A geochemical equilibrium modeling approach to assessing soil acidification impacts due to depositions of industrial air emissions

Soil acidification impacts arising from depositions of industrial air emissions may become a serious environmental concern. Currently, in the literature quantitative mechanistic modeling and the experimental acid neutralizing capacity (ANC) approach and a qualitative evaluation approach classifying soils into various levels of sensitivity to acid additions have been reported to assess the long-term soil acidification impacts due to industrial air emissions. Another alternative quantitative approach proposed by this study is the geochemical modeling approach that can be used to similate an ANC curve based on relevant soil chemistry data by calculating the equilibrium distributions of chemical species in the soil solution according to the specified geochemical processes. The purpose of this syudy was essentially to illustrate the potential applications and practical utility of the proposed geochemical modeling approach to assessing soil acidification impacts due to industrial air emissions. The application of the geochemical modeling approach was illustrated by comparisons of the experimental and simulated ANC curves for a calcareous and a noncalcareous soil representing insensitive and sensitive soil cases, respectively. Results obtained from these comparisons reveal that, in terms of producing the ANC curve for the soil solution, the geochemical modeling approach seems to perform well and produce more reliable results for calcareous soil than for noncalcareous soil. However, the approach can also be used for noncalcareous soils when the air emission rates are low and may need further testing with additional measured data for a wide range of soils other than those presented in this study

Effect of Charge on the Deposition of Electrostatically Charged Inhalable Aerosol in Lung Model

Inhalable drugs are widely used for treating lung diseases such as asthma, emphysema, and cystic fibrosis. The aerosol particles in these inhalable drugs may be charged electrostatically. The deposition of these inhaled therapeutic aerosol particles in the different regions of the lung depends on the particle aerodynamic diameter, electrostatic charge distribution, particulate number density, breathing rate, aerodynamics of the lung, ambient temperature, and relative humidity (RH). The primary mechanisms for lung deposition of inhaled particles are impaction, gravitational settling, diffusion, interception, and electrostatic attraction. To simulate lung deposition, electrostatically charged aerosol particles are introduced through a throat section into a glass bead lung model. The E-SPART analyzer was used to measure aerosol deposition as a function of the particle charge and size. Experiments were carried out to determine the increase in deposition efficiency as a function of the net charge-to-mass ratio (Q/M) of aerosol particles. Using a fairly monodisperse aerosol of 5.0 um count median aerodynamic diameter, it was found that the total deposition efficiency increased from 54% to 91% when Q/M increased from 0.5 to 9.67 |muC/g. The data show that enhanced delivery of the therapeutic aerosol in the lung can be achieved by controlling the electrostatic charge on the inhaled aerosol particles

Reduction of Dendrite Formations to Improve the Appearance of the Powder Cured Films for Automotive Industry

The appearance of powder-coated films is dependent upon powder chemistry and spraying parameters. One of the most important physical factors controlling the powder film appearance is the microdeposition of the powder particles on the grounded substrate. During the electrostatic deposition of powder, the formation of dendrites and agglomerates was observed; these formations have an adverse effect on the final film appearance and their elimination may result in smoother and glossier films. Dendrites are generated due to bipolar charging and inter-particulate electrostatic attractive forces. The corona charging technique is mostly used in industrial powder coating applications. At low corona voltages (- 40 to - 60 kV) a greater degree of bipolar charging was observed compared to that at higher voltages (- 80 to - 100 kV). At the higher voltages, the increase n number of ions produces a more unipolar charging and higher charge-to-mass ratios. As the film builds up, the powder transfer efficiency decreases as the repulsion forces between oncoming charged particles and the already deposited powder layer increase. By controlling the deposition patterns, the final film appearance can be improved. The smoothest films were obtained when the voltage was ramped from - 60 to - 100 kV. Another method to reduce dendrite formations was to deposit powder particles charged unipolarly by first separating them from the oppositely charged ones by using a charge separator

Electrostatic Microencapsulation of Composite Particulate Materials for Manufacturing and Environmental Applications

