EP1044051A1 - Nouveaux procedes et appareil de filtration amelioree de particules submicroniques - Google Patents

Nouveaux procedes et appareil de filtration amelioree de particules submicroniques

Info

Publication number
EP1044051A1
EP1044051A1 EP99946750A EP99946750A EP1044051A1 EP 1044051 A1 EP1044051 A1 EP 1044051A1 EP 99946750 A EP99946750 A EP 99946750A EP 99946750 A EP99946750 A EP 99946750A EP 1044051 A1 EP1044051 A1 EP 1044051A1
Authority
EP
European Patent Office
Prior art keywords
filter
filters
matrix
metallic
filtration
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99946750A
Other languages
German (de)
English (en)
Inventor
Jerzy Lukasik
Samuel R. Farrah
Dinesh O. Shah
Peter K. Kang
Ben L. Koopman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Florida
Original Assignee
University of Florida
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of Florida filed Critical University of Florida
Publication of EP1044051A1 publication Critical patent/EP1044051A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/0027—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours with additional separating or treating functions
    • B01D46/0028—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours with additional separating or treating functions provided with antibacterial or antifungal means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/18—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being cellulose or derivatives thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
    • B01D39/2003—Glass or glassy material
    • B01D39/2017—Glass or glassy material the material being filamentary or fibrous
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/0027—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours with additional separating or treating functions
    • B01D46/0035—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours with additional separating or treating functions by wetting, e.g. using surfaces covered with oil
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0414—Surface modifiers, e.g. comprising ion exchange groups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0414—Surface modifiers, e.g. comprising ion exchange groups
    • B01D2239/0428—Rendering the filter material hydrophobic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0471—Surface coating material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/0604—Arrangement of the fibres in the filtering material
    • B01D2239/0613—Woven
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/0604—Arrangement of the fibres in the filtering material
    • B01D2239/0618—Non-woven
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/10—Filtering material manufacturing

