Joël Albet

Ozonation of imidacloprid in aqueous solutions: Reaction monitoring and identification of degradation products

This paper presents the degradation of imidacloprid by ozonation. Solutions of 39.0 μg/mL imidacloprid were prepared either by dissolution of standard or by dilution of Gaucho Blé(®) seed loading solution and then ozonated under different conditions. The concentration of imidacloprid and oxidation products in both solutions was monitored by HPLC-UV as a function of the treatment time for a concentration of 100g/m(3) of ozone in the inlet gas. No significant difference was observed: in both cases, imidacloprid degradation was a pseudo-first order reaction with similar reaction rates (0.129-0.147 min(-1)), degradation by-products with the same HPLC retention times were observed and their concentrations as a function of the treatment time followed a very similar trend. The study of ozone concentration in the inlet gas (from 25 to 100g/m(3)) showed that imidacloprid degradation is also a first-order reaction with respect to ozone. The ozonation by-products were then collected and identified by ESI(+)-MS. A degradation pathway of imidacloprid was finally proposed.

Effect of Oxidative Treatment on Corn Seed Germination Kinetics

Corn seeds were treated with high purity oxygen ([O3] = 0 g/m3) and oxygen mixed with ozone ([O3] = 20 g/m3) during 6.8 or 20.5 minutes. Germination tests started immediately or 48 h after treatment. Effects of oxidative treatments on germination were determined by measuring seedlings and roots (>3 and >20 mm) rate at 3, 4 and 5 days of germination test. Results obtained for treated seed samples were higher than for untreated ones. A faster start of germination was observed for treated samples. This early germination start led to a larger number of germinated seeds with longer roots at 4 and 5 days. Nevertheless, too long an ozone treatment seemed to be unfavorable for seed growth, whereas a short one seemed to be most beneficial.

Kinetic aspects and identification of by-products during the ozonation of bitertanol in agricultural wastewaters

The degradation of bitertanol by ozone treatment is investigated. Solutions of bitertanol (8.4 μg mL(-1)) were prepared either by dissolution of the standard or by dilution of Gaucho Blé seed loading solution and then ozonated under different conditions. Evolution of the concentrations of bitertanol and its ozonation by-products in both solutions was monitored by HPLC-UV as a function of the treatment time for a concentration of 100 gm(-3) of ozone in the inlet gas. Bitertanol degradation was found to follow a pseudo-first order reaction in both cases. However, the rate of the reaction in diluted seed loading solution was much lower (0.19 vs. 0.27 min(-1) in standard solution) and was close to the reaction rate observed in the presence of a radical scavenger, tert-butanol (0.11 min(-1)). Thus, it may be suggested that additives present in the seed loading solution may play the role of radical scavengers. Study of ozone concentration in the inlet gas (from 25 to 100 gm(-3)) showed that ozone degradation is also a first-order reaction with respect to ozone. Four ozonation by-products were highlighted, collected and identified by HPLC coupled with an ion trap mass spectrometer using positive electrospray ionization mode. A degradation pathway of bitertanol was finally proposed.

Urban Wastewater Treatment by Catalytic Ozonation

ABSTRACT This study focuses on the catalytic ozonation of organic matter recalcitrant to usual water treatment technologies. Experiments aimed to investigate the efficiency of the process TOCCATA®, which uses a granular catalyst coupled with ozonation. Comparison was made between single ozonation, single adsorption onto the catalyst and catalytic ozonation. Adsorption was proven to contribute to decreased dissolved organic carbon. Catalytic ozonation enhanced organic matter removal and ozone transfer compared to single ozonation. Catalytic ozonation was modeled with global apparent first-order kinetics and single adsorption with pseudo–second-order sorption kinetics.

Evolutions et tendances en simulation de colonnes de rectification discontinue

Abstract This paper is devoted to the development of a general methodology for application to the simulation of multicomponent batch distillation with or without chemical reactions. After a survey of the field of batch distillation and dynamic simulation applied to batch distillation, evolutions and trends are reviewed through the presentation of the proposed methodology. This methodology is based on the formulation and development of a rigorous model in comparison with those commonly used in batch distillation. The resulting set of differential-algebraic equations (DAE) is solved using an efficient numerical strategy based on Gears method, which is especially adapted to deal with DAE systems and numerical features arising in the batch context. Numerical difficulties due to detection of time and state events, the occurrence of discontinuities and start-up policy schemes (involving chemical reactions or not) are emphasized. Original and interesting solutions are proposed to tackle each of these problems. Finally, the flexibility, reliability and efficiency of the proposed methodology are illustrated through academic and industrial case studies, the results of which are compared with plant data.