Pyridine assisted CO₂ reduction to methanol at high pressure

Significant research efforts have been directed towards exploring electrocatalysts for the selective reduction of CO₂ to fuels such as methanol. Bocarsly et al (Princeton University) have recently reported the use of aromatic amines (e.g. pyridine (C₅H₅N)) as electrocatalysts in aqueous electrolytes for the reduction of CO₂ at low overpotentials (50-150 mV). Importantly, the CO₂-pyridine reduction process was claimed to selectively produce methanol with Faradaic efficiencies of ~100% on p-GaP electrode and 22-30% on Pt and Pd electrodes. Moreover, the initially proposed mechanism based on a radical intermediate interaction with CO₂ as a key step toward the production of methanol was subsequently disproved. In this project, methanol formation by the CO₂-pyridine (C₅H₅N) system was assessed by conducting electrolysis under various conditions at platinum electrodes. High pressure CO₂ was used with the aim of increasing the methanol yield. In the course of the present study, the bulk electrolysis confirmed the methanol production at 1 bar and at 55bar of CO₂ in the presence of pyridine. However, the methanol yield was found to be persistently limited to sub-ppm level (<1ppm) under all conditions investigated. The observed methanol yield limitation could not be overcome by the electrode reactivation techniques used. Moreover, the methanol formation seemed unaffected by the current density or the biasing mode. This was an indication of the independence of methanol production from the charge transfer on the electrode. In agreement with these observations, analysis of the voltammetric data supported by simulation revealed that the CO₂-pyridine reduction system is mainly pyridinium assisted molecular hydrogen production under all conditions investigated. In particular, protonated pyridine (C₅H₅N) ‘pyridinium’ was confirmed to behave as a weak acid on platinum. It was found that CO₂ is merely a proton source of pyridine reprotonation via the hydration reaction followed by carbonic acid dissociation. The reprotonation reaction coupled to the electrode reaction ultimately leads to the dihydrogen production. No direct contribution of CO₂ in the reduction process was observed. The production of methanol seems to occur chemically rather than directly driven by the charge transfer on the electrode. The role of pyridine (C₅H₅N) appears to be restricted to assisting in the generation of the hydrogen necessary for the alcohol production

Atmospheric Degradation of Ecologically Important Biogenic Volatiles:Investigating the Ozonolysis of (E)-β-Ocimene, Isomers of α and β-Farnesene, α-Terpinene and 6-Methyl-5-Hepten-2-One, and Their Gas-Phase Products

Biogenic volatile organic compounds (bVOCs), synthesised by plants, are important mediators of ecological interactions that can also undergo a series of reactions in the atmosphere. Ground-level ozone is a secondary pollutant generated through sunlight-driven reactions between nitrogen oxides (NOx) and VOCs. Its levels have increased since the industrial revolution and reactions involving ozone drive many chemical processes in the troposphere. While ozone precursors often originate in urban areas, winds may carry these hundreds of kilometres, causing ozone formation to also occur in less populated rural regions. Under elevated ozone conditions, ozonolysis of bVOCs can result in quantitative and qualitative changes in the gas phase, reducing the concentrations of certain bVOCs and resulting in the formation of other compounds. Such changes can result in disruption of bVOC-mediated behavioural or ecological interactions. Through a series of gas-phase experiments using Gas Chromatography Mass Spectrometry (GC-MS) and Proton Transfer Reaction Mass Spectrometry (PTR-MS), we investigated the products and their yields from the ozonolysis of a range of ubiquitous bVOCs, which were selected because of their importance in mediating ecological interactions such as pollinator and natural enemy attraction and plant-to-plant communication, namely: (E)-β-ocimene, isomers of α and β-farnesene, α-terpinene and 6-methyl-5-hepten-2-one. New products from the ozonolysis of these compounds were identified, and the formation of these compounds is consistent with terpene-ozone oxidation mechanisms. We present the degradation mechanism of our model bVOCs and identify their reaction products. We discuss the potential ecological implications of the degradation of each bVOC and of the formation of reaction products

Recovery of oil from palm oil mill effluent using polypropylene micro/nanofiber

Residual palm oil that goes into the river untreated can become detrimental to the environment. Residual oil discharge during milling process into palm oil mill effluent (POME) is unavoidable. About 1 wt% of residual oil in POME causes major problems to the mills, in terms of environment, wastewater treatment and economy losses. This paper reports the recovery of residual oil from POME by adsorption on polypropylene micro/nanofiber (PP-MNF) and desorption of oil by hands pressing, and oil extraction from the PP-MNF using solvent and supercritical-CO2 extraction techniques. The characterization of the PP-MNF and the quality of oil extracted were analyzed using analytical instruments. The reusability of the PP-MNF was also investigated. The experimental results showed the adsorption capacity of the PP-MNF was 28.65 g of oil/g of PP-MNF on average using refined palm oil, whilst recovery of oil from POME was 10.93 g of oil/g of PP-MNF. The extraction yield of oil from PP-MNF using hand pressing was 89.62%. The extraction of residual oil from the pressed PP-MNF showed comparable yield between solvent and supercritical CO2 techniques. The quality of recovered oil was similar with the quality of the crude oil, and no trace of polypropylene contamination was detected in the oil recovered. The PP-MNF showed no significant physical change after the extraction process. In conclusion, the PP-MNF has great potential to be used commercially in residual oil recovery from POME

Esterification of residual palm oil using solid acid catalyst derived from rice husk

