Valerie Hequet

Valerie Hequet
IMT Atlantique - Bretagne-Pays de la Loire, Ecole Mines-Telecom · GEPEA Laboratory - UMR CNRS 6144

Professor - IMT Atlantique

About

59
Publications
6,241
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Introduction
Valerie Hequet currently works at IMT Atlantique - Bretagne-Pays de la Loire, Ecole Mines-Telecom. Valerie does research in the GEPEA Laboratory - UMR CNRS 6144, in Chemical Engineering, adsorption and advanced oxidation techniques.

Publications

Publications (59)
Book
Full-text available
La façon dont les sociétés prennent en charge la question de l’environnement met en jeu des transactions entre les différents acteurs sociaux impliqués. Le défaut de consensus social sur ce qui est dangereux ou non, sur le niveau de dangerosité ou sur ce qu’il convient de faire en situation d’incertitude et, en définitive, sur le degré d’acceptatio...
Article
The media geometry design is a parameter that influences the efficiency of PCO device for indoor air treatment. However, there is little information in the literature to show how it impacts degradation efficiency. In this work, media geometry influence on the degradation of acrylonitrile is investigated experimentally and with numerical simulations...
Article
Photocatalytic oxidation (PCO) is an advanced air cleaning technology that is used as a means to improve air quality in indoor environments and could also potentially be used in hospital operating rooms (ORs). However, when it comes to the feasibility of using PCO to remove VOCs, most studies have been on those that are commonly found in indoor env...
Article
In hospitals, operating rooms (ORs) are very demanding in terms of the indoor air quality (IAQ) and require systems that minimize the concentrations of pollutants (microorganisms, chemical and particulate matter). Air treatment devices that use photocatalytic oxidation (PCO) could potentially be used in the OR to improve IAQ. In this work, the fate...
Article
Photocatalytic oxidation (PCO) is a technology that has been suggested as an alternative energy efficient method to improve Indoor Air Quality (IAQ) in several indoor air spaces. In the past few years, several studies have been made to assess the feasibility of PCO for the removal of VOCs that are commonly found in most indoor environments like hom...
Article
An investigation of the photocatalytic degradation of indoor air model pollutants: toluene, n-decane and trichloroethylene (TCE), as single contaminants and in a mixture is proposed. The degradation of these contaminants was performed in a continuous closed-loop reactor operating in recirculation mode. Degradations were conducted at ppb level conce...
Article
This work addresses photocatalytic oxidation for indoor air purification and more especially the key and realistic issue of VOC mixture treatment. The VOC mixture effect needs to be investigated since indoor air contains several tens of VOCs which may impact photocatalytic oxidation performances. In order to be closer to realistic conditions, conce...
Article
Full-text available
The performances of a laboratory PhotoCatalytic Oxidation (PCO) device were determined using a recirculation closed-loop pilot reactor. The closed-loop system was modeled by associating equations related to two ideal reactors: a perfectly mixed reservoir with a volume of VR = 0.42 m3 and a plug flow system corresponding to the PCO device with a vol...
Article
Full-text available
This study demonstrated that a laboratory-scale recirculation closed-loop reactor can be an efficient technique for the determination of the Clean Air Delivery Rate (CADR) of PhotoCatalytic Oxidation (PCO) air purification devices. The recirculation closed-loop reactor was modeled by associating equations related to two ideal reactors: one is a per...
Article
The photocatalytic degradation of toluene in indoor air conditions was performed in a closedloop multi-pass photocatalytic reactor using the Box-Behnken experimental design methodology. The objective of this work was to rigorously determine a kinetic model in order to understand the behavior of the reactor in real indoor air conditions and to relat...
Article
Full-text available
The photocatalytic degradation of three common indoor VOCs - acetone, toluene and heptane - is investigated in a dynamic photocatalytic oxidation loop using Box-Behnken designs of experiments. Thanks to the experimental results and the establishment of a kinetic rate law based on a simplified mechanism, a predictive model for the VOC degradation in...
Article
Full-text available
The photocatalytic oxidation of seven typical indoor volatile organic compounds (VOCs) is experimentally investigated using novel nanocrystalline TiO2 dip-coated catalysts. Not only the role of hydrophilicity of the reactants but also other physico-chemical properties and molecular descriptors are studied and related to kinetic and equilibrium cons...
Article
Nanostructured titanium materials with high UV-visible activity were synthesized in the collaborative project Clean Water FP7. In this study, the efficiency of some of these catalysts to degrade endocrine disruptor compounds, using bisphenol A as the model compound, was evaluated. Titanium dioxide P25 (AEROXIDE(®) TiO2, Evonik Degussa) was used as...
Article
245th National Meeting of the American-Chemical-Society (ACS), New Orleans, LA, APR 07-11, 2013
Article
The use of photocatalysis to improve the biodegradability of an antibiotic compound, tetracycline (TC) was investigated. The toxicity of TC and its degradation products were also examined. The Sturm test was conducted to assess the biodegradability of by-products formed in the photocatalytic process. The toxicity of tetracycline and its by-products...
