Oxidation catalyst of iron oxide suppressing dioxin formation in polyethylene combustion

A new iron oxide catalyst, which has a superior oxidation activity in carbon monoxide and polyethylene (PE) combustion, was synthesized by an aqueous solution reaction. Catalytic oxidation of carbon monoxide over six kinds of hematite obtained from the goethite was done using a microcatalytic pulse reactor, and the composition of the hematite with the highest oxidation activity was determined. With the aim of suppressing dioxin formation on combustion, incineration tests of solid wastes in PE refuse bags with and without the goethite were carried out using a commercial semibatch-type incinerator with a combustion chamber of 6.2 m³. The result confirmed that the concentration of dioxins in the flue gas decreased considerably when the refuse was incinerated in PE bags manufactured with goethite. Received: July 24, 2000 / Accepted: October 18, 2000     

利用含砷氧化锌尘制备活性氧化锌

用NH3-（NH4）2SO4溶液浸取处理含砷氧化锌尘,可彻底清除砷,制备出合格的活性氧化锌。对于含砷质量分类为1%-2%的原料,产品中所含砷质量分数可降至0.0005%以下。该方法具有除砷彻底,不易产生二次污染的优点,为含砷氧化锌尘的综合利用提供了一种新方法。     

An estimate of the contribution of outdoor concrete yards used by livestock to the UK inventories of ammonia, nitrous oxide and methane

Many farms have unroofed concrete yards used by livestock. These concrete yards have received little attention as sources of gaseous emissions. From 1997 to 1999 measurements were made of emissions of ammonia (NH₃), nitrous oxide (N₂O) and methane (CH₄) from 11 concrete yards used by livestock. A postal survey was carried out to assess the areas of yards on farms in England and Wales to enable the measurements to be scaled up to estimate national emissions. Using the results of this study NH₃-N emissions from farm concrete yards were calculated to be ca. 35×10³ t annually. This is 13% of the current estimated total NH₃-N emission from UK livestock. Concrete yards were an insignificant source of N₂O and CH₄ which were both <0.01% of current estimates of agricultural emissions.     

秸秆还田和添加生物炭对热带地区稻菜轮作体系中淹水后土壤温室气体排放的影响

热区稻菜轮作系统瓜菜季施肥后大量硝态氮积累,导致后续的水稻季淹水后硝态氮的淋失以及大量N₂O排放,使氮素损失以及温室效应加剧.如何提高硝态氮利用率,减少N₂O排放成为了亟待解决的问题.试验共设置6个处理：添加200 mg·kg^-1 （以N计,下同）KNO₃（CK）;添加200 mg·kg^-1 KNO₃+2%生物炭（B）;添加200 mg·kg^-1 KNO₃和1%花生秸秆（P）;添加200 mg·kg^-1 KNO₃+2%生物炭+1%花生秸秆（P+B）;添加200 mg·kg^-1 KNO₃+1%水稻秸秆（R）;添加200 mg·kg^-1 KNO₃+2%生物炭+1%水稻秸秆（R+B）,进行114 d的25℃恒温淹水培养,来探究有机物料添加对土壤淹水后温室气体排放和氮素利用的影响.结果表明,与CK相比,添加秸秆或秸秆和生物炭配施显著增加了土壤pH（P<0.05）;B和P处理分别显著增加了41.6%和28.5%的N₂O累计排放（P<0.05）,P+B、R和R+B处理分别显著降低了14.1%、24.7%和36.7%的N₂O累计排放（P<0.05）;添加秸秆增加了净温室气体增温潜势（NGWP）,增施椰壳生物炭能够显著减缓秸秆对NGWP的影响（P<0.05）,秸秆和生物炭配合施用降低了NGWP,其中P+B显著降低NGWP（P<0.05）,R+B不显著;添加秸秆或生物炭显著增加了土壤微生物量碳（MBC）（P<0.05）,P+B最高,为502.26 mg·kg^-1;秸秆和生物炭配施增加了土壤微生物量氮（MBN）,P+B最高.N₂O排放通量与pH呈极显著负相关（P<0.01）,与NH₄⁺-N和NO₃^--N呈极显著正相关（P<0.01）;N₂O累计排放量与MBN呈极显著负相关（P<0.01）;NO₃^--N与MBN呈显著负相关（P<0.05）,说明硝态氮的减少可能被微生物固持,微生物对硝态氮固持的增加也减少了N₂O排放.综上所述,花生秸秆和椰壳生物炭配合施用能够显著抑制N₂O排放,增加土壤MBC和MBN,是一种海南瓜菜季后充分利用氮肥,减少氮素损失,减缓N₂O排放的一种合理措施.     

