced during the photodegradation of benzene revealed that doping lanthanum into TiO2 thin film favors a cleavage of benzene ring. An optimal lanthanum amount with respect to photocatalytic activity was about 2.5 wt% (La2O3/TiO2). 相似文献
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A comparison of CaOs produced by calcining two types of hydrated lime and calcium carbonate was made for decomposition of trichloroethylene and in-situ dry sorption of the decomposed Cl-products using a lab-scale gas flow type tubular packed bed reactor. About 20 mg of CaO sample was mixed with about 2 g of Al2O3 particles and packed in the reactor and allowed to react with a flowing standard gas containing 500 ppm of C2HCl3 (N2 balance) at 673 and 873 K, under the condition that the reaction of CaO with C2HCl3 might be completed within a few hours.It was found that no thermal decomposition of C2HCl3 at or below 673 K was observed in a reactor packed only with Al2O3 particles. However, a considerable amount of decomposition of C2HCl3 was obtained in a reactor packed with CaO and Al2O3, even at 673 K. For 1 mol of CaO prepared by calcining highly reactive Ca(OH)2 at 673 K, decomposition of 0.42 mol of C2HCl3 and in-situ absorption product of 0.53 mol of CaCl2 were obtained. At 873 K, about 46% of C2HCl3 was thermally decomposed. The total amount of C2HCl3 decomposed in CaO-Al2O3 particle bed at 873 K became nearly twice larger than that at 673 K. For 1 mol of CaO prepared by calcining highly reactive Ca(OH)2 at 873 K, decomposition of 0.59 mol of C2HCl3 and in-situ absorption product of 0.67 mol of CaCl2 were obtained. Small amounts of C2Cl2, C2Cl4, CCl4, etc. were detected during decomposition of C2HCl3 at 673 and 873 K.It was recognized that the data on decomposition of C2HCl3 as well as in-situ dry sorption of Cl-products in CaO particle bed were correlated with specific surface area of the CaO employed. 相似文献
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为探讨厌氧氨氧化MBBR的快速启动及处理低浓度含氮废水特性,采用某城市污水处理厂A2/O系统中缺氧池填料作为MBBR的载体直接启动并运行。结果表明,经过248 d启动,MBBR处理负荷(以N计)达到5 046.57 mg·(m2·d)−1,Anammox活性(以NH$\ _4^ + $ -N计)达到4 627.25 mg·(m2·d)−1;NH$\ _4^ + $ -N与NO$\ _2^ - $ -N的消耗量和${\rm{NO}}_3^ - $ -N的生成量之间的比值关系和反应器内各微生物活性及反应器运行条件及方式有关。采用基质利用速率测定方法对Anammox活性进行测定,探讨Anammox菌在常温条件下的增殖情况,确定Anammox菌增殖系数为0.026 1 d−1。Anammox菌MBBR的成功启动为Anammox技术处理低浓度含氮废水提供了参考。 相似文献
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过渡金属氧化物催化氧化NO实验研究 总被引:3,自引:1,他引:2
采用沉淀法制备出一系列过渡金属氧化物催化剂,在内径为10 mm的固定床反应器中考察其对低浓度NO的催化氧化活性,催化反应活性顺序为:MnCrCoCuFeZn,并考察了以锰为活性组分采用低温固相法、流变相法和浸渍法制备的催化剂催化氧化NO的活性。实验结果表明,采用流变相法和低温固相法制备的锰氧化物催化剂,在反应温度150℃,NO浓度为5×10-4,O2为3%,N2为平衡气,空速51 000 h-1条件下,NO转化率分别为65%和57%;采用浸渍法制备的Mn/TiO2-10%催化剂,在反应温度200℃,空速相同的条件下,NO转化率为47%。 相似文献
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通过沉淀法制备了纯CuO和3种CuO/SiO2、CuO/ZrO2和CuO/Al2O3负载型脱硫剂。利用固定床反应器进行了硫化氢吸附测试,并采用XRD、SEM、TEM、H2-TPR、比表面积和孔结构等表征技术对脱硫剂的结构进行了分析。结果表明,载体的存在明显提高了纯CuO脱硫剂的利用率和脱硫活性,其中以SiO2为载体制备的脱硫剂性能最佳,硫容达14.3%,是纯CuO硫容的2.6倍;分析认为SiO2抑制了CuO晶粒的形成,使得CuO/SiO2脱硫剂的比表面积明显增大,活性组分的结晶度较差,因而有利于脱硫反应的进行。 相似文献
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Effect of clays, metal oxides, and organic matter on rhamnolipid biosurfactant sorption by soil 总被引:1,自引:0,他引:1
Rhamnolipids produced by Pseudomonas aeruginosa have been proposed as soil washing agents for enhanced removal of metal and organic contaminants from soil. A potential limitation for the application of rhamnolipids is sorption by soil matrix components. The objective of this study is to empirically determine the contribution of representative soil constituents (clays, metal oxides, and organic matter) to sorption of the rhamnolipid form most efficient at metal complexation (monorhamnolipid). Sorption studies show that monorhamnolipid (R1) sorption is concentration dependent. At low R1 concentrations that are relevant for enhancing organic contaminant biodegradation, R1 sorption followed the order: hematite (Fe(2)O(3))>kaolinite>MnO(2) approximately illite approximately Ca-montmorillonite>gibbsite (Al(OH)(3))>humic acid-coated silica. At high R1 concentrations, relevant for use in complexation/removal of metals or organics, R1 sorption followed the order: illite>humic acid-coated silica>Ca-montmorillonite>hematite>MnO(2)>gibbsite approximately kaolinite. These results allowed prediction of R1 sorption by a series of six soils. Finally, a comparison of R1 and R2 (dirhamnolipid) shows that the R1 form sorbs more strongly alone than when in a mixture of both the R1 and R2 forms. The information presented can be used to estimate, on an individual soil basis, the extent of rhamnolipid sorption. This is important for determining: (1) whether rhamnolipid addition is a feasible remediation option and (2) the amount of rhamnolipid required to efficiently remove the contaminant. 相似文献
19.
Richardson J. B. Görres J. H. Friedland A. J. 《Environmental science and pollution research international》2016,23(18):18253-18266
Environmental Science and Pollution Research - Earthworms have the potential to reduce the retention of pollutant and plant essential metals in the forest floor (organic horizons) by decomposing... 相似文献
20.
《Atmospheric environment (Oxford, England : 1994)》2007,41(15):3203-3216
The diffusion coefficient, D, partition coefficient, K, and the initial volatile organic compounds (VOCs) in dry building materials, are the three key parameters used to predict the VOC emissions. D and K may be strongly affected by temperature. We have developed a new and simple method, the C-history method, to measure the diffusion coefficient, D and the partition coefficient, K of formaldehyde in dry building materials at temperatures of 18, 30, 40 and 50 °C. The measured variations of the diffusion coefficients and the partition coefficients with temperature for particle board, vinyl floor, medium- and high-density board are presented. A formula relating the partition coefficient and related factors is obtained through analysis. This formula can predict the partition coefficient in principle and provide an insight for fitting experimental data, and it agrees well with the experimental results. 相似文献