Definitions

  • Waterborne gastroenteritis is an important public health problem in both developed and developing countries (Payment et al. 1991a, Payment et al. 1991b, Rao 1976). Many cases of human infections by waterborne enteric pathogens have occurred in the United States and throughout the world. In the late eighties, more than 50 waterborne disease outbreaks were reported (Lev ine et al.). Between 1991 and 1992, 17 states and territories in the United States reported 34 outbreaks associated with drinking water. These outbreaks caused an estimated 17,464 persons to become ill (Moore et al. 1993). In 1993, a waterborne outbreak of cryptosporidiosis occurred in Milwaukee. During this outbreak over 400,000 people had intestinal disease (MMWR, June 16, 1995). A recent report by the Academy of Microbiology (Colwell, R.
  • Deep bed filtration through particulate media is a commonly used method for removing particles from water (Bitton, 1994).
  • This filtration process may not be efficient for the removal of microorganisms and relies either on the addition of flocculants to the influent water or the development of a biof ⁇ lm on the surface of the filter media.
  • Metallic hydroxides floes (ferric hydroxide and aluminum hydroxide) have been used to treat water and waste water for many years (Bitton, 1994). These floes adsorb microorganisms and remove them from the water following settling or filtration.
  • combining flocculation with filtration has had limited success in producing flow-through filters for removing microorganisms from large volumes of water. There are potential drawbacks to this approach; the floes may not be retained by the filters or clog the filters and greatly restrict the flow of water, thus requiring frequent backwashing (Bitton 1994).
  • particulate contaminants is very important for many applications including, for example, water reclamation, potable water treatment, water purification in microelectronics and pharmaceutical industries, and other point-of-use filters where ultrapure water is required.
  • the efficacy of particulate contaminant filtration is dependent on several factors including particle size, physicochemical properties of the particles, and the collectors or filter media. For example, due to their large pore sizes, conventional filters cannot be used to filter submicron/nanoparticles or biological particles such as bacteria and viruses. Although large particles can be filtered by entrapment mechanisms, as the size of the particle decreases, particle removal becomes more difficult and thus other techniques may be necessary for efficient filtration.
  • Polypropylene is commonly used to make prefilters and filters because it is extremely inexpensive and very inert. A technique which could alter polypropylene filters such as to increase the interaction between particles and such filters would enhance the filtration efficiency of such filters.
  • the subject invention pertains to novel methods of filtration, novel methods for production of filters, and novel filters, for the efficient filtration of impurities.
  • impurities include, but are not necessarily limited to, particles and chemical species.
  • the materials and methods of the subject invention are particularly advantageous for the filtration of submicron particles, for example nanoparticles, and can utilize the electrostatic attraction between particles and the matrix of microporous filters.
  • the subject methods of filtration can lower the energy barrier between the particles and the filter surface and thus increase the deposition of particles on the surface of the filter.
  • the methods and materials of the subject invention can be used to filter particles and dissolved chemical contaminants from many fluids including water and air.
  • the subject surface modified filters can result in increased fluid flow, for the same pressure drop, compared to unmodified filters.
  • a monomolecular layer of cationic surfactant is added to a microporous polyropylene filter in order to give the surface of the filter a positive charge.
  • adsorption of negatively charged and/or neutral particles on these surface modified filters and the resulting filtration efficiency are enhanced.
  • These surface modified filters can be useful for removing bacteria, viruses, and nanoparticles in waste water treatment, and can also be useful in resource recovery processes.
  • a monomolecular layer of anionic surfactant can be added to a microporous polyropylene filter in order to give the surface of the filter a negative charge, resulting in enhanced filtration efficiency for positively charged and/or neutral particles.
  • a monomolecular layer of nonionic surfactant can be added to a microporous polyropylenefilter, resulting in enhanced filtration efficiency for positive, negative, and/or neutral particles.
  • the subject surface modified filters can be stacked, resulting in a further increase in filtration efficiency.
  • surface modified filters having a positive charge, negative charge, or neutral charge can be stacked in a variety of combinations to more efficiently filter target particles, for example, negative, positive, and neutral particles simultaneously.
  • Filters made of materials other than microporous polyropylene can also be modified by the addition of surfactants or polymers in accordance with the subject invention.
  • the subject invention also pertains to novel methods of coating filter media, novel filter media, for the efficient filtration of chemical and biological contaminants from fluids.
  • the materials and methods of the subject invention are particularly advantageous for filtration of ions, particulates, bacteria, viruses, protazoan parasites, fungus, yeast, and other submicron particles from aqueous and gaseous systems.
  • the subject coatings can be applied to a variety of filter media, for example woven and unwoven filters or fabrics, fiberglass, fiberglass air filters, polypropylene, cellulose, sand, diatomaceous earth, fine sand, gravel, and any particulate filter media.
  • in situ precipitation of metallic hydroxides and/or metallic oxides can be utilized to coat filter media.
  • the coated filter media can be useful for removing, for example, bacteria, viruses, protozoan parasites, fungus, organic and inorganic chemicals, and/or dust.
  • the subject materials and methods can be utilized in, for example, survival or personal water purification devices, household water filters, air filters, water reclamation filter media, water remediation processes, soil remediation processes, viral removal filters, and/or protective clothing.
  • the subject invention pertains to novel methods of filtration, novel methods for production of filters, and novel filters, for the efficient filtration of impurities in a fluid.
  • the materials and methods of the subject invention are particularly advantageous for the filtration of submicron particles, for example nanoparticles, and can utilize the electrostatic attraction between particles and the matrix of a filter.
  • the subject methods of filtration can lower the energy barrier between the particles and the filter surface and thus increase the deposition of particles on the surface of the filter.
  • the methods and apparatus of the subject invention can be used to filter impurities from many fluids including water and air.
  • the subject surface modified filters can result in increased fluid flow, for the same pressure drop, as compared to unmodified filters. In a specific embodiment, because most natural particles are negatively charged (Rosen,
  • a thin layer of cationic surfactant is added to a microporous polyropylene filter in order to give the surface of the filter a positive charge.
  • this layer can be monomolecular.
  • the adsorption of negatively charged and/or neutral particles on these surface modified filters and the resulting filtration efficiency are enhanced.
  • These surface modified filters are useful for removing bacteria, viruses, and nanoparticles in waste water treatment, and are also useful in resource recovery processes.
  • a thin layer of anionic surfactant can be added to a microporous polyropylene filter in order to give the surface of the filter a negative charge, resulting in enhanced filtration efficiency for positively charged and/or neutral particles.
  • a thin layer of nonionic surfactant can be added to a microporous polyropylene filter, resulting in enhanced filtration efficiency for neutral particles. These layers may be monomolecular.
  • cationic polymers can be used to coat filter surfaces, resulting in increased filtration efficiency of negative and/or neutral particles; anionic polymers can be used to coat filter surfaces, resulting in increased filtration efficiency of positive and/or neutral particles; and nonionic polymers can be used to coat filter surfaces, resulting in increased filtration efficiency of negative, positive, and/or neutral particles.
  • the subject invention is applicable to many types of prefilters and filters, including polymeric filters.
  • the subject filters are microporous polyropylene filters, which are inexpensive and very inert.
  • the methods and apparatuses of the subject invention allow the monitoring of the charge neutralization of the filter surface to determine when the filter needs to be replaced. This monitoring can be accomplished by, for example, measuring the zeta potential of a filter using, for example, a streaming potential apparatus.
  • Surfactants and polymers which can be utilized in the subject invention include the following:
  • Hydrophobically modified cationic polymers Hydrophobically modified anionic polymers Zwitterionic surfactants (both - and + groups) such as lecithin (Soya Lecithim)
  • the subject surface modified filters can be stacked resulting in a further increase in filtration efficiency.
  • surface modified filters having a positive charge, negative charge, or neutral charge can be stacked in a variety of combinations to more efficiently filter target particles, for example, negative, positive, and neutral particles simultaneously.
  • Filters made of materials other than microporous polyropylene can also be modified by the addition of surfactants or polymers in accordance with the subject invention.
  • the subject invention also pertains to novel methods of coating filter media, and novel filter media, for the efficient filtration of chemical and biological contaminants from fluids.
