An Exploratory Study of a Photonic Crystal Monolith Reactor for Air Pollution Control

摘要：Kalliat T.Valsaraj和Raghunathan Ravikrishna研究所：路易斯安那州立大学研究该项目的总体目标是开发一种使用光子带隙(PBG)二氧化钛来处理稀薄废气的整体光催化反应器。我们的假设是，采用溶胶-凝胶法在剥离的光纤管上原位制备和接枝PBG二氧化钛，并以整体式结构使用，可以极大地提高紫外光吸收、量子效率和光催化活性，并降低大型反应器中光催化降解废气中有机物的传质限制。与在光纤上使用二氧化钛粉末涂层相比，使用在光纤上生长的表现出二氧化钛的长程有序多孔结构的光子带隙有望提高整体光催化效率，因为这是因为改善了光传输性能和更好的传质。PBG二氧化钛将使用两种用于溶胶凝胶处理的模板在光纤上制造--a)聚苯乙烯微球和b)聚光体(乳剂)。单独的光纤与PBG二氧化钛将捆绑在一起，形成一个复合整体反应器。在合成阶段将定制PBG材料的特性，以提高复合整体块光催化反应器在紫外光下的反应效率。复合整体反应器将用于降解水溶液中的受试化合物1，2-二氯苯。具体目标是：1.采用溶胶/凝胶(溶液)法在光纤上制备PBG二氧化钛晶体。PBG二氧化钛薄膜的表征及其光子学性能的测定。建造整体式反应堆的内部结构。在一种候选化合物上测试各种反应条件下的反应器。获得一个数学模型来提取动力学速率常数和传质特性，这对过程的可能放大是有用的。广泛影响由于在连续整体光催化反应器结构中使用PBG材料是一个尚待检验的概念，因此该提议是高风险的。这项技术的发展将对光催化技术在废气处理中的应用产生重大影响。这是高回报的，因为如果成功，反应堆设计提供了扩大规模的潜力，可以缓解目前使用光催化反应器处理工业废气的障碍。因此，广泛的影响体现在环境可持续性领域。

ABSTRACTPI: Kalliat T. Valsaraj and Raghunathan RavikrishnaInstitution: Louisiana State UniversityProposal Number: 0520524ResearchThe overall objective of this project is the development of a monolith photocatalytic reactor using photonic band gap (PBG) titania for the treatment of dilute waste gases. The hypothesis is that, PBG titania produced in-situ and grafted on stripped fiber optic tubes using sol-gel chemistry and used in a monolithic configuration, can vastly improve UV absorption, quantum efficiency, the photocatalytic activity, and reduce the mass transfer limitations in a large scale reactor for photocatalytic degradation of organics in gaseous waste streams. The use of long range ordered porous structures of photonic band-gap exhibiting titania grown on optical fibers is expected to enhance the overall photocatalytic efficiency as compared to using powdered titania coating on stripped optical fibers due to improved light transmission properties and better mass transfer. The PBG titania will be manufactured on the optical fibers using two templates for solgel processing- a) polystyrene microspheres and b) polyaphrons (emulsions). The individual optical fiber monoliths with the PBG titania will be bundled together to form a composite monolith reactor. PBG material characteristics will be tailored at the synthesis stage in order to enhance the reactive efficiency of the composite monolith photocatalytic reactor in UV light. The composite monolith reactor will be used to degrade a test compound, 1,2-dichlorobenzene, in aqueous solutions. The specific objectives are:1. Preparation of PBG titania crystals on optical fibers using a sol/gel (solution) method2. Characterization of the PBG titania thin films and determination of their photonic properties.3. Construction of the internal configurations for the monolithic reactor.4. Testing the reactor on a candidate compound under various reaction conditions.5. Obtaining a mathematical model to extract kinetic rate constants and mass transfer characteristics useful for possible scale-up of the process.Broad ImpactThe proposal is high risk since the use of PBG materials in a continuous monolith photocatalytic reactor configuration is a concept that is yet to be tested. The development of this technology could have a significant impact on the application of photocatalytic processes to the treatment waste gas streams. It is high return because if successful, the reactor design offers a potential for scale up that can alleviate the current barriers to the use of photocatalytic reactors for industrial waste gas treatment. The broad impact is thus in the area of environmental sustainability.