Synthesis,Characterization and Nanocomposite Formation of Poly(glycerol succinate-co-maleate) with Nanocrystalline Cellulose

A novel biodegradable polymer based on glycerol, succinic anhydride and maleic anhydride, poly(glycerol succinate-co-maleate), poly(GlySAMA), was synthesized by melt polycondensation and tested as a matrix for composites with nanocrystalline cellulose. This glycerol-based polymer is thermally stable as a consequence of its targeted cross-linked structure. To broaden its range of properties, it was specifically formulated with nanocrystalline cellulose (NCC) at concentrations of 1, 2 and 4 wt%, and showed improved mechanical properties with NCC. Specifically, the effect of reinforcement on mechanical properties, thermal stability, structure, and biodegradability was evaluated, respectively, by tensile tests and thermogravimetric analyses, X-ray diffraction and respirometry. The neat poly(GlySAMA) polymer proved flexible, exhibiting an elongation-to-break of 8.8 % while the addition of nanowhiskers (at 4 wt%) caused tensile strength and Young’s modulus to increase, 20 and 40 %, respectively. Stiffness improved without significantly decreasing thermal stability as measured by thermogravimetric analysis. Biodegradation tests indicated that all samples were degradable but NCC reduced the rate of biodegradation.     

A Combined Ca(OH)2/NH3 Flue Gas Desulfurization Process for High Sulfur Coal: Results of a Pilot Plant Study

The removal of SO₂ with atomization of a slaked lime slurry and supplemental injection of gaseous NH₃ were tested in a conventional spray dryer/baghouse system for SO₂ concentrations of 2000 ppm and 3000 ppm and a 30° F approach to saturation. Results at 3000 ppm of SO₂ showed an average SO₂ removal efficiency of 90.3 percent at a combined stoichiometric ratio of 0.95-1.10 and an average overall sorbent utilization of 91.6 percent. The overall molal ratio of NH₃/SO₂ reaction was found to be 2:1 under the test conditions Particle size analyses, and EP toxicity tests were conducted on the products of the reactions.     

The Effects of Infiltration and Insulation on the Source Strengths and Indoor Air Pollution from Combustion Space Heating Appliances

Many energy conservation strategies for residences involve reducing house air exchange rates. Reducing the air exchange rate of a house can cause an increase in pollutant levels if there is an indoor pollution source and if the indoor pollutant source strength remains constant. However, if the indoor pollutant source strength can also be reduced, then it is possible to maintain or even improve indoor air quality. Increasing the insulation level of a house is a means of achieving energy conservation goals and, in addition, can reduce the need for space heating and thereby reduce the pollutant source strengths of combustion space heaters such as unvented kerosene space heaters, unvented gas space heaters, and wood stoves. In this paper, the indoor air quality trade-off between reduced infiltration and increased insulation in residences is investigated for combustion space heaters. Two similar residences were used for the experiment. One residence was used as a control and the other residence had infiltration and insulation levels modified. An unvented propane space heater was used as the source in this study. A model was developed to describe the dependence of both indoor air pollution levels and the appliance source strengths on house air exchange rates and house insulation levels. Model parameters were estimated by applying regression techniques to the data. Results show that indoor air pollution levels in houses with indoor combustion space heating pollution sources can be held constant (or lowered) by reducing the thermal conductance by an amount proportional to (or greater than) the reduction of the air exchange rate.     

Flow Injection Analysis of MWC Fly Ash Leaching Characteristics

Abstract

A completely mixed batch reactor leaching method utilizing flow injection analysis (the CMBR-FIA method) was developed to study the lead leaching characteristics of municipal waste combustor fly ash. Flow injection analysis (FIA) coupled with atomic absorption spectrophotometry enabled the determination of lead concentrations at one minute intervals. The pH and oxidation-reduction potential of the solution were continuously monitored to characterize the leaching conditions. Automatic titration was used to alter the solution pH to defined endpoints. The CMBR-FIA method offers the ability to immediately observe alterations to the leaching solution, and grants the freedom to study a number of parameters concurrently. The CMBR-FIA method is a rapid and reliable means to investigate leaching characteristics. This paper describes the method and demonstrates its use to monitor the leaching of lead from municipal solid waste combustor fly ash as a function of pH. Soluble lead concentrations are shown to increase quickly with decreasing pH.

A maximum of 50% of the total lead concentration was available in solution at pH 2. This value gradually decreased with time to over 35% of the total.     

Modeling Emissions from Elevated Cylindrical Bins

Abstract

This paper demonstrates how wind tunnel modeling data that accurately describe plume characteristics near an unconventional emission source can be used to improve the near-field downwind plume profiles predicted by conventional air pollution dispersion models. The study considers a vertical, cylindrical-shaped, elevated bin similar to large product storage bins that can be found at many industrial plant sites. Two dispersion models are considered: the U.S. Environmental Protection Agency's ISC2(ST) model and the Ontario Ministry of the Environment and Energy's GAS model. The wind tunnel study showed that plume behavior was contrary to what was predicted using conventional dispersion models such as ISC2(ST) and GAS and default values of input parameters. The wind tunnel data were used to develop a protocol for correcting the dispersion models inputs, resulting in a substantial improvement in the accuracy of the dispersion estimates.     

