铜铈掺杂六铝酸盐的脱硝性能

用共沉淀法制备用于脱除NO的六铝酸盐催化剂LaMxAl12-xO19(M =Cu,Ce,CuCe).用XRD、H2-TPR和BET对催化剂进行了结构和物性表征.用微型催化反应装置考察了催化剂在CO选择性催化还原NO中的活性.结果表明,Cu离子易于进入六铝酸盐晶格内,形成完整的六铝酸盐结构.Ce离子不易于进入六铝酸盐晶格内,主要以CeO2的形式存在.在CO+ NO条件下,3种催化剂都表现出较好的脱硝活性,LaCuCeAl10O19中由于Cu离子与Ce离子间产生协同作用,该催化剂的脱硝活性有所增加.加入SO2后,3种催化剂都有不同程度的失活现象发生,其中LaCuAl11O19催化剂受SO2中毒影响最严重,LaCuCeAl10O19催化剂的脱硝活性在三者中最好.     

不同方法制备LaCu0.8Zn0.2Al11O19-δ催化剂及其催化分解N2O活性研究

采用共沉淀法、溶胶-凝胶法和反相微乳液法制备了六铝酸盐催化剂LaCu0.8Zn0.2Al11O19-δ,进行了X射线衍射(XRD)和BET表征.并考察了它们对N2O催化分解反应的活性,研究了制备方法对催化剂LaCu0.8Zn0.2Al11O19-δ的结构、粒径、比表面积和催化分解N2O活性的影响.结果表明,3种方法制备的催化剂经1200℃焙烧4 h后.都能形成六铝酸盐晶相,其中反相微乳液法制备的催化剂具有较小的粒径和较大的比表面积,其催化分解N2O的活性表现最佳,起始反应温度(T10%)为494℃,完全反应温度(T99%)为678℃.     

过渡金属离子复合掺杂的六铝酸盐催化剂的脱硝性能

采用CO为还原气催化还原NO,考察了Mn与Fe复合掺杂六铝酸盐对催化剂结构和NO+CO反应活性的影响,采用X射线衍射(XRD)、比表面积、H2-程序升温还原(H2-TPR)等对形成的SrMnFex Al11-x O19-δ系列催化剂(x为铁的掺杂量,x为1、2、4、6、8;δ为校正系数,在多数情况下小于0.5)进行表征...     

γ-Al_2O_3负载Ni、Fe催化剂同时脱硫脱硝

采用浸渍法制备了不同负载量的Ni(x)Fe(y)/γ-AL2O3催化剂,通过XRD、H2-TPR、BET和SEM对催化剂进行表征,使用微型催化反应装置考察催化剂在以CO作为还原气时,同时脱硫脱硝的催化活性。结果表明,Ni O和Fe2O3做为活性组分可以很好地分散在γ-Al2O3载体上,并且不破坏其结构;Ni(8)Fe(2)/γ-Al2O3催化剂有最佳的脱硫脱硝活性,脱硫率达到96.55%,脱硝率达到97.92%。     

Cu_xFe_(1-x)@γ-Al_2O_3催化剂湿式氧化陶瓷印花废水的性能及表征

采用常温浸渍法制备催化剂Cu_xFe_(1-x)@γ-Al_2O_3,并用于陶瓷印花废水的催化湿式氧化处理,考察组分构成对催化剂Cu_xFe_(1-x)@γ-Al_2O_3活性和稳定性的影响。结果表明:在4种样品Cu0.5Fe0.5@γ-Al_2O_3,Cu@γ-Al_2O_3,Fe@γ-Al_2O_3和γ-Al_2O_3中,Cu0.5Fe0.5@γ-Al_2O_3的催化活性和稳定性最高。催化剂Cu0.5Fe0.5@γ-Al_2O_3中的Fe促进Cu进入γ-Al_2O_3载体内部并形成稳定的固溶体Al2Cu O4,故此催化剂的硬度和稳定性最高;此催化剂应用前后的SEM图无明显的形貌变化,XRD谱图无明显的物相变化,证实了其稳定性的存在。在优化的操作条件下,催化剂Cu0.5Fe0.5@γ-Al_2O_3催化湿式氧化陶瓷印花废水的COD及色度分别为280 mg·L~(-1)、20倍,达到《污水综合排放标准》(GB 8978~(-1)996)中染料类废水的三级排放标准。     

