Comparison of particulate matter emission and soluble matter collected from combustion cigarettes and heated tobacco products using a setup designed to simulate puffing regimes

An experimental setup was designed and optimized to collect particulate matter suspended in cigarettes smoke or in the aerosol generated during the use of heated tobacco products (HTPs). The setup is mainly based on a gas washing flask containing water where particulate matter and soluble compounds can be trapped, resembling interaction in the body. This system allows to perform puffing experiments in conditions similar to those of the Health Canada Intense puffing regime. In the study, cigarettes and Heets (in IQOS heater) from Philip Morris Products were used. Complementary characterization of this particulate matter has been extracted from experiments on a gas washing flask containing isopropanol. Total organic carbon analysis, laser diffraction, UV-vis spectrophotometry and transmission electron microscopy measurements have shown that cigarette smoke contains a large number and content of compounds soluble in water and isopropanol, together with solid particles generated during combustion. In contrast, negligible presence of non-combustion related particles was detected in Heets aerosol samples. These facts, together with the higher amount of water soluble compounds and higher number of polyaromatic hydrocarbons detected in the cigarettes smoke, allow to conclude that HTPs are less harmful than combusted cigarettes.The research described in this study was funded by Philip Morris Products S.A., Switzerland (part of Philip Morris International group of companies)

Photocatalytic Oxidation of Propane Using Hydrothermally Prepared Anatase-Brookite-Rutile TiO2 Samples. An In Situ DRIFTS Study

Photocatalytic oxidation of propane using hydrothermally synthesized TiO2 samples with similar primary crystal size containing different ratios of anatase, brookite and rutile phases has been studied by measuring light-induced propane conversion and in situ DRIFTS (diffuse reflectance Fourier transform infrared spectroscopy). Propane was found to adsorb on the photocatalysts, both in the absence and presence of light. The extent of adsorption depends on the phase composition of synthesized titania powders and, in general, it decreases with increasing rutile and brookite content. Still, the intrinsic activity for photocatalytic decomposition of propane is higher for photocatalysts with lower ability for propane adsorption, suggesting this is not the rate-limiting step. In situ DRIFTS analysis shows that bands related to adsorbed acetone, formate and bicarbonate species appear on the surface of the photocatalysts during illumination. Correlation of propane conversion and infrared (IR) data shows that the presence of formate and bicarbonate species, in excess with respect to acetone, is composition dependent, and results in relatively low activity of the respective TiO2. This study highlights the need for precise control of the phase composition to optimize rates in the photocatalytic oxidation of propane and a high rutile content seems to be favorable.This research was by funded by GV/FEDER (PROMETEO/2018/076), MICINN and FEDER (RTI2018-095291-B-I00), University of Alicante (VIGROB-136 and Mobility Grants from the EDUA to facilitate obtaining the title of International Doctor)

Removal of malachite green from water: Comparison of adsorption in a residue-derived AC versus photocatalytic oxidation with TiO2 and study of the adsorption-photocatalysis synergy

