Thesis (M.Arch.)--University of Hong Kong, 1994. / Includes special report study entitled : Insolation CAD modelling. Includes bibliographical references. Also available in print.

abstract: The release of organophosphorus compounds (OPs) and subsequent exposure to these compounds is of concern to humans and the environment. The goal of this work was to control the concentrations of gaseous OPs through interaction with sorbent oxides. Experimental and computational methods were employed to assess the interactions of dimethyl phosphite (DMHP), dimethyl methylphosphonate (DMMP), dimethyl ethylphosphonate (DMEP), diethyl ethylphosphonate (DEEP), and triethyl phosphate (TEP) with amorphous silica (a-silica), ã-alumina, and monoclinic zirconia (m-zirconia) for applications in air pollution control. Interactions of the selected OPs with a-silica were chosen as a baseline to determine the applicability of the computational predictions. Based on the a-silica results, computational methods were deemed valid for predicting the trends among materials with comparable interactions (e.g. -OH functionality of a-silica interacting with the phosphonyl O atoms of the OPs). Computational evaluations of the interactions with the OPs were extended to the oxide material, m-zirconia, and compared with the results for ã-alumina. It was hypothesized that m-zirconia had the potential to provide for the effective sorption of OPs in a manner superior to that of the a-silica and the ã-alumina surfaces due to the surface charges of the zirconium Lewis acid sites when coordinated in the oxidized form. Based on the computational study, the predicted heats of adsorption for the selected OPs onto m-zirconia were more favorable than those that were predicted for ã-alumina and a-silica. Experimental studies were carried out to confirm these computational results. M-zirconia nanoparticles were synthesized to determine if the materials could be utilized for the adsorption of the selected OPs. M-zirconia was shown to adsorb the OPs, and the heats of adsorption were stronger than those determined for commercial samples of a-silica. However, water interfered with the adsorption of the OPs onto m-zirconia, thus leading to heats of adsorption that were much weaker than those predicted computationally. Nevertheless, this work provides a first investigation of m-zirconia as a viable sorbent material for the ambient control of the selected gaseous OPs. Additionally, this work represents the first comparative study between computational predictions and experimental determination of thermodynamic properties for the interactions of the selected OPs and oxide surfaces. / Dissertation/Thesis / Ph.D. Chemical Engineering 2011

Volatile organic compounds (VOCs) and carbon monoxide are considered the main greenhouse gas pollutants from either automotive engines or stationary sources. The increased concentration of these pollutants in air severely affects human health and causes changes in earth climate and vegetation growth rates. Ethylene is one of the VOCs closely related with photocatalytic pollution when it reacts with nitrogen oxides in the presence of sun light to form ground-level ozone. It is also responsible for quick repining of fruits and vegetables. Carbon monoxide, on the other hand, is a poisonous gas mainly released by vehicle emissions, and when inhaled in high concentrations, it causes severe health problems related to the respiratory system leading to significant rates of deaths annually in Europe and North America. Globally, The World Health Organization (WHO) estimates that seven million people die yearly due to poor air quality-related reasons which urges current and future stringent regulations to control air pollution emissions. In the past four decades, several equipment modifications and processes have been studied for reducing these emissions. Among them is the phenomenon of Electrochemical Promotion of Catalysis (EPOC) which was first reported in the early 1980s. EPOC has been successfully shown to convert automotive, indoor and industrial air pollutants such as VOCs, CO and nitrogen oxides (NOx) to harmless gases. It involves reversible changes in the catalytic properties of catalysts deposited on solid electrolytes when a small electric current or potential is applied. More recently, it was demonstrated that EPOC can be thermally induced without any electrical polarization, in analogy to the well-known phenomenon of metal-support interaction, by using noble metal nanocatalysts supported on ionically conducting materials such as yttria-stabilized zirconia (YSZ). The objective of this research is to gain deeper understanding of the factors affecting metal-support interaction between the active metal and the support to enhance their catalytic activity for environmentally-important reaction systems; specifically, ethylene and carbon monoxide oxidation as well as hydrogen fuel purification by carbon monoxide methanation. First, the activity of platinum nanoparticles deposited on carbon black, which is a conventional support used in catalysis, is studied. The effect of particle size of four Pt/C nanoparticles synthesized using a modified reduction method for ethylene (C2H4) complete catalytic oxidation is investigated. These catalysts show high activity towards C2H4 oxidation which is found to be a strongly size-dependent reaction. Full conversion of 1000 ppm C2H4 is achieved over the smallest nanoparticles (1.5 nm) at 100oC while higher temperature 170oC is required to completely oxidize ethylene over the largest nanoparticle (6.3 nm). The second stage of this research compares the catalytic activity of platinum and ruthenium nanoparticles when deposited on ionic or mixed ionic conductive vs. non ionic conductive supports for CO and VOCs oxidation. The Pt and Ru nanoparticles are deposited on yttria-stabilized zirconia (8% Y2O3-stabilised ZrO2), cerium (IV) oxide (CeO2), samarium-doped ceria (SDC), gamma-alumina (γ-Al2O3), carbon black and on novel perovskite group Sm1-xCexFeO3 (x = 0, 1, 5) resulting in ≤ 1 wt. (weight) % of Pt and Ru on each support. It is found that the nanocatalysts deposited on ionic conductive or mixed ionic conductive supports outperformed the catalysts deposited on non ionic conductors due to strong metal-support interaction that greatly affects the electronic and catalytic properties of the catalysts. The enhanced catalytic activity towards CO and C2H4 oxidation reactions is shown by earlier catalytic activity and complete conversion, lower activation energies, greater turnover frequencies and higher intrinsic rates per active surface area. To further investigate the effect of ionic conductivity of the supports and the exchange of O2- (oxygen vacancy) between the support and the catalyst surface, complete oxidation of pollutants is studied in the absence of oxygen in the gas phase. For the first time, complete oxidation of CO and C2H4 in an oxygen-free environment at low temperatures (< 250oC) is achieved, which represents the main novel finding in this research. The idea of pollutant removal in the absence of oxygen is extended to a practical reaction for fuel cells application which is hydrogen fuel purification from CO impurities at temperatures < 100oC. Moreover, the effect of particle size, pollutant concentration, operating conditions and support nature in the absence of oxygen in the gas feed is studied. It is proposed that the metal nanoparticles and the solid electrolyte form local nano-galvanic cells at the vicinity of the three-phase boundary where the anodic reaction is CO or C2H4 oxidation and the cathodic reaction is the surface partial reduction of the support. A systematic catalyst reactivation process is suggested and the catalytic activity of these nano-catalysts is studied which can be further investigated for air pollution control applications such as in vehicle catalytic converters, indoor air quality units and power plant emissions.

