Search results for "FILTRATION"
showing 10 items of 908 documents
Analysis of amino acids using serially coupled columns.
2017
Single conventional columns in reversed-phase LC are insufficient for analysing the isoindoles of primary amino acids, due to their limited functionality. An interesting possibility for increasing the separation power is the combination of several columns of different nature, where the length is modified by coupling small segments. This approach may require a considerable investment to have multiple lengths for each stationary phase. However, the combination of only two columns of fixed length can be enough to resolve satisfactorily relatively complex mixtures, provided that an optimised gradient program is applied. In this work, a mixture of 19 primary amino acid isoindoles found in protei…
Biofiltration of ethylbenzene vapours: influence of the packing material.
2006
In order to investigate suitable packing materials, a soil amendment composed of granular high mineralized peat (35% organic content) locally available has been evaluated as carrier material for biofiltration of volatile organic compounds in air by comparison with a fibrous peat (95% organic content). Both supports were tested to eliminate ethylbenzene from air streams in laboratory-scale reactors inoculated with a two-month conditioned culture. In pseudo-steady state operation, experiments at various ethylbenzene inlet loads (ILs) were carried out. Maximum elimination capacity of about 120 g m(-3) h(-1) for an IL of 135 g m(-3) h(-1) was obtained for the fibrous peat. The soil amendment re…
Comparative study for separation of aquatic humic-type organic constituents by DAX-8, PVP and DEAE sorbing solids and tangential ultrafiltration: ele…
2005
Aquatic humic-type solutes were separated in parallel from the same fresh water source by four different procedures: non-ionic polymethyl methacrylate (DAX-8) and functional cross-linked polyvinylpyrrolidone (PVP) resins, functional diethylaminoethyl cellulose (DEAE) and tangential ultrafiltration completed with a weakly basic anion exchange resin (IRA-67). The similarity-dissimilarity between the quantities and qualities of the different humic samples is discussed, especially in the light of the original dissolved organic matter (DOM). During the past two decades, a significant progress has occurred in the aquatic humic research due to the so-called hydrophobic-hydrophilic properties posse…
Coupling Adsorption and Biological Technologies for Multicomponent and Fluctuating Volatile Organic Compounds Emissions Abatement: Laboratory-Scale E…
2015
The capacity of activated carbon as a buffer pretreatment combined with biotrickling filtration for volatile organic compound (VOC) removal has been studied. The adsorption capacity of commercial activated carbons for m-xylene, acetone and n-butyl acetate (typical paint solvents) was evaluated, including the response to the interchanging of adsorbed compounds and to mixtures over fluctuating inlet conditions. The adsorption of m-xylene and n-butyl acetate was mainly irreversible and more than three times higher than for acetone. The prior use of activated carbon influenced adsorption and buffer capacities in consecutive adsorption/desorption cycles. The Dubinin–Radushkevich equation was use…
Changes in soil redox potential in response to flood irrigation with waste water in central Mexico
2017
Irrigation with untreated sewage water adds fresh organic matter to the soil. When it is applied by flooding, as in the Mezquital Valley of Mexico, many of the pores in the soil become temporarily waterlogged and depleted of oxygen, and reduction generates nitrous oxide (N2O) and methane (CH4). We monitored the redox potential, Eh, in the soil at two sites in the Mezquital Valley to discover whether the short-term gaseous emissions matched the changes in Eh. One site is irrigated periodically by flooding with waste water and has alfalfa, rye grass and maize grown in succession; the other site grows maize with water from summer rain only. Each electrode buried in the soil for the purpose pro…
Utilization of enzymatic detergents to clean inorganic membranes fouled by whey proteins
2005
In this work inorganic membranes used for whey protein fractionation were cleaned with enzymatic detergents. The inorganic membrane Carbosep ® M1 (Orelis S.A., France), of 150 kg/mol molecular weight cut-off and ZrO2 filtering layer, was used and the commercial detergent P3-Ultrasil ® 62 (Henkel IbS.A., Spain) was selected for the cleaning. Hydraulic and chemical methods were considered to characterize the membrane cleanliness. Cleaning efficiency was observed to be a function of the operating conditions: recycling versus non-recycling of permeate, cleaning solution pH, enzymatic agent concentration and cleaning time. The optimum conditions to perform the cleaning were related to the optimu…
Equilibrium and transport properties of ion-exchange membranes
1984
Abstract Specific properties (ion-exchange capacity, water content, pore volume fraction) and transport properties (counterion transport number and electrical conductivity) have been measured in four commercial cation-exchange membranes loaded with a variety of cations of different nature and charge. Not surprisingly, equivalent conductances are lower than in free solution and transport numbers decrease with valency of the counterion. This behavior is explained by taking into account a “tortuosity factor”, due to a lengthening of the pores across the membrane, except for a membrane with a lower water content and for ions of higher charge, in which electrostatic interactions between mobile a…
Understanding the impact of poly(allylamine) plasma grafting on the filtration performances of a commercial polymeric membrane
2019
Abstract Commercial membranes often exhibit difficulties in rejecting specific ionic species, and especially multivalent cations, due to their usual negative charge. To face this drawback, it is proposed here to functionalize the membrane surface by allylamine plasma polymerization. The impact of this modification on both permeation flux and ion rejection is investigated for single salt solutions and ion mixtures. It is shown that the membrane behaves like a positive membrane from the point of view of cation rejection but the negative charge (and the corresponding electrical field) inside pores leads to high rejection of divalent anions like a negative membrane. This allows a high selectivi…
Absorption and desorption of liquid water by a superabsorbent polyelectrolyte: Role of polymer on the capacity for absorption of a ground
2001
To study the potentialities of a polyelectrolyte superabsorbent for the storage of water, we have studied a ground representative of the area of Haouz (area of Marrakesh, South of Morocco) in the presence of polymer. We sought the optimal proportions allowing the best retention of water by the mixture made up of the polymer and the ground and to prolong the storage period of water in the ground. We have also studied the effect of certain ions and the pH on the capacity for absorption of polymer. These ions can be naturally present in the ground or introduced by the means of manure and pesticides. The presence of polymer in the ground makes it possible to increase the capacity for absorption…
Effects of solvent-free microwave extraction on the chemical composition of essential oil of Calamintha nepeta (L.) Savi compared with the convention…
2008
The essential oil of Calamintha nepeta has been obtained by solvent-free microwave extraction (SFME) and by classical hydrodistillation (HD). A comparative qualitative-quantitative study on the composition of the oils was carried out. A total of 38 compounds, constituting 97.6% of the oil, were identified in the oil obtained by SFME, whereas 46 compounds, representing 95.4% of the oil, were characterized in the HD oil. SFME-distilled oil is richer in lightly oxygenated monoterpenes (LOM) than HD oil. It also has a higher amount of sesquiterpenes and a lower quantity of hydrocarbon monoterpenes. HD oil seems to be affected by chemical changes more than SFME oil.