  • the materials and methods of the subject invention are particularly advantageous for filtration of chemical species, particulates, bacteria, viruses, protozoan parasites, fungus, yeast, and other submicron particles from aqueous and gaseous systems.
  • the subject coatings can be applied to a variety of filter media, for example woven and unwoven filters or fabrics, fiberglass, fiberglass air filters, polypropylene, cellulose, sand, diatomaceous earth, find sand, gravel, activated carbon, activated charcoal, and any particulate filter media.
  • the subject invention also relates to the precipitation of metallic (hydr)oxides on a filter matrix, the resulting filters, and method of filtering a fluid utilizing such filter.
  • in situ precipitation of metallic hydroxides and/or metallic oxides can be utilized to coat filter media.
  • the coated filter media can be useful for removing, for example, bacteria, viruses, protozoan parasites, fungus, organic and inorganic chemicals, and/or dust.
  • the subject materials and methods can be utilized in, for example, survival or personal water purification devices, household water filters, air filters, water reclamation filter media, water remediation processes, soil remediation processes, viral removal filters, and/or protective clothing.
  • metallic (hydr)oxides on a filter matrix where metallic
  • the filter matrix can, for example, first be wet with a metallic chloride solution.
  • Other solutions can also be used, such as a metallic sulfate solution.
  • a basic solution can be applied.
  • such basic solutions include ammonium hydroxide, sodium hydroxide, and potassium hydroxide.
  • Other strong base solutions which raise the pH can also be used.
  • the pH of such basic solution is at least pH 9, and more preferably at least pH 11.
  • the subject filter media particles are preferably heated to an elevated temperature. Applying the coatings while the filter media is at elevated temperatures is particularly advantageous for sand, diamaceous earth, and particulate filter media. For example, in range of 60°C to 100°C, more preferably 70°C to 95°C, even more preferably 75°C to 85°C, and most preferably about 80° C.
  • the filter media can also be agitated mechanically, for example on a vibrating platform . The agitation helps to encourage uniformity of the coating which is to be applied.
  • the heating process can involve the use of, for example, infra red radiation, the blowing of hot air on to the vibrating particles, microwaves, or any other heating mechanism which can be incorporated with the subject coating process without interference.
  • a metallic chloride solution can be applied to the media' s surface.
  • a mist of a preheated solution at approximatelythe same temperature as the filter media (e.g., about 80°C) of 0.25M ferric chloride and 0.5 M aluminum chloride in a 50 % ethanol solution is sprayed onto the vibrating particles.
  • the solution is sprayed in short bursts to avoid excessive wetting of the surface and to allow even drying. Heating and agitation can be continued throughout the spraying process.
  • the misting is preferably continued until the surface of the solid substrate is evenly treated and fully coated with the metal chloride solution. It should be noted that a variety of methods can be used to apply the metallic chloride solution.
  • the coating is then allowed to dry. In order to dry quickly and evenly, heating and agitation can be continued. Excessive heating should be avoided in order to avoid the corresponding metallic oxides.
  • the coated material tends to turn a yellowish coloration when coated appropriately.
  • the solids can then be coated, for example sprayed by a mist or exposed to saturated vapors of ammonium hydroxides, by a 3.0 M ammonium hydroxide solution. A 3.0 M ammonium hydroxide solution is preferred. Again, the coating is preferably applied while the media is being heated and agitated. This forms the corresponding precipitate of metallic (hydr)oxideson the surface.
  • the coated solids can then be rinsed in deionized water and dried.
  • the filter media is then ready for use.
  • the metallic chloride solution can have a range of molarities.
  • the ferric chloride is in the range of 0.1M to 2.0 M, more preferably 0.2M to 0.4M, and most preferably about 0.25M
  • the aluminum chloride is preferably in the range of 0.1 M to 2.0 M, more preferably 0.2 M to 0.8 M and most preferably about 0.5M.
  • the subject metallic (hydr)oxide coating can be generated utilizing metallic sulfates, such as Aluminum sulfate and/or Ferric sulfates.
  • the metallic chloride solution can be in, for example, 100% water, however ethanol is preferably added to speed the drying process. It was found that 50% ethanol - 50% water worked well. As mentioned heating was stopped after the metallic chloride solution dried to avoid the coating going to the oxide. A dark brown or black color may indicate oxide formation.
  • Other coatings can be applied, such as magnesium peroxide, silver chloride, and Manganese oxide.
  • the metallic chloride and ammonium hydroxide coatings can be applied in a variety of ways, for example immersion of the filter media is appropriate solutions or contact of filter media with saturated vapors. It was found that misting provides a uniform coating, but other application techniques, for example immersion, may be more practical for large volumes.
  • fiberglass filter media can be precipitated with metallic
  • (hydr)oxides This embodiment is particularly advantageous for porous filters where misting can adequately wet the filter matrix.
  • Heated air can be passed through the filters in order to raise the temperature of the substrates to be coated to about 80 °C.
  • a mist of a solution preheated ( about 80°C) of 0.25M ferric chloride and 0.5 M aluminum chloride in a 50 % ethanol solution can then be sprayed onto the filter surface.
  • Other combinations of metallic chlorides and/or sulfates can also be used.
  • the hot air can continually be blown through it while the solution is sprayed.
  • the solution is preferably sprayed evenly and sporadically to allow even drying. Heating can be continued throughout the spraying process.
  • the surface of the solid substrate can be evenly treated and fully coated with a dry film of, for example, the metal chloride or metal sulfate. Again, excessive heating should be avoided in order to avoid forming the corresponding metallic oxides.
  • the coated material may sustain a yellowish brown coloration when adequately coated.
  • a basic solution can then be applied.
  • the solids can then be sprayed by a mist of a 3.0 M ammonium hydroxide solution or exposed to saturated vapors of ammonium hydroxides while being heated. This forms the corresponding precipitate of metallic (hydr)oxides onto the surface. Drying by the passing of hot air can be continued until the filter is dry.
  • the coated solids can then be rinsed in deionized water and dried. After drying, they are ready for use.
  • the subject coating methods can also be applied to would fiber filters such as those used under a sink for filteringtap water. These filters are often made from a dense filter media such as cellulose, where misting can be inadequate to wet the filter matrix.
  • the substrates can be heated to preferably about 80° C.
  • a preheated (about 80°C) solution of 0.25M ferric chloride and 0.5 M aluminum chloride in a 50 % ethanol solution can be passed through the filter.
  • the filter is preferably saturated with the solution.
  • a contact time of 10 min allows adequate contact, although longer or shorter periods can also be utilized. Heating can be continued during the contact time. Hot air can then be passed through the filter to flush the excessive solution. The passing of the hot air can be continued until the filter is thoroughly dried.
  • the filter should now be evenly treated and fully coated with a dry film of the metal chloride. Excessive heating should be avoided in order to avoid the corresponding metallic oxides.
  • the coated material can sustain a yellowish-brown coloration when adequately coated.
  • a solution of a 3.0 M ammonium hydroxide preheated to about 80 °C can then be passed through the filter rapidly or saturated vapors of ammonium hydroxides can be passed through the filters while being heated. This forms the corresponding precipitate of metallic hydroxides on the surface.
  • Hot air can then be passed through the filter to remove excessive liquid and dry the filter.
  • the coated solids can be rinsed in deionized water and dried. Once dry the coated solids are ready for use. Following are examples which illustrate procedures for practicing the invention. These examples should not be construed as limiting. All percentages are by weight and all solvent mixture proportions are by volume unless otherwise noted.
  • the filters used in this example are melt-blown microporous polypropylene disk filters with a diameterof25 mm (Millipore,MA).
  • the average pore sizes are 0.6 ⁇ m (AN06), 1.25 ⁇ m (AN 12), 2.5 ⁇ m (AN25), 5.0 ⁇ m (AN50), and 10.0 ⁇ m (AN1H).
  • These filters were treated with a two-tailed water insoluble cationic surfactant, dimethyldioctadecylammomiun bromide (DDAB), by first dissolving the surfactant in methanol and then soaking the filters in the methanol solution (4 ml per filter) for 3 hours. After the 3-hour treatment, the filters were vacuum dried overnight.
  • DDAB dimethyldioctadecylammomiun bromide
  • the filters were flushed with 30 ml of distilled water to remove excess and/or loose surfactants from the filter surface.
  • the average pore diameters were supplied by the manufacturer.
  • Dimethyldioctadecylammonium bromide was purchased from Sigma Chemical Company (St. Louis, M0) and used without further purification.
  • the nanoparticles were purchased from Bangs Labs, Inc.(Carmel, IN).
  • the negatively charged particles, P(S/A V-COOH) are composed of polystyrene, an acrylic polymer (unspecified), a vinyl group (unspecified polymerizable group), and a functional carboxylate group.
  • the average diameter and surface charge density of these nanoparticles are 60 ⁇ 3.6 nm and 365 ⁇ eq/g, respectively, and 197 nm (no standard deviation given) and 141 ⁇ eq/g, respectively.
  • the positively charged particles are quaternary ammonium modified polystyrene particles (P(S/Quat Ammonium)) with an average diameter of 200 nm and a surface charge density of 121 ⁇ eq/g.