微波—Cu/Fe双金属催化剂—过氧化氢工艺催化降解甲基橙废水的研究

采用超声浸渍法制备了具有较高催化活性的Cu/Fe双金属催化剂。采用微波—Cu/Fe双金属催化剂—过氧化氢工艺处理甲基橙废水,并研究了相关影响因素。结果表明,Cu/Fe双金属催化剂的Cu和Fe具有协同催化效应,可大大提高甲基橙废水的降解率。在Cu/Fe双金属催化剂投加量10g/L、过氧化氢(质量分数为30%)投加体积1.0mL、微波功率500 W、辐照时间5min的最优化条件下,50mL质量浓度为100mg/L的甲基橙废水降解率可达98.94%。     

Fe2O3-Cr2O3/TiO2系列催化剂的结构和脱硝性能

研究以纳米TiO2为载体,浸渍负载过渡金属氧化物,以CO为还原剂的脱硝催化剂的脱硝性能。实验中以计算量的Ni（NO3）2和Fe（NO3）3混合溶液浸渍纳米TiO2粉末,室温下搅拌30 min至混合均匀,放入旋转蒸发器中,70℃下至水分蒸干为止;所得粉末在550℃下、空气气氛中焙烧4 h即得所需催化剂。用以上方法分别制备2%Fe2O3-10%Cr2O3/TiO2、4%Fe2O3-8%Cr2O3/TiO2、6%Fe2O3-6%Cr2O3/TiO2、8%Fe2O3-4%Cr2O3/TiO2与10%Fe2O3-2%Cr2O3/TiO2等5种催化剂样品。实验结果表明,制备的催化剂具有较好的结构,分散较为均匀。对于CO＋NO反应,Fe2O3-Cr2O3/TiO2系列催化剂具有较好的催化活性,NO的转化率都达到了100%。其中,10%Fe2O3-2%Cr2O3/TiO2样品具有最好的低温活性,H2-TPR结果表明,这是由于10%Fe2O3-2%Cr2O3/TiO2催化剂更易于被CO预还原。     

Fe2O3-Cr2O3/TiO2系列催化剂的结构和脱硝性能

研究以纳米TiO2为载体,浸渍负载过渡金属氧化物,以CO为还原剂的脱硝催化剂的脱硝性能。实验中以计算量的Ni(NO3)2和Fe(NO3)3混合溶液浸渍纳米TiO2粉末,室温下搅拌30 min至混合均匀,放入旋转蒸发器中,70℃下至水分蒸干为止;所得粉末在550℃下、空气气氛中焙烧4 h即得所需催化剂。用以上方法分别制备2%Fe2O3-10%Cr2O3/TiO2、4%Fe2O3-8%Cr2O3/TiO2、6%Fe2O3-6%Cr2O3/TiO2、8%Fe2O3-4%Cr2O3/TiO2与10%Fe2O3-2%Cr2O3/TiO2等5种催化剂样品。实验结果表明,制备的催化剂具有较好的结构,分散较为均匀。对于CO+NO反应,Fe2O3-Cr2O3/TiO2系列催化剂具有较好的催化活性,NO的转化率都达到了100%。其中,10%Fe2O3-2%Cr2O3/TiO2样品具有最好的低温活性,H2-TPR结果表明,这是由于10%Fe2O3-2%Cr2O3/TiO2催化剂更易于被CO预还原。     

催化湿式氧化法处理糖蜜酒精废液的研究

以非贵金属Cu、Fe、Mn和Ce为主要活性成分和TiO2、-γA l2O3为载体,制备了10种用于催化湿式氧化法处理糖蜜酒精废液的催化剂。考察了载体、焙烧温度、成分配比对催化剂催化活性与稳定性的影响,研究了氧气分压、催化剂投加量、反应温度和反应时间对催化湿式氧化过程的影响规律。结果表明:(1)Fe-Mn/-γA l2O3(3∶1∶1)催化剂是催化湿式氧化法处理糖蜜酒精废液的可选催化剂;(2)适宜的氧气供应量为理论需氧量的3.4~4.6倍,催化剂的投加量以10 g/L为佳;在300℃下反应30 m in或在280℃下反应60 m in,处理水可达到污水综合排放标准GB9878-1996的三级标准。     

