Efficient Air Desulfurization Catalysts Derived from Pig Manure Liquefaction Char

Biochar from the liquefaction of pig manure was used as a precursor of H2S desulfurization adsorbents. In its inorganic matter, it contains marked quantities of calcium, magnesium and iron, which are known as hydrogen sulfide oxidation catalysts. The char was used either as-received or mixed with 10% nanographite. The latter was added to increase both the content of the carbon phase and conductivity. ZnCl2 in two different ratios of char to an activation agent (1:1 and 1:2) was used to create the porosity in the carbon phase. The content of the later was between 18–45%. The activated samples adsorbed 144 mg/g H2S. Sulfur was the predominant product of reactive adsorption. Its deposition in the pore system and blockage of the most active pores ceased the materials’ activity. The presence of the catalytic phase was necessary but not sufficient to guarantee good performance. The developed porosity, which can store oxidation products in the resulting composite, is essential for the good performance of the desulfurization process. The surface of the composite with nanographite showed the highest catalytic activity, similar to that of the commercial Midas® carbon catalyst. The results obtained indicate that a high quality reactive adsorbent/catalyst for H2S removal can be obtained from pig manure liquefaction wastes

Review of the effects of Asphalt fume emission (VOCs and PAHs) in vitro, in vivo and human studies

Review of the effects of Asphalt fume emission (VOCs and PAHs) in vitro, in vivo and human studies Omran Taqi, Nastassja Lewinski1 1) Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, VA Background Asphalt is abundantly available around human operations including road paving and roofing sites. However, their emissions and fumes (specifically volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs)) have been found to have adverse effects on health. Asphalt fumes are a class 2A carcinogen and exposure can increase the risk of lung cancer, asthma, headache, fatigue, and other cardiovascular diseases. Methods We used three literature sources (Google Scholar, PubMed and Web of Science) to gather in vitro, animal in vivo, and human studies about VOCs and/or PAHs exposure, and specifically asphalt/bitumen exposure and their effects on lungs, as well as focusing on biomarker measurements, such as interleukin-8 (IL-8) concentration in blood and 1-hydroxypyrene (1-OHP) in urine samples. Results Our review resulted in 80 papers describing various human, in vitro, and in vivo studies. Analyzing the biomarkers reported in these papers revealed that the IL-8 concentration in exposed cells/animals or workers in the asphalt industry is nearly double that of the unexposed control group, and the (1-OHP) concentration in exposed asphalt workers is nearly 11 times the amount of (1-OHP) as the control group. Conclusions Due to the limited number of research papers addressing in vitro studies on lung cells (A549 and BEAS-2B cells), future work should focus on developing optimal in vitro asphalt/bitumen exposure conditions for lung cells, as well as developing new technologies that can remove pollutants for people who work in industries with high levels of VOCs or PAHs exposure.https://scholarscompass.vcu.edu/uresposters/1410/thumbnail.jp

Phenolic Compounds in the Built Environment

This chapter examines source and application of phenolic compounds in the built environment as well as their environmental fate and treatment methods. We further describe the role of phenolic compounds in delaying aging and degradation of outdoor construction elements when exposed to intense solar radiation. In this chapter both plant-based and synthetic sources of phenolic compounds and their fate in the environment were examined. In addition, merits of select sources of phenolic compounds to resist ultraviolet radiation in composites as well as delaying degradation were studied. This chapter further provides insights pertaining to the underlying molecular interactions which afford phenol’s role as an anti-aging additive for outdoor construction elements. This in turn provides a solution to promote bio-economy and enhance sustainability in the built environment

Systems biology of asphalt pollutants and their human molecular targets

More than 90% of all the roads in the United States are covered with asphalt, despite hundreds of scientific studies demonstrating the detrimental effect of asphalt on human health. Asphalt is a complex mixture of thousands of compounds. Here, we not only review studies of the effects of asphalt on human health, but go a step further by taking a novel view of these health effects from a systems biology perspective. In particular, we propose an analogy to protein-protein interaction networks, which can be within species and across species when looking at host-pathogen interactions. While in the former, all nodes are of the same type (e.g., human proteins), in the latter nodes can be of different types, such as human proteins and pathogen proteins. To build a corresponding network of interactions between different nodes for asphalt, we retrieved the literature studying the molecular targets of identified components in asphalt and their corresponding cellular biomarkers. Using this approach, we show that a complex trans pollutant-human target network appears in which multiple health effects can be triggered through interactions of multiple pollutant molecules with multiple human targets. We envision that the insights gained from this analysis may assist future efforts at regulating the use of asphalt