Article
The development of photocatalysis for indoor air treatment will be clearly possible only if kinetic laws allowing the scaling up of the process in real conditions are available. Consequently, this chemical engineering study deals with the photocatalytic oxidation of volatile organic compounds (VOC) for the improvement of indoor air quality. We have...
Article
This work reports the influence of the meso-structure of TiO2 films in the photocatalytic oxidation of methyl ethyl ketone. Five types of TiO2 films were prepared combining the sol–gel route with the Evaporation Induced Self-Assembly (EISA) method. Sols were prepared from titanium tetrachloride (TiCl4) using different types of pore generating agent...
Article
Full-text available
ARTICLES Résumé Lʼoxydation photocatalytique (OPC) est une technique développée pour lʼélimination des composés organiques volatils (COV) présents dans lʼair intérieur. Lʼoriginalité de ces travaux réside dans lʼétude des performances de lʼOPC dans des conditions expérimentales reproduisant lʼair intérieur en termes de niveaux de concentrations en...
Article
An investigation of toluene photocatalytic oxidation was conducted with initial concentrations of toluene ranging from 50 to 800 ppbv under dry and wet (50% RH) atmosphere in order to characterize photocatalysis performances close to indoor air conditions. A batch reactor system was developed in order to perform kinetic studies of (i) toluene remov...
Article
Nowadays, with the increase in the thermal insulation of buildings, indoor air quality (IAQ) has deteriorated, particularly because of the presence of volatile organic compounds (VOC). To improve IAQ, photocatalytic processes can be used. Photocatalytic reactions can be broken down into three steps: adsorption of pollutants, chemical reaction, and...
Article
Une procedure analytique associant la chromatographie liquide et la spectrometrie de masse en tandem (CL-SM/SM) a ete developpee pour la determination d'hormones steroides, d'alkylphenols et du bisphenol A dans des eaux chargees en matieres organiques (eaux usees domestiques). Deux protocoles d'extraction en phase solide ont ete developpes pour les...
Conference Paper
Activated carbons (ACs) are nanoporous adsorbent widely used to remove organic compounds from air. Due to rather low oxidation temperatures, these materials are prone to ignition which causes safety problems in industrial practice. This study aims at identifying the physical and chemical properties of the carbon materials which control the process...
Article
The aim of this work is to understand the influence of textural, chemical, and structural properties on the reactivity of activated carbons toward air. Multiscale organization of activated carbons was studied using high-resolution transmission electron microscopy (HRTEM) and their quantitative structural data, like individual fringe length, interla...
Article
Current filters were evaluated in real conditions to explore an alternative way to assess their performance over time. A pilot unit was set up in an equipped cabin in an urban area. BTEX, CO and NOx concentrations (μg.m-3) were monitored upstream and downstream of the filters. The methodology was i) to evaluate the limits of detection of the monito...
Article
The influence of material properties on the reactivities of activated carbon materials have been studied on a laboratory scale. Carbon samples having diversified origin and properties were characterized using a thermogravimetry (TG) coupled with a differential scanning calorimetry (DSC). Reactivity parameters like the Point of Initial Oxidation (PI...
Article
Full-text available
The biodegradation of 17 beta-estradiol (E2) and bisphenol A (BPA) was compared to that of a reference pollutant, sodium benzoate (SB), known for its high biodegradability. The biodegradation was measured using the Sturm test (ISO 9439 modified Sturm test). The susceptibility of the target pollutants to be degraded by microorganisms of activated sl...
Article
Full-text available
The determination of steroid hormones, alkylphenolic compounds and bisphenol A at the ng l(-1) level in environmental water samples (surface water and WasteWater Treatment Plant samples (WWTP)) is performed by a specific analytical procedure. Pre-concentration by solid-phase extraction conditions was optimized using C18 cartridges for steroid hormo...
Article
Industrialization and the intensive use of domestic chemical products lead to the spreading of various substances considered as emerging pollutants. Thus, the scientific community has focused its attention the past ten years on their fate in the environment. Among them, some compounds can interfere with the normal endocrine functions of wildlife an...
Article
Full-text available
This paper presents an analytical method applied to the determination of 3 natural steroid hormones, estrone, 17 beta-estradiol, and 16 alpha-hydroxyestrone, and the contraceptive estrogen, 17 alpha-ethynylestradiol, at the sub-ng/L level in water samples [surface water and wastewater treatment plant (WWTP) samples]. The solid-phase extraction cond...
Article
Two photoactive TiO2-supported materials are considered for toluene degradation in the gas phase. A kinetic study is performed over these two catalysts. The mechanisms involved are well represented by the Langmuir-Hinshelwood (L-H) relation at initial time. The kinetic rates and adsorption constants are then calculated to compare the catalysts. Par...
Article
