Validation of a method to elute viruses from different types of face masks

Due to the SARS-CoV-2 pandemic, it is crucial to study the efficiency of face masks in retaining viruses for the upcoming years. The first objective of this study was to validate a method to elute viruses from polyester and cotton face masks. We observed that deionized water followed by 3% beef glycine (pH 9.5 or pH 7.2) was significantly more efficient (p < 0.05) in eluting the bacteriophage phiX174 virus from polyester (4.73% ± 0.25% to 28.67% ± 1.89%), polyester/cotton (3% ± 0.33%), and cotton (1.7% ± 0.21%) face masks than 3% beef glycine only (pH 9.5 or pH 7.2) as a single eluent (3.4% ± 0.16% to 21.33% ± 0.94% for polyester, 1.91% ± 0.08% for polyester/cotton, and 1.47% ± 0.12% for cotton face masks). Also, deionized water was significantly less efficient as a single eluent for eluting bacteriophage phiX174 from all the studied face mask types. The polyethylene glycol (PEG) precipitation method was substantially more efficient (p < 0.05) as a second step concentration method for the viruses in the eluates than the organic flocculation (OF) method. Higher viral loads were eluted from polyester face masks than cotton ones. We also found varying viral loads in the eluate solutions from different commercial polyester face masks, with the highest percentage seen for the N95 face mask. The second objective was to apply the validated method to study the effect of autoclaving on the different face mask materials. Results of the study did not show any significant differences in the viral loads eluted from the studied face masks before and after one and five autoclaving cycles. Moreover, a scanning electron microscope (SEM) analysis revealed no changes in the yarns, elongation, tensile strength, and contact angle measurements of the polyester or cotton materials after one or five autoclaving cycles

Dérives greffés de l'acétate de cellulose pour la purification d'un biocarburant par un procédé de séparation membranaire dans une politique de développement durable

During the industrial production of ethyl tert-butyl ether (ETBE) biofuel, this ether forms an azeotropic mixture containing 20 wt% of ethanol. Compared to the ternary distillation currently used for ETBE purification, the pervaporation membrane process could offer an interesting alternative and important energy savings. Cellulosic membranes have been mainly reported for this application. In particular, the selectivity of cellulose acetate (CA) was outstanding but its flux was too low. In this work, different grafting strategies were developed for improving the CA membrane properties for ETBE purification. The first strategy used "click" chemistry to graft CA with polylactide oligomers leading to original bio-based membranes for the targeted application. The grafting of ionic liquids onto CA was then investigated first by "click" chemistry (unsuccessful due to side reactions) and then by another two-step strategy implying simple nucleophilic substitution. A second series of cellulosic materials was obtained by grafting different ionic liquids containing the same bromide anion and different cations (imidazolium, pyridinium or ammonium) with increasing polar feature. A third series of new membrane materials was finally developed by exchanging the bromide anion with different anions Tf2N-, BF4-, and AcO-. The membrane properties of all grafted CA membranes were finally assessed on the basis of the sorption-diffusion model, which revealed that both sorption and pervaporation properties were improved by the different grafting strategiesLors de la production industrielle du biocarburant éthyl tert-butyl éther (ETBE), cet éther forme un azéotrope contenant 20 % d'éthanol. Comparé à la distillation ternaire utilisée pour la purification de l'ETBE, le procédé membranaire de pervaporation pourrait offrir une alternative intéressante et d'importantes économies d'énergie. Des membranes cellulosiques ont principalement été décrites pour cette application. En particulier, la sélectivité de l'acétate de cellulose (CA) était extrêmement élevée mais son flux trop faible. Dans cette thèse, différentes stratégies de greffage ont été explorées pour améliorer ses propriétés membranaires. La première a mis en œuvre la chimie "click" pour le greffage d'oligomères polylactide, conduisant à des membranes bio-sourcés originales pour cette application. Le greffage de liquides ioniques (LIs) a ensuite été étudié, initialement par chimie "click" (échec dû à des réactions secondaires) puis par une autre stratégie en 2 étapes impliquant une simple substitution nucléophile. Une seconde série de matériaux cellulosiques a été obtenue avec des LIs contenant un même anion bromure et différents cations (imidazolium, pyridinium ou ammonium) de polarité croissante. Une troisième série de nouveaux matériaux membranaires a ensuite été développée en échangeant l'anion bromure par différents anions Tf2N-, BF4-, and AcO-. Les propriétés membranaires de tous les matériaux greffés ont finalement été évaluées sur la base du modèle de sorption-diffusion, révélant que la sorption et la pervaporation étaient conjointement améliorées par les différentes stratégies de greffage développées

Grafting of cellulose acetate with ionic liquids for biofuel purification by a membrane process: Influence of the cation

International audienceA new strategy was developed for grafting ionic liquids (ILs) onto cellulose acetate in order to avoid IL extraction and improve its performance for ethyl tert-butyl ether (ETBE) biofuel purification by the pervaporation membrane process. This work extended the scope of IL-containing membranes to the challenging separation of organic liquid mixtures, in which these ILs were soluble. The ILs contained the same bromide anion and different cations with increasing polar feature. The membrane properties were strongly improved by IL grafting. Their analysis in terms of structure-property relationships revealed the influence of the IL content, chemical structure and chemical physical parameters alpha, beta, pi* in the Kamlet-Taft polarity scale. The ammonium IL led to the best normalized flux of 0.182 kg/m(2)h for a reference thickness of 5 mu m, a permeate ethanol content of 100% and an outstanding infinite separation factor for the azeotropic mixture EtOH/ETBE at 50 degrees C

Grafting cellulose acetate with ionic liquids for biofuel purification membranes : Influence of the anion

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