The literature rarely compiles studies devoted to removing pollutants in aqueous media comparing adsorption versus photocatalytic degradation and does not pay enough attention to the analysis of combined adsorption-photocatalytic oxidation processes. In the present manuscript, the removal of malachite green (MG) from aqueous solutions has been investigated in three different cheap and sustainable scenarios: i) adsorption on activated carbon (AC) derived from a residue, luffa cylindrica, ii) photocatalytic oxidation under simulated solar light using titanium dioxide (TP) and iii) combined adsorption-photocatalytic oxidation using TP-AC (70/30 wt/wt.) under simulated solar light. The study has revealed that in the three scenarios and studied conditions, the total removal of this endocrine-disrupting dye from the solution takes place in the assayed time, 2 h, although in some cases just in a few minutes. MG adsorption on the AC is the fastest removal method. MG photocatalytic oxidation with TP also occurs efficiently, although the oxidized MG is not totally mineralized. MG removal using the TP-AC composite under simulated solar light occurs at a rate comparable to that of the MG adsorption on AC, since adsorption is the dominating removal mechanism, more than 90% of the removed MG with TP-AC under simulated solar light is adsorbed in this carbon-containing composite. The obtained results highlight the interest in adsorption, being the selection of the most suitable removal method dependent on several factors (i.e., cost of the AC regeneration, if adsorption, or the toxicity of the intermediate oxidation species, if photooxidation). Paying attention to MG photooxidation with TiO2, comparison of two working photodegradation schemes shows that the direct photodegradation of MG from solution, avoiding any initial dark equilibrium period, is the more efficient option from a time perspective. The use of scavengers has proved that MG photodegradation occurs via an oxidation mechanism dominated by superoxide anion radicals.This work was supported by the following research projects: PID2021-123079OB-I00 (project funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe (European Union)), CIPROM/2021/070 (Generalitat Valenciana) and VIGROB-136 (University of Alicante). Souad BOUMAD thanks Mujeres por Africa foundation for the scholarship offer within the 2019 Learn Africa program and, the Ministry of Higher Education and Scientific Research for the 2019–2020 scholarship of the P.N.E. program

Effect of the Preparation Method (Sol-Gel or Hydrothermal) and Conditions on the TiO2 Properties and Activity for Propene Oxidation

Since the two most commonly used methods for TiO2 preparation are sol-gel (SG) and hydrothermal (HT) synthesis, this study attempts to compare both methods in order to determine which one is the most suitable to prepare photocatalysts for propene oxidation. In addition, this work studies how the concentration of the HCl used for hydrolysis of the TiO2 precursor affects the properties of the obtained materials. Also, the effect of avoiding the post-synthesis heat-treatment in a selection of samples is investigated. The photocatalysts are characterized by XRD, N2 adsorption-desorption isotherms and UV-vis spectroscopy, and the study tries to correlate the properties with the photocatalytic performance of the prepared TiO2 samples in propene oxidation. TiO2 materials with high crystallinity, between 67% and 81%, and surface area (up to 134 m2/g) have been obtained both by SG and HT methods. In general, the surface area and pore volume of the TiO2-HT samples are larger than those of TiO2-SG ones. The TiO2-HT catalysts are, in general, more active than TiO2-SG materials or P25 in the photo-oxidation of propene. The effect of HCl presence during the TiO2 synthesis and of the post synthesis heat treatment are much more marked in the case of the SG materials.This research was funded by MINECO and FEDER, project of reference CTQ2015-66080-R, GV/FEDER (PROMETEO/2018/076) and University of Alicante (VIGROB-136)

Cu/TiO2 Photocatalysts for the Conversion of Acetic Acid into Biogas and Hydrogen

Comunicación presentada en 9th European meeting on Solar Chemistry and Photocatalysis: Environmental Applications (SPEA), Strasbourg, France, June 13-17, 2016.The authors thank Ministerio de Economía y Competitividad (CTQ2015-66080-R), Generalitat Valenciana (PROMETEOII/2014/010) and Universidad de Alicante (VIGROB-136) for financial support

Síntesis hidrotermal de materiales híbridos TiO2-carbón para su aplicación en fotocatálisis

Comunicación presentada en la XIV Reunión del Grupo Español del Carbón, Málaga, 22-25 octubre 2017.Los autores agradecen la financiación económica a los proyectos CTQ2015-66080-R (MINECO/FEDER), PROMETEOII/2014/010 (GV/Feder) y VIGROB-136 (UA)

One step hydrothermal synthesis of TiO2 with variable HCl concentration: Detailed characterization and photocatalytic activity in propene oxidation

