旋转薄膜浆态光催化反应器

在分析现有光催化反应器特点的基础上,提出了一种新型的旋转薄膜式浆态光催化反应器（RFFS）。用商品化光催化剂Degussa P25,以苯酚模型有机物为降解对象,对比了RFFS与传统鼓泡浆态光催化反应器（TBS）的性能,研究了RFFS的光催化性能。结果表明,与传统浆态光催化反应器相比,RFFS具有较高的光催化性能,尤其是能够在较高的光催化剂浓度下运行。在光催化体系的循环流速大于2.7 L·min-1、供气流量为1.0 L·min-1、催化剂浓度为3.0 g·L-1的条件下,RFFS比传统浆态鼓泡光催化反应器的降解速率提高1.6倍。RFFS利用旋转浆态薄膜强化了光催化反应体系的传质,同时提高了体系中光催化剂对光能的利用率,较好地解决了光在传统浆态体系中的传递问题,为开发新型的具有工业应用前景的光催化反应器提供了方案。苯酚在RFFS中的降解动力学符合表观一级动力学模型,理论值与实验结果吻合较好。     

搅拌式浆态光催化反应器对偶氮染料X-3B的降解特性研究

构建了体积为5 L的搅拌式浆态光催化反应器,以偶氮染料活性艳红X-3B为目标污染物,进行光催化降解特性研究。结合对X-3B在小规模反应器中悬浮TiO2表面的吸附行为研究,考察了TiO2投加量、搅拌速率和曝气量等对光催化效果的影响,分析了光催化过程的降解动力学,并从传质的角度对搅拌强度和初始反应速率进行了关联。实验结果表明,在搅拌式浆态光催化反应器中,Langmuir模型和Freundlich模型均能较好地描述TiO2对X-3B的吸附行为;在催化剂最佳浓度0.5 g.L 1的条件下,初始反应速率r0随搅拌雷诺数Re的增加呈现先增大后稳定的趋势,进一步增加空气曝气量可以显著提高初始反应速率。根据相关理论推导得出在该反应器光催化降解X-3B时,氧的传质是影响初始反应速率r0的关键因素。     

环状液-固光催化反应器内流场模拟

多相光催化反应器中,催化剂颗粒在反应器中分布均匀性是衡量多相光催化反应器重要因素.本文用计算流体力学的方法,选用商用软件CFX对液-固光催化反应器内催化剂颗粒分布进行了模拟计算,并进一步对反应器结构进行优化.     

循环流化床厌氧氨氧化反应器脱氮性能研究

对循环流化床上部附加无纺布作填料的固定床复合式厌氧氨氧化反应器的性能进行了研究,通过控制废水的循环量来调节反应器底部微生物颗粒的流化状态,并对反应器内对富集的厌氧氨氧化菌除氮性能进行了研究。结果表明,反应器稳定运行270 d,总氮去除率及亚硝氮去除率分别维持在80%及90%以上;最大氮负荷达到15.2 kg/m3.d-1,相应的最大氮去除速率达9.9 kg/m3.d-1。通过批实验,得到反应器稳定运行期厌氧氨氧化菌比活性为0.3 kg/k.gd-1。出水悬浮物(SS)浓度检测、微生物颗粒粒径分布测试、微生物颗粒的扫描电镜(SEM)观测结果均表明,循环流化床厌氧氨氧化反应器具有较高的生物滞留能力,形成的微生物颗粒具有较佳性能。采用荧光原位测定(FISH)分析结果显示,厌氧氨氧化菌在反应器微生物群落中含量超过70%。     

浆态光催化反应器有机模拟废水光催化氧化特性与动力学

采用循环式浆态光催化反应器对苯甲酰胺模拟废水光催化氧化特性和动力学进行了研究,系统地考察了操作条件对模拟污染物光催化降解的影响,并与搅拌式和鼓泡床式浆态光催化反应器中苯甲酰胺的降解效果进行对比.结果表明,循环式浆态光催化反应器中光催化剂的用量、污染物的初始浓度和初始pH值对模拟污染物光催化降解性能的影响存在适宜值;体系中H₂PO^-₄、Cl^-、Cu²⁺、Al³⁺对其光催化降解过程有明显的抑制作用.与传统的搅拌式和鼓泡床式浆态光催化反应器相比,循环式浆态光催化反应器中催化剂和废水的混合效果较好,光利用率高,较大程度上减少催化剂的用量和提高废水处理能力.同时,对不同催化剂的用量和污染物初始浓度下的光催化氧化反应动力学研究表明,此过程符合拟一级动力学,催化剂表面反应速率常数k₀和催化剂吸附平衡常数K_TiO2分别为0.0279 min^-1和17.99 L•g^-1.     