Fe/Ga2O3-Al2O3催化甲烷还原NO的性能

以甲烷为还原剂的选择性催化脱硝技术(SCR-CH_4)是一种很有潜力的新的脱硝方法,但催化剂的催化活性比较低。为了提高催化剂的活性以及抗水能力,可使用Fe对Al_2O_3负载的Ga_2O_3催化剂进行改性。采用共沉淀法,制备了xFe/Ga_2O_3-Al_2O_3催化剂,在固定床反应器中测试其选择性催化CH_4还原NO的性能。使用XRD、N_2吸附脱附、XPS、H_2-TPR、Py-IR等方法进行表征。结果表明:经过Fe改性后的催化剂提高了中高温的催化活性,提高了催化剂的N_2选择性,并改善了催化剂的抗水特性;5Fe/Ga_2O_3-Al_2O_3催化剂在500℃、富氧条件下,达到76%的NO转化率和100%的N_2选择性;在5%水蒸气条件下,5Fe/Ga_2O_3-Al_2O_3在500℃仍保持60%以上的NO转化率。N_2吸附脱附结果显示,引入Fe后,催化剂保持了原有比表面积,并且大大增加了催化剂孔径,可提高催化剂抗水能力。XPS与UV-vis显示,5Fe/Ga_2O_3-Al_2O_3具有高含量的游离态Fe~(3+),可提高催化剂的中高温活性。H2-TPR结果显示,Fe的引入提高了催化剂氧化还原能力,增强了原有Ga_2O_3-Al_2O_3中高温的还原活性。Py-FT-IR结果显示,催化剂表面同时存在Lewis酸和Br?nsted酸,铁的引入增加了催化剂表面的Lewis酸量。因此,Fe修饰Ga_2O_3-Al_2O_3是提高Ga_2O_3-Al_2O_3催化剂的SCR-CH_4脱硝性能的有效方法。     

Persistence and dissipation kinetics of trifloxystrobin and tebuconazole in onion and soil

The persistence and dissipation kinetics of trifloxystrobin and tebuconazole on onion were studied after application of their combination formulation at a standard and double dose of 75 + 150 and 150 + 300 g a.i. ha^?1. The fungicides were extracted with acetone, cleaned-up using activated charcoal (trifloxystrobin) and neutral alumina (tebuconazole). Analysis was carried out by gas chromatograph (GC) and confirmed by gas chromatograph mass spectrometry (GC-MS). The recovery was above 80% and limit of quantification (LOQ) 0.05 mg kg^?1 for both fungicides. Initial residue deposits of trifloxystrobin were 0.68 and 1.01 mg kg^?1 and tebuconazole 0.673 and 1.95 mg kg^?1 from standard and double dose treatments, respectively. Dissipation of the fungicides followed first-order kinetics and the half life of degradation was 6–6.6 days. Matured onion bulb (and field soil) harvested after 30 days was free from fungicide residues. These findings suggest recommended safe pre-harvest interval (PHI) of 14 and 25 days for spring onion consumption after treatment of Nativo 75 WG at the standard and double doses, respectively. Matured onion bulbs at harvest were free from fungicide residues.     

Sorption and Desorption Behavior of Chloroanilines and Chlorophenols on Montmorillonite and Kaolinite

The bioavailability of pollutants, pesticides and/or their degradation products in soil depends on the strength of their sorption by the different soil components, particularly by the clay minerals. This study reports the sorption-desorption behavior of the environmentally hazardous industrial pollutants and certain pesticides degradation products, 3-chloroaniline, 3,4-dichloroaniline, 2,4,6-trichloroaniline, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol on the reference clays kaolinite KGa-1 and Na-montmorillonite SWy-l. In batch studies, 2.0 g of clay were equilibrated with 100.0 mL solutions of each chemical at concentrations ranging from 10.0 to 200.0 mg/L. The uptake of the compounds was deduced from the results of HPLC-UV-Vis analysis. The lipophilic species were best retained by both clay materials. The most lipophilic chemical used in the study, 2,4,6-trichloroaniline, was also the most strongly retained, with sorption of up to 8 mg/g. In desorption experiments, which also relied on HPLC-UV-Vis technique, 2,4,6-trichloroaniline was the least desorbed from montmorillonite. However, on kaolinite all of the compounds under study were irreversibly retained. The experimental data have been modelled according to the Langmuir and Freundlich isotherms. A hypothesis is proposed concerning the sorption mechanism and potential applications of the findings in remediation strategies have been suggested.     

