羟基氧化铁催化臭氧氧化去除水中阿特拉津

以实验室制备的羟基氧化铁(FeOOH)为催化剂,研究了其催化臭氧氧化去除水中痕量阿特拉津的效能,并对影响催化效果因素及降解机理进行了探讨。在本实验条件下,反应8 min时催化氧化阿特拉津的去除率比单独臭氧氧化高出63.2%,而FeOOH对阿特拉津的吸附量很小,结果表明,FeOOH对臭氧氧化水中的痕量阿特拉津具有明显的催化活性。探讨了催化剂投量、pH、阿特拉津初始浓度和重碳酸盐碱度对催化氧化阿特拉津的影响。催化剂最佳投量为150 mg/L,去除率随pH和阿特拉津初始浓度的增加而升高,重碳酸盐浓度为200 mg/L时催化作用受到明显抑制。通过研究叔丁醇对催化反应的影响间接推断了催化反应的机理,叔丁醇作为羟基自由基抑制剂有效地抑制了水中羟基自由基的生成和它对阿特拉津的氧化反应,间接证明这种催化作用遵循羟基自由基的反应机理。     

Self-sustained catalytic combustion of CO enhanced by micro fluidized bed: stability operation,fluidization state and CFD simulation

● Catalytic combustion in fluidized bed realizes efficient heat and mass transfer. ● Catalytic combustion in fluidized bed reduces the lean combustion limits. ● Catalytic combustion and flame combustion can be coupled. ● The diffusion/kinetics limited reaction model is suitable for catalytic combustion. A micro fluidized bed reactor was used to study the self-sustaining catalytic combustion of carbon monoxide (CO). The Cu_1−xCe_xO_y catalyst, as well as the pure CuO and CeO₂, are used to investigate the contributing mechanism of different active sites including dispersed CuO and Cu–Ce solid solutions. The ignition temperature (T_i) of CO over these catalysts at a flow rate of 2000 mL/min followed the order: 74 °C (Cu_0.5Ce_0.5O_y) < 75 °C (Cu_0.25Ce_0.75O_y) < 84 °C (Cu_0.75Ce_0.25O_y) < 105 °C (CuO) < 500 °C (CeO₂). Furthermore, the lean combustion limits (equivalence ratio ϕ) over these catalysts under the flow rates of 750–3000 mL/min (through fixed, bubbling, and fluidized bed) were also measured, which are Cu_0.5Ce_0.5O_y < Cu_0.25Ce_0.75O_y < Cu_0.75Ce_0.25O_y < CuO < CeO₂. The fluidized bed was simulated using the Eulerian two-fluid model (TFM) coupled with a diffusion/kinetic-limited reaction model to evaluate the influence of operation conditions on the self-sustained combustion of CO. The predicted maximum temperature agreed with the experimental measurements, demonstrating the validity of the kinetic model and simulation parameters. The results of catalytic combustion with increasing CO concentrations suggest that the catalytic combustion reaction could co-exist with the flamed combustion. When a high concentration of CO is used, a blue-purple flame caused by CO combustion appears in the upper part of the fluidized bed, indicating that the range of CO-containing exhaust gas purification could be expanded to a larger range using the fluidized-bed catalytic combustion technique.     

基于便携式氢火焰离子化检测器法测定固定污染源废气中非甲烷总烃的研究

通过实验室和固定污染源废气现场比对测试,对便携式氢火焰离子化检测器法(催化氧化法和气相色谱法)测定非甲烷总烃的检出限、转化效率、精密度和准确度等性能指标开展研究。实验室测试结果表明,便携式氢火焰离子化检测器法测定非甲烷总烃的检出下限(0.3 mg/m^3)、转化效率(98.2%)、精密度(3.49%)、准确度(-2.38%)基本满足方法技术指标的要求,但是对于催化氧化法还需重点关注其转化效率。固定污染源废气现场比对测试结果表明,便携式氢火焰离子化检测器法与实验室方法测试结果的相对准确度(33.2%)、相对误差(-9.27%~23.7%)基本能满足测试方法的测试要求,趋势性也保持一致,适用于现场测试。     

混凝-催化氧化法预处理氨基C酸生产废水

采用混凝-催化氧化组合工艺预处理氨基C酸生产废水,考察了混凝剂加入量、废水pH、氧化剂加入量、反应时间和催化剂的重复使用次数等因素对废水处理效果的影响。混凝-催化氧化法预处理氨基C酸生产废水的最佳工艺条件为：质量分数为10％的FeSO4溶液作混凝剂,加入量为250InL／L;质量分数为1％的ClO2溶液作氧化剂,加入量为75mL／L;Ni／AC作催化剂,加入量为40g/L;废水pH为3．2;催化氧化反应时间为60min。在该条件下,废水的COD去除率可达78．4％,BOD,／COD由原来的0．076提高到0．292,可生化性得到明显改善。Ni／AC催化剂连续使用7次后仍保持稳定的催化活性。经济性初步分析表明,1t废水的处理成本约为16元。     