超重力场强化固-液界面光催化反应过程

根据固定床光催化反应过程存在界面传质限制和激发光传递等问题,提出了超重力技术强化固-液界面光催化反应过程的方法.实验结果表明,在超重力强化固-液界面光催化反应过程中,存在一个临界液膜厚度,此值约130μm.当催化剂表面液膜厚度低于此值时,光催化过程效率得到大大提高.但当液膜厚度小于约60μm后,超重力强化光催化过程的效...     

悬浮态光催化超滤膜反应器降解偶氮染料4BS

采用悬浮态光催化超滤膜反应器处理偶氮染料直接耐酸大红4BS。系统地研究了溶液pH值、TiO2和4BS浓度对光催化过程以及进水流速、操作时间对PAN700和PVDF700两种超滤膜分离TiO2过程的影响,得出悬浮态光催化超滤膜反应器的最佳操作条件。实验结果表明,pH为5.5时,TiO2对4BS的吸附性最好,吸附过程符合Langmuir等温吸附规律。在UV=100W、T=20℃、染料初始浓度为50mg·L-1以及催化剂TiO2浓度为1g·L-1的最佳光催化操作条件下反应60min后,染料4BS去除率可达到97.9%。超滤膜回收TiO2的过程中,随着流速增加,产水通量增加,出水水质维持稳定,且PAN700比PVDF700性能更好,出水浊度低,产水通量更大。PAN700膜在0.12MPa、40L·h-1的进水流速下连续运行120min后,通量仅衰减28%,为214.00L·m-2h-1。通过滤饼模型计算了分离过程的污染常数β值,结果表明PAN700比PVDF700膜更适合用于耦合分离过程。     

精细化工中的气-液-固加氢反应器

气-液-固加氢反应器在精细化工中有广泛的应用,本文介绍了气-液-固加氢反应器的混合和操作,并为气-液-固加氢反应器的设计和选择提出-些参考.     

气-液-固三相浆态反应器冷模考察

由于气—液—固三相浆态反应器有温度易控制等独特的优点,近年来在化学反应工程上得到广泛的研究和实际应用,我们结合浆态反应工艺的开发,对气—液—固三相浆态反应器进行了比较系统的冷模考察,关联了气含率与各种影响因素的经验方程,确定了有关参数,这对实际反应器的设计提供了有价值的依据。     

The degradation of an azo dye in a batch slurry photocatalytic reactor

The photocatalytic degradation of a commercial azo-reactive textile dye, Remazol Red F-3B, has been investigated in a batch slurry reactor using semiconductor catalysts like, ZnO and TiO₂, and two UV sources emitting mainly at 254 and 365 nm. Non-irradiated catalysts and non-catalyzed UV irradiation have negligible effect on the dye degradation. Initial pH, dye concentration, light power and catalyst loading as well as the catalyst type and UV wavelength are considered as process variables. The results showed that decolorization and TOC removal efficiencies of ZnO are higher under 365 nm UV. On the other hand, when two photocatalysts are compared, the decolorization performance of ZnO is higher than TiO₂ under 365 nm UV_, while TiO₂ performs better under 254 nm UV. Furthermore, from the TOC removal point, TiO₂ performs better than ZnO irrespective of the UV wavelength. TiO₂ irradiated under 254 nm UV degrades successfully both benzene and naphthalene derivatives.     

Radiation absorption and degradation of an azo dye in a hybrid photocatalytic reactor

Results are presented for the photocatalytic degradation of an azo dye, reactive blue 69, in a novel hybrid photocatalytic reactor, illuminated by solar radiation and artificial light, under different experimental conditions. A radiative transfer model, based on the P1 approximation, is proposed to evaluate the distribution of local volumetric rate of photons absorption (LVRPA) in the reaction space of the hybrid photocatalytic reactor. This radiation transfer model, together with a first order kinetic model, is used to fit the experimental results. The model correlates well with the experiments, and values for an apparent first order kinetic constant for the degradation of RB69 are obtained. The proposed radiative transfer model (P1 approximation) is simple enough to allow for an analytical solution, yet complex enough to take into account scattering of radiation in all directions and to all orders. Simulations show a distribution of LVRPA that varies smoothly at small catalyst concentration, and is very quickly attenuated for high concentrations. Around of 70% of photons supplied by both illumination sources to the hybrid photocatalytic reactor are absorbed by the catalyst. The experimental results show the decolorization degree increases as catalyst concentration increase. In relation to mineralization process, the removal of total organic carbon is nearly complete after 5 hours irradiation. This indicates that not only the azo bond breakage is carried out, but also that the intermediate species are mineralized. The apparent kinetic constant has a dependence on catalyst concentration which is described by an adsorption model. Addition of oxygen by means of an air diffuser proves to be beneficial to the process.     