No description available.

A gas-phase system to oxidize and remove the platinum and palladium from automotive catalytic converter units was studied. The effects of varying reaction temperature, time and reactant gas concentration upon yields were monitored using a colorimetric procedure based on the regent p-nitroso-N, N-dimethyl amiline. Chlorine plus carbon monoxide at 700°-900°C. displayed the most promise for commercial application.

A widely used roadway runoff best management practice (BMP) used in Florida is an ex.filtration trench. Traditionally, exfiltration trenches are constructed without any filtration media. Therefore, the potential for groundwater contamination by the roadway runoff exists. Roadway runoff contains metals and nutrient pollutants. Nitrogen and Phosphorus are the most common nutrients causing impacts to receiving waters. To reduce the impact these pollutants will have on groundwater quality, Black and Gold™ media, which mainly consists of tire crumb, is evaluated. The Black and Gold™ media was found to be a good filtration media for removal of total nitrogen and nitrate + nitrite. It was found that all of the wells had experienced total nitrogen removal. These reductions ranged from 32% to 56%. The nitrate + nitrite reduction was experienced in the four wells. These reductions ranged from 4 7% to 88% in the three wells. The ortho-phosphorous and total phosphorus concentrations did not change significantly. Also, the metals concentrations did not change significantly.During the post sampling period, the turbidity of the groundwater increased. This was experienced in three of the four wells.

Thesis. 1979. Ph.D.--Massachusetts Institute of Technology. Dept. of Urban Studies and Planning. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography: p. 273-278. / by Gregory G.Y. Pai. / Ph.D.

One of our greatest threats to surface-water quality is polluted stormwater runoff. In this research, investigated is the use of a green roof irrigated with recycled stormwater runoff to remove pollutants from stormwater runoff and reduce the volume of stormwater runoff leaving developed areas. The green roof properties of interest are the filtration and biological processes as well as the roof's ability to hold water and increase evapotranspiration, reducing the volume of stormwater runoff from the source. Because of the above mentioned reasons the experiment consists of a water quality analysis and a water budget done on several experimental chambers modeled after the green roof on the student union building at the University of Central Florida. The green roof chambers are used to study different types of growing media, different irrigation rates, and the addition of plants and how stormwater runoff quality and quantity is affected. There are also control chambers built to model the conventional roof on the student union building. The purpose of the control is to determine the effectiveness of the different media's filtration/adsorption processes and ability to hold water, in addition to identifying the benefits of adding a green roof to both water quality and the water budget. This research showed that a specifically designed green roof stormwater treatment system with a cistern is an effective way to reduce both the volume of and mass of pollutants of stormwater runoff. The year long water budget showed that this system can reduce the volume of stormwater runoff by almost 90%. The green roof model developed within this work showed similar results for the same conditions. Design curves produced by the model have also been presented for several different geographic regions in Florida. The green roof stormwater treatment system presented within this work was effective at reducing the mass of pollutants. However, the concentration of several of the examined pollutants in the effluent of the cistern was higher or equivalent to that of a control roof. Nitrate and ammonia were two that had a lower concentration than the control roof. The use of a pollution control growing media was also examined. The results of this study show that the Black & GoldTM growing media is effective at removing both ortho-phosphorus and total phosphorus. Isotherm analysis was also preformed to quantify the adsorption potential. Despite the promise of the Black & GoldTM growing media to remove phosphorus the plants did not grow as well as in the expanded clay growing media. It is suggested that the pollution control media be used as a layer under the growing media in order to get the benefits of both media.

No description available.

Master of Arts / Department of Economics / Tracy M. Turner / The report examines the extent to which the United States market for tradable pollution permits has been an efficient way to reduce sulfur dioxide emissions from coal-burning power plants. To do so, this report first provides background information on the effects of SO2 emissions on the environment in the United States. It discusses the initial attempt with the 1970 Clean Air Act to reduce these emissions and its degree of success. The details of the 1990 Amendments are then given. The economic theory behind the different methods of pollution control (quantity regulation, technology mandate, taxation, and emissions restriction through tradable permits) is explained and their efficiency regarding consumer and producer surplus is contrasted. The report then reviews published articles regarding the topic at hand. The U.S. Acid Rain Program has been found to be very efficient in its ability to reduce sulfur dioxide emissions at a low cost to the producers.