旋流板塔湿法脱硫技术在炼油废气减排治理中的应用

硫氧化物是PM_(2.5)的重要组成部分,是国家和地方政府减排和控制的重要指标。本文以佛山市某炼油厂的炼油废气的旋流板塔湿法脱硫改造为例,从系统设计、工艺流程等方面对旋流板塔湿法脱硫技术进行介绍,为中小型锅炉脱硫工程提供有利的借鉴。     

稀土废水处理技术研究

包头尾矿坝是世界上规模最大的"稀土湖",但是在开发、提取过程中由于监管不善,没有处理好废水问题,导致尾矿坝方圆5 km散发着刺鼻的气味,附近村民相继患上癌症。近年来,随着我国加强对稀土行业的整顿、监管,《中国的稀土状况与政策》白皮书提到"无序开发稀土造成环境极大破坏,而且资源浪费严重。"综合分析了我国稀土废水污染现状以及废水的分类方法,总结近年来国内外稀土废水相对应的处理技术,旨在为提升稀土提取技术、改善生态环境提供参考。     

稀土已成为一个战略制高点

在现代战争中,美国的"爱国者"导弹为什么能够轻易击毁前苏联的"飞毛腿"导弹?美军的M1主战坦克在伊拉克战场上,为什么总能先发现对手的踪迹,为什么F-22战斗机具有超音速巡航的功能?答案就是:这些武器中使用了大量含有稀土成份的特种材料.专家断言,稀土已成为21世纪最重要的战略资源之一.     

稀土矿萃取分离过程皂化工艺改造工程

介绍了广西某稀土冶炼分离厂皂化工艺改造工程。该厂采用自主研发的氧化钙-氢氧化钙皂化工艺替代原有氨皂化工艺,该工艺能大幅降低生产运行成本、提高稀土产品品质和产量、产生无氨氮皂化废水。     

Removal of formaldehyde over MnxCe1-xO2 catalysts: Thermal catalytic oxidation versus ozone catalytic oxidation

MnxCe1- xO2（x： 0.3–0.9） prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde（HCHO）. At x = 0.3 and 0.5, most of the manganese was incorporated in the fluorite structure of Ce O2 to form a solid solution. The catalytic activity was best at x = 0.5, at which the temperature of 100% removal rate is the lowest（270°C）. The temperature for 100% removal of HCHO oxidation is reduced by approximately 40°C by loading 5 wt.% Cu Oxinto Mn0.5Ce0.5O2. With ozone catalytic oxidation, HCHO（61 ppm） in gas stream was completely oxidized by adding 506 ppm O3 over Mn0.5Ce0.5O2 catalyst with a GHSV（gas hourly space velocity） of 10,000 hr-1at 25°C. The effect of the molar ratio of O3 to HCHO was also investigated. As O3/HCHO ratio was increased from 3 to 8, the removal efficiency of HCHO was increased from 83.3% to 100%. With O3/HCHO ratio of 8, the mineralization efficiency of HCHO to CO2 was 86.1%. At 25°C, the p-type oxide semiconductor（Mn0.5Ce0.5O2） exhibited an excellent ozone decomposition efficiency of 99.2%,which significantly exceeded that of n-type oxide semiconductors such as Ti O2, which had a low ozone decomposition efficiency（9.81%）. At a GHSV of 10,000 hr-1, [O3]/[HCHO] = 3 and temperature of 25°C, a high HCHO removal efficiency（≥ 81.2%） was maintained throughout the durability test of 80 hr, indicating the long-term stability of the catalyst for HCHO removal.     