纳米钙钛矿型LaMnO3的制备与汽车尾气处理

用PEG法制备了钙钛矿LaMnO3纳米材料,并将其负载在涂有γ－Al2O3的堇青石载体上作为净化尾气的催化剂。用XRD、TEM对产物的结构及表面性能进行了分析。在依维柯汽车上进行了怠速、正常行驶及倒拖时催化剂三效性能的测试。发现纳米晶活性组分的催化效率比溶液浸渍法制得的催化剂好。     

外源NO对Cu胁迫下番茄幼苗L-精氨酸代谢的影响

一氧化氮(nitric oxide,NO)作为生物活性分子,广泛参与各种生物和非生物胁迫。采用营养液培养,研究Cu胁迫下番茄体内L-精氨酸、NO、多胺代谢对外源NO的响应机制,以期为铜污染区域蔬菜种植提供科学依据和技术支持。结果表明,Cu胁迫下添加外源SNP(硝普钠,外源NO供体)能够调节番茄根系和叶片中精氨酸脱羧酶(Arginine Decarboxylase,ADC)、鸟氨酸脱羧酶(Ornithine Decarboxylase,ODC)及一氧化氮合酶(Nitric Oxide Synthase,NOS)活性。根系中,外源SNP能够上调NOS活性,L-精氨酸代谢向着NO合成方向进行;叶片中,外源SNP能够同时上调ADC、ODC、NOS活性,PA、NO的合成同时进行;此外,Cu胁迫下添加外源SNP能够增加根系和叶片L-精氨酸含量,而作为PA、NO的合成前体,精氨酸含量升高无疑会间接促进PA、NO的合成,从而提高番茄对Cu胁迫的抵抗能力。     

复合氧化物催化剂用于汽车尾气净化的研究

研制了一系列非贵金属复合氧化物催化剂,测定这些催化剂净化汽车尾气的活性和抗硫、磷、铅及析碳中毒等性能,排出了它们的活性和抗硫中毒的顺序。实验表明,ASC(Re-Mn-Pb-Cu-Cr-A-O_x/Al_2O_3,A助剂)催化剂具有较高的活性及较好的抗硫磷、铅及析碳中毒性能,具有较好的应用前景。     

Investigating the phenol removal from aqueous media by photocatalytic magnetized graphene oxide nanocomposite

As a large and diverse group of secondary metabolites, phenolic compounds are one of the most common chemical pollutants present in water resources. these compounds can have toxic effects on ecosystems and humans. Therefore, their removal from water sources appears to be of great importance. In this study, a magnetic graphene oxide (MGO) photocatalyst was synthesized and used to remove phenol from water. The fabricated GO magnetic nanocomposites were determined by SEM and FTIR techniques. Afterward, these nanoparticles were used to remove phenol from aquatic media considering different operational parameters, including pH of the solution, initial concentration of phenol, contact time, and adsorbent dosage. The results showed that the magnetized GO nanoparticles could remove 90.83% of phenol molecules under the optimal conditions of solution pH = 3.0, initial phenol concentration of 20 mg/L, adsorbent concentration of 300 mg/L, and contact time of 120 min. additionally have compared the results of UV, Fe₃O₄/GO, and Fe₃O₄/GO/UV on the removal of phenol under optimum conditions. Accordingly, the phenol removal efficiencies for UV alone, Fe₃O₄/GO, and Fe₃O₄/GO/UV were obtained at 4.5, 65.73, and 90.83%, respectively. Based on the findings, the prepared magnetic GO nanoparticles have extended capabilities such as easy and rapid separation from sample and high potential in removing phenolic compounds, so, it can be introduced as an appropriate adsorbent for removal of this pollutant from water and wastewater.     

三亚河水体中甲烷和氧化亚氮的分布、释放及影响因素研究

甲烷(CH₄)和氧化亚氮(N₂O)是大气中重要的温室气体,对全球变暖和大气化学有重要作用。受人为活动影响较大的河流、河口是大气中CH₄和N₂O的重要源。于2019年春季、2020年秋季台风前后沿三亚河从下游到上游采集了11个站位的样品,测定三亚河水体中CH₄、N₂O浓度及相关参数,并估算了水-气界面释放通量。结果表明：春季、秋季以及台风后CH₄平均浓度分别为(15.92±23.04)、(364.43±265.41)、(666.02±502.60) nmol/L,N₂O平均浓度分别为(24.37±19.88)、(8.47±5.19)、(47.48±33.47) nmol/L,台风后大于台风前。水体中CH₄、N₂O主要受溶解氧(DO)和降雨影响,下游河段主要受潮汐作用影响。现场产生和沉积物释放是水体中CH₄的主要源,硝化作用是水体中N₂     

催化臭氧化降解含微囊藻毒素污水

应用金属氧化物构建催化臭氧化工艺处理含微囊藻毒素污水,比较了不同催化剂的性能差异,分析了催化剂投加量、温度、pH、原水浓度对该工艺的影响.结果表明,选用CuO作催化剂能较好地处理含微囊藻毒素污水.温度与原水浓度对该工艺影响较小;催化剂投加量与pH是该工艺的主要影响因素.实验温度40℃、混合气体流量1.8 L.L-.1min-1、pH=9、催化剂投加量5 g.L-1、处理时间60 min,原水MC-LR去除率达到90%以上、COD去除率达到64%以上.处理20 min,该工艺催化作用去除MC-LR贡献率达到28%、去除COD贡献率达到52%.