  • Particle concentrations (wt% solids) were measured by UV absorbance with a Hewlett Packard 8453 UV/VIS spectrophotometer at a wavelength of 255 nm.
  • AN06 (0.6 ⁇ m) filters were treated with different concentrations of DDAB accordingto the procedure mentioned above. After the filters were rinsed with 30 ml of distilled water, they were cut into four strips. The strips were then submerged onto a rectangularpiece ofPMMA (4 mm in thickness) in a 50 ml beaker(Pyre No. 1000) containing 20 ml of distilled water. A drop, approximately 1.5 ⁇ l, of 1 , 1 ,2,2-tetrabromoethane was placed on top of the filter with a microsyringe.
  • the contact angle of the droplet was measured with a contact angle goniometer. Six readings at different locations on the filter surface were taken with each of the filters to get an average contact angle value. Zeta potential of the filters were measured with the Brookhaven BI-EKA Electrokinetic Analyzer on loan for equipment evaluation (Brookhaven Instruments Corporation, New York).
  • the filters both untreated and treated AN06, were rinsed with 30 ml of deionized distilled water. Each filter was then soaked in 25 ml of a particle suspension containing 0.012 wt% solids (2.8xl0 10 particles/ml) of 197 nm P(S/A/V-COOH) or 200 nm P(S/Quat Ammonium) for 30 minutes. The filter was then removed from the suspension and rinsed in 100 ml of distilled water and then vacuum dried overnight before it was coated with gold for scanning electron microscopy. SEM pictures were taken with a Hitachi S4000 Field Emission Scanning Electron Microscope (Tokyo, Japan). Particle analysis was performed on a Macintosh computer using the public domain NIH Image program (developed at the U.S.
  • Filtration was accomplished by using a stainless steel filter holder, a 12-ml glass syringe and a syringe pump with variable speed control (Dual Infusion/Withdrawal Pump, Model 944,
  • Microporous polypropylene filters were coated with a monomolecular layer of dimethyldioctadecylammonium bromide (DDAB) to give them a positively charged surface.
  • DDAB dimethyldioctadecylammonium bromide
  • Contact angle was used as a measure of the amount of DDAB adsorption at the surface of the filters. For smooth, nonporous planar solids, contact angle measurements can be easily accomplished by placing a droplet of liquid such as carbon tetrachloride on the surface of the substrate and measuring the angle by using a microscope fitted with a goniometer eyepiece.
  • contact angle measurements is a little more difficult.
  • carbon tetrachloride should not be used because it is too hydrophobic and is absorbed into the fibers upon contact.
  • a preferable liquid that is suitable for this material is 1 , 1 ,2,2-tetrabromoethane.
  • the surface of a microporous filter is not smooth. Surface roughness can increase or decrease the contact angle. For wetting surfaces, ⁇ ⁇ 90°, surface roughness reduces the contact angle, but increases for non-wetting surfaces (Davies et al., 1961). For this reason, an average of six readings were taken at different locations on the filter surface. High contact angle can indicate that the surface is hydrophilic.
  • low contact angle can mean that the surface is hydrophobic.
  • the average contact angle for the untreated filters was approximately 25°.
  • the 5 mM DDAB solution treated filters had the lowest contact angles among the treated filters, and the 10 mM DDAB treated filters had the highest contact angles. Since the standard deviation of these measurement were very large, the difference in 10 and 20 mM DDAB treated filters were not very significant. Therefore, the 10 mM treatment was chosen as the standard method of treatment for the filters.
  • the adsorption strength of the cationic surfactant was tested by flushing the treated filters with different amounts of water and then measuring the contact angles. The amount of water pumped through the filters did not have a significant effect on the contact angle, which indicated that the surfactantwas not desorbing. The effluents were collected for surface tension measurements. The results indicated that the surfactantwas not desorbing as detected by surface tension measurements. From previous experiments, it has been shown that 2.5x10 "5 moles/L of the surfactant in water decreased the surface tension of water from 72.4 to 43.9 dynes/cm. Therefore, surface tension method is able to detect DDAB in the range of micromoles per liter of water.
  • both the filters and the particles are nonconductive, they were coated with gold before scanning electron micrographs were taken. Due to the limitation of the method and availability of the particles, adsorption of particles of larger sizes ( 197 nm and 200 nm) than those used in the actual filtration experiments (60 nm) were studied.
  • the zeta potential of the untreated filters indicated that the filters were slightly negatively charged.
  • the untreated and 10 mM DDAB treated AN06 filters were made by a melt-blown process and were fibrous. Since the untreated filters are slightly negatively charged, negatively charged particles will not adsorb on the surface due to the electrostatic repulsion, but positively charged particles will adsorb due to the electrostatic attraction. Experimental results confirm this.
  • Filtration efficiency or percent removal was significantly enhanced with DDAB treatment.
  • the filtration efficiency ranged from 5% to 10%, but after the filters were treated with 10 mM DDAB, filtration efficiency increased to 50% or 60% for the lower initial concentration range.
  • the increase in capture efficiency was mainly due to the electrostatic attraction between the negatively charged particles and the positively charged polar head of the surfactant molecules on the filter surface. Since the average pore size was 0.6 ⁇ m, the increase in capture efficiency was partly due to the smaller pore size in certain regions of the filters due to surfactant adsorption in clusters.
  • the treated filters were flushed with pH 10.0 solution.
  • the effluents were collected for surface tension measurements. If the DDAB was desorbing, then surface tension of the effluents should have been lower than the pure water due to the surfactants at the surface. Results indicated that there was no change in surface tension of the effluents. Further proof that the surfactants were not desorbing was offered by contact angle measurements. Even with 200 ml of pH 10.0 solution flush, the average contact angle of the surface, 70.7 ⁇ 12.7 degrees, remained approximately the same as those that were flushed with 30 ml distilled water.
  • the filters were rinsed with 30 ml of pH 10.0 solution, followed by 20 ml of distilled water, and then used to filter particles at pH 4.0. Results indicated that the filters were just as effective as those that were rinsed with distilled water, which is another indication that the surfactant was not desorbing at the higher pH values.
  • the subject invention pertains to a novel method for coating filter media with precipitates of metallic hydroxides and/or metallic oxides and the resulting coated filter media.
  • the resulting coated filter media can be utilized in, for example, survival or personal water purification devices, household water filters, air filters, water reclamation filter media, water remediation processes, soil remediation processes, viral removal filters, and protective clothing.
  • Fiberglass air filters, woven and nonwoven filters or fabrics, sand, and diatomaceous earth were coated in this experiment, as already discussed above. Their removal efficiencies were determined for the individual contaminants studied.
  • This example pertains to the use of surfactant treated polypropylenefilters for filtration of bacteria and bacteriophages.
  • Two different types of bacteria and three different types of bacteriophages were chosen for experiments to determine the effectiveness of such filtration.
  • the two bacteria were Staphylococcus aureus (ATCC 12600), a gram-positive bacterium, and Escherichia coli (ATCC 15597), a gram-negative bacterium.
  • Bacteriophages were used as surrogates for human pathogens. Three well-studied phages were chosen to represent a wide range of properties that human pathogens may have.
  • the phages and their respective hosts were MS2 (Escherichia coli C-3000), ⁇ X- 174 (Escherichia coli KC), and PRD-1 (Salmonella typhimurium).
  • MS2 Esscherichia coli C-3000
  • ⁇ X- 174 Esscherichia coli KC
  • PRD-1 Salmonella typhimurium
  • a comparison between MS2 and PRD-1 can assist to delineate the effect of size of viruses and that between MS2 and ⁇ X-174 can help reveal the effect of isoelectric point or charge characteristics. All of the filtration efficiency and filter coefficient calculations are based on the number of viable bacteria and bacteriophages.
  • the microporous polypropylene filters can be treated as earlier described in Example 1.
  • AN25 filters which has mean pore diameter of 2.5 ⁇ m, were used. By using larger pore size filters, pressure drop can be decreased and leakage through the filter holders minimized.
  • multiple layers of filters can be used.
  • the bacteria used for the experiments were grown overnight in a 3% tryptic soy broth and then diluted by a factor of 1000 in a buffer made of 0.02 M imidazole and 0.02 M glycine and adjusted with HC1 to pH 7.0. This gives approximate initial concentrations of 2x 10 5 for S. aureus and lxlO 5 for E. Coli.
  • the filtration apparatus consisted of a variable speed Infusion- Withdrawal Syringe Pump (Harvard Apparatus Co., MA), six 25 mm stainless steel filter holders (Fisher Scientific) connected in series, and plastic valves and connectors for sampling ports. Each filter holder contained 1 layer of the polypropylene filter. The filters were oriented vertically and the flow direction was upward so that no air bubbles would be trapped in the filters or in the line. The flowrate was kept a constant flow of 10 ml/minute. A total of 120 ml of contaminated water was pumped through the filters. After approximately 20 ml of the contaminated water had passed through the filters, the first sample was taken starting from port 1 on the bottom.