Solar photocatalytic decolorization of synthetic dye solution using pilot scale slurry type falling film reactor

Ag deposited TiO₂ was prepared by simple chemical reduction method and its photocatalytic efficiency was evaluated for the decolorization of methylene blue dye using pilot scale slurry type falling film reactors (FFR) under sunlight. The characterization of the prepared catalysts by XRD, TEM, EDAX, DRS and PL confirmed that silver, which acts as electron trap, was deposited over the TiO₂ surface. The operational parameters, such as catalyst loading, concentration of the dye solution, pH of the slurry, addition of oxidizing agents and effect of different substrates, were optimized. The photocatalytic efficiency of Ag deposited TiO₂ increased two-fold times than pure TiO₂ and the maximum decolorization of dye was observed under acidic conditions. The reaction rate significantly increased with the addition of oxidizing agent H₂O₂. The ceramic tile as well as double skin reactor have higher photocatalytic efficiency than glass as substrate. In addition, Ag-deposited TiO₂ photocatalyst could be easily recovered by simple sedimentation process and reused for repeated experimental cycles with more than 95% decolorization efficiency.     

气液固三相浆态床反应器研究进展

由于在甲醇合成、费托合成等工艺中的成功应用,气液固三相浆态床反应器的研究引起了越来越多的重视.本文综述了有关浆态床反应器方面的研究,包括:流体力学性能、反应器设计、固液分离以及产业化进程.详细地介绍了影响浆态床反应器流体力学性能的主要因素:压力、温度、气体表观气速、液体性质及固含率等对流型、气含率、气泡停留时间分布和传质系数的影响.总结了近年来在浆态床反应器设计和固液分离方面的研究成果.     

Degradation of an azo dye Orange II using a gas phase dielectric barrier discharge reactor submerged in water

A dielectric barrier discharge (DBD) system employing wastewater as one of the electrodes was applied to the degradation of an azo dye, Orange II. The main advantage of this system is that reactive species like ozone and ultraviolet (UV) light produced by the DBD can be utilized for the treatment of wastewater. This system was able to remove the chromaticity and destroy the benzene and naphthalene rings in the dye molecule effectively. The results obtained under several conditions revealed that the UV emission from the DBD reactor could enhance the degradation of the dye, particularly in the presence of titanium oxide photocatalyst. The products resulting from the destruction of the rings in the dye molecule were found to be highly recalcitrant against further oxidation to smaller molecules. The change in the initial dye concentration showed that the reaction order was around 0.8 with respect to the dye concentration. The reduction in the concentration of total organic carbon was much more efficient with oxygen than with air.     

三相强制外循环环流反应器内的局部气泡行为

为适应新兴的工艺过程，提出一种带有强制外循环的中心气升式内环流反应器。根据结构特点及流动状态不同，将强制外循环环流反应器分为6个流动区域，即环流反应器底部区、气体分布器影响区、浆液进料影响区、导流筒上行区、气液分离区和环隙区。研究了不同流动区域内的局部气泡特性。发现不同流动区域内气泡直径沿径向的分布有较大差异，倒锥形底部结构显著影响了环流气泡的数量与直径。推导出了不同流动区域内平均气泡直径的理论模型，模型结果与实验数据吻合较好。     

Low-temperature methanol synthesis in a circulating slurry bubble reactor

A circulating slurry bubble reactor was developed to synthesise methanol via methyl formate from the gas mixture of carbon monoxide and hydrogen at low temperature. The strategy for designing and scaling up the bubble reactor involved a preliminary understanding of fluid dynamics in a cold model, continuous operations under industrial conditions and a parallel experiment in an autoclave. Per-pass syngas conversion was investigated during 100-h operations. The axial profile of solid catalyst concentration was measured just before the shutdown and the composition of liquid product was analysed after the shutdown. These results show that the circulating slurry bubble column will become a potential reactor for the commercial process of low-temperature methanol synthesis after the catalyst system has been improved.     

三维镍网负载Ti02光催化反应器降解活性红3BS

采用负载纳米Ti02的三维镍网装配的光催化水处理器对活性红溶液进行降解实验研究,获得了在不同影响因素下,如活性红溶液初始浓度、pH值、H202投加量等,染料的降解规律.实验结果表明在相同的反应时间内,UV/镍网/Ti02组合模式对活性红的降解效果最佳,脱色率能达到98.6%.活性红溶液的脱色率随初始浓度的增大而减小,当浓度为20 mg/L时,降解效果最佳,处理390 min脱色率能达到98%以上;在pH值为7时,对活性红溶液进行降解效果最佳,脱色率能达到99.2%;溶液中投加H2O2可以增强光催化降解效率,H202最佳投加量为1g/L,在150 min反应时间内,脱色率能达到99.4%.