In this study, carbon-silica based acid catalysts derived from rice husks (RH) were successfully synthesised using microwave (MW) technology. The results showed that MW sulphonation produced Sulphur (S) content of 17.2–18.5 times higher than in raw RH. Fourier-transform Infrared Spectroscopy (FTIR) showed peak at 1035 cm−1 which corresponded to O˭S˭O stretching of sulphonic (-SO3H) group. XRD showed sulfonated RH catalysts (SRHCs) have amorphous structure, and through SEM, broadening of the RH voids and also formation of pores is observed. RH600 had the highest surface area of 14.52 m2/g. SRHCs showed high catalytic activity for esterification of oleic acid with methanol with RH600 had the highest initial formation rate (6.33 mmol L−1 min−1) and yield (97%). The reusability of the catalyst showed gradually dropped yield of product for every recycle, which might be due to leaching of –SO3H. Finally, esterification of oil recovered from palm oil mill effluent (POME) with methanol achieved a conversion of 87.3% free fatty acids (FFA) into fatty acid methyl esters (FAME)

Mapping the effects of ozone pollution and mixing on floral odour plumes and their impact on plant-pollinator interactions

The critical ecological process of animal-mediated pollination is commonly facilitated by odour cues. These odours consist of volatile organic compounds (VOCs), often with short chemical lifetimes, which form the strong concentration gradients necessary for pollinating insects to locate a flower. Atmospheric oxidants, including ozone pollution, may react with and chemically alter these VOCs, impairing the ability of pollinators to locate a flower, and therefore the pollen and nectar on which they feed. However, there is limited mechanistic empirical evidence to explain these processes within an odour plume at temporal and spatial scales relevant to insect navigation and olfaction. We investigated the impact of ozone pollution and turbulent mixing on the fate of four model floral VOCs within odour plumes using a series of controlled experiments in a large wind tunnel. Average rates of chemical degradation of α-terpinene, β-caryophyllene and 6-methyl-5-hepten-2-one were slightly faster than predicted by literature rate constants, but mostly within uncertainty bounds. Mixing reduced reaction rates by 8–10% in the first 2 m following release. Reaction rates also varied across the plumes, being fastest at plume edges where VOCs and ozone mixed most efficiently and slowest at plume centres. Honeybees were trained to learn a four VOC blend equivalent to the plume released at the wind tunnel source. When subsequently presented with an odour blend representative of that observed 6 m from the source at the centre of the plume, 52% of honeybees recognised the odour, decreasing to 38% at 12 m. When presented with the more degraded blend from the plume edge, recognition decreased to 32% and 10% at 6 and 12 m respectively. Our findings highlight a mechanism by which anthropogenic pollutants can disrupt the VOC cues used in plant-pollinator interactions, which likely impacts on other critical odour-mediated behaviours such as mate attraction

Transcultural and familial factors in bilingualism and language transmission: A qualitative study of maternal representations of French-Maghrebi Arabic bilingual children

International audienceThis qualitative exploratory study examined transcultural and familial factors involved in bilingualism and minority language transmission among French and Arabic-speaking children. Participants included 30 children aged 4 to 6 years, born in France, and their bilingual French-Maghrebi Arabic-speaking parents. Children’s bilingual language profiles were assessed with the ELAL Scale for Maghrebi Arabic (minority language) and the Neel Scale for French (majority language). Mothers participated in qualitative interviews about cultural and language practices and representations. Interview contents were compared with the children’s language profiles. Results indicated that parents closely associated the transmission of the Arabic language with their cultural heritage transmission. The parents of fluent bilinguals had a strong desire to transmit the minority language. Mothers of minority language dominant bilingual children reported little perception of change in their lives since migration. Half of the mothers of majority language dominant bilingual children reported relationship or emotional difficulties with their children. Four minority language transmission types were identified: direct parent-child transmission; indirect transmission through private classes; indirect transmission through visits to family in the parents' native countries; and alternative transmission by another family member. Direct parent-child transmission was most frequent among the fluent bilinguals. Families' processes of hybridity were related to language transmission and bilingual development of children. Parental cultural affiliations to native country were related to minority language transmission. Perception of change since migration and affiliation to host country may also play a role in harmonious bilingual development. Moreover, the quality of family relationships can affect minority language transmission

L’elal d’AvicenneUn outil transculturel inédit pour évaluer et soutenir les compétences en langues maternelles des enfants

International audienceNous avons maintenant à notre disposition, et pour la première fois sur le plan international, un test d’évaluation du langage en langue maternelle des enfants vivant dans un contexte multilingue, ce qui est de plus en plus fréquent dans le monde. Ce test a été validé pour les enfants de 3,5 à 6,5 ans mais peut être utilisé aisément de 3 à 10 ans, voire au-delà dans un contexte clinique. Il permet de valoriser les compétences des enfants dans leurs langues maternelles et, quel que soit leur niveau de langage. Toute compétence dans leur langue maternelle est bonne à prendre pour ces enfants tant sur le plan linguistique, cognitif, qu’affectif ou relationnel. Cette langue maternelle permet à l’enfant de s’inscrire dans la langue qui lui a été transmise, dans son histoire, dans son système de relations. Notre ambition est que ce test, au-delà de ses capacités à évaluer les compétences des enfants dans leurs langues maternelles, soit un outil performatif de valorisation de ses habilités langagières comme l’est devenu le Brazelton pour les compétences des bébés, par exemple. Ce test permet de révéler leurs compétences en langue maternelle. Il est aussi un outil de prévention dans la mesure où valoriser la langue maternelle et se sentir en sécurité dans cette langue première aide à investir la langue seconde et les apprentissages dans cette langue. La langue maternelle est un puissant protecteur du développement des enfants, de leur capacité à parler et à apprendre. Enfin il peut être utilisé à des fins