  • the untreated prolypropylene filter is negatively charged in the range of pH 4.0 to 10.0, where the 10-mM DDAB treated filter, on the other hand, is positively charged in the same pH range. Results of the filtration of both E. coli and S. aureus are shown. The 10 mM surfactant treated filters had much better bacterial removal than the untreated filters. The data points are fitted with the following equation in order to obtain the filter coefficient: ⁇ l -e -XL
  • ⁇ is the filtration efficiency or percent removal
  • C ⁇ is the initial concentration in colony forming units per milliliter (CFU/ml) for bacteria and plaque forming units (PFU/ml) for phages
  • C out is the final concentration
  • L is the length of the filter in units of number of layers
  • ⁇ is the filter coefficient with units of 1/layer of filter. Converting the results into filter coefficients is desirable for comparing the effectiveness of the different coatings for bacterial removal.
  • the filter coefficients and coefficients of linear regression are shown in Table 3-2. The coefficient of linear regression indicates how well the data points are fitted to the filtration equation, with a value of 1.0 being a perfect fit.
  • the filter coefficients of the untreated filters are 0.485 and 0.353 [1 /number of filters] in the filtration of S. aureus and E. Coli, respectively.
  • the filter coefficients of the lO mM DDAB treated filters are 1.039 and 0.896 in the filtration of S. aureus and E. Coli, respectively. From the filtration equation, it is obvious that the higher the filter coefficient, the better the filtration efficiency.
  • the filter coefficients as defined in this application have units of 1/number of filters. In the filtration of S. aureus, there is a 1 14% improvement in the filter coefficient. In other words, to obtain the same percent removal of S. aureus, the untreated filters would require 114% more layers of filters than the surfactant treated filters. For the filtration of E. coli, the improvement in filtration coefficient is even more significant than the improvement for S. aureus. The improvement for E. coli filtration was 154%.
  • the results for both the untreated and treated filters have a high degree of scattering or standard deviation.
  • the data for the untreated filters have a very poor fit, R 2 of 0.28 to 0.38, when fitted to Equation 3-1.
  • the isoelectric points (IEP), the pH at which the zeta potential is zero, of bacteriophageMS2, PRD-1 and ⁇ X-174 are 3.9, 4.2 and 6.6, respectively. At pH values below the isoelectric points, the phages are positively charged and at pH above the isoelectric points, they are negatively charged.
  • the filter coefficients for the untreated polypropylenefilters are 0.062, 0.069 and 0.069 forthe filtration of MS2, PRD- 1 and ⁇ X- 174, respectively. As expected the filter coefficients are very low because the phages are much smaller than the bacteria. In addition, the filter coefficients for the filtration of the three different phages for the untreated filters are the same because removal is negligible and probably due to straining or entrapment mechanism.
  • the filter coefficients are 0.345, 0.269 and 0.084 for the filtration of MS2, PRD-1 and ⁇ X- 174, respectively.
  • MS2 there is an improvement of 458% in the filter coefficient.
  • PRD-1 there is an improvement of 288% in filter coefficient, and in the filtration of phage ⁇ X-174 a 22% improvement is obtained.
  • This small improvement is within the standard deviation and therefore, surface modifications based on Coulombic interaction may not be helpful in the filtration of phage ⁇ X- 174. This is possibly due to the fact that the phage is very close to its isoelectric point (i.e. pH 6.6).
  • Bacteriophage MS2 has the lowest isoelectric point and the highest filter coefficient. These results reinforced the idea that electrostatic attraction is an important factor in bacterial and viral adso ⁇ tion to surfaces. Since the concentrations used in the experimentswere too low for the bacteriato be seen on the filter surface under higher magnification, the filters were soaked in a solution containing high concentrations (lx 10 7 CFU/ml) of both E. coli and S. aureus for 30 minutes. After soaking in the solution for 30 minutes, the filters were thoroughly washed three times with deionized water. They were then placed in a container containing osmium tetraoxide vapor for two days to fix the cells so that they would not burst, rupture or shrink in the drying stage. The filters were then air-dried and coated with gold for SEM analysis. By looking at the wettability of the filters, it appeared that the filter wettability was not uniform throughout the whole filter.
  • Polyester yam has many consumer and industrial uses, including clothing, tire cord thread, conveying belts, wate ⁇ roof canvas, and fishing nets.
  • Microdenierpolyestertextile fabric was chosen for the filtration of nanoparticles and biological particles because it is readily available, and it is tenacious. Therefore, it can handle high flowrates and high pressure drops.
  • Microdenierpolyestertextile fabric because it is textured and woven, it increases the tortuosity of the flow path and therefore increases the probability that particles will collide with the surface of the filters.
  • microdenier polyester and “polyester” will be used interchangeablythroughout the discussion of experimental result in this application since only one type of yam was tested.
  • Other terms, which will have the same meaning in this context are bacteriophages, phages and viruses.
  • Bacteriophages or phages are host-specific viruses. Therefore, they will be used interchangeably.
  • the microdenier polyester fabric used in the subject experiments consists of a 2 x 2 right-hand twill, weighing approximately 5.5 ounces per square yard and constructed from a microdenier 1/140/200 textured polyester yam, Type 56T Dacron® from DuPont in the wa ⁇ direction and a microdenier 1/150/100 textured polyester yam, Type 56T Dacron® from DuPont, in the filling direction.
  • the fabric construction was 76 picks in the filling direction and 176 ends in the wa ⁇ direction.
  • the fabric was cut into 25-mm circles with a die cutter before the surfactant treatment was applied. Once the filters were cut into circles, they were treated with a 10 mM DDAB solution using procedures described earlier in.
  • the zeta potentials of the untreated and 10 mM DDAB treated microdenier polyester filters were measured with a streaming potential apparatus. Six layers of the fabric were used in each measurement. The untreated filters are negatively charged from pH 4 to pH 9.0 while the surfactant treated polyester filters are positively charged in the same pH range.
  • the apparatus is the same as that for the filtration experiments. The flowrate was kept at a constant rate of 10 mi/minute and the pressure at each port was measured with a digital pressure gauge. From these pressures, the pressure drop for each filter holder (4 layers of fabric filters) was calculated.
  • the standard deviations are larger than the surfactant treated filters.
  • the pressure drops ranges from 0.7 psi for 4 layers of filters to 3.1 psi for 24 layers of filters.
  • the pressure drop is much lower due to the increase in wettability of the textile fabric.
  • the pressure drops of the surfactant treated filters are 0.2 psi and 1.1 psi for 4 layers and 24 layers of the fabric filters, respectively. The decrease in pressure drop with the surfactant treatment is beneficial because it will require less energy to pass the liquid through the filters. Essentially, for the same pressure drop, more throughputs can be achieved.
  • the gram-positive bacterium was E. coli and the gram-negative was S. aureus. These bacteria were prepared accordingto the procedures described in Example 3. Filtration was done at pH 7.0 using a 0.02 M imidazole-glycinebuffer. The initial concentrations of the bacteria were approximately lxlO 5 CFU/ml for both bacteria. Flowrate was maintained at a constant rate of 10 mi/minute with the use of a syringe pump. Samples were collected at three separate times and each sample was plated in duplicate. In general, the standard deviations of the untreated filters are larger than those of the surfactant treated filters. Also, the results of the first four layers always has a higher degree of scattering when compared to the rest of the filters. This is a common problem in filtration experiments, probably due to the fact that the flow has not been fully developed at the entrance of the set-up.
  • the filter coefficients of the untreated polyester fabric filters are 0.085 and 0.055 [1 /filter] for the filtration of S. aureus and E. coli, respectively.
  • the process is not transport or diffusion limited because of the repulsive barrier between the bacteria and the filter surface. Since there is a difference in the filter coefficient or filter efficiency of the untreated filters, factors other than Coulombic interaction are probably involved. It is possible that hydrophobic or other specific interactions are involved.
  • the filter coefficients are 0.251 and 0.238 for the filtration of S. aureus and E. coli, respectively. Within experimental errors, these two numbers can be considered to be identical.
  • the surfactant treatment improved the filter coefficient by 195% for the filtration of S. aureus and 330% for the filtration of E. coli.
  • the filter coefficient of the untreated filters for the filtration of MS2, PRD- 1 and ⁇ X-174 are 0.008, 0.005 and 0.009, respectively. Because of the large scattering of the data for the untreated filters, the coefficients are statistically the same. The viruses or phages are not expected to adsorb to the surface of the untreated filters. Therefore, the removal is likely due to straining or entrapment of the particles in the structure of the filters. For the surfactant treated filters, however, the results of the different phages are very different.
  • the filter coefficients are 0.268, 0.158 and 0.018 for the filtration of MS2, PRD-1 and ⁇ X-174, respectively.
  • the isoelectric point of bacteriophage MS2, PRD-1 and ⁇ X-174 are 3.9, 4.2 and 6.6, respectively. Looking at these numbers, MS2 has the lowest isoelectric point, followed by PRD- 1 and then ⁇ X174.
  • MS2 should be the most negatively charged ph age at the experiment condition, follow by PRD- 1 and ⁇ X- 174. Due to this high charge density, MS2 has the highest adso ⁇ tion to the filter.