Field and laboratory studies of the fate and enantiomeric enrichment of venlafaxine and O-desmethylvenlafaxine under aerobic and anaerobic conditions

The stereoselectivity of R,S-venlafaxine and its metabolites R,S-O-desmethylvenlafaxine, N-desmethylvenlafaxine, O,N-didesmethylvenlafaxine, N,N-didesmethylvenlafaxine and tridesmethylvenlafaxine was studied in three processes: (i) anaerobic and aerobic laboratory scale tests; (ii) six wastewater treatment plants (WWTPs) operating under different conditions; and (iii) a variety of wastewater treatments including conventional activated sludge, natural attenuation along a receiving river stream and storage in operational and seasonal reservoirs. In the laboratory and field studies, the degradation of the venlafaxine yielded O-desmethylvenalfaxine as the dominant metabolite under aerobic and anaerobic conditions. Venlafaxine was almost exclusively converted to O-desmethylvenlafaxine under anaerobic conditions, but only a fraction of the drug was transformed to O-desmethylvenlafaxine under aerobic conditions. Degradation of venlafaxine involved only small stereoisomeric selectivity. In contrast, the degradation of O-desmethylvenlafaxine yielded remarkable S to R enrichment under aerobic conditions but none under anaerobic conditions. Determination of venlafaxine and its metabolites in the WWTPs agreed well with the stereoselectivity observed in the laboratory studies. Our results suggest that the levels of the drug and its metabolites and the stereoisomeric enrichment of the metabolite and its parent drug can be used for source tracking and for discrimination between domestic and nondomestic wastewater pollution. This was indeed demonstrated in the investigations carried out at the Jerusalem WWTP.     

Synthesis and characterization of m- and p-methylbenzyl-mercapturic acids derived from m- and p-xylenes

Chemical synthesis and physical properties of two mercapturic acids suggested as urinary metabolites of m- and p-xylenes ace described. These compounds may be used for the identification and quantivative determination by high-performance liquid chromatography of the corresponding mercapturic acids in urine.     

Copper-catalyzed chlorination and condensation of acetylene and dichloroacetylene

The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur only in the presence of the copper catalyst. C₂ through C₈ organic products were observed in the effluent; PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low temperatures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of hexachlorobenzene from dichloroacetylene.     

Aerobic and anaerobic degradation of profluralin and trifluralin

Abstract

The degradation of profluralin [N‐(cyclopropylmethyl)‐α,α,α‐trifluoro‐2,6‐dinitro‐N‐propyl‐]p‐toluidine] and trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) was studied under aerobic and anaerobic soil conditions. Three soils (Goldsboro loamy sand, Cecil loamy sand, Drummer clay loam) were each treated with 1 ppmw herbicide; anaerobic conditions were maintained by flooding. Soil samples were extracted monthly and subjected to TLC analysis. No degradation was detected in sterile controls. Aerobic degradation of both herbicides was greatest in the Cecil loamy sand soil over the entire incubation period. Degradation of profluralin in Cecil soil under aerobic conditions was 86 percent after 4 months with three products detected; 83 percent of the trifluralin was degraded with two products detected. Anaerobic degradation accounted for 72 percent of the profluralin and 78 percent of the trifluralin after 4 months. Degradation of both herbicides increased with incubation time for the first 3 months and decreased slightly thereafter. Generally there was more extensive degradation (percent and in number of products formed) of profluralin than trifluralin under the conditions tested. More degradation products were detected for both herbicides under aerobic conditions than under anaerobic conditions.     

