V. G. Guerra

• Federal University of São Carlos

Ultrafine particulate matter and airborne microorganisms present in the atmosphere significantly affect human health, leading to serious respiratory diseases. Among these particulates are bioaerosols, which include viruses, bacteria, and fungi. When inhaled, these microorganisms can cause diseases, such as influenza, tuberculosis, and COVID-19. The...

The increased production of polystyrene waste has led to the need to find efficient ways to dispose of it. One possibility is the use of solid waste to produce filter media by the electrospinning technique. The aim of this work was to develop an ultra-fast electrospinning process applied to recycled polystyrene, with statistical evaluation of the i...

In the electrostatic precipitation of microparticles, it is common to evaluate the voltages between the corona onset voltage and the breakdown point. However, the charging of particles in the nanoscale size range mainly occurs by diffusion, suggesting the possibility of its occurrence, even at low values. This paper investigates the implications of...

Com a intensificação da industrialização, o descarte de contaminantes na atmosfera cresceu, causando impactos no meio ambiente. Além disso, a alta geração de resíduos agroindustriais tem motivado o reaproveitamento de materiais. Nesse sentido, o desenvolvimento de tecnologias capazes de tratar o ar poluído torna-se cada vez mais necessário, bem com...

Electrostatic precipitation is a process widely used as gas cleaning device, to removal particles from gas flows. However, in a conventional and well-sized precipitator, the collection efficiency decreases for ultrafine particles, making it difficult to employ this equipment for controlling nanoparticle pollution. This paper investigates the influe...

The growing increase in emissions of ultrafine particles or nanoparticles by industries and urban centers has become worrisome due to the potential adverse health effects when inhaled. Particles in this size range have greater ease of pulmonary penetration, being able to access the bloodstream and deposit in other regions of the body. Thus, the dev...

The corona onset voltage is an important operating parameter in the electrostatic precipitation of nanoparticulate, however, its experimental determination depends on the accuracy of the measuring equipment. In this study, a theoretical approach based on the Townsend law was developed to determine the onset voltages and to further investigate the c...

The development of new materials with specific functionalities for certain applications has been increasing with the advent of nanotechnology. A technique widely used for this purpose is electrospinning, because control of several parameters involved in the process can yield nanoscale fibers. In addition to the production of innovative and small-sc...

Meios filtrantes de nanofibras usados na filtração de nanopartículas dispersas em ar podem ser confeccionados por electrospinning de soluções poliméricas. No entanto, este processo está condicionado à influência de inúmeras variáveis operacionais, incluindo condições de alimentação das soluções. Neste trabalho, foi realizado um planejamento fatoria...

Números adimensionais são facilitadores para a descrição matemática de relações entre diferentes forças envolvidas em diversos fenômenos, bem como para a realização de experimentos e análises com múltiplas variáveis. No presente trabalho, são apresentados adimensionais desenvolvidos a partir do teorema de Vaschy-Buckingham, considerando o processo...

Uma das maiores preocupações sanitárias na atualidade é a contaminação por inalação de partículas ultrafinas. A solução para a mitigação deste risco encontra-se em parte nos sistemas de ventilação e condicionamento de ar (HVAC, de Heating, Ventilating and Air Conditioning). No presente trabalho, foi realizada uma análise dos parâmetros de projeto d...

Theoretical and semi-empirical models of viscous flow relative to fibres were used to obtain the porosity of micro-fibrous and nano-fibrous mats applied in air filtration. Overall efficiencies of collection of sodium chloride particles (5.94–224.7 nm) were calculated for the mats considering the porosities obtained using different models. The lowes...

Electrostatic precipitator (ESP) is an equipment used on air pollution control systems to reduce the particulate material concentration. The main components of the ESP are the discharge and collecting electrodes, which are negatively charged and grounded, respectively. Due to the electrode different polarities, an electric field is generated inside...

Poly(vinyl alcohol) nanofibers for air filtration were produced by electrospinning using citric acid and different concentrations of Triton X-100 surfactant that enhances nanofibers production by electrospinning. Filtration tests with nanoparticles (5.94–224.7 nm) and tests of resistance to wet air streams were performed and it was found that there...

Poly (Vinyl Alcohol) (PVA) is used to produce nanofibers with electrospinning for several applications related to the non-toxicity of the material, however, the application in air filtration in hindered by the high hydrophilicity of the material, which requires the crosslinking with additives. In this work, different techniques were assessed to ver...

Very small particles dispersed in the atmosphere display complex dynamics, due to their characteristics of Brownian motion and low sedimentation rate, while chemical and physical transformations in the air can lead to the formation of compounds that present greater risk. In this context, one of the most efficient gas-solid separators is the electro...

Although electrostatic precipitators are commonly used in the removal of particulate matter, the use of this equipment in the removal of nanoparticles needs to be further elucidated. Thus, this study’s objective was to evaluate the use of a single-stage, wire-plate electrostatic precipitator in the collection of sodium chloride nanoparticles using...