Electrostatic microencapsulation is a dry coating process where two powders, one containing the fines and the other relatively larger particles, are separately dispersed in air and pre-charged with opposite polarity, using corona charging for electrostatic coagulation. These oppositely charged core and guest particles experience attractive electrostatic forces and generate composite particles. Preliminary experiments of electrostatic microencapsulation were performed using Anionic Exchange Resin (AG 1-X8) as the host particle and Red Toner (Omega 4000) as the guest particles. An electrostatic microencapsulation tower has been designed for generation of composite particles using particles of different particle size distribution

Twenty-First Century Research Needs in Electrostatic Processes Applied to Industry and Medicine

From the early century Nobel Prize winning (1923) experiments with charged oil droplets, resulting in the discovery of the elementary electronic charge by Robert Millikan, to the early 21st century Nobel Prize (2002) awarded to John Fenn for his invention of electrospray ionization mass spectroscopy and its applications to proteomics, electrostatic processes have been successfully applied to many areas of industry and medicine. Generation, transport, deposition, separation, analysis, and control of charged particles involved in the four states of matter: solid, liquid, gas, and plasma are of interest in many industrial and biomedical processes. In this paper, we briefly discuss some of the applications and research needs involving charged particles in industrial and medical applications including: (1) Generation and deposition of unipolarly charged dry powder without the presence of ions or excessive ozone, (2) Control of tribocharging process for consistent and reliable charging, (3) Thin film (less than 25 micrometers) powder coating and Powder coating on insulative surfaces, (4) Fluidization and dispersion of fine powders, (5) Mitigation of Mars dust, (6) Effect of particle charge on the lung deposition of inhaled medical aerosols, (7) Nanoparticle deposition, and (8) Plasma/Corona discharge processes. A brief discussion on the measurements of charged particles and suggestions for research needs are also included

Evaluation studies of a sensing technique for electrostatic charge polarity of pharmaceutical particulates

Electrostatic charge due to inter-particle and particle-wall contacts may generate significant hazards during the processing of particulates within the pharmaceutical industry. Although charge behaviour of particulates is erratic and not easy to predict, it would be desirable to characterise the tendency of tribocharging prior to manufacturing. The work reported in this paper concentrates on a new and novel techniques for the detection of the active ingredient and excipient in a bipolar material. Three different case studies are presented for demonstration of the applicability of the method in different practical situations. Work confirmed through an experimental rig set-up indicates that materials that accumulate opposite charge via contact and rubbing can be detected from their charge sign as well as their relative magnitude. The results reported clearly demonstrated that the developed method for charge characterisation is a useful tool to understand how the charges are distributed in a population of particles showing a number of advantages over conventional methods

OZONATION OF TRACE ORGANIC-COMPOUNDS - MODEL PREDICTIONS VERSUS EXPERIMENTAL-DATA

This paper is focused on the use of ozone for the elimination of manmade organic micropollutants from drinking waters and waste effluents requiring advanced treatment. A mathematical model was developed to simulate the physical transport and chemical oxidation phenomena prevailing during the process of ozonation. A packed column reactor was constructed in order to test the aptness of the process model. After determining the fluid-dynamic and mass transfer properties of the reactor, stock water solutions spiked with toluene were brought into contact with gaseous O2-O3 mixtures. Toluene removal efficiencies observed under different experimental conditions then were compared with the model predictions

Regulatory leaching tests for fly ash: A case study

In many countries throughout the world, fly and bottom ashes originating from coal-fired thermal power plants are declared as wastes requiring special care during reuse and disposal. In this regard, a number of toxicity tests have been developed to assess the metal leaching potential of ash residues. In this study, fly ash samples obtained from the Catalagzi thermal power plant, located on the northwestern coast of Turkey, were subjected to toxicity tests such as the extraction (EP) and toxicity characteristic leaching (TCLP) procedures of the U.S. Environmental Protection Agency (U.S. EPA), and the so-called Method A extraction procedure of the American Society of Testing and Materials (ASTM). The results observed for the extracts were compared with each other and the selected tests were evaluated in terms of their use in representing leaching under natural held conditions. (C) 1996 ISW