Adhesion Mechanisms of Bituminous Crack Sealant to Aggregate and Laboratory Test Development

Crack sealing is a common pavement maintenance treatment because it extends pavement service life. However, crack sealant often fails prematurely due to a loss of adhesion. Since current test methods are mostly empirical and only provide a qualitative measure of bond strength, they cannot predict sealant adhesive failure accurately. Hence, there is an urgent need for test methods based on bituminous sealant rheology that can better predict sealant field performance. This study introduces three laboratory tests aimed to assess the bond property of hot-poured crack sealant to pavement crack walls. The three tests are designed to serve the respective needs of producers, engineers, and researchers. The first test implements the principle of surface energy to measure the thermodynamic work of adhesion, which is the energy spent in separating the two materials at the interface. The work of adhesion is reported as a measure of material compatibility at an interface. The second test is a direct adhesion test, a mechanical test which is designed to closely resemble both the installation process and the crack expansion due to thermal loading. This test uses the Direct Tension Test (DTT) device. The principle of the test is to apply a tensile force to detach the sealant from its aggregate counterpart. The maximum load, Pmax, and the energy to separation, E, are calculated and reported to indicate interface bonding. The third test implements the principles of fracture mechanics in a pressurized circular blister test. The apparatus is specifically designed to conduct the test for bituminous crack sealant, asphalt binder, or other bitumenbased materials. In this test, a fluid is injected at a constant rate at the interface between the substrate (aggregate or a standard material) and the adhesive (crack sealant) to create a blister. The fluid pressure and blister height are measured as functions of time; the data is used to calculate Interfacial Fracture Energy (IFE), which is a fundamental property that can be used to predict adhesion. The stable interface debonding process makes this test attractive. This test also may be used to estimate the optimum annealing time, and to quantify other interface characteristics, such as the moisture susceptibility of a bond. In addition, the elastic modulus of the sealant and its residual stresses can be determined analytically. While the direct adhesion test is proposed as part of newly developed performance-based guidelines for the selection of hot-poured crack sealant, the blister test may be used to estimate the optimum annealing time, in addition to IFE determination.Federal Highway Administration and Canada-US Crack Sealant Consortiumunpublishedis peer reviewe

Adhesion Mechanisms of Bituminous Crack Sealant to Aggregate and Laboratory Test Development

183 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008.While the direct adhesion test is proposed as part of newly-developed performance-based guidelines for the selection of hot-poured crack sealant, the blister test may be used to estimate the optimum annealing time, in addition to IFE determination.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Adhesion Mechanisms of Bituminous Crack Sealant to Aggregate and Laboratory Test Development

183 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008.While the direct adhesion test is proposed as part of newly-developed performance-based guidelines for the selection of hot-poured crack sealant, the blister test may be used to estimate the optimum annealing time, in addition to IFE determination.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

A Molecular Dynamics Approach to the Impacts of Oxidative Aging on the Engineering Characteristics of Asphalt

Oxidative aging is an inevitable environmental factor that accelerates asphalt pavement deterioration. This study employed a molecular dynamics simulation to investigate the impact of aging on asphalt cement from the perspectives of thermodynamic properties, and diffusion and adhesion characteristics. Results indicate that aging increased bulk density from 1.008 to 1.081 g/cm3 and cohesive energy density by 15.6%, which was attributed to the promoted molecular polarity and intermolecular attractiveness. The enhanced molecular interactions also reduced molecular mobility, which led to an increase in the glass transition temperature by 30 K, suggesting that aging diminished the resistance of asphalt to thermal cracking. Simulations of the diffusion behaviors across different temperatures demonstrated that the Arrhenius relationship described well the temperature dependence of the diffusion coefficient, and that aging considerably slowed down the diffusion process as represented by Arrhenius prefactor D0, which dropped by 38.2%. The asphalt–aggregate adhesion was assessed using layered models with and without a water interlayer of different thicknesses. The adhesion was enhanced upon aging due to the significantly improved electrostatic interactions at the interface. Evaluation of the residual adhesion with the presence of interfacial water suggested that aging would raise the moisture susceptibility of asphalt pavement. The increase in molecular polarity was considered to be highly responsible for these aging consequences, and was thus further investigated via the electrostatic potential surface and dipole moment