Air pollution and solid pollution are considered global problems, and endanger human health mainly due to the emission of fine particulate matter released into the atmosphere and improper disposal of post-consumer plastic bottles. Therefore, it is urgent to develop filter media to effectively protect the public. The properties of plastics make them...

Currently, the inappropriate disposal of plastic materials, such as polyethylene terephthalate (PET) wastes, is a major environmental problem since it can cause serious damage to the environment and contribute to the proliferation of pathogenic microorganisms. To reduce this accumulation, PET-type bottles have been recycled, and also explored in ot...

Theoretical expressions of gas filtration science were applied for a rigorous evaluation of the enhanced efficiency of a micro-fibrous filter medium after coating it with electrospun nanofibers. An extended form of the Kuwabara hydrodynamic factor was used to cover the particle size range considered (5.94-224.7 nm). A Boltzmann particle charge dist...

RESUMO-A precipitação eletrostática é um processo amplamente utilizado na remoção de material particulado de fluxos de gás. No entanto, ainda há uma lacuna no desempenho para a faixa nanométrica. Dessa forma, o objetivo do trabalho foi avaliar a condições operacionais, como velocidade e campo elétrico, na remoção de partículas de faixa nanométrica...

RESUMO-Embora os precipitadores eletrostáticos sejam comumente utilizados na remoção de material particulado, o emprego desse equipamento na remoção de nanopartículas precisa ser melhor elucidado. Dessa forma, o objetivo do trabalho foi realizar uma varredura para identificar o comportamento do campo elétrico na remoção de partículas de faixa nanom...

Electrostatic precipitators (ESPs) can achieve high collection efficiencies. However, their application for nanoparticle removal has not been widely discussed, largely because the charging mechanism is affected by the small diameter of these particles. Therefore, this work evaluated the influence of the discharge electrode parameters such as number...

Low air velocities are not fully explored yet in the field of electrostatic precipitation due to the size limitations of the industrial devices, but they had provided high collection efficiencies for nanoparticles in studies in laboratory scale. In order to contribute to the science of electrostatic precipitation, a full 3² factorial design of expe...

Erosion of metallic electrodes by sputtering is undesirable in electrostatic precipitators and must be avoided. This work reports the operational variables promoting sputtering, the applied voltage (−8.5 to −13.0 kV) and the air velocity (3.3 to 9.9 cm s−1), during the collection of NiO and KCl particles with a dry, wire-plate electrostatic precipi...

Electrostatic precipitators and bag filters are traditionally used to separate particulate matter from gas streams. The combination of these two technologies originated the hybrid filters. Several configurations of hybrid filters were developed in the last three decades, mainly for application in the treatment of flue gas from coal-fired power plan...

Often, solid matter is separated from particle-laden flow streams using electrospun filters due to their high specific surface area, good ability to capture aerial particulate matter, and low material costs. Moreover, electrospinning allows incorporating nanoparticles to improve the filter’s air filtration efficiency and bacterial removal. Therefor...

Wet cyclonic separators can be a viable solution for process intensification of gas-cleaning in industries. Owing to the difficulty of modeling interactions between droplets and particles as well as the high computational effort needed to simulate this process, this field has been rarely studied. In this study, a model for determining the collectio...

In studies on the electrostatic precipitation of metal oxide nanoparticles (especially NiO, a commercially interesting material in this particle size range), the dispersion of metal oxide nanoparticles by pneumatic atomization is not commonly used due to the insolubility issues, besides the agglomeration and sedimentation of the particles. Therefor...

The dispersion of metal oxide nanoparticles by pneumatic atomization of oxide suspensions has rarely been used in laboratory-scale research on electrostatic precipitation, due to the insolubility of the oxides under ambient conditions, the particle agglomeration and sedimentation in aqueous mixtures. Therefore, the aim of this work was to evaluate...

Human exposure to air pollution and especially to nanoparticles is increasing due to the combustion of carbon-based energy vectors. Fibrous filters are among the various types of equipment potentially able to remove particles from the air. Nanofibers are highly effective in this area; however, their utilization is still a challenge due to the lack...

Cyclones are not classified as effective devices for removing fine particles, while high efficiency wet scrubbers usually have high operational costs. In order to achieve better performance, the aim of this study is to evaluate, for the first time, a cyclone scrubber design based on the dimensions of a Stairmand cyclone separator with the inclusion...

The influence of gas velocity on the efficiency of electrostatic precipitators has previously been discussed exclusively in terms of the gas residence time, even when there are changes in aerosol concentration. Therefore, the aim of this work was to separately evaluate the influences of residence time and concentration by performing sets of experim...

Gas velocity is a critical operational variable in the electrostatic precipitation process. However, studies concerning the collection of nanoparticles have ignored the effect of low gas velocities. Therefore, the aim of this work was to use a wire-plate electrostatic precipitator to investigate the effects of atypical gas velocities under differen...

