Search results for "isotherms"

Experimental and robust modeling approach for lead(II) uptake by alginate gel beads: influence of the ionic strength and medium composition.

2014

Abstract Systematic kinetic and equilibrium studies on the lead ions removal ability by Ca-alginate gel beads have been performed by varying several internal parameters, namely, number of gel beads, nature and composition of the ionic medium and pH, which allowed us to model a wastewater in order to closely reproduce the composition of a real sample. Moreover, the effects brought about the different ionic species present in the reacting medium have been evaluated. Differential Pulse Anodic Stripping Voltammetry (DP-ASV), has been systematically used to perform kinetic and equilibrium measurements over continuous time in a wide range of concentration. Kinetic and equilibrium data have been q…

Experimental study and physical modeling of simultaneous heat and moisture transfer in bio-sourced insulating materials.

2019

The conventional heat transfer models are not sufficiently suitable for thermal characterization of bio-sourced thermal insulating materials due to their strongly hydrophilic nature. The proposed work in this PhD thesis aims to answer this problem with experimental and theoretical approaches of coupled heat-moisture transfers. In the experimental approach, a thermal insulating material based on Flax Fiber Felt (FFF) is developed and then characterized at different hygrometric conditions with an asymmetric hot plate device. The humidity diffusion characterization of the samples is done using the GAB, GDW and Park theoretical moisture adsorption isotherm models. In the theoretical approach, a…

Toxicity of binary mixtures of Cu, Cr and As to the earthworm Eisenia andrei

2020

AbstractChromated copper arsenate (CCA) mixtures were used in the past for wood preservation, leading to large scale soil contamination. This study aimed at contributing to the risk assessment of CCA-contaminated soils by assessing the toxicity of binary mixtures of copper, chromium and arsenic to the earthworm Eisenia andrei in OECD artificial soil. Mixture effects were related to reference models of Concentration Addition (CA) and Independent Action (IA) using the MIXTOX model, with effects being related to total and available (H2O and 0.01 M CaCl2 extractable) concentrations in the soil. Since only in mixtures with arsenic dose-related mortality occurred (LC50 92.5 mg/kg dry soil), it wa…

Modeling of the process of moisture loss during the storage of dried apricots

2011

[EN] Moisture content is a reference parameter for dried food because the growth of most microorganisms is inhibited below certain water activity levels. In addition, it has a determining influence on the evolution of important parameters, such as color and flavor, and on other properties and deterioration reactions, such as texture, oxidation processes and nutritional value. During the storage of some dried fruits, moisture is produced due to Maillard reactions and exchanged with the surrounding environment through the packaging. The evolution of dried foods during their shelf life depends on the storage conditions. The aim of this study is to analyze the evolution of the moisture content …

Removal of Cypermethrin from Water by Using Fucus Spiralis Marine Alga

2019

Alpha-cypermethrin is a synthetic pyrethroid that was extensively used for insect control, since the early 1980s. However, it is known that its presence in the environment has toxic effects on humans and aquatic life forms. For this reason, it is commendable for it to be removed completely from the contaminated environment. In this study, we evaluated the adsorption capacity of a marine alga for the removal of cypermethrin from water. The adsorption experiments were performed based on the batch equilibrium technique. The samples containing the pesticide were analyzed using gas chromatography with an electron capture detector, after liquid-liquid extraction in hexane. The results obtained fr…

Photoadsorption determination for irradiated catalyst in liquid-solid system

2008

A comparative study for the removal of methylene blue dye by N and S modified TiO2 adsorbents

2015

Successful removal of methylene blue (MB) dye from aqueous solutions using nitrogen and sulfur modified TiO2(P25) nanoparticles has been demonstrated in this study. The modified adsorbents were characterized using various analytical methods, such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The adsorption potential of S-TiO2, N-TiO2 and TiO2(P25) type adsorbents was tested for the removal of MB dye. The kinetic studies indicated that the adsorption of MB dye followed the pseudo-first order model, while desorption processes followed the second order model. The adsorption capacity of the adsorbent proved to be increasing as a f…

Molecular Selectivity of CH 4 –C 2 H 6 Mixed Hydrates: A GCMC Study

2021

International audience; In this paper, we report the first grand canonical Monte Carlo simulation study aiming at characterizing the competitive trapping of CH4 and C2H6 molecules into clathrate hydrates under temperature conditions typical of those encountered at the surface of Titan. Various compositions of the fluid in contact with the clathrate phase have been considered in the simulations, including pure methane, pure ethane, and mixed fluids made of various methane/ethane ratios. The trapping isotherms obtained from the simulations clearly show that ethane molecules can be enclathrated at lower pressures than methane molecules. In addition, they provide evidence that the methane molec…

Design d'un iprodione-MIP (molecularly imprinted polymer) : application à la pré-concentration des fongicides dans le vin

2014

The aim of this study was the synthesis of a MIP (molecularly imprinted polymer) specific for a fungicide that is found in the majority of the french wine: iprodione. The challenge for extracting iprodione from wine medium was that the hydoralcoholic solution is a dipolar solvent, whereas the interaction between the MIP and iprodione is based on dipolar interactions. The first extraction study of iprodione was made on a MIP synthesized by bulk polymerization using methacrylamide and ethylene glycol dimethacrylate (EGDMA). The MIP was found to be more efficient than the NIP (non-imprinted polymer) in hydroalcoholic solutions which demonstrates that the molecular imprinting was successful. Th…

Biosorption of nickel (II) and zinc (II) from aqueous solutions by the biomass of yeast Yarrowia lipolytica

2017

Abstract This study examined the biosorption process of Ni(II) and Zn(II) from an aqueous solution by dead biomass of Yarrowia lipolytica. Optimum biosorption conditions were determined as a function of pH, biomass dosage, contact time, and temperature. The biosorbent was characterized by FTIR, which indicated the participation of hydroxyl, carboxyl, amide and amine groups in the process of binding the metal ions. The results showed that the biosorption processes of both metal ions closely followed pseudo-second order kinetics. The equilibrium data of Ni(II) and Zn(II) ions at 20, 30 and 40°C fitted the Langmuir and Freundlich isotherm models. Langmuir isotherm provided a better fit to the …