臭氧催化氧化处理活性蓝染料废水及催化剂的研究

进行了臭氧化学氧化体系和臭氧催化氧化体系对活性蓝处理效果的比较。提出了常温常压下臭氧催化氧化预处理活性蓝染料废水的新方法。实验结果表明,臭氧催化氧化处理COD为13 800 mg/L的活性蓝染料废水时,最佳反应pH值为5～6,臭氧用量为80 mg/L时,反应时间约40 min,COD去除率大于80%,色度去除率大于90%,达到了预处理要求。     

六六六在饲养鸡体内的残留水平

用气相色谱-电子捕获器法测定了北京郊区某养鸡场不同生长期的饲养鸡的肌肉、表皮、肝脏、胃、心脏以及鸡蛋、饲料和粪便中HCH的残留浓度.分析结果表明,饲养鸡体内肌肉、表皮、肝脏、胃和心脏的∑HCH湿重浓度分别为(0.35±0.37)、(3.91±2.52)、(1.78±1.26)、(1.00±0.85)和(1.35±0.75)ng/g,脂标化浓度分别为(64.3±171)、(19.6±7.33)、(64.9±27.2)、(74.5±74.1)和(17.8±4.42)ng/g,远低于国家<食品中农药残留最大限量>标准.肝脏∑HCH脂标化浓度显著高于其他器官,而未观察到HCH各异构体残留水平在肌肉、表皮、心脏与胃之间具有显著差别.除饲料、胃和粪便内各HCH异构体成分中以δ-HCH为主外,β-HCH是鸡体内与鸡蛋中残留最高的异构体.β-HCH在鸡体内各器官都体现出富集的特性,肝脏对除δ-HCH以外的3种异构体也都体现出显著的富集特性.对成年绿柴鸡(雄)和绿壳蛋鸡(雌)样品中HCHs残留水平的对比分析显示,雄性较雌性具有更强的HCHs富集能力.     

危险度评价法与蒙德法在催化裂化装置中的对比及原因研究

以催化裂化装置为例子,分别运用危险度评价法与蒙德法两种评价法分别进行评价,得出的评价结论既有共同点也有区别.通过危险度评价法与蒙德法评分项目的比较分析,得出危险度评价法与蒙德法的内在区别与联系,验证了上述例子结论,同时得出蒙德法将危险度评价进行了拓展与延伸,它将危险度评价法得出的危险性高的单元,更深入的找出导致危险性高的原因与参数.     

铜锰基整体式催化剂对烧结烟气CO净化特性

基于改性铜锰氧化物作为CO催化活性组分,分别制备了催化剂原粉、以泡沫金属、堇青石为载体的两种整体式催化剂,在实验室配气条件下对比了3种样品的CO催化效率及稳定性,优选了堇青石整体式催化剂,并在某钢厂实际烧结烟气条件下测试了其在不同催化剂负载量、空速、温度下的CO催化效率、稳定性以及衰减后样品催化特性;最后批量制备了2m³优选整体式催化剂并开展了6000m³/h烧结烟气CO净化中试实验.结果表明,烟气高浓水蒸气显著抑制CO催化反应,经240h催化后T₉₀最大提升38℃;催化剂负载量越高,T₉₀越低,催化效率衰减时间越短,稳定后的效率越高,但随着空速增加,该优势减小;1440h(2个月)中试实验中,进气温度185~195℃下,CO催化效率大于85%(平均90%),出口CO浓度低于1000×10^-6,出口平均烟温达220℃,具有节能减排双重效益.     

Effects of cobalt doping on the reactivity of hausmannite for As(III) oxidation and As(V) adsorption

Hausmannite is a common low valence Mn oxide mineral, with a distorted spinel structure, in surficial sediments. Although natural Mn oxides often contain various impurities of transitional metals (TMs), few studies have addressed the effect and related mechanism of TM doping on the reactivity of hausmannite with metal pollutants. Here, the reactivity of cobalt (Co) doped hausmannite with aqueous As(III) and As(V) was studied. Co doping decreased the point of zero charge of hausmannite and its adsorption capacity for As(V). Despite a reduction of the initial As(III) oxidation rate, Co-doped hausmannite could effectively oxidize As(III) to As(V), followed by the adsorption and fixation of a large amount of As(V) on the mineral surface. Arsenic K-edge EXAFS analysis of the samples after As(V) adsorption and As(III) oxidation revealed that only As(V) was adsorbed on the mineral surface, with an average As-Mn distance of 3.25–3.30 Å, indicating the formation of bidentate binuclear complexes. These results provide new insights into the interaction mechanism between TMs and low valence Mn oxides and their effect on the geochemical behaviors of metal pollutants.     

铁锰基整体式催化剂催化燃烧甲苯和氯苯性能

对比了3种不同合成方法(等体积浸渍法、超声辅助浸渍法、氧化还原沉淀法)制备的铁锰复合过渡金属氧化物负载堇青石整体式催化剂,通过BET、SEM、XRD、H₂-TPR、XPS等表征手段分析了催化剂物理结构和化学性质.结果表明,氧化还原沉淀法负载的铁锰氧化物具有独特的片层状结构,暴露出较大的比表面积和较多的活性位点,其表面氧物种还原温度更低、Mn⁴⁺含量更高,增强了其催化燃烧性能.该催化剂对甲苯和氯苯表现出优异的催化性能,T₅₀分别为200℃和261℃,T₉₀分别为270℃和320℃,其热稳定性及耐久性也表现良好.