To this day, any photosensitizers for the photodynamic treatment of pulmonary illnesses have been administered intravenously. There is, however, an intrinsic difficulty in reaching the target cells or bacteria in the respiratory system. Nebulization could overcome distribution problems and alleviate side effects by delivering the photosensitizers d...

Venturi scrubbers provide highly efficient removal of particles from dust laden gases. A uniform distribution of droplets improves the collection efficiency. Most computational models used to predict the dispersion of liquid in scrubbers employ the Boll correlation to calculate the mean droplet size. Given the lack of studies considering the effect...

Nowadays, removing nanoparticles in a filtration using fibrous filter media become a technique very useful. There are a lot of applications of these filters which can be found in air conditioner and clean rooms. Filter media used in this work have very similar characteristics and among them can be cited heterogeneous distribution and small diameter...

Porous SiC ceramics bonded with mullite [MBS of fractional porosity of 0.29-0.56, average pore size (dpore) of 5-11 μm, flexural strength (δ) of 9-34 MPa, and elastic modulus (E) of 7-28 GPa] and cordierite (CBS with " of 0.33-0.72, dpore of 6-50 μm, δ of 5-54 MPa, and E of 6-42 GPa) were prepared by heating in air at 1350-1500°C compacts of desire...

A theoretical relation between processing parameters and porosity (29–56%) of mullite-bonded porous SiC ceramics was derived and validated with experimental data. Porosity-dependent variation of fracture strength (9–34 MPa) and elastic modulus (7–28 GPa) was explained by the minimum solid area model. At room temperature, the Darcian, k1 (1.2 × 10−1...

Venturi scrubbers are widely used to control industrial emissions, because of their high efficiency in the removal of particles from gases. To correctly size and design these equipments, detailed information on the fluid dynamics is very important. The purpose of this article is to study, both experimentally and through CFD simulations, the fluid d...

A Pease-Anthony Venturi scrubber is a gas cleaning device that uses liquid, injected in the equipment as jets, to remove contaminants from the gas. The liquid jet is atomized into droplets, which are dispersed throughout the equipment due to the turbulence. The performance of the scrubber is affected by the spatial distribution of the droplets. Alt...

It has been reported by previous studies [1–7] that droplet size in a Pease-Anthony Venturi scrubber depends on the jet atomization conditions, such as jet velocity and gas velocity. The assumption of this paper is that actual collector-droplet size in a confined tube such as the Venturi scrubber also depends significantly on preferential droplet d...

The liquid film affects significantly the Venturi scrubber efficiency. Film fraction was measured in a vertically mounted laboratory scale Venturi scrubber with a 0.020 m throat diameter. The liquid was injected at the throat by one to six 0.001 m holes. The throat gas velocity varied from 50 to 90 m/s and the relative jet penetration varied betwee...

The Venturi scrubber, equipment frequently used in the removal of particles from gases is constituted basically by a duct with a convergent section followed by a constriction, or throat, and a divergent section. A liquid, usually injected in the throat, is atomized by the flowing air at high speed. The formed droplets act as collectors of particles...

A Pease-Anthony Venturi scrubber is a relatively simple and very efficient device used for gas cleaning. This paper presents photographic images of the atomization of a liquid jet in the throat of a Pease-Anthony Venturi scrubber, obtained through the development and use of an electronic flash of short duration. This new evidence was used to improv...

The objective of this work is to study the dynamics of nanoparticle formation by atomization of saline solutions at different concentrations. The nanoparticles were generated by a two fluid particle atomizer. Saline solutions were atomized and, with the immediate evaporation of the dispersion liquid in the droplets, resulted in an aerosol of solid...

The Venturi scrubber, equipment frequently used in the removal of particles from gases, is constituted basically by a duct with a convergent section followed by a constriction, or throat, and a divergent section. A liquid, usually injected in the throat, is atomized by the flowing air at high speed. The formed droplets act as collectors of particle...

Venturi scrubbers are widely utilized in gas cleaning. The cleansing elements in these scrubbers are droplets formed from the atomization of a liquid into a dust-laden gas. In industrial scrubbers, this liquid is injected through several orifices so that the cloud of droplets can be evenly distributed throughout the duct. The interaction between dr...

The Venturi scrubber is used for removing particulate matter from gaseous effluents and finds a large application in industry. The size of the droplet is of fundamental importance to the performance of the equipment. This work aims at studying the effect of some design parameters, namely liquid flow rate and liquid injection system in the droplet s...

A Pease-Anthony Venturi scrubber is a gas cleaning device which uses liquid, injected in the equipment as jets, to remove contaminants from the gas. The liquid jet is atomized into droplets, which are dispersed throughout the equipment due to the turbulence. The performance of the scrubber is affected by the spatial distribution of the droplets. Al...