Recent advances in the catalytic oxidation of volatile organic compounds: a review based on pollutant sorts and sources

It is well known that urbanization and industrialization have resulted in the rapidly increasing emissions of volatile organic compounds (VOCs), which are a major contributor to the formation of secondary pollutants (e.g., tropospheric ozone, PAN (peroxyacetyl nitrate), and secondary organic aerosols) and photochemical smog. The emission of these pollutants has led to a large decline in air quality in numerous regions around the world, which has ultimately led to concerns regarding their impact on human health and general well-being. Catalytic oxidation is regarded as one of the most promising strategies for VOC removal from industrial waste streams. This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades. It addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions. It also highlights the primary routes for catalyst deactivation and discusses protocols for their subsequent reactivation. Kinetic models and proposed oxidation mechanisms for representative VOCs are also provided. Typical catalytic reactors and oxidizers for industrial VOC destruction are further discussed. We believe that this Review will provide a great foundation and reference point for future design and development in this field

Characterisation of cold atmospheric plasma afterglow for decontamination

The exploration missions of outer space and the associated search for extra-terrestrial lifeforms require to fulfil the international planetary protection policies of COSPAR. Today, dry heat microbial reduction (DHMR) and vapor phase bioburden reduction using hydrogen peroxide (VHP) are validated sterilisation methods for space missions. However, the fact that these methods could negatively influence sensitive materials increases the demand of alternative decontamination methods for space research. Cold atmospheric plasma (CAP) provides one of the most promising low-temperature decontamination methods and comprises various benefits such as low cost, simple design and comfortable usage. In the presented work, a newly developed plasma afterglow circulation apparatus (PACA) based on the surface micro-discharge (SMD) technology is investigated. To understand the important chemical reaction processes and to evaluate the presented PACA as a useful alternative decontamination method for planetary protection, this thesis combines interdisciplinary research fields of physics, biology and chemistry. In particular, the chemical reaction processes, the microbial inactivation and the material compatibility of the plasma treatment are investigated

ALUMINA SUPPORTED MANGANESE-BASED CATALYSTS FOR CATALYTIC OZONATION OF ACETONE AND TOLUENE IN AIR

Volatile organic compounds (VOCs) are hazardous substances produced from anthropogenic emissions and are among the main sources of air pollution. Catalytic ozonation is an efficient process for VOCs removal from indoor air at room temperature. In this Ph.D. thesis, alumina supported Mn oxides which are considered as one of the most active catalysts for ozonation of VOCs are used to oxidize acetone and toluene in air at room temperature. The primary aim of this research is to develop the catalyst for catalytic ozonation of VOCs at room temperature. Therefore, the influence of addition of second metal oxide, catalyst preparation procedure, and calcination temperature on catalytic properties and activity in ozonation of VOCs were investigated. In addition, kinetics and mechanism of the catalytic ozonation reaction were studied to clarify the role of metal oxide and support in the reaction pathway. It was found that addition of manganese and cobalt at lower loading levels (2.5% or 5%) to single metal oxide catalysts improved the catalytic activity significantly. By changing the loading of the secondary metals, its oxidation state changed. It is suggested that lower oxidation state of the secondary metal improves ozone decomposition and oxidation of acetone. Polyol process can produce catalysts with smaller manganese cluster size, higher surface area, and lower oxidation states than impregnation method which led to enhancing the VOC conversion. An increase in the calcination temperature increased the manganese particle size while reducing the surface area and dispersion of the catalyst. The results indicated that the oxidation state of manganese shifted to lower values by increasing the calcination temperature. An increase in the calcination temperature to 800 ºC, increased acetone oxidation, while no significant change was observed in toluene oxidation. In the binary mixture of acetone and toluene, the oxidation behaviors were different from the single component system. The toluene conversion was promoted whereas the acetone conversion was inhibited. Kinetic modeling was conducted on catalytic ozonation of acetone using the catalysts that exhibited the best catalytic activity. The kinetic experimental data were expressed well by Langmuir-Hinshelwood dual-site (LHd) mechanism, indicating that both MnOx and Al2O3 sites are essential and involved in the reaction. The cooperation of these sites on the surface of the catalysts provides the adjacent attack and migration of intermediates and enables the dual-site mechanism