The present work follows a study that permitted to enlighten the influence of TiO2 coating types on the role of water vapor during Methyl Ethyl Ketone photocatalytic oxidation. For catalysts constituted of a film of TiO2, the formation of a water layer at the catalyst surface was suggested. Consequently, for this kind of catalysts, not only the ads...
Article
Full-text available
This work focuses on the photocatalytic oxidation of gaseous methyl ethyl ketone chosen as a typical indoor air pollutant. Two types of TiO coatings were prepared and deposited on glass plates: one using the commercial Degussa P25 TiO2 and the other one by sol-gel method. The first objective of this study was to compare different ways of preparing...
Article
Four TiO2-based materials, named A, B, C and D, are used to investigate the influence of water vapor on the gas–solid adsorption and heterogeneous photocatalytic oxidation of gaseous methyl ethyl ketone (MEK). Two of the photocatalysts (A and B) are constituted of powdered TiO2 deposited onto two different supports (ordinary glass and non-woven cel...
Article
Statistical designs were used to investigate the effects of various processing conditions on the fissuring and/or fragmentation of sol–gel catalytic materials. Three types of sol–gel materials were studied: SiO2, TiO2-doped SiO2 and CeO2-doped SiO2. Five processing variables were investigated: the quantity of water included in the sol–gel preparati...
Article
Photocatalytic oxidation of two ketones, acetone, and 2-butanone, over TiO2-containing paper was studied under two different levels of relative humidity. Adsorption of these ketones on TiO2-containing paper is significantly affected by the presence of water vapor. Adsorption isotherms of both acetone and 2-butanone, under dry and humid atmosphere,...
Article
Gas-solid photocatalyzed oxidation of air contaminants is being explored more and more for possible application to decontamination, purification and deodorization of enclosed atmospheres. Indoor air is characterized by a huge number of pollutants at low concentrations. Volatile organic compounds (VOC) represent the main indoor air pollutants catego...
Article
Emissions of volatile organic compounds (VOCs) from wastewater in municipal sewage or industrial wastewater treatment plants are often overlooked as sources of exposure to hazardous substances. The impact of such emissions on local airborne environments represents a growing source of scientific, toxicological and public health interest. Actually, V...
Article
Fly ashes from two fluidised bed power plants were tested to remove Pb2+, Cu2+, Cr(III), Ni2+, Zn2+ and Cr(VI) from aqueous solutions. Experimental design methodology was used to study the removal and the leaching as a function of (i) the water pollutant content, (ii) the metal concentration in water, (iii) the pH of the solution and (iv) the addit...
Article
Numerous studies have been carried out on s-triazines, and more specifically on atrazine, with the long-term objective of resolving the problems caused by these herbicides: removing them from drinking water. However, applications have remained too limited. So far, processes based on photochemical degradation have been little implemented. We, theref...
Article
Disposal of a growing amount of fly ash creates environmental problems due to the leachability of their heavy metal content. However, fly ash is shown to be efficient in the removal of heavy metallic ions in the aqueous phase, for example, in the polluted wastewater resulting from desulfurization treatment in power plants. The objectives of this wo...
Article
This study principally focused on a new kind of photochemical reaction catalyst: porphyrin and phthalocyanine complexes. In a first step, the preparation of the catalysts was optimized. A resin has been chosen to be the support of the complexes. Efficiency of catalytic activity is performed on the degradation of a pesticide: atrazine. The best atra...
Article
Experimental design methodology was used to define conditions for the adsorption and the stabilization of nickel ions (initial concentration of 500 mg.L-1) on coal fly ash/lime sorbent. This type of sorbent allows the reuse of by-products and increases the stabilization of metallic ions by lime addition. It was shown that the solution pH, the metal...
Article
Activated carbon fabrics show interesting properties for treatment of air loaded with volatile organic compound (VOC). The gas-solid transfer velocity is very intensive and adsorption capacities is very efficient. Design of new reactors is performed. Cylindrical pleated filters produced with activated carbon fabrics and polypropylene layers are stu...
Article
An approach by experimental design has been applied to measure the influence of different parameters in the hydrolysis of atrazine First, experiments were carried out in the laboratory under extreme conditions to reveal evolution phenomena. Then, a methodology was used to allow a representative equation of the degradation reactions. Three parameter...
Article
Several studies have pointed out ash efficiency in the removal of heavy metal ions present in aqueous solutions. Contact time, pH and ash origin seem to be the major operating parameters in the metal concentration control. The mechanisms of interactions between metal and solid are a function of pH and are found to be precipitation, adsorption or io...
Article
Disposal of a growing amount of fly ash creates environmental problems and utilizations of the material has to be developed in industrial fields. Ash is known to remove metal ion from water. However, the best operating conditions have to be found and a better mechanism knowledge has to be approached. Coal fly ash was used to study adsorption of sev...

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