TiO2 materials have been prepared by a novel one-step hydrothermal synthesis method at mild conditions (low temperature and time) using titanium tetraisopropoxide as precursor and HCl solutions of different concentration, ranging from 0.5 to 12 M. A detailed physico-chemical characterization has been done, putting especial attention to the quantification of crystallinity and surface OH content. All the obtained samples have high surface areas (100–135 m2/g), small anatase crystal size (8–11 nm) and high crystallinity (around 80%). The concentration of the HCl used in the synthesis has a significant effect on the two first mentioned parameters and on the proportion of crystalline phases (anatase-brookite-rutile) developed. There is a good correlation between the amount of hydroxyl surface groups and the specific surface area (SBET), but regarding surface density of OH groups there are, as well, some differences between samples (the samples with higher OH surface densities are those prepared with less concentrated HCl solutions). Most of the prepared photocatalysts are more active than commercial TiO2-P25 in the gas phase oxidation of propene at low concentration. The best photocatalytic performance is found for samples prepared with 0.5 and 0.8 M HCl, what can be explained by a suitable combination of properties: high surface area and developed porosity, high surface OH groups’ content and density and large proportion of anatase with small crystal size.The authors thank the Spanish Ministry of Economy and Competitiveness (MINECO) and FEDER, project of reference CTQ2015-66080-R, GV/FEDER (PROMETEOII/2014/010) and University of Alicante (VIGROB-136) for financial support

Synthesis of TiO2 with Hierarchical Porosity for the Photooxidation of Propene

The elimination of volatile organic compounds (VOCs) at low concentration is a subject of great interest because these compounds are very harmful for the environment and human health. In this work, we have developed a synthesis methodology of TiO2 that allows obtaining meso-macroporous materials with hierarchical porosity and with high thermal stability for their application as photocatalysts in the removal of VOCs, specifically propene. The materials synthesized in this work were characterized by Scanning electron microscope (SEM), Transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Thermogravimetric Analysis (TG), and nitrogen adsorption. It is observed that the samples calcined at 250 °C and 500 °C present a high photoactivity for the photooxidation of propene, which is similar to the benchmark material P25 (commercial TiO2). Moreover, the textural properties are better than those for P25, indicating that the samples are interesting for the preparation of photocatalysts with different conformations, such as in the form of coatings and fillings in different size scales.The authors thank MINECO (CTQ2015-66080-R, MINECO/FEDER, BES-2016-078079) and Generalitat Valenciana (PROMETEOII/2014/010) for financial support

TiO2-AC hybrid materials to produce H2 and biogas by photocatalytic decomposition of acetic acid

Comunicación presentada en 13th European Congress on Catalysis, EuropaCat, Florence, Italy, 27 August-01 September 2017.The authors thank MINECO (CTQ2015-66080-R), Generalitat Valenciana/Feder (PROMETEOII/2014/010) and Universidad de Alicante (VIGROB-136) for financial support

TiO2 Modification with Transition Metallic Species (Cr, Co, Ni, and Cu) for Photocatalytic Abatement of Acetic Acid in Liquid Phase and Propene in Gas Phase

The commercial P25 titania has been modified with transition metallic species (Cr, Co, Ni, and Cu), added by impregnation with aqueous solutions of the corresponding nitrates. The preparation procedure also includes a heat treatment (500 °C) in argon to decompose the nitrates, remove impurities and to strengthen the metal–TiO2 interaction. The catalysts have been thoroughly characterized using N2 adsorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible diffuse-reflectance spectroscopy (UV-vis DRS) and X-ray photoelectron spectroscopy (XPS), and have been tested in the aqueous phase decomposition of acetic acid and in the gas phase oxidation of propene, using an irradiation source of 365 nm in both cases. The photocatalytic activity of the four metal-containing catalysts varies with the nature of the metallic species and follows a similar trend in the two tested reactions. The effect of the nature of the added metallic species is mainly based on the electrochemical properties of the supported species, being Cu/P25 (the sample that contains copper) the best performing catalyst. In the photodecomposition of acetic acid, all the metal-containing samples are more active than bare P25, while in the gas phase oxidation of propene, bare P25 is more active. This has been explained considering that the rate-determining steps are different in gas and liquid media.This research was funded by MINECO and FEDER, project of reference CTQ2015-66080-R, GV/FEDER (PROMETEO/2018/076) and University of Alicante (VIGROB-136)