Valorization of Date Palm Wastes by Lignin Extraction to be Used for the Improvement of Polymeric Membrane Characteristics

This work aimed to valorize Date Palm Wastes (DPW) by the extraction of lignin and its application for polymeric membrane modification. Lignin was extracted from five types of DPW (date palm kernel, leaflet, pedicel, palm frond, and fibrilium) using the Klason method. Following DPW characterization, we remark the highest amount of extractives content in the leaflet sample (10.07 %) and the lowest in the fibrilium sample (6.51 %). The ash content ranged from 1.56 % for fibrilium to 7.96 % for palm frond. After extraction, the lignin yield was in the range of 22–32 %. The extracted lignins were characterized by Infrared and Ultraviolet–visible spectroscopy. All extracted lignins provide a high concentration of (-OH) group. Besides, both syringyl and guaiacyl are present in the extracted lignins with a slightly more syringyl unit. The extracted lignins were added to the polymeric solution, prepared from waste plastic, to produce membranes. These membranes showed improved hydrophilicity marked a decrease in the contact angle of 28 % when the lignin concentration increased from 0.125 to 0.5 %. In addition, the membrane porosity increased with the use of the extracted lignins as an additive

Calcination improves the in vivo efficacy of a montmorillonite clay to bind aflatoxin G1 in broiler chickens : a toxicokinetic approach

The goal of this study was to investigate the toxicokinetic characteristics of aflatoxin G1 (AFG1) in broiler chickens and the effect of calcination of a Tunisian montmorillonite clay on the in vivo absorption of AFG1. In this study, broiler chickens were randomly distributed into four groups of 10 animals. Group 1 was administered AFG1 (2 mg/kg body weight (BW)) by single intravenous injection (IV), group 2 received an intra-crop bolus (PO) of AFG1 without any clay, group 3 was dosed AFG1 PO together with an oral bolus of purified clay (CP), and group 4 received AFG1 PO with an oral bolus of calcined clay. A significant difference in the area under the curve (AUC(0-t)) was observed for group 4 (6.78 +/- 4.24 h*ng/mL) in comparison with group 2 (12.83 +/- 4.19 h*ng/mL). A significant reduction of the oral bioavailability of AFG1 was observed for group 4 (7.61 +/- 4.76%) compared with group 2 (14.40 +/- 4.70%), while no significant effect was observed of CP. In this experiment, no phase I nor phase II metabolites of AFG1 were observed. These findings confirm that calcination of the purified montmorillonite clay enhances the adsorption of AFG1 in the gastrointestinal tract after oral administration, thereby reducing its bioavailability, thus reducing its toxic effects

Calcination enhances the aflatoxin and zearalenone binding efficiency of a Tunisian clay

Clays are known to have promising adsorbing characteristics, and are used as feed additives to overcome the negative effects of mycotoxicosis in livestock farming. Modification of clay minerals by heat treatment, also called calcination, can alter their adsorption characteristics. Little information, however, is available on the effect of calcination with respect to mycotoxin binding. The purpose of this study was to characterize a Tunisian clay before and after calcination (at 550 degrees C), and to investigate the effectiveness of the thermal treatment of this clay on its aflatoxin B1 (AFB1), G1 (AFG1), B2 (AFB2), G2 (AFG2), and zearalenone (ZEN) adsorption capacity. Firstly, the purified clay (CP) and calcined clay (CC) were characterized with X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR-IR), cation exchange capacity (CEC), specific surface area (S-BET), and point of zero charge (pH(PZC)) measurements. Secondly, an in vitro model that simulated the pH conditions of the monogastric gastrointestinal tract was used to evaluate the binding efficiency of the tested clays when artificially mixed with aflatoxins and zearalenone. The tested clay consisted mainly of smectite and illite. Purified and calcined clay had similar chemical compositions. After heat treatment, however, some changes in the mineralogical and textural properties were observed. The calcination decreased the cation exchange capacity and the specific surface, whereas the pore size was increased. Both purified and calcined clay had a binding efficacy of over 90% for AFB1 under simulated poultry GI tract conditions. Heat treatment of the clay increased the adsorption of AFB2, AFG1, and AFG2 related to the increase in pore size of the clay by the calcination process. ZEN adsorption also increased by calcination, albeit to a more stable level at pH 3 rather than at pH 7. In conclusion, calcination of clay minerals enhanced the adsorption of aflatoxins and mostly of AFG1 and AFG2 at neutral pH of the gastrointestinal tract, and thus are associated with protection against the toxic effects of aflatoxins

Synthesis of novel biocomposite powder for simultaneous removal of hazardous ciprofloxacin and methylene blue: Central composite design, kinetic and isotherm studies using Brouers-Sotolongo family models