铁镧复合氧化物纳米吸附剂的制备、表征及As（Ⅲ）吸附性能研究

本研究采用共沉淀法制备了一种新型铁镧复合氧化物吸附剂(Fe-La),并对其表面特性及As(Ⅲ)吸附行为进行了系统研究.扫描电镜(SEM)和透射电镜(TEM)结果表明,铁镧复合氧化物具有纳米结构,初级粒子粒径范围为20~200 nm.X-射线衍射仪(XRD)表征结果表明,铁镧复合氧化物具有类似氢氧化镧的晶型结构.N2吸附BET法结果表明,铁镧复合氧化物的比表面积为99.3 m2·g-1.盐加入法测得吸附剂的等电点为7.8.As(Ⅲ)吸附实验结果分析表明,铁镧复合氧化物对As(Ⅲ)具有良好的吸附效果,最大吸附量(pH 7.0)为58.2 mg·g-1,Langmuir吸附等温线可较好地拟合铁镧复合氧化物对溶液中As(Ⅲ)的吸附(R2=0.95);吸附速率较快,240 min内可完成吸附容量的80%,Elovich模型能较好地描述吸附过程(R2=0.97);溶液pH对铁镧复合氧化物吸附As(Ⅲ)的影响较为明显;共存阴离子对吸附影响的大小顺序为SO2-4相似文献   

还原共沉淀法制备Fe-Ti复合氧化物及其吸附水中As(Ⅴ)的研究

采用还原-共沉淀法制备了无定型纳米复合Fe-Ti氧化物(FFT)吸附剂,并研究其对水中低浓度As(Ⅴ)的去除性能.XRD表征结果表明,制备的纳米FFT物相为无定型,BET比表面积达325.3 m2·g-1,计算得到的BJH吸附平均孔径为2.46 nm(4V/A),颗粒分布均匀.同时,考察了纳米FFT吸附As(Ⅴ)的动力学、热力学、吸附等温线,以及温度、水中共存离子对其去除As(Ⅴ)的影响.结果发现,纳米FFT对As(Ⅴ)的吸附符合拟二级动力学模型,计算出的孔道扩散系数DP在10-11~10-13cm2·s-1之间,显示孔扩散是速率限速步骤.Langmuir、Freundlich和DubininRadushkevich(D-R)吸附等温式均可较好地拟合吸附行为,低浓度下Langmuir吸附模型计算出的Qm达到26.46 mg·g-1.最后,研究了地下水中常见的共存离子对吸附的影响,发现Ca2+、Mg2+能够促进吸附,H2PO-4和HCO-3则明显抑制吸附过程.     

Catalytic combustion of soot over ceria-zinc mixed oxides catalysts supported onto cordierite

Modified substrates as outer heterogeneous catalysts was employed to reduce the soot generated from incomplete combustion of diesel or diesel/biodiesel blends, a process that harms the environment and public health. The unique storage properties of ceria(CeO2) makes it one of the most efficient catalysts available to date. Here, we proposed that ceria-based catalysts can lower the temperature at which soot combustion occurs; more specifically, from 610℃ to values included in the diesel exhausts operation range(300–450℃). The sol-gel method was used to synthesize mixed oxide-based catalysts(CeO2:ZnO); the resulting catalysts were deposited onto cordierite substrates. In addition, the morphological and structural properties of the material were evaluated by XRD, BET, TPR-H2, and SEM. Thermogravimetric(TG/DTA) analysis revealed that the presence of the catalyst decreased the soot combustion temperature by 200℃ on average, indicating that the oxygen species arise at low temperatures in this situation, promoting highly reactive oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy(DRS) showed that catalyst-impregnated cordierite samples efficiently oxidized soot in a diesel/biodiesel stationary motor: soot emission decreased by more than 70%.     

Zn2+对铁氧化物吸附苄嘧磺隆的影响

研究2种人工合成的铁氧化物对磺酰脲类除草剂--苄嘧磺隆(bensulfuron-methyl,BSM)的吸附,以及Zn2 对供试样品吸附苄嘧磺隆的影响.实验结果表明,用Langmuir、Freundlich、Temkin等方程对供试样品加入Zn2 后吸附BSM的数据进行了拟合,发现供试样品吸附苄嘧磺隆的等温曲线较好地符合Freundlich方程.加入Zn2 后,铁氧化物吸附苄嘧磺隆的量较未加Zn2 有较大幅度的增加,但在苄嘧磺隆的平衡质量浓度较低(＜4 mg/L)时,氧化物吸附苄嘧磺隆的量不随Zn2 浓度的增加而增加;在苄嘧磺隆的平衡质量浓度较高(＞6 mg/L)时,氧化物吸附苄嘧磺隆的量随Zn2 浓度的增加而增加.这可能是Zn2 和苄嘧磺隆被吸附时存在竞争和协同交互作用的结果.