CNT/CdS/壳聚糖-H2O2可见光光催化甲基橙脱色研究

利用共沉淀法制备了具有可见光响应的CNT/CdS复合薄膜光催化材料.以氙灯模拟日光光源,并以双氧水辅助氧化,对甲基橙进行光催化降解,探讨了不同工艺、催化剂用量、双氧水用量、甲基橙初始浓度、溶液pH值、无机阴离子对光催化降解脱色的影响以及催化剂的重复使用性.实验结果表明:双氧水对CNT/CdS光催化甲基橙脱色产生协同作用...     

铬掺杂TiO2液相沉积膜可见光下降解甲基橙研究

实验用液相沉积法制备铬掺杂改性的二氧化钛(Cr-TiO2)薄膜电极,并在可见光下利用制备的电极对甲基橙溶液(MO)进行光电降解实验研究.并对制备的薄膜进行光电流(I-t)、交流阻抗(EIS)和Mott-Schottky等电化学相关表征.当掺杂浓度为0.2％时,薄膜电极具有最好的光电催化活性.在以0.2％ Cr-TiO2...     

废催化剂再生后对甲基橙的吸附动力学研究

废催化剂为生产醋酸乙烯过程中产生的废弃物,经过热处理直接得到ZnO／活性炭。以ZnO／活性炭为吸附剂,进行了吸附水溶液中甲基橙（MO）实验,在优化条件下,实验浓度范围内甲基橙溶液的吸附去除率均高于97％,表明ZnO／活性炭适于吸附甲基橙。采用准二级动力学模型和粒子内扩散模型研究ZnO／活性炭对水溶液中甲基橙的吸附动力学,并计算得到动力学参数和相关系数。结果表明,两种模型较好地描述了实验数据,其吸附过程的速率控制步骤为膜扩散控制,并随溶液初始浓度的增加准二级速率常数降低,面内扩散速率常数增加。     

光电化学协同催化降解甲基橙的研究

以TiO2/Ti薄膜电极为阳极、石墨电极为阴极、饱和甘汞电极为参比电极,设计了一种新型的双槽光电化学协同催化反应器,考察了阴极电位、反应时间、电解质浓度、溶液pH值等因素对甲基橙降解效果的影响.结果表明,电解质浓度对甲基橙的降解脱色效果影响不明显,而阴极电位、溶液pH值和反应时间则影响显著;色度为200度的甲基橙溶液,在阴极电位(Ec)为-0.6V、阴极槽初始pH3.0和阳极槽初始pH5.6、反应90min的条件下,阴极槽和阳极槽中甲基橙的脱色率分别为98.3%和51.3%,与仅靠TiO2/Ti薄膜阳极对有机物进行催化降解的“双槽单效”光电催化反应器相比,对甲基橙的催化氧化降解效率显著提高.降解前后的紫外-可见吸收光谱的变化表明,该双槽光电化学协同催化反应器不但可以同时使阴、阳两槽中的甲基橙脱色,且其苯环结构也被降解和矿化.     

A concept model to estimate the potential distribution of the Asiatic citrus psyllid (Diaphorina citri Kuwayama) in Australia under climate change—A means for assessing biosecurity risk

Increasing global temperatures as a result of climate change are widely considered inevitable for Australia. Despite this, the specific effects of climate change on Australian agriculture are little studied and the effects on agricultural pests and diseases are virtually unknown. In this paper we consider the impact of climate change on the Asiatic citrus psyllid (Diaphorina citri Kuwayama [Hemiptera: Psyllidae]); one of two known vectors of huanglongbing (citrus greening); a debilitating disease which is caused in Asia by a phloem-limited bacterium ‘Candidatus Liberibacter asiaticus’ (α-Proteobacteria). D. citri does not occur in Australia, but if introduced would pose a major threat to the viability of the Australian citrus industry and to native Citrus species. This paper presents an approach developed to understand how climate change may influence the behaviour, distribution and breeding potential of D. citri. Here we developed and describe an initial dynamic point model of D. citri biology in relation to its citrus host and applied it to a scenario of increasing temperatures, as indicators of climate change, on a continental scale. A comparison between model outputs for the three time frames considered (1990, 2030 and 2070) confirms that increasing temperatures projected under climate change will affect the timing and duration of new citrus growth (flush) necessary for psyllid development throughout Australia. Flushing will start progressively earlier as the temperature increases and be of shorter duration. There will also be a gradual southward expansion of shorter durations of the occurrence of flush. Increasing temperatures will impact on D. citri both directly through alteration of its temperature dependant development cycle and indirectly through the impact on the host flushing cycle. For the whole of Australia, a comparison between model outputs for the three scenarios considered indicates the seasonality of D. citri development will change to match changes in citrus flush initiation. Results indicate that the risk of establishment by D. citri is projected to decrease under increasing temperatures, mainly due to shortened intervals when it can feed on new leaf flushes of the host. However, the spatially heterogeneous results also suggest that regions located on the southern coastline of Australia could become more suitable for D. citri than projected under current temperatures. These results confirm the value of a linked host-pest approach as based on D. citri climatic requirements alone the model would have accounted only for shorter development periods and predicted an increased risk of potential distribution.     

