单双介质阻挡放电降解苯的对比研究

在相同实验条件下,研究了单、双介质阻挡放电反应器的等离子体发射光谱,对苯的降解效率,以及CO和CO2的生成,检测了NO和NO2的浓度.结果表明,与单介质阻挡放电反应器相比,双介质阻挡放电反应器的发射光谱具有红移现象;单、双介质阻挡放电反应器对苯的降解效率、CO2的生成浓度及选择性几乎一致;采用双介质阻挡放电明显降低了CO的生成浓度,CO的生成选择性也有所下降.更为重要的是,双介质阻挡放电反应器极大地降低了NO2的生成,在本文的实验条件下,没有检测到NO.     

介质阻挡放电对水中敌草隆的降解研究

采用介质阻挡放电方法降解水溶液中的敌草隆,对影响敌草隆降解的因素进行了研究,并初步探讨了其降解动力学.结果表明,提高放电功率、减小介质层厚度和减小放电间距均能提高敌草隆的降解率,酸性条件下更有利于敌草隆的降解.相同实验条件下敌草隆初始浓度的升高会导致其降解率降低.添加不同种类的金属离子(Fe2 ,Fe3 ,Cu2 )均能提高敌草隆的降解率,不同金属离子在投加量为30 mg·l -1时,敌草隆降解率提高量的大小顺序为: Fe2 >Fe3 >Cu2 .自由基清除剂(叔丁醇、异丙醇、碳酸钠)的加入抑制了敌草隆的降解.敌草隆在介质阻挡放电反应器中的降解符合一级反应动力学.     

冷电弧技术脱除甲醛气体

自行研制了平板式介质阻挡放电冷电弧装置,探讨了施加电压、气体流量、甲醛初始浓度和不同设备形式对甲醛气体脱除率的影响。结果表明:在电极间距1.6 cm、施加电压20 kV、气体流量667 mL/min、甲醛初始浓度为50.0 mg/m3以及添加涂有TiO2膜的陶瓷拉西环催化剂的条件下,甲醛的脱除率可以达到90%以上。     

介质阻挡放电对水中双氯芬酸钠的降解

本实验采用介质阻挡放电方法降解水溶液中的双氯芬酸钠,考察了初始浓度、Fe2+、腐植酸、硝酸根离子对双氯芬酸钠降解的影响,及降解过程中溶液TOC含量和UV的变化,并初步探讨了其降解动力学.结果表明,双氯芬酸钠在介质阻挡放电反应器中的降解符合一级反应动力学.对于初始浓度为10mg·1-1、20 mg·1-1和30 mg·1-1的双氯芬酸钠,降解率随着初始浓度的增加而降低.影响因子腐植酸和硝酸根离子的添加均能显著提高双氯芬酸钠的降解率,但相同实验条件下,亚铁离子的添加抑制了双氯芬酸钠的降解,当Fe2+添加量为1.0 mmol·1-1时,双氯芬酸钠的降解率仅为74.94%.降解过程中溶液TOC的含量减少缓慢,TOC残留含量仅从13.69 mg·1-1降为11.1 mg·1-1,可见双氯芬酸钠的矿化程度不高,而双氯芬酸钠的紫外-可见吸收光谱在吸收波段递减,介质阻挡放电对双氯芬酸钠有稳定的降解效果.     

介质阻挡放电降解SF6的研究

采用GC-TCD考察介质阻挡放电技术(DBD)处理SF6的效果,并采用红外吸收光谱进行产物分析.结果表明,电源电压的增加、放电时间的延长、气体介质分压的降低,以及少量其它气体(Ar,N2,O2,H2O,空气)的加入能够提高转化效果.另外,SF6的降解率随着空气湿度的增加而增加,28.2 kPa相对湿度为51%的空气与2.0 kPa SF6的混合气体放电后SF6降解率达92%.放电产物包括SiF4,SF4,SOF2,SOF4,SO2F2.     

温度对等离子体与催化剂结合脱除Nox的影响

考察了温度对介质阻挡放电和CuZSM-5催化剂"一段法"结合脱除氮氧化物(NOx)的影响.实验表明,在250℃和300℃时,对于NO/N2,NO/O2/N2和 NO/C2H4/N2三个体系,"一段法"脱除NOx的活性都相对较低.在NO/O2/C2H4/N2体系中,250℃介质阻挡放电和CuZSM-5结合脱除NOx产生了明显的协同效应.在300℃,等离子体对脱除NOx起负作用.相对低温(150℃)时,等离子体的促进作用很小.电学实验表明,当反应温度由25℃升至450℃,"一段法"体系的李萨如(Lissajous)图形由平行四边形(25℃)逐渐变为椭圆形(450℃),表明较高温度时催化剂的介电性质发生了变化.原位发射光谱证明在不同温度下,"一段法"体系中等离子体气相产生的活性物种数量明显不同.     

介质阻挡放电常压降解哈隆的研究

本文以介质阻挡放电的方式产生低温等离子体，利用低温等离子体技术成功地降解了常压状况下的气态ＣＦ２ＣｌＢｒ，ＣＦ２ＣｌＢｒ含量为０．６％的空气在放电１０ｓ的条件下，可使ＣＦ２ＣｌＢｒ达到９５％的降解率。本文研究了常压状况下的ＣＦ２ＣｌＢｒ低温等离子体空间反应机理，以及ＣＦ２ＣｌＢｒ初妈压力，电场强度和外加气体分别对低温等离子体降解ＣＦ２ＣｌＢｒ的影响。     

活性炭吸附-介质阻挡放电等离子体处理五氯酚

研究了介质阻挡放电(DBD)与活性炭(AC)吸附相结合用于高浓度五氯酚(PCP)废水的处理.含有高浓度的PCP溶液被富集在AC上,通过DBD等离子体降解吸附在AC上的PCP,并且实现AC的循环再利用.主要考察了DBD等离子体作用条件下AC上PCP的降解效果以及3次循环处理后AC吸附等温线的变化.结果表明:随着放电电压和处理时间的增加,AC上PCP的降解效率增加,较高的电源频率有助于PCP的降解,而且经过3次吸附/处理循环后,AC仍然具有较高的吸附能力.     

Ce/TiO_2/Fe_3O_4粒子电极光电催化降解藏红T模拟染料废水

采用化学共沉淀-超声辅助法,制备出磁性纳米材料Fe3O4,利用溶胶-凝胶法在Fe3O4表面包裹Ce/TiO2,得到磁性复合材料Ce/TiO2/Fe3O4.用XRD、SEM、BET等对其结构和性能进行了表征,催化剂主要以催化活性较高的锐钛矿相存在,Ce/TiO2包覆在纳米Fe3O4的表面形成多孔结构,复合材料具有LangmuirⅣ吸附-脱附等温线,比表面积76.68m2·g-1,平均孔径8nm,主要分布在4.5—15.4nm之间.通过电助光催化降解藏红T溶液研究了Ce/TiO2/Fe3O4的光电催化活性.在催化剂的加入量为6g·L-1,降解时间为60min,外加电压为5V,50mg·L-1的藏红T溶液的降解率可达到90%以上,COD去除率达84.7%.所制备的Ce/TiO2/Fe3O4在重复使用5次后仍能保持较好的光电催化活性.     

介质阻挡放电与活性炭纤维协同去除水中的3,4-二氯苯胺木

采用介质阻挡放电(DBD)非平衡等离子体与活性炭纤维(ACF)相联合的方法去除水中3,4-二氯苯胺(3,4-DCA),考察了放电功率、空气流量、溶液初始浓度、电导率、pH值以及活性炭纤维用量等因素对联合处理效率的影响,并分析了可能的去除机理.实验结果表明,在DBD非平衡等离子体与ACF联合处理有机污染物3,4-DCA的...     

Benzene conversion by manganese dioxide assisted silent discharge plasma

Non-thermal plasma technologies have shown their promising potential specially for the low concentration of volatile organic compound control in indoor air in recent years. But it is also high energy consuming. So, to improve the energy efficiency, adding catalysts which enhance the plasma chemical reactions to plasma reactors may be a good selection. Therefore, in this study the manganese dioxide assisted silent discharge plasma was developed for benzene conversion at a relatively high energy efficiency. The results show that MnO₂ could promote complete oxidation of benzene with O₂ and O₃ produced in the plasma discharge zone. The energy efficiency of benzene conversion with MnO₂ was two folds as much as that without catalysts. It was also found that the site of MnO₂ in the reactor and the energy density had effects on benzene conversion. While the energy density was lower than 48 J/L, benzene conversion decreased with the increase in the distance between MnO₂ bed and the plasma discharge zone. Whereas when the energy density was higher than 104 J/L, benzene conversion had an optimal value that was governed by the distance between MnO₂ bed and the plasma discharge zone. The mechanism of benzene oxidation in plasma discharges and over MnO₂ is discussed in detail.     

A review on application of dielectric barrier discharge plasma technology on the abatement of volatile organic compounds

• Applications of non-thermal plasma reactors for reduction of VOCs were reviewed. • Dielectric barrier discharge (DBD) plasma was considered. • Effect of process parameters was studied. • Effect of catalysts and inhibitors were evaluated. Volatile organic compounds (VOCs) released from the waste treatment facilities have become a significant issue because they are not only causing odor nuisance but may also hazard to human health. Non-thermal plasma (NTP) technologies are newly developed methods and became a research trend in recent years regarding the removal of VOCs from the air environment. Due to its unique characteristics, such as bulk homogenized volume, plasma with high reaction efficiency dielectric barrier discharge (DBD) technology is considered one of the most promising techniques of NTP. This paper reviews recent progress of DBD plasma technology for abatement of VOCs. The principle of plasma generation in DBD and its configurations (electrode, discharge gap, dielectric barrier material, etc.) are discussed in details. Based on previously published literature, attention has been paid on the effect of DBD configuration on the removal of VOCs. The removal efficiency of VOCs in DBD reactors is presented too, considering various process parameters such as initial concentration, gas feeding rate, oxygen content and input power. Moreover, using DBD technology, the role of catalysis and inhibitors in VOCs removal are discussed. Finally, a modified configuration of the DBD reactor, i.e. double dielectric barrier discharge (DDBD) for the abatement of VOCs is discussed in details. It was suggested that the DDBD plasma reactor could be used for higher conversion efficiency as well as for avoiding solid residue deposition on the electrode. These depositions can interfere with the performance of the reactor.     

甲醇分解催化剂及其在甲醇汽车上的应用

以Al_2O_3为载体、由浸渍法制备的负载型铜镍基和铜锌基催化剂,对甲醇分解制取H_2和CO的反应具有优良的低温活性、选择性、耐高温性和使用寿命,对乙醇分解也有良好的活性。两种催化剂在甲醇汽车的车载分解器中的应用巳达实用水平。     

MCM-41介孔分子筛水热结构稳定性对介质阻挡放电脱除甲苯的影响

采用介质阻挡放电(DBD)和MCM-41介孔分子筛结合脱除甲苯,考察了MCM-41介孔分子筛水热结构稳定性与甲苯脱除的关系.XRD表征显示,通过水热合成制备的纯硅MCM-41(Si- MCM-41)和含铝MCM-41(Al-MCM-41)介孔分子筛都具有典型的六方介孔结构,结晶度良好.水热结构稳定性实验显示纯硅MCM-41介孔分子筛的结构最稳定,结晶保留度最高,而含铝MCM-41介孔分子筛则随铝含量的上升结构稳定性下降.介质阻挡放电脱除甲苯实验结果显示,甲苯转化率与MCM-41介孔分子筛水热结构的稳定性保持一致,纯硅MCM-41介孔分子筛脱除甲苯的效率最高.     

Degradation of metronidazole by dielectric barrier discharge in an aqueous solution

The discharge characteristics during the degradation of MNZ by DBD were investigated. Increasing the discharge frequency can promote the degradation of MNZ. MNZ removal reaches 99.1% at the initial concentration of 40 ppm within 120 min. Coexisting organic matter inhibits the degradation of MNZ. The energy efficiency of DBD for MNZ removal is higher than other technologies. Degradation of metronidazole (MNZ) which is a representative and stable antibiotic by dielectric barrier discharge (DBD) in an aqueous solution has been studied. Effects of initial MNZ concentration, solution pH and coexisting organics on the degradation were investigated. The results illustrated that increasing the input power and the discharge frequency can improve the removal of MNZ. At low initial concentration, the removal of MNZ can reach up to 99.1%. Acidic and neutral conditions are more favorable for MNZ removal than alkaline condition in the early stage of degradation. However, the difference in MNZ removal between those in acidic or neutral media and that in alkaline one could be neglected with prolonging of the treatment time. Therefore, this method can be applied to MNZ degradation with a wide pH range. Coexisting organic matter in water can attenuate the removal to some extent. This study could provide valuable references for the degradation of nitroimidazole antibiotics by DBD.     

In situ electron-induced reduction of NOx via CNTs activated by DBD at low temperature

• An in situ electron-induced deNO_x process with CNT activated by DBD was achieved. • Carbon atoms on CNT surface were verified to be excited by plasma in DBD-CNT system. • Reactions between NO_x and excited C result in synergistic effect of DBD-CNT system. In this study, a new in situ electron-induced process is presented with carbon nanotubes (CNTs) as a reduction agent activated by dielectric barrier discharge (DBD) for nitrogen oxide (NO_x) abatement at low temperature (<407 K). Compared with a single DBD system and a DBD system with activated carbon (DBD-AC), a DBD system with carbon nanotubes (DBD-CNT) showed a significant promotion of NO_x removal efficiency and N₂ selectivity. Although the O₂ content was 10%, the NO_x conversion and N₂ selectivity in the DBD-CNT system still reached 64.9% and 81.9% at a specific input energy (SIE) of 1424 J/L, and these values decreased to 16.8%, 31.9% and 43.2%, 62.3% in the single DBD system and the DBD-AC system, respectively. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were utilized to investigate surface changes in the CNTs after activation by DBD to explore the NO_x reduction abatement mechanism of this new process. Furthermore, the outlet gas components were also observed via Fourier transform infrared spectroscopy (FTIR) to help reveal the NO_x reduction mechanism. Experimental results verified that carbon atoms excited by DBD and the structure of CNTs contributed to the synergistic activity of the DBD-CNT system. The new deNO_x process was accomplished through in situ heterogenetic reduction reactions between the NO_x and carbon atoms activated by the plasma on the CNTs. In addition, further results indicated that the new deNO_x process exhibited acceptable SO₂ tolerance and water resistance.     

ZrO2负载过渡金属氧化物催化剂对CO＋NO（O2）反应的影响

本文运用固定床微反技术考察了Ｃｕ,Ｆｅ,Ｍｎ,Ｃｒ,Ｃｏ和Ｎｉ负载（ＺｒＯ２载体）氧化物对ＣＯ＋ＮＯ（Ｏ２）反应的催化活性。研究了ＮＯ和ＣＯ在不同比例时,催化剂对Ｎ２Ｏ和Ｎ２生成的影响。结果表明,在ＮＯ＋ＣＯ反应中,ＮＯ和ＣＯ的比例对催化剂活性和Ｎ２Ｏ,Ｎ２生成均有明显的影响,ＣｕＯｘ／ＺｒＯ２催化剂的活性最高;Ｎ２Ｏ是ＮＯ＋ＣＯ反应的中间产物,低温或ＮＯ过量时有利于生成Ｎ２Ｏ,高温或ＮＯ不足时有