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Indoor Air Quality: Study, Optimization and Implementation of a Novel Hybrid Air Cleaning Process
Full text linkUn’aria salubre è un requisito essenziale, insieme a cibo e acqua. Nonostante gli ultimi due siano stati maggiormente percepiti come prioritari da molte civiltà per diversi secoli, l’aria è un qualcosa di imposto, senza possibilità di scelta. Sin dalla rivoluzione industriale, quando la popolazione iniziò a spendere buona parte del tempo in ambienti confinati, l’aria indoor avrebbe meritato maggiore considerazione, poiché risulta quella a cui essere maggiormente esposti.
Gli inquinanti più comuni possono essere classificati in base alla loro natura: particolata o gassosa. Le strategie convenzionali per rimuoverli sono: rimozione della sorgente, diluzione tramite ventilazione e purificazione dell’aria. Mentre le emissioni indoor sono diffuse e non è sempre possibile isolarle e per ottemperare alle direttive di efficienza energetica, le strategie attive di rimozione degli inquinanti risultano essere preferibili.
Le tecnologie per il trattamento dell’aria indoor vengono classificate in base al tipo di inquinante rimosso: filtri, precipitatori elettrostatici, separatori inerziali e scrubbers vengono generalmente utilizzati per la rimozione di particolato, mentre materiali adsorbenti, (foto)catalizzatori e reattori con lo sviluppo di plasma vengono utilizzati per la rimozione di gas.
In questo studio è stata accuratamente valutata l’applicazione in loco e simultanea di tre diversi processi (adsorbimento, fotocatalisi e precipitazione elettrostatica) per la rimozione aumentata di inquinanti indoor. Per evidenziare le singole sinergie emergenti, e le interazioni tra processi e materiali, sono stati studiati prima i singoli processi accoppiati e, successivamente, l’innovativo processo ibrido risultante dalla loro azione combinata.Clean air is an essential requirement of life, together with food and water. Although the latter two have been a primary concern for many civilizations for multiple centuries, air is something imposed, with no possibility of choice. Since the industrial revolution, as people started to spend most of their time in confined environments, clean air should have been considered a prerogative, as indoor air had become a leading exposure for humans.
The most common indoor pollutants can be classified by their form: particulate or gaseous. Conventional strategies to combat the formers are source removal, dilution through ventilation and air treatment. While indoor emissions are ubiquitous and it is not always possible to remove the source, dilution through mechanical and natural ventilation and air cleaners are the generally preferred. As sustainability and energy-efficiency are becoming prerogatives in many countries, ventilation may imply energy losses, and therefore it can not be the only applicable strategy. For these reasons, air cleaners constitute a solution for removing harmful indoor pollutants.
Indoor air treatment technologies are classified according to the type of pollutant removed: filters, electrostatic precipitators, inertial collectors, scrubbers are generally used for the removal of particles, while adsorptive media, (photo)catalysts, and plasma-operated reactors are adopted for the removal of gases.