  • the surfactant treatment increases the filter coefficient by 3300%>, which means that to obtain the same percentage removal of MS2, the length (or number of filter in this case) of the untreated filters must be 33 times longer than the treated filters.
  • the filter coefficient improves by 2800% in the filtration of phage PRD-1. In the filtration of ⁇ X-174, the filter coefficient improves by only 98%. This improvement is rather insignificant because the standard deviation is fairly high.
  • ⁇ X-174 is one of the most difficult phage to remove from aqueous and air streams because of its poor adhesion to surfaces.
  • the first layer was examined with a scanning electron microscope after 1.0 L of the bacterial solution, containing both S. aureus (approximately lx 10 5 CFU/ml) and E. coli (approximately lxl 0 5 CFU/ml), had passed through it.
  • the filter was then rinsed with deionized water in a beaker to remove loose bacteria from the surface.
  • the wet sample was prepared for SEM analysis by placing the contaminated filter in a chamber saturated with osmium tetraoxide vapor for 2 days. The filter was then taken out and allowed to dry overnight.
  • the untreated filters are negatively charged and, therefore, may actually repel the bacteria rather attractthem.
  • the surfactant treated filters are positively charged and, therefore, the bacteria are likely attracted to the filter surface.
  • Example 5 Removal of Microorganisms from Water by Sand Coated with Ferric and Aluminum Hydroxides.
  • the source of sand was "All Pu ⁇ ose Sand" from Pebble Junction, Division of Delaware
  • sand was sieved to a size less than 100 mesh before use.
  • the sand was soaked in one of the following solutions: aluminum chloride or ferric chloride (Fisher Scientific, Pittsburgh, PA) at concentrations of 0.05 M, 0.1 M, 0.5 M, or 1.0 M. In some tests a combination of 1.0 M ferric chloride and 1.0 aluminum chloride was used.
  • the coating was applied with heat and agitation similar to temperatures and agitation described in Examples 2 and 6. Sufficient solution was used to completely cover the sand. After 30 minutes, the solution was poured off and the sand was allowed to dry. Occasional stirring was used to break up the clumps that formed and ensure that the sand was thoroughly dry.
  • Escherichia coli ATCC 13607 was obtained from the American Type Culture Collection and was used in batch and column adso ⁇ tion experiments. Escherichia coli was routinely grown in Tryptic Soy Broth (Difco Labs, Detroit, MI) and assayed using MacConkey Agar (Difco Labs, Detroit, MI). A Vibrio cholera strain 124 isolated from Chillon River, Lima, Peru, was supplied by Dr. Tamplin of Department of Food Science at the University of Florida . It was grown in Tryptic Soy Broth and assayed using Tryptic Soy Agar (Difco Labs, Detroit, MI) plates containing 1% sodium chloride (pH 7).
  • Poliovirus 1 (strain LSc-2ab) was grown on buffalo green monkey (BGM) cells and assayed as plaque forming units (PFU) by using an agar overlay technique (Smith and Gerba, 1982).
  • BacteriophageMS-2 was grown on Escherichia coli C-3000 (ATCC 15597) and assayed by soft agar overlay (Snustad and Dean, 1971).
  • Modified or untreated sand was packed in columns of different sizes. The sizes of columns used and the weight of dry sand added were as followed: A. Small: 10 X 2.5 cm with 80g sand; B: Large: 35 X 5 cm, with 1kg sand. Glasswool (Fisher Scientific, Pittsburgh, PA) was placed in the bottom of each columns. Before being used in experiments, deionized water was passed through the columns till the unbound metallic hydroxide was removed and the column effluents were clear and free of precipitates.
  • Samples were passed through the columns by using gravity flow (small-sized columns) or under a positive pressure by pressurized nitrogen gas ( large-sized columns). In small-sized columns, 160 ml of samples were separately passed through the columns. Samples of 40 ml were collected and assayed. The initial samples, the column effluents, and the rinse were assayed to determine the removal efficiency. In the large-sized columns, four liters of sample was passed through the columns at 450 ml/min. After the passage of the first 500 ml, we assayed the column effluents. Both the initial samples and the column effluents, were assayed for bacteria or viruses.
  • Modified or unmodified sand (5 g) was mixed with 7 ml of one of each of the following buffers that had been seeded with E. coli or MS-2: A: 0.02M imidazole and 0.02M glycine, pH 7; B: Buffer A + 0.1M sodium citrate, pH 7; C: Buffer A + 0.1% teen 80, pH 7; D: Buffer A + 0.1M sodium citrate, 0.1% teen 80, pH 7).
  • the samples were mixed on a rotary shaker at approximately 100 ⁇ m for 15 minutes. The initial and final supernatant were assayed. Microorganisms were also added to the buffer samples without sand as controls.
  • Modified or unmodified sand (5 g) was shaken with 7 ml of buffer (0.02M imidazole and 0.02M glycine, pH 7) that had been seeded with E. coli or MS-2 at approximately 100 ⁇ m for 15 minutes. After this period of adso ⁇ tion, the supernatant was removed and assayed. Next, 7 ml of one of each of the following buffers was added: A: 0.02M imidazole and 0.02M glycine, pH 7; B: Buffer A + 0.1M sodium citrate, pH 7; C: Buffer A + 0.1% teen 80, pH 7; D: Buffer A + 0.1 M sodium citrate, 0.1% teen 80, pH 7; E: 3% beef extract, pH 7).
  • the samples were shaken for another 15 minutes at 100 ⁇ m on a New Brunswick Scientific orbital shaker.
  • the initial seeded buffer, the supernatant sample from the adso ⁇ tion step, and the supernatant samples from the elution steps were assayed.
  • the buffer samples without sand were seeded with E. coli and MS-2 and shaken for 15 minutes to observe their effects on the test organisms.
  • Standard deviations, slopes, correlation and general t test probabilities were determined using PSI-Plot software (Poly Software International, Salt Lake City, Utah).
  • Adso ⁇ tion were conducted m the presence of the buffer that contained 5 93 ⁇ 0 15 log, 0 cfu/ml E colt and 5 28 ⁇ 0 48 log 10 pfu/ml MS-2 Buffers 0 02 M imidazole and 0 02 M glycine, pH 7, all the chemical solutions were made in this buffer and were adjusted to pH 7 Values represent the mean and standard deviation for triplicate determinations (5 g 100 mesh sand treated with 1M FeCl 5 + 1M A1C1 5 ) For each column, values followed by the same letter were not significantly different then P > 0 05 level
  • Adso ⁇ tion were conducted in the presence of the buffer that contained 5.93 ⁇ 0.15 log 10 cfu/ml. __ coli and 5.28 ⁇ 0.48 log 10 pfu/ml. MS-2. Buffers: 0.02 M imidazole and 0.02 M glycine, pH 7; all the chemical solutions were made in this buffer and were adjusted to pH 7. Values represent the mean and standard deviation for Triplicate determinations (5 g. 100 mesh sand treated with 1M FeCl 5 + 1M
  • Bacterial Cultures The following bacterial strains were used in removal studies Eschertchiacoli C-3000 (ATCC 15597), which was routinely grown in Tryptic Soy Broth (TSB) and assayed using MacConkey Agar (Difco Labs, Detroit, MI), and Staphylococcus aureus (ATCC 12600), which was grown on TSB and assayed on Manitol Salt Agar (Difco Labs, Detroit, MI)
  • Polio virus 1 (strain Lsc), Echo virus 1 , and Coxsackie B5 virus were grown on buffalo green monkey (BGM) cells and assayed as plaque forming units (PFUs) by using an agar overlay technique (Smith and Gerba, 1982) Rotavirus SA1 1 was grown with serum free media on MA 104 Cells and assayed using Most Probable Number software (Environmental Protection Agency, 1994) The following bacteriophages and their host bacteria were used MS2 (Escherichia coli C-3000, ATCC 15597), ⁇ X 174 (Escherichia colt, ATCC 13607), PRD-1 (Salmonella typhimunum, ATCC 19585) Bacteriophages were grown on their respective hosts and assayed by soft agar overlay (Snustad and Dean, 1971)
  • Protozoan parasites Viable oocysts of Cr ⁇ ptospondium parvum were obtained from Waterborne Inc ( New Jersey, LA)
  • CryptoglowTM stain Waterborne Inc, New Jersey, LA
  • Filter set up and water samples Two identical filtration systems were used, one contained sand modified as described above and the other contained unmodified sand Each filter system consisted of a Po ⁇ oise 180 commercial swimming pool filter (Po ⁇ oise, Jacksonville, FL.) that was run by a 40 gal./min. timer controlled electrical pump connected to 100 gallon water container. Each filter contained 220 Kg of sand in a 0.05 M 3 area. Tap water was circulated through the filter for 5 hours per day during the 170 day test period. A total chlorine residual of 2 ppm was maintained in the water tanks while the filters were running. Ten times that residual was used for super chlorination at monthly intervals to mimic swimming pool treatment practices. Tank water was frequently changed, and samples were taken for metal analysis.
  • Cryptospo dium oocysts were reduced by 51% in one pass experiments and by 95% following recirculation through the filter containing treated sand. Under the same conditions, percent reductions of 21% and 37% of Cryptosporidium oocysts were obtained by filters containing unmodified sand.
  • Filter effluents always contained less than 0.01 mg/1 of iron or aluminum ions even when the 50 gallons of water was circulated for 50 hours through the filter.
  • a preferred procedure involves soaking the polyester filters in FeCl 3 , drying the filters overnight, and then precipitating the iron oxides, for example, with a strong ammonium hydroxide solution. The filters can then be dried in a vacuum oven.
  • the preferred FeCl 3 concentration was determined to be about 0.4 M.
  • the preferred concentration of NH 4 OH used was about 2 M. These concentrations were chosen to allow the maximum amount of coating to be deposited on the filter surface without clogging the filters.
  • the zeta potential of the iron oxide coated filters is positive below pH 4
  • the isoelectric point of the treated filters is approximately 4 5
  • the treated filters are slightly less electronegativethan the untreated filters
  • the treated filters were more wettable than the untreated filters
  • the pressure drop of the untreated filters was 0 8 psi across 4 layers of filters and 3 3 psi across 24 layers of filters
  • the pressure drop of the iron oxide treated filters was only 0 1 psi across 4 layers of filters and 1 2 psi across 24 layers of filters
  • the pressure drop of the treated filters was significantly lower than the untreated filters

