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Physical and Chemical Properties of Pesticides and Other Contaminants: Volatilization, Adsorption, Environmental Distribution, and Reactivity
Published in James N. Seiber, Thomas M. Cahill, Pesticides, Organic Contaminants, and Pathogens in Air, 2022
James N. Seiber, Thomas M. Cahill
This applies only to liquid surfaces that are unaffected by the underlying solid substrate, as occurs in the standard ASTM evaporation rate test and to quiescent liquid pools. The inclusion of M increased the slope of previous Ln flux vs. Ln VP regressions to a value close to 1.0. This correlation can be used for screening level assessment and ranking of liquid chemicals for evaporation rate, such as pesticides, fumigants, and hydrocarbon carrier fluids used in pesticide formulations, liquid consumer products used indoors, and accidental spills of liquids. In addition to vapor pressure, other factors that influence volatilization include movement of air over chemical deposits exposed to the open environment and the thickness of the deposit. The direct effect of wind flow rate on the volatilization of weed oil mixtures (e.g., Beacon oil, Chevron oil) was demonstrated in an earlier study (Woodrow et al., 1986). This study also showed that the weed oils (mixtures of hydrocarbons of varying molecular weight and vapor pressure) volatilized differentially from deposits on inert Teflon and glass surfaces (Figure 3.2). That is, components with higher vapor pressures and lower molecular weights volatilized early on, eventually leaving the original deposit enriched in the components of higher molecular weight and lower vapor pressure. This phenomenon was demonstrated both in the laboratory and in the field. In the field, weed oils applied to seed alfalfa led to significant volatilization, which is thought to have contributed to photochemical smog formation (see Table 2.2).
Microalgae for Removing Pharmaceutical Compounds from Wastewater
Published in Sreedevi Upadhyayula, Amita Chaudhary, Advanced Materials and Technologies for Wastewater Treatment, 2021
Eliana M. Jimenez-Bambague, Aura C. Ortiz-Escobar, Carlos A. Madera-Parra, Fiderman Machuca-Martinez
Microalgae-based wastewater treatment systems are a dynamic ecosystem in which different biotic and abiotic processes occur. The main removal mechanisms of micropollutants identified are sorption in the biomass and/or sediments present in the bioreactor, volatilization, photodegradation, and biodegradation. Sorption is a physical mechanism by which the contaminants transfer from the liquid matrix to the solid fraction. Volatilization is the change of a substance into a gaseous form. This mechanism is more common in compounds with moderately high Henry's Law constant values (11–12 Pam−3 mol−1), such as musk fragrances (Matamoros et al. 2015), while in pharmaceutical compounds it is less likely, thus explaining why it will not be included in this item.
Risk Assessment Techniques and Methods of Approach
Published in D. Kofi Asante-Duah, Hazardous Waste Risk Assessment, 2021
Volatilization — Volatilization is the process by which a chemical compound evaporates into the vapor phase from another environmental compartment. The volatilization of chemicals is an important mass transfer pathway. Knowledge of volatilization rates is necessary to determine the amount of chemical that enters the atmosphere and the change of pollutant concentrations in the source media. The transfer process from the source (e.g., water body, sediments, soil) to the atmosphere is dependent on the physical and chemical properties of the chemical compound in question, the presence of other pollutants, and the physical properties of the source media and the atmosphere. Lyman et al. (1990), among others, elaborate several estimation methods for evaluating this parameter.
Evaluation of long-term oven aging protocols on field cracking performance of asphalt binders containing reclaimed asphaltic materials (RAP/RAS)
Published in Road Materials and Pavement Design, 2023
Raquel Moraes, Fan Yin, Chen Chen, Adrian Andriescu, David J. Mensching, Nam Tran
The effects of moisture on mixture durability are accounted for by (1) testing in the presence of moisture or (2) conditioning mixtures before conducting performance tests. The aging of asphalt binders is caused by volatilisation (i.e. evaporation of the light fractions of asphalt), thermal and ultraviolet oxidation, and other chemical processes. Volatilisation and oxidation occur rapidly during the production and construction of asphalt mixtures when the asphalt is spread in thin films to coat the aggregate at a high temperature. This is sometimes referred to as short-term aging (STA). The oxidative aging then progresses throughout the pavement service life, often referred to as long-term aging (LTA). Unlike thermal oxidation [simulated in rolling thin-film oven (RTFO) and pressure aging vessel (PAV)], ultraviolet (UV) aging methods for asphalt samples are not standardised, allowing researchers to vary several UV chamber conditioning parameters such as UV intensity and aging temperature.
A net-shape forming process of Ti–6Al–4V sphere joints
Published in Powder Metallurgy, 2021
Ce Zhang, Yu Pan, Jianzhuo Sun, Xin Lu, Jiazhen Zhang
After injecting, the green parts are placed in a furnace under nitric acid vapour for catalytic debonding. The relationships between debonding time, temperature and binder removal rate are shown in Figure 6(a). It can be seen that as the debonding time increases, the removal rate of the binder POM increases. But the rate of increase gradually slows down, and finally tends to be constant (∼70%). The temperature decides the time of catalytic debonding. The minimum time is about 5 h at 125 °C, while the maximum time is 12 h at 100 °C. Figure 6(b) shows the TG and differential scanning caborimetry (DSC) curves of the POM feedstock. Two endothermic peaks at 170 °C and 390 °C correspond to the melt of POM and decomposition of LDPE. TG curve shows the thermal debinding process can be divided into four stages. The first stage at 78–260 °C corresponds to the volatilisation of the low-melting-point component and this stage is dominated by evaporation. The second stage at 260–330 °C corresponds to the pyrolysis of low molecular weight components in the binder, like SA and EVA. The third stage at 330–400 °C is the decomposition of principal component (POM), leading to a rapid weight loss. The last one after 400 °C is the decomposition of LDPE.
Anti-aging additives: proposed evaluation process based on literature review
Published in Road Materials and Pavement Design, 2021
Ingrid Gabrielle do Nascimento Camargo, Taha Ben Dhia, Amara Loulizi, Bernard Hofko, Johannes Mirwald
Asphalt binder ageing is a thermal-oxidative process commonly associated with three major mechanisms, namely volatilisation, steric hardening, and oxidation (Airey, 2003; Tauste et al., 2018). Volatilisation is the evaporation of lightweight components occurring during hot-mix asphalt (HMA) production (Hu et al., 2020). Steric hardening (physical ageing) refers to the progressive hardening of asphalt binder when there is the molecular restructuring of its molecules, which can be partially reversed by heat (Masson et al., 2005; Sirin et al., 2018). Oxidation is characterised by the chemical interaction between atmospheric oxygen, reactive oxygen species (ROS), and asphalt molecules which leads to irreversible changes (oxidative hardening) of the chemical and physical properties of the asphalt (Das et al., 2014; Hofko et al., 2020; Petersen & Glaser, 2011). The resistance of the asphalt binder to oxidation depends on its component compatibility or state of dispersion of micellar components (Petersen, 2009).