The Impact of Air Pollution on Health, Economy, Environment and Agricultural Sources

This book aims to strengthen the knowledge base dealing with Air Pollution. The book consists of 21 chapters dealing with Air Pollution and its effects in the fields of Health, Environment, Economy and Agricultural Sources. It is divided into four sections. The first one deals with effect of air pollution on health and human body organs. The second section includes the Impact of air pollution on plants and agricultural sources and methods of resistance. The third section includes environmental changes, geographic and climatic conditions due to air pollution. The fourth section includes case studies concerning of the impact of air pollution in the economy and development goals, such as, indoor air pollution in México, indoor air pollution and millennium development goals in Bangladesh, epidemiologic and economic impact of natural gas on indoor air pollution in Colombia and economic growth and air pollution in Iran during development programs. In this book the authors explain the definition of air pollution, the most important pollutants and their different sources and effects on humans and various fields of life. The authors offer different solutions to the problems resulting from air pollution

Photodiodes

Photodiodes or photodetectors are in one boat with our human race. Efforts of people in related fields are contained in this book. This book would be valuable to those who want to obtain knowledge and inspiration in the related area

Carbon black reborn: Structure and chemistry for renewable energy harnessing

Carbon Black (CB) is one of the most abundantly produced carbon nanostructured materials, and approximately 70% of it is used as pigment and as reinforcing phase in rubber and plastics. Recent scientific findings report on other uses of CB that are of current interest, such as renewable energy harvesting and carbon capture. The present review focuses on the use and role of CB in renewable and environmental applications relevant to contemporary global challenges focusing specifically on clean energy. Key and recent research on the structure and chemistry of CB, including its uses as precursors to graphene quantum dots and hollow carbon spheres, is discussed in relation to renewable energy devices, electrochemical energy storage and environmental remediation. The surface chemistry of CB is closely related to that of graphitic and of turbostratic carbons through the predominant hexagonal carbon lattice from graphene fragments forming its basic structural units. Consequently, modern methods for grafting polymers and functional groups are easily translated to this abundant nanostructured material. Moreover, recent advances in electron microscopy that probe the structure of CB, and its electronic and physicochemical properties in nanocomposites revived the attention of what is wrongfully considered as a scientifically uninspiring material with limited potential for future technology breakthrough. CB has the potential to surge as a key player in renewable energy and environmental applications, meaning “When Black Turns Green”

XPS characterization of dilute nitride indium gallium arsinide materials nanoporous silica for active sampling of aldehydes

Multi-junction solar cells have been of recent interest due to their ability to achieve efficiencies as high as 50%. When small amounts of nitrogen are incorporated into the lattice, material quality problems can arise with the formation of Ga-N and Ga-In-N defects. The creation of nonradiative centers, and a decrease in homogeneity results in lower efficiencies. Annealing these solar cells in a nitrogen-rich environment can facilitate the rearrangement to the favorable In-N configuration. X-ray photoelectron spectroscopy was used to characterize these binding configurations to determine if these defects were passivated after annealing and hydrogenation treatments. The nitrogen associated region was studied, illuminating details that have not been seen previously. A second project investigated methods to look at natural or anthropogenic sources of air pollution. Among various indoor air pollutants, low molecular weight aldehydes (formaldehyde and acetaldehyde) have become an important class of volatile organic compounds because of their classification as known or probable human carcinogens. A nanoporous silica sorbent, named OSU-6, was explored in this study for its use in aldehyde sampling with subsequent thermal desorption and gas chromatography/mass spectrometry analysis. A series of analyses were performed to determine the materials sorption capacity in a variety of sampling conditions