Clean synthesis of adipic acid from cyclohexene in microemulsions with stearyl dimethyl benzyl ammonium chloride as surfactant: From the laboratory to bench scale

Adipic acid, HOOC(CH2)4COOH, is a white crystalline solid used primarily in the manufacture of nylon-6,6 polyamide. In industry, adipic acid is mainly produced by oxidation of cyclohexane with air and nitric acidfollowing a homogeneous two-step route. However, this process leads to the formation of nitrous oxide, a greenhouse gas that has to be decomposed. The aim of this study was the development of a clean technology at pilot scale in order to obtain and recover pure adipic acid, and the evaluation of its industrial practicability. Adipic acid was synthesized from cyclohexene and hydrogen peroxide in microemulsions with stearyl dimethyl benzyl ammonium chloride as surfactant. The non-polluting catalyst sodium tungstate, which contains no heavy metal, was used and the reaction conducted under mild conditions (85 C, 8 h). Yields of up to 81% were reached at the 0.14 L scale. However at the end of the reaction the catalyst and the surfactant must be separated and recycled for subsequent cycles. The reuse of the reaction media enabled the conversion to be increased up to 92% but a loss of surfactant and/or catalyst through the cycles progressively reduced the yields. Yields at the bench scale (1.4 L) increased during the two first cycles and then decreased to conversions of between 60% and 70%. Globally the yield is a little lower at bench scale. The results obtained show that the synthesis of adipic acid by a heterogeneous one-step oxidation of cyclohexene in the presence of hydrogen peroxide is an attractive route for developing a future green industrial process

Green process for adipic acid synthesis: oxidation by hydrogen peroxide in water micromelusions using Benzalkonium Chloride C12-14 surfactant

Adipic acid was synthesized by the oxidation of cyclohexene using 30% hydrogen peroxide in a microemulsion in the presence of sodium tungstate as catalyst. The proposed green process is environmentally friendly since catalyst and surfactant are recycled and pure adipic acid is produced in high yield (70% to 79%). Microemulsions are used as a “green solvent” and give a better contact between the phases. Alkyldimethylbenzylammonium chloride (C12-C14) was used as a surfactant for the generation of the microemulsion since it enables the use of harmful organic solvents and phase-transfer catalysts to be avoided. Optimised operating conditions (temperature, reaction time, separation process) have been defined and applied to evaluate the industrial practicability. The main interest of the present work is the easy recovery of pure adipic acid and the reuse of the reaction media (surfactant and catalyst). This shows promise for developing a future green industrial process that will enable greenhouse gas emissions (N2O), among others, to be reduced

Environmental good production in the optimum activities portfolio of a risk averse-farmer

An analytical framework is proposed for analysis of environmental good production by farmers in the case of price uncertainty. Environmental good production contracted by means of agri-environmental agreements is treated as a riskless option in the farmer’s production activities portfolio. It is shown that agri-environmental agreements aiming at biodiversity competing with beef production are likely to increase management intensity on the non-enrolled land, and that the effect of the payments for these agreements on the number of hectares enrolled is ambiguous. It is also demonstrated that an increase in the output price variability and/or a decrease in the level of decoupled subsidies will induce an increase (decrease) in the area enrolled in agreements aiming at biodiversity competing with (complementary to) beef production. The obtained results are illustrated by means of efficient frontiers generated using mathematical programming farm level models of suckler cow farms in Monts du Cantal, in France.uncertainty, portfolio optimisation, biodiversity, agricultural policy, mathematical programming

Demographic Growth and Environment In Sub-Saharan Africa : An Analysis of the Panel Data on the 1980-2016 Period

The objective of this paper is to determine the impact of the demographic growth on environment in the Sub- Saharan Africa The data come from the World Bank Africa Development Indicators 2017 The study period goes from 1980 to 2016 37 years and the sample contains 25 Sub- Saharan Africa countries The estimate Within Between method is used to value the parameters of a multiple regression model developed by York and al 2003 The results show that the demographic growth deteriorate the environmental quality in the Sub-Saharan Afric

Ouverture Commerciale, Croissance Economique et Environnement au Cameroun : Une Etude Empirique de la Courbe Environnementale de Kuznets

The objective of this paper is to examine the effects of economic growth and the trade openness on the quality of the environment. Pesaran’s et al (2001) Auto-Regressive Distributed Lags (ARDL) was applied on the macroeconomic data of Cameroon dating from 1971 to 2011. The results reveal that: the economic growth induces a deterioration of the environment in the short-term but improves it in the long-term while the trade openness deteriorates the environment in Cameroon.L’objet de ce papier est de déterminer les effets de la croissance économique et de l’ouverture commerciale sur la qualité de l’environnement. La méthode de cointégration par les retards échelonnés ou Auto Regressive Distributed Lags (ARDL) développée par Pesaran et al. (2001) a été appliquée sur les données macroéconomiques du Cameroun sur la période allant de 1971 à 2011. Les résultats révèlent que : la croissance économique induit la détérioration de l’environnement à court terme, mais l’améliore à long terme tandis que l’ouverture commerciale détériore l’environnement au Cameroun

Trophic transfer of pesticides : The fine line between predator–prey regulation and pesticide–pest regulation

Acknowledgments JF benefited from a Marie Skłodowska-Curie fellowship (European Commission, project "VOLES", 660718). VB was employed with this project funds. We are very grateful to Deon Roos for reviewing drafts. We thank Alessandro Massolo, Thibault Moulin and Francis Raoul for helpful suggestions. This work benefited from long-term data collected at Zone atelier (ILTER) Arc jurassien (http://zaaj.univ-fcomte.fr) and its financial support. DATA availability statement All code and data used for this manuscript are available on Github https://zenodo.org/badge/latestdoi/233555669 (Baudrot et al., 2020).Peer reviewedPostprin

Mobilisation des transferts intergouvernementaux et dépenses des collectivités locales au Cameroun : cas de la ville de Douala

Pour l’heure, les ressources propres des collectivités locales, dont la mobilisation ne dépend pas des autorités publiques centrales, sont très faibles au Cameroun. Par conséquent, les transferts financiers de l’Etat se positionnent comme une source fondamentale de revenus pour les collectivités locales. L’objectif de ce papier est de déterminer la contribution des transferts intergouvernementaux à la croissance des dépenses des collectivités locales de la ville de Douala. La méthode des moindres carrés ordinaires a permis d’estimer un modèle à effets individuels fixes à partir des données de panel de six collectivités locales sur la période 2011-2015. Lorsque la fiscalité partagée et la fiscalité de péréquation varient d’une unité, les dépenses des collectivités locales varient de 163.69% et 13.65%, respectivement. Les transferts intergouvernementaux favorisent donc la croissance des dépenses des collectivités locales. L’Etat et les collectivités locales devraient mettre sur pied des mécanismes de transferts intergouvernementaux efficients afin d’améliorer les recettes budgétaires locales. L’Etat pourrait donc augmenter la part de son budget qu’elle accorde aux collectivités locales