Comparison of Short-Term Variations (15-Minute Averages) in Outdoor and Indoor PM2.5 Concentrations

ABSTRACT

Measurements of 15-min average PM_2.5 concentrations were made with a real-time light-scattering instrument at both outdoor (central monitoring sites in three communities) and indoor (residential) locations over two seasons in the Minneapolis-St. Paul metropolitan area. These data are used to examine within-day variability of PM_2.5 concentrations indoors and outdoors, as well as matched indoor-to-outdoor (I/O) ratios. Concurrent gravimetric measurements of 24-hr average PM_2.5 concentrations were also obtained as a way to compare real-time measures with this more traditional metric. Results indicate that (1) within-day variability for both indoor and outdoor 15-min average PM_2.5 concentrations was substantial and comparable in magnitude to day-to-day variability for 24hr average concentrations; (2) some residences exhibited substantial variability in indoor aerosol characteristics from one day to the next; (3) peak values for indoor short-term (15-min) average PM_2.5 concentrations routinely exceeded 24-hr average outdoor values by factors of 3-4; and (4) relatively strong correlations existed between indoor and outdoor PM_2.5 concentrations for both 24-hr and 15-min averages.     

Forecasting Air Pollution Potential: A Synoptic Climatological Approach

ABSTRACT

This paper describes the development and application of an air pollution potential (APP) forecast model based on a synoptic climatological approach in a heavily industrialized area in Durban, South Africa. The aim of the forecasting procedure, based on a system of orange, red, and all-clear alerts, was to give industry advance warning of periods of poor atmospheric dispersion so that it could take action to reduce emissions. The key meteorological parameter in accurately identifying the commencement of an APP episode was found to be negative surface pressure tendency. Wind direction was the most useful parameter in estimating the end point of an APP episode. The model was very successful in identifying periods of elevated SO₂, but there is a need for further refinement in forecasting the end point of an episode.     

An Environmental Decision-Making Tool for Evaluating Ground-Level Ozone-Related Health Effects

Abstract

A computer model called the Ozone Risk Assessment Model (ORAM) was developed to evaluate the health effects caused by ground-level ozone (O₃) exposure. ORAM was coupled with the U.S. Environmental Protection Agency’s (EPA) Third-Generation Community Multiscale Air Quality model (Models-3/CMAQ), the state-of-the-art air quality model that predicts O₃ concentration and allows the examination of various scenarios in which emission rates of O₃ precursors (basically, oxides of nitrogen [NO_x] and volatile organic compounds) are varied. The principal analyses in ORAM are exposure model performance evaluation, health-effects calculations (expected number of respiratory hospital admissions), economic valuation, and sensitivity and uncertainty analysis through a Monte Carlo simulation. As a demonstration of the system, ORAM was applied to the eastern Tennessee region, and the entire O₃ season was simulated for a base case (typical emissions) and three different emission scenarios. The results indicated that a synergism occurs when reductions in NO_x emissions from mobile and point sources were applied simultaneously. A 12.9% reduction in asthma hospital admissions is expected when both mobile and point source NO_x emissions are reduced (50 and 70%, respectively) versus a 5.8% reduction caused by mobile source and a 3.5% reduction caused by point sources when these emission sources are reduced individually.     

Particulate Emissions from Construction Activities

Abstract

Although it has long been recognized that road and building construction activity constitutes an important source of particulate matter (PM) emissions throughout the United States, until recently only limited research has been directed to its characterization. This paper presents the results of PM₁₀ and PM_2.5 (particles ≤10 μm and ≤2.5 μm in aerodynamic diameter, respectively) emission factor development from the onsite testing of component operations at actual construction sites during the period 1998 –2001. Much of the testing effort was directed at earthmoving operations with scrapers, because earthmoving is the most important contributor of PM emissions across the construction industry. Other sources tested were truck loading and dumping of crushed rock and mud and dirt carryout from construction site access points onto adjacent public paved roads. Also tested were the effects of watering for control of scraper travel routes and the use of paved and graveled aprons at construction site access points for reducing mud and dirt carryout. The PM₁₀ emissions from earthmoving were found to be up to an order of magnitude greater than predicted by AP-42 emission factors drawn from other industries. As expected, the observed PM_2.5:PM₁₀ emission factor ratios reflected the relative importance of the vehicle exhaust and the resuspended dust components of each type of construction activity. An unexpected finding was that PM_2.5 emissions from mud and dirt carryout were much less than anticipated. Finally, the control efficiency of watering of scraper travel routes was found to closely follow a bilinear moisture model.