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Filtering Materials (AREA)

Abstract

La présente invention concerne de nouveaux procédés de filtration, de nouveaux procédés de production de filtres, et de nouveaux filtres permettant une filtration efficace de particules. Les matériaux et les procédés de la présente invention sont particulièrement avantageux pour la filtration de particules submicroniques, par exemple, des nanoparticules, et ils peuvent utiliser l'atraction électrostatique entre les particules et les fibres des filtres microporeux, par exemple, des filtres en polypropylène. Les procédés de filtration de l'invention peuvent réduire la barrière d'énergie entre les particules et la surface des filtres et accroître ainsi le dépôt de particules sur la surface du filtre. Les procédés et l'appareil de l'invention peuvent être utilisés pour filtrer des particules provenant de nombreux fluides notamment de l'eau et de l'air. De manière avantageuse, les filtres modifiés en surface de l'invention permettent d'obtenir un écoulement de fluide accru, pour la même chute de pression, comparé aux filtres classiques.
EP99946750A 1998-09-03 1999-09-03 Nouveaux procedes et appareil de filtration amelioree de particules submicroniques Withdrawn EP1044051A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US9892498P 1998-09-03 1998-09-03
US98924P 1998-09-03
PCT/US1999/020352 WO2000013764A1 (fr) 1998-09-03 1999-09-03 Nouveaux procedes et appareil de filtration amelioree de particules submicroniques