In this study, a simultaneous and in situ combination of the three previously reported methods (adsorption, photocatalysis and electrostatic precipitation) was deeply studied for the enhanced removal of indoor pollutants. The synergistic effect between each coupled process was investigated, in order to highlight the novelty of operating photocatalysis, adsorption and electrostatic precipitation in the single hybrid reactor
Volatile Organic Compounds Removal in a Hybrid Photocatalytic-Electrostatic Reactor
Full text linkAir cleaners that remove gaseous contaminants have primarily been used for protecting materials and artifacts (e.g., in museums) and for industrial applications (e.g., in semi-conductor manufacturing facilities). However, the use of gaseous air cleaners in other types of buildings could potentially reduce occupant exposure to a myriad of hazardous volatile organic compounds (VOCs). At present, residential and commercial gaseous air cleaning technologies have not gained wide acceptance in the marketplace, in part due to the lack of test methods and the existence of only limited field performance data. This paper focuses on experiments to measure the removal of VOCs with a combined photocatalytic-electrostatic-based gaseous air cleaner. As photocatalyst, Titanium Dioxide (TiO2) has been chosen because of its known photoactivity, stability and low cost. Electrostatic precipitation (ESP) is a highly efficient process for removing fine particles by the action of an induced electrostatic field. We have developed a new synergic one-step oxidation method with augmented VOC removal performance
A Hybrid Photocatalytic-Electrostatic Reactor for Nitrogen Oxides Removal
Full text linkA combined photocatalytic-electrostatic apparatus for the removal of indoor levels of nitrogen oxides (NOx) has been evaluated. Titanium Dioxide (TiO2) photocatalysis has been reported as inexpensive promising method to reduce gaseous environmental pollutants while electrostatic precipitation (ESP) is a highly efficient process for removing fine particles through the action of an induced electrostatic field. This article is aimed to study the synergic effect of the two processes combined into one reactor. In particular it has been studied: (i) the efficiency of NO removal and the selectivity for nitrogen dioxide (NO2), (ii) their dependence from the plate-wire configuration and the inlet mass flow, (iii) the generation of ozone by ESP and its reduction by the photo activated TiO2, (iv) the photo inhibitory effect on TiO2 by adsorbed nitrates. A simplified path flow reaction will be also presented
Dispositivo e processo per la purificazione dell’aria
No full textVengono descritti un dispositivo ed un processo per la purificazione dell’aria da agenti inquinanti
Enhanced Adsorption of Organic Compounds over an Activated Carbon Cloth by an External-Applied Electric Field
Full text linkAdsorption of pollutants on activated carbon is an effective air pollution control technique. In this study, a strong and non-uniform electric field was applied over an activated carbon fiber cloth. The adsorption kinetic of several organic compounds (Acetone, Acetaldehyde, Benzene, Cyclohexane, Ethanol, Methyl Ethyl Ketone, Toluene, 1-Propanol) on the activated carbon cloth was evaluated in the presence and in the absence of an electric field. Results suggest that its application enhances the adsorptive process. A linear correlation was found between such enhancement and the specific heat
of liquefaction of the organic compounds
Appraisal of a hybrid air cleaning process
No full textNowadays, there is an amplified interest in maintaining suitable indoor air quality (IAQ). Besides a wide range of available interventions, air cleaners are considered a valuable tool, since based on inexpensive and easily implementing technologies to improve IAQ. The purpose of this work is to combine the TiO2-photocatalysis with the electrostatic and adsorption processes, in order to improve efficiency and reliability. A TiO2-photocatalytic oxidation combined with an electrostatic filter has been studied. Nitrogen oxides reduction and degradation of many VOC over different catalyst support were monitored jointly with CO and CO2 production. The coupling of photocatalysis with an external electric field enhances efficiency of the process. The choice of materials with diversified adsorptive characteristics plays an important role in the durability of the process over time
Appraisal of a Multitasking Air Cleaner Process Based on Multiple Combined Techniques
Full text linkNowadays there is an amplified interest in maintaining suitable Indoor Air Quality (IAQ). Besides a wide range of available interventions, air cleaners are considered a valuable tool since based on inexpensive and easily implementing technologies to improve IAQ. The purpose of this work is to combine the TiO2-photocatalysis with the electrostatic and adsorptive processes, in order to improve efficiency and selectivity. A TiO2-photocatalytic oxidation combined with an electrostatic filter has been studied. Nitrogen oxide reduction and degradation of many Volatile Organic Compounds over different catalyst support were monitored jointly with CO and CO2 production. The choice of materials with diversified adsorptive characteristics plays an important role in the observed efficiency and selectivity
Efficiency of landfill leachate treatment in a MBR/UF system combined with NF, with a special focus on phthalates and bisphenol A removal
No full textFate and significance of phthalates and bisphenol A in liquid by-products generated during municipal solid waste mechanical-biological pre-treatment and disposal
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