Over the past decades, extensive efforts have been made to use biomass-based-materials for wastewater-treatment. The first purpose of this study was to develop and characterize regenerated-reed/reed-charcoal (RR-ChR), an enhanced biosorbent from Tunisian-reed (Phragmites-australis). The second aim was to assess and optimize the RR-ChR use for the removal of binary ciprofloxacin antibiotic (CIP) and methylene blue dye (MB), using Central Composite Design under Response Surface methodology. The third purpose was to explain the mechanisms involved in the biosorption-process. The study revealed that the highest removal-percentages (76.66 % for the CIP and 100 % for the MB) were obtained under optimum conditions: 1.55 g/L of adsorbent, 35 mg/L of CIP, 75 mg/L of MB, a pH of 10.42 and 115.28 min contact time. It showed that the CIP biosorption mechanism was described by Brouers–Sotolongo-fractal model, with regression-coefficient (R2) of 0.9994 and a Person’s Chi-square (X2) of 0.01. The Hill kinetic model better described the MB biosorption (R2 = 1 and X2 = 1.0E-4). The isotherm studies showed that the adsorbent surface was heterogeneous and the best nonlinear-fit was obtained with the Jovanovich (R2 = 0.9711), and Brouers–Sotolongo (R2 = 0.9723) models, for the CIP and MB adsorption, respectively. Finally, the RR-ChR lignocellulosic-biocomposite-powder could be adopted as efficient and cost-effective adsorbent

De la friction à la nano-usure du polystyrène (Rôle des interactions interfaciales)

L'objectif de ce travail est de préciser l'influence des interactions interfaciales sur la friction et l'usure du polystyrène en contact avec un substrat lisse. Pour modifier la nature des interactions, deux substrats sont utilisés : un substrat hydrophobe (wafer de silicium greffé avec un silane terminé CH3) et un substrat hydrophile (wafer hydroxylé). Les essais de friction sont réalisés à l'aide d'un tribomètre en translation. La couche de transfert est étudiée par microscopie à force atomique (AFM) et par spectrométries FTIR et XPS. Des mesures de nano-friction sont également réalisées par AFM. Ces travaux ont montré que le transfert de polymère sur le substrat ne se produit qu'à partir d'une contrainte seuil qui dépend davantage des propriétés du polymère (masse molaire...) et non directement de la nature du substrat. Des corrélations entre les caractéristiques de la couche de transfert, les propriétés interfaciales et le comportement viscoélastique du polymère sont proposées.The objective of this work is to precise the rote of interfacial interactions in the friction and nano-wear behavior of polystyrene. Studies are focused on the analysis of the transfer layer induced by the friction of polystyrene in contact with a smooth substrate. In order to change the nature of interfacial interactions, two substrates are used : a hydrophilic silicon wafer (hydroxylated by a piranha treatment) and a hydrophobic wafer (chemical grafting with CH3 erminated silanes). Friction experiments are performed with a translation tribometer. The transfer layer is analysed using atomic force microscopy (AFM) and IR and XPS spectroscopies. Nano-scale friction is also measured by AFM. Results show that the transfer appearance needs a critical interfacial shear which depends on intrinsic polymer properties (molecular weight) and not on chemical nature of substrates. Correlations between transfer layer characteristics, interfacial properties and viscoelastic behavior are proposed.MULHOUSE-SCD Sciences (682242102) / SudocSudocFranceF

Sliding Friction of Polymers: The Complex Role of Interface

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Friction and nanowear of polystyrene against hydrophobic and hydrophilic substrates

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Friction of polystyrene: Consequence on nano-wear

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Nano-friction of polystyrene : the role of the surface chemistry

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The in-situ characterization and structuring of electrografted polyphenylene films on silicon surfaces. An AFM and XPS study.

International audienceAn atomic force microscope was used so as to structure by nanofriction films of polynitrophenylene electrografted on substrates of n-type silicon (100) with the native oxide on the top of the surface. AFM measurements of thin films thickness have been carried out in the electrolytic solution for different applied potentials during the electrografting. This investigation allows (i) to determine the relationship between the applied potential and the final thickness of electrografted polyphenylene films and (ii) to specify how the thin layers grow. XPS analysis confirmed the AFM observations on (i) the effective shaving of the grafted polymer chains under mechanical stress and (ii) the existence of a potential threshold for electrografting a polyphenylene film on silicon oxide surfaces. The presence of a residual film in the rubbed zone was attributed to stronger interactions between the first electrografted layer and the native oxide of silicon (through Si-C or/and Si-O-C bonds) than those insuring the cohesion of the multilayer (C-C and C-N bonds)