Publications (1)

Publication Number Publication Date
EP1044051A1 true EP1044051A1 (fr) 2000-10-18

Family

ID=22271590

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99946750A Withdrawn EP1044051A1 (fr) 1998-09-03 1999-09-03 Nouveaux procedes et appareil de filtration amelioree de particules submicroniques

Country Status (3)

Country Link
EP (1) EP1044051A1 (fr)
BR (1) BR9906684A (fr)
WO (1) WO2000013764A1 (fr)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7488520B2 (en) 2003-10-16 2009-02-10 Kimberly-Clark Worldwide, Inc. High surface area material blends for odor reduction, articles utilizing such blends and methods of using same
US7837663B2 (en) 2003-10-16 2010-11-23 Kimberly-Clark Worldwide, Inc. Odor controlling article including a visual indicating device for monitoring odor absorption
US7794737B2 (en) 2003-10-16 2010-09-14 Kimberly-Clark Worldwide, Inc. Odor absorbing extrudates
US7754197B2 (en) 2003-10-16 2010-07-13 Kimberly-Clark Worldwide, Inc. Method for reducing odor using coordinated polydentate compounds
US7879350B2 (en) 2003-10-16 2011-02-01 Kimberly-Clark Worldwide, Inc. Method for reducing odor using colloidal nanoparticles
US7678367B2 (en) 2003-10-16 2010-03-16 Kimberly-Clark Worldwide, Inc. Method for reducing odor using metal-modified particles
US7413550B2 (en) 2003-10-16 2008-08-19 Kimberly-Clark Worldwide, Inc. Visual indicating device for bad breath
EP2062978A1 (fr) * 2007-11-23 2009-05-27 Nederlandse Organisatie voor toegepast- natuurwetenschappelijk onderzoek TNO Système de détection de contamination microbienne
US9309131B2 (en) * 2012-06-27 2016-04-12 Argonide Corporation Aluminized silicious powder and water purification device incorporating same
US20160228825A1 (en) * 2013-10-07 2016-08-11 Novartis Ag Treated filter

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4652379A (en) * 1978-09-05 1987-03-24 Ture Hultman Filtering impurities from liquid using mineral wool fiber material
JPS5556814A (en) * 1978-10-23 1980-04-26 Mitsubishi Heavy Ind Ltd Impregnated material for dust-preventing filter
FR2497685B1 (fr) * 1981-01-09 1985-12-20 Inst Rech Hydrologiques Procede de traitement d'un liquide par passage a travers un lit de particules solides
US4747955A (en) * 1987-04-13 1988-05-31 The Graver Company Purification of liquids with treated polyester fibers
JPH05123513A (ja) * 1991-11-07 1993-05-21 Mitsubishi Paper Mills Ltd エアフイルター用ガラス繊維シート及びその製造方法
JPH05188053A (ja) * 1992-01-10 1993-07-27 Sanwa Kagaku Kenkyusho Co Ltd 血液から血清又は血漿成分を分離する器具
RU2058812C1 (ru) * 1992-07-29 1996-04-27 Физико-Химический Институт Защиты Окружающей Среды И Человека Способ получения фильтрующего материала
JP3222683B2 (ja) * 1994-03-22 2001-10-29 憲司 中村 エアーフイルター

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0013764A1 *

Also Published As

Publication number Publication date
WO2000013764A1 (fr) 2000-03-16
BR9906684A (pt) 2000-10-17

Similar Documents

Publication Publication Date Title
Lukasik et al. Removal of microorganisms from water by columns containing sand coated with ferric and aluminum hydroxides
Sriram et al. Naturally available diatomite and their surface modification for the removal of hazardous dye and metal ions: a review
CA1169234A (fr) Milieu filtrant; methode d'oxydation et d'extraction du fer soluble; methode d'extraction et d'inactivation de micro-organismes; adjuvant de filtration de particules
Das et al. Nano-silica fabricated with silver nanoparticles: antifouling adsorbent for efficient dye removal, effective water disinfection and biofouling control
US4396512A (en) Bacteriostatic filter media
Paprowicz et al. Application of biologically activated sorptive columns for textile waste water treatment
CA2519235C (fr) Support de filtre a capacite d'interception microbiologique amelioree
US20110139726A1 (en) Filtration media coated with zero-valent metals, their process of making, and use
CA2437721A1 (fr) Compositions de mineraux contenant du magnesium insoluble destinees a etre utilisees pour la filtration de fluides
Hsieh et al. Addition of biochar as thin preamble layer into sand filtration columns could improve the microplastics removal from water
EP1044051A1 (fr) Nouveaux procedes et appareil de filtration amelioree de particules submicroniques
Zhang et al. Improved removal performance of Gram-negative and Gram-positive bacteria in sand filtration system with arginine modified biochar amendment
Luziana et al. Production of adsorbent from activated carbon of palm oil shells coated by Fe3O4 particle to remove crystal violet in water
US6896813B1 (en) Sorbant sequestration and removal of toxic metal ions
AU2002333995B2 (en) Use of a material based on organic and/or inorganic fibres and chitosan for fixing metal ions
Wang et al. Bacterial capture and inactivation in sand filtration systems with addition of zero-valent iron as permeable layer under both slow and fast filtration conditions
GB2051770A (en) Bacteriostatic filter media
DE69936139T2 (de) Verfahren zur reinigung von wasser
MXPA00004316A (en) Novel methods and apparatus for improved filtration of submicron particles
Nasr et al. Application of activated carbon fibers for removal of iron and lead salts from waste water
Anjum et al. Arsenic removal from water: an overview of recent technologies
Walsh et al. Blending membrane treated WTP waste residuals with finished water: impacts to water quality and biofilm formation
Khan et al. Biosorption of Lead by Rhizopus stolonifer Biomass: Role of Functional Groups
US20150014240A1 (en) Filter media for gravity filtration applications
Tien et al. Green Synthesis of Copper Nanoparticles Deposited on Polyester Filter for Antibacterial Applications

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

17P Request for examination filed

Effective date: 20000904

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN

18W Application withdrawn

Withdrawal date: 20021104