Levels of PCDDs and PCDFs in products and effluent from the Swedish pulp and paper industry and chloralkali process

Within the Swedish Dioxin Survey various samples from the pulp and paper industry and the chloralkali process have been analyzed by congener specific analytical methods. In addition to the generally discussed “bleaching pattern” of the tetrachlorinated congeners, these samples also contained higher chlorinated congeners like hexa-CDDs, hepta-CDFs, octa-CDD and octa-CDF. Consequently it is recommended that samples from the pulp industry should be analyzed for all PCDDs and PCDFs (tetra- through octa-). Counted as Nordic Toxic Equivalents (NTEQ), the recycled pulp samples had the highest contamination level followed by TMP, unbleached sulfite and bleached softwood and hardwood. In addition to the bleaching process, various chemicals used in the pulping, bleaching and wastewater treatment can contribute to the contamination.     

Uptake and translocation of metformin, ciprofloxacin and narasin in forage- and crop plants

Transfer of bioactive organic compounds from soil to plants might represent animal and human health risks. Sewage sludge and manure are potential sources for bioactive compounds such as human- and veterinary drugs. In the present study, uptake of the anti-diabetic compound, metformin, the antibiotic agent ciprofloxacin and the anti-coccidial narasin in carrot (Daucuscarota ssp. sativus cvs. Napoli) and barley (Hordeumvulgare) were investigated. The pharmaceuticals were selected in order to cover various chemical properties, in addition to their presence in relevant environmental matrixes. The root concentration factors (RCF) found in the present study were higher than the corresponding leaf concentration factors (LCF) for the three test pharmaceuticals. The uptake of metformin was higher compared with ciprofloxacin and narasin for all plant compartments analyzed. Metformin was studied more explicitly with regard to uptake and translocation in meadow fescue (Festucapratense), three other carrot cultivars (D.carota ssp. sativus cvs. Amager, Rothild and Nutri Red), wheat cereal (Triticumaestivum) and turnip rape seed (Brassicacampestris). Uptake of metformin in meadow fescue was comparable with uptake in the four carrot cultivars (RCF 2-10, LCF approximately 1.5), uptake in wheat cereals were comparable with barley cereals (seed concentration factors, SCF, 0.02-0.04) while the accumulation in turnip rape seeds was as high as 1.5. All three pharmaceuticals produced negative effects on growth and development of carrots when grown in soil concentration of 6-10 mg kg⁻¹ dry weight.     

Sources and distribution of polychlorinated-dibenzo-p-dioxins and -dibenzofurans in soil and sediment from the Yellow Sea region of China and Korea

Polychlorinated-dibenzo-p-dioxins and -dibenzofurans (PCDD/Fs) were measured in soils and sediments from the Yellow Sea region. Korean soils and sediments mostly contained detectable PCDD/Fs and showed a widespread distribution among locations. Soil and sedimentary PCDD/Fs from China were comparable to or less than those in Korea. The patterns of relative concentrations of individual congeners in soils were different between the two countries, but similar in sediments. Sources of PCDD/Fs in China and Korea were found to be independent of each other and their distributions reflected matrix-dependent accumulation. Spatial distribution indicated some point sources in Korea while Chinese sources were more widespread and diffuse. PCDD/Fs measured in the coastal areas of the Yellow Sea were comparable to or less than those previously reported in for eastern Asia. However, ∑TEQs in soils and sediments were near to or, in some cases exceeded environmental quality guidelines.     

Sorption and desorption of Cu and Cd by macroalgae and microalgae

The sorption and desorption of Cu and Cd by two species of brown macroalgae and five species of microalgae were studied. The two brown macroalgae, Laminaria japonica and Sargassum kjellmanianum, were found to have high capacities at pHs between 4.0 and 5.0 while for microalgae, optimum pH lay at 6.7. The presence of other cations in solution was found to reduce the sorption of the target cation, suggesting a competition for sorption sites on organisms. Sorption isotherms obeyed the Freundlich equation, suggesting involvement of a multiplicity of mechanisms and sorption sites. For the microalgae tested, Spirulina platensis had the highest capacity for Cd, followed by Nannochloropsis oculata, Phaeodactylum tricornutum, Platymonas cordifolia and Chaetoceros minutissimus. The reversibility of metal sorption by macroalgae was examined and the results show that both HCl and EDTA solutions were very effective in desorbing sorbed metal ions from macroalgae, with up to 99.5% of metals being recovered. The regenerated biomass showed undiminished sorption performance for the two metals studied, suggesting the potential of such material for use in water and wastewater treatment.