水溶液中甲基橙的超声化学降解动力学研究

研究了水溶液中甲基橙的超声化学降解动力学。结果表明 ,水溶液中甲基橙可通过超声化学方法降解 ,降解动力学为一级反应 ,降解速率常数为 -2 .2 5× 10 - 3m in- 1。甲基橙降解速率随初始浓度的升高而降低 ,随介质温度的下降而升高 ,随介质酸度的变化而变化。 H2 O2 、F e2 +和 I- 等自由基促进剂可有效加速甲基橙的降解     

阴极电生H_2O_2及电-Fenton法降解甲基橙

对石墨-PTFE阴极的主要制作参数和在无隔膜系统中电生H2O2的主要工艺参数进行了研究。结果发现,石墨与PTFE的质量比为4∶1~3∶1之间的石墨-PTFE阴极经350℃1 h煅烧后性能最好。采用磁力搅拌代替通常的氧气扩散和空气鼓泡等供氧方法,可简化系统的供氧设备,降低废水的处理成本,更易于放大和实施,且可充分利用阳极电生的氧气。石墨-PTFE阴极有较好的稳定性,重复使用10次之后,电生H2O2的活性没有下降。在由石墨-PTFE阴极和铁阳极组成的电-Fenton系统中对甲基橙溶液进行了降解,脱色效果显著。     

壳聚糖-沸石杂化膜的制备及其对甲基橙的吸附

采用物理共混法制备了壳聚糖-沸石杂化膜,用扫描电镜(SEM)和热重分析仪(TGA)对其进行表征,并系统地研究了壳聚糖-沸石杂化膜对甲基橙的吸附行为。结果表明,最佳质量配比为(沸石/壳聚糖)为1∶20;pH值对吸附的影响最为关键,在实验浓度的范围内对甲基橙溶液最大吸附量为974.05 mg/g。杂化膜对甲基橙的等温吸附行为符合Lang-muir模型,吸附动力学模式符合准二级动力学方程,考虑以化学吸附行为为主。杂化膜有良好的再生能力。     

非均相Fenton和非均相US-Fenton体系中甲基橙降解动力学

在初始pH=3的条件下研究了甲基橙在非均相Fenton体系和非均相US-Fenton体系中的降解动力学。研究内容包括表观动力学方程和活化能。研究表明,超声的引入可以提高甲基橙的降解效率和降解速率。对比非均相Fenton和非均相US-Fenton体系中的表观动力学方程表明超声的引入可以提高反应速率常数,此外,还可以提高H2O2的利用率。通过对比分析,超声的引入可以降低反应所需的活化能,在超声的存在下,甲基橙的氧化活化能为25.12 kJ/mol,而在没有超声的条件下,需要的活化能为41.49 kJ/mol。     

Photocatalytic degradation of an azo dye using N-doped NaTaO3 synthesized by one-step hydrothermal process

N-doped NaTaO₃ compounds (NaTaO_3−xN_x) with nano-cubic morphology were successfully synthesized by one-step hydrothermal method and Methyl Orange (MO) was used as a model dye to evaluate their photocatalytic efficiency under visible-light irradiation. The as-prepared NaTaO_3−xN_x samples were characterized by various techniques, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra and GC-MS. The results indicate that NaTaO_3−xN_x displays a pure perovskite structure when the synthesis temperature is higher than 180 °C. Moreover, as observed by SEM images, the particles of resultant NaTaO_3−xN_x show cubic morphology with the edge length of 200-500 nm, which can be easily removed by filtration after photocatalytic reaction. Doping of N increases the photocatalytic activity of NaTaO₃, and NaTaO_2.953N_0.047 shows the highest visible-light photocatalytic activity for the degradation of MO. Based on the experiment results, a possible mechanism of the photocatalysis over NaTaO_3−xN_x